@article{sheoran_boland_thornton_bochinski_clarke_2023, title={Enhancing ionic conductivity in polymer melts results in smaller diameter electrospun fibers}, volume={123}, ISSN={["1077-3118"]}, url={https://doi.org/10.1063/5.0162384}, DOI={10.1063/5.0162384}, abstractNote={Chemically compatible additives were utilized to increase the ionic conductivity of polyethylene melts. When subjected to unconfined electrospinning, a predictable and significant decrease in the resultant fiber diameter with enhanced melt conductivity was observed. This generalized approach was confirmed for viscous melts, varying in conductivity over five orders of magnitude and viscosity 5×, from multiple commercial polyethylene formulations with various additives. These experimental results are connected to theory for the relevant length scales of capillary length, jet spacing, and jet radius. In particular, jet radius scales as conductivity to the −1/4 power. Fitting experimental fiber radius vs ionic conductivity data results in a similar power law exponent (−0.29). This trend, occurring at orders of magnitude higher viscosity and six orders of magnitude lower conductivity, is similar to results from needle-based, solution phase electrospinning, suggesting the generality of the effect. The connection between larger length scales, such as the distance between jets and the thickness of the film at the plate edge, and fluid properties (surface tension, viscosity, and conductivity) is also discussed.}, number={7}, journal={APPLIED PHYSICS LETTERS}, author={Sheoran, N. and Boland, B. and Thornton, S. and Bochinski, J. R. and Clarke, L. I.}, year={2023}, month={Aug} }
 @article{fontecha_mahn_bochinski_clarke_2022, title={Tracking the complete degradation lifecycle of poly(ethyl cyanoacrylate): From induced photoluminescence to nitrogen-doped nano-graphene precursor residue}, volume={195}, ISSN={["1873-2321"]}, DOI={10.1016/j.polymdegradstab.2021.109772}, abstractNote={Poly(ethyl cyanoacrylate) (PECA) is a commercial polymer which degrades easily at temperatures between 150 - 200 °C via an unzipping reaction where volatile monomer is produced. In this report, the complete moderate-temperature degradation lifecycle is delineated, which also includes formation of a carbonaceous by-product where the ester side groups are lost and ring formation between the backbone and cyano side group occurs. Degradation-induced photoluminescence is observed at an intermediate point where the remaining PECA (or re-polymerized oligomers) has sp3 carbons but sp2-carbon-containing clusters of the by-product that will ultimately form aromatic structures are also present. This observation supports the hypothesis that degradation-induced photoluminescence in polymers, which has been observed widely, is connected to the formation of such sp2 containing clusters, and that this process is relatively independent of the original polymer chemistry, as PECA dominantly degrades through a mechanism distinctly different than the thermo-oxidative cascade associated with many thermoplastic materials. As degradation further advances, a residue of approximately 8% of the original mass is produced which is no longer photoluminescent and can ultimately transform into nitrogen-substituted nano-graphene. Observing the entire lifecycle further solidifies the previously-proposed connection between degradation-induced luminescence in polymers and photoluminescence in hydrogenated amorphous carbon. The low degradation temperature of PECA also provides a bridge between classic polymer degradation and waste-to-graphene strategies that generally involve much more aggressive processing.}, journal={POLYMER DEGRADATION AND STABILITY}, author={Fontecha, Daniela and Mahn, Chelsea and Bochinski, Jason R. and Clarke, Laura I}, year={2022}, month={Jan} }
 @article{sheoran_boland_thornton_bochinski_clarke_2021, title={Increasing ionic conductivity within thermoplastics via commercial additives results in a dramatic decrease in fiber diameter from melt electrospinning}, volume={9}, ISSN={["1744-6848"]}, url={https://doi.org/10.1039/D1SM01101D}, DOI={10.1039/D1SM01101D}, abstractNote={Role of conductivity and viscosity in determining jet size and fiber diameter in melt electrospinning is explored by new data and application of theory. Increasing conductivity via an additive leads to a large fraction of sub-micron diameter fibers.}, journal={SOFT MATTER}, publisher={Royal Society of Chemistry (RSC)}, author={Sheoran, Neelam and Boland, Brent and Thornton, Samuel and Bochinski, Jason R. and Clarke, Laura I.}, year={2021}, month={Sep} }
 @article{huang_firestone_fontecha_gorga_bochinski_clarke_2020, title={Nanoparticle-based photothermal heating to drive chemical reactions within a solid: using inhomogeneous polymer degradation to manipulate mechanical properties and segregate carbonaceous by-products}, url={https://doi.org/10.1039/C9NR07401E}, DOI={10.1039/C9NR07401E}, abstractNote={Nanoparticle-based photothermal heating degrades polymer from the inside-out, creating pockets of depolymerized material around each nanoscale heating site.}, journal={Nanoscale}, publisher={Royal Society of Chemistry (RSC)}, author={Huang, Honglu and Firestone, Gabriel and Fontecha, Daniela and Gorga, Russell E. and Bochinski, Jason R. and Clarke, Laura I.}, year={2020} }
 @article{firestone_huang_bochinski_clarke_2019, title={Photothermally-driven thermo-oxidative degradation of low density polyethylene: heterogeneous heating plus a complex reaction leads to homogeneous chemistry}, volume={30}, url={https://doi.org/10.1088/1361-6528/ab3bc0}, DOI={10.1088/1361-6528/ab3bc0}, abstractNote={Photothermal heating from embedded nanoparticles, a process whereby visible light is converted into heat resulting in a high temperature in each particle’s immediate vicinity, was utilized to degrade low density polyethylene (LDPE) via thermo-oxidation. The spatially-varying steady-state photothermal temperature field is a potential mechanism by which ambient light (e.g. sunlight) could be used to drive chemical reactions within solid materials and may result in a non-uniform pattern of products, an advantage or disadvantage depending on application. Novel approaches to control polymer degradation are of interest because of the goal of remediating plastic waste, including autonomous means to minimize its effect when unconfined in the environment. For thermoplastic auto-oxidation, heterogeneous degradation would likely enhance deleterious micro-fragmentation however, the multi-step, multi-site nature of the reaction mitigated the temperature non-uniformity. A photothermally-heated LDPE nanocomposite with silver nanoparticle and cobalt-stearate additives showed degradation, characterized by ultraviolet–visible and Fourier-transform infrared absorption spectroscopy, electron microscopy, and mechanical testing, nearly identical to that resulting from uniform conventional treatment at the same average temperature.}, number={47}, journal={Nanotechnology}, publisher={IOP Publishing}, author={Firestone, Gabriel and Huang, Honglu and Bochinski, Jason R and Clarke, Laura I}, year={2019}, month={Sep}, pages={475706} }
 @article{firestone_bochinski_meth_clarke_2018, title={Facile measurement of surface heat loss from polymer thin films via fluorescence thermometry}, volume={56}, ISSN={["1099-0488"]}, DOI={10.1002/polb.24571}, abstractNote={ABSTRACT}, number={8}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Firestone, Gabriel and Bochinski, Jason R. and Meth, Jeffrey S. and Clarke, Laura I.}, year={2018}, month={Apr}, pages={643–651} }
 @article{dong_firestone_bochinski_clarke_gorga_2017, title={In situcuring of liquid epoxy via gold-nanoparticle mediated photothermal heating}, volume={28}, DOI={10.1088/1361-6528/aa521b}, abstractNote={Metal nanoparticles incorporated at low concentration into epoxy systems enable in situ curing via photothermal heating. In the process of nanoparticle-mediated photothermal heating, light interacts specifically with particles embedded within a liquid or solid material and this energy is transformed into heat, resulting in significant temperature increase local to each particle with minimal warming of surroundings. The ability to use such internal heating to transform the mechanical properties of a material (e.g., from liquid to rigid solid) without application of damaging heat to the surrounding environment represents a powerful tool for a variety of scientific applications, particularly within the biomedical sector. Uniform particle dispersion is achieved by placing the nanoparticles within solvent miscible with the desired epoxy resin, demonstrating a strategy utilizable for a wide range of materials without requiring chemical modification of the particles or epoxy. Mechanical and thermal properties (storage modulus, Tg, and degradation behavior) of the cured epoxy are equivalent to those obtained under traditional heating methods. Selective curing of a shape is demonstrated within a liquid bath of epoxy, where the solid form is generated by rastering a spatially confined, photothermal-driving light beam. The non-irradiated regions are largely unaffected and the solid part is easily removed from the remaining liquid. Temperature profiles showing minimal heating outside the irradiated zone are presented and discussed.}, number={6}, journal={Nanotechnology}, publisher={IOP Publishing}, author={Dong, Ju and Firestone, Gabriel E and Bochinski, J R and Clarke, L I and Gorga, R E}, year={2017}, month={Jan}, pages={065601} }
 @article{maity_wu_tracy_clarke_bochinski_2017, title={Nanoscale steady-state temperature gradients within polymer nanocomposites undergoing continuous-wave photothermal heating from gold nanorods}, volume={9}, ISSN={["2040-3372"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000407812000028&KeyUID=WOS:000407812000028}, DOI={10.1039/c7nr04613h}, abstractNote={Anisotropically-shaped metal nanoparticles act as nanoscale heaters via excitation of a localized surface plasmon resonance, utilizing a photothermal effect which converts the optical energy into local heat.}, number={32}, journal={NANOSCALE}, publisher={Royal Society of Chemistry (RSC)}, author={Maity, Somsubhra and Wu, Wei-Chen and Tracy, Joseph B. and Clarke, Laura I. and Bochinski, Jason R.}, year={2017}, month={Aug}, pages={11605–11618} }
 @article{bao_clarke_gorga_2016, title={Effect of Constrained Annealing on the Mechanical Properties of Electrospun Poly(ethylene oxide) Webs Containing Multiwalled Carbon Nanotubes}, volume={54}, ISSN={["1099-0488"]}, DOI={10.1002/polb.23960}, abstractNote={ABSTRACT}, number={8}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Bao, Jiaxing and Clarke, Laura I. and Gorga, Russell E.}, year={2016}, month={Apr}, pages={787–796} }
 @article{viswanath_maity_bochinski_clarke_gorga_2016, title={Enhanced Crystallinity of Polymer Nanofibers without Loss of Nanofibrous Morphology via Heterogeneous Photothermal Annealing}, volume={49}, ISSN={["1520-5835"]}, DOI={10.1021/acs.macromol.6b01655}, abstractNote={Poly(ethylene oxide) electrospun nanofibers with a low concentration of embedded gold nanoparticles (AuNP) were subjected to postfabrication annealing via photothermal heating from the nanoparticles. The results, including nanofibrous mat morphology, crystallinity fraction as a function of annealing time and modality, and average crystallite size, were compared with that for conventional heating at the same average temperature. Maximum crystallinity is achieved more quickly under photothermal heating, and higher maximum crystallinity values, approaching the theoretical maxima for an entangled polymer (∼80%), are obtained. Photothermal heating better preserves the unique nanostructured morphology of the nanofibrous mat whereas significant fiber thickening and loss of porosity occur under conventional annealing treatment. With photothermal heating, heat may be predominantly applied within amorphous material within the fiber, which provides energy for the amorphous chains to reorient and then possibly crysta...}, number={24}, journal={MACROMOLECULES}, author={Viswanath, Vidya and Maity, Somsubhra and Bochinski, Jason R. and Clarke, Laura I. and Gorga, Russell E.}, year={2016}, month={Dec}, pages={9484–9492} }
 @article{abbott_maity_burkey_gorga_bochinski_clarke_2014, title={Blending with Non-responsive Polymers to Incorporate Nanoparticles into Shape-Memory Materials and Enable Photothermal Heating: The Effects of Heterogeneous Temperature Distribution}, volume={215}, ISSN={["1521-3935"]}, DOI={10.1002/macp.201400386}, abstractNote={Blending a shape‐memory polymer (SMP) (e.g., thermoplastic polyurethane) with an immiscible carrier polymer (e.g., poly(ethylene oxide) (PEO) or poly(vinyl alcohol) (PVA)) containing dispersed metal nanoparticles (AuNPs) is a simple approach to enable actuation via photothermal heating. For blends containing up to 90% carrier polymer, the shape‐memory capability can be thermally triggered either conventionally or utilizing internal heating via application of light that is resonant with the particle's surface plasmon resonance. When incorporating nanoparticles in this manner, neither chemical modification of the shape‐memory moiety nor solvation of the SMP is necessary. Actuation times are determined by the particular heterogeneous temperature distribution, which generally occurs under both conventional and photothermal heating methods, but with different spatial patterns. Blending an SMP with PEO containing AuNPs imposes a higher transition temperature (the melting point of PEO), enabling heat generated within the nanoparticle‐containing regions to equilibrate throughout the sample, resulting in performance under photothermal conditions comparable with that achieved in a conventional heating approach. SMP:PVA blends actuate at the SMP transition temperature and the response depends on the size of phase segregation between the PVA and SMP; when decreasing the characteristic size of the segregated regions, heat is efficiently transferred and optimal photothermal performance is observed.
image}, number={23}, journal={MACROMOLECULAR CHEMISTRY AND PHYSICS}, author={Abbott, David B. and Maity, Somsubhra and Burkey, Mary T. and Gorga, Russell E. and Bochinski, Jason R. and Clarke, Laura I.}, year={2014}, month={Dec}, pages={2345–2356} }
 @article{thoppey_gorga_clarke_bochinski_2014, title={Control of the electric field-polymer solution interaction by utilizing ultra-conductive fluids}, volume={55}, ISSN={["1873-2291"]}, DOI={10.1016/j.polymer.2014.10.007}, abstractNote={Dramatically raising the conductivity of a polymer solution by using a salt additive allows control over the electric field-induced jet feed rate when electrospinning from an unconfined fluid without altering the applied voltage. As the solution conductivity increases, the flow rate drops by an order of magnitude. At a high voltage level and fluid conductivity value, the jets undergo a whipping instability over almost the entire path from the source to the collector experiencing only a negligibly short linear region which, along with the flow rate data, indicates that the jet narrows due to the high conductivity. Under these conditions, even while possessing relatively large individual jet feed rates, thin diameter nanofibers (200–300 nm) are readily produced. In contrast with other approaches to obtain narrow fibers from unconfined fluids (e.g., voltage reduction to control feed rate), here the fiber forming jets are present indefinitely. Continuous, scaled up nanofiber production rate of >125× over the traditional single needle electrospinning method is observed from the presence of multiple jets, each possessing a relatively high solution feed rate. These fundamental experiments reveal new pathways for exploring novel electrospinning configurations where the jet feed rate can be controlled by manipulating the solution conductivity.}, number={24}, journal={POLYMER}, author={Thoppey, N. M. and Gorga, R. E. and Clarke, L. I. and Bochinski, J. R.}, year={2014}, month={Nov}, pages={6390–6398} }
 @article{maity_wu_xu_tracy_gundogdu_bochinski_clarke_2014, title={Spatial temperature mapping within polymer nanocomposites undergoing ultrafast photothermal heating via gold nanorods}, volume={6}, ISSN={["2040-3372"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000345458200080&KeyUID=WOS:000345458200080}, DOI={10.1039/c4nr05179c}, abstractNote={Polarized fluorescence temperature measurements combined with direct detection of nanorod rotation within the polymer melt regions reveal the steady-state temperature gradient on the nanoscale.}, number={24}, journal={NANOSCALE}, author={Maity, Somsubhra and Wu, Wei-Chen and Xu, Chao and Tracy, Joseph B. and Gundogdu, Kenan and Bochinski, Jason R. and Clarke, Laura I.}, year={2014}, pages={15236–15247} }
 @article{wang_curtis_thoppey_bochinski_gorga_clarke_2014, title={Unconfined, melt edge electrospinning from multiple, spontaneous, self-organized polymer jets}, volume={1}, DOI={10.1088/2053-1591/1/4/045304}, abstractNote={Commercial grade polyethylene is melt electrospun from a thin film of unconfined molten polymer on a heated, electrically-grounded plate. Under the influence of an applied electric field, the melt spontaneously forms fingering perturbations at the plate edge which then evolve into emitting fiber-forming jets. Jet-to-jet spacing (∼5 mm), which is dependent on the applied voltage amplitude, is in agreement with estimates from a simple theoretical treatment. The broad applicability of the approach is verified by spinning a second polymer—polycaprolactone. In both cases, the fabricated fibers are similar in quality to those obtained under needle melt electrospinning; however for this method, there are no nozzles to clog and an enhanced production rate up to 80 mg min−1 is achieved from approximately 20–25 simultaneous parallel jets. The process of jet formation, effective flow rates, cone-jet diameters, as well as limits on jet density and differences with polymer type are compared with theoretical models. This particular approach allows facile, high throughput micro- and nano-fiber formation from a wide variety of thermoplastics and other high viscosity fluids without the use of solvents or the persistent issues of clogging and pumping that hamper traditional methods, resulting in mechanically strong meso-scale fibers highly desirable for industrial applications.}, number={4}, journal={Materials Research Express}, publisher={IOP Publishing}, author={Wang, Qingqing and Curtis, Colin K and Thoppey, Nagarajan Muthuraman and Bochinski, Jason R and Gorga, Russell E and Clarke, Laura I}, year={2014}, month={Nov}, pages={045304} }
 @article{maity_kozek_wu_tracy_bochinski_clarke_2013, title={Anisotropic Thermal Processing of Polymer Nanocomposites via the Photothermal Effect of Gold Nanorods}, volume={30}, ISSN={["1521-4117"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000315360400010&KeyUID=WOS:000315360400010}, DOI={10.1002/ppsc.201200084}, abstractNote={By embedding metal nanoparticles within polymeric materials, selective thermal polymer processing can be accomplished via irradiation with light resonant with the nanoparticle surface plasmon resonance due to the photothermal effect of the nanoparticles which efficiently transforms light into heat. The wavelength and polarization sensitivity of photothermal heating from embedded gold nanorods is used to selectively process a collection of polymeric nanofibers, completely melting those fibers lying along a chosen direction while leaving the remaining material largely unheated and unaffected. Fluorescence‐based temperature and viscosity sensing was employed to confirm the presence of heating and melting in selected fibers and its absence in counter‐aligned fibers. Such tunable specificity in processing a subset of a sample, while the remainder is unchanged, cannot easily be achieved through conventional heating techniques.}, number={2}, journal={PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION}, author={Maity, Somsubhra and Kozek, Krystian A. and Wu, Wei-Chen and Tracy, Joseph B. and Bochinski, Jason R. and Clarke, Laura I.}, year={2013}, month={Feb}, pages={193–202} }
 @article{roman_thoppey_gorga_bochinski_clarke_2013, title={Maximizing Spontaneous Jet Density and Nanofiber Quality in Unconfined Electrospinning: The Role of Interjet Interactions}, volume={46}, ISSN={["1520-5835"]}, DOI={10.1021/ma4013253}, abstractNote={The interplay between an applied electric field and fluid properties was studied for a polymer solution forming high quality nanofibers via electrospinning. Unconfined electrospinning—in which a fluid thin film or bath exposed to an electric field spontaneously generates many parallel fiber-forming jets—is a practical approach to achieving a high fabrication rate of quality nanofibers as compared to traditional single-needle electrospinning. The density of fiber-forming jets is controlled by surface tension effects at the lowest applied voltages but by jet-to-jet interactions as the voltage amplitude is increased, resulting in an intermediate operating voltage level at which jet number is maximized. This general result is applicable to electric-field-driven fluid instabilities in a wide range of systems. The optimal voltage level occurs when interjet interactions begin to solely determine the characteristic jet spacing, and in this regime, compression of the cone-jet slightly chokes the feed rate, allowin...}, number={18}, journal={MACROMOLECULES}, author={Roman, Michael P. and Thoppey, Nagarajan M. and Gorga, Russell E. and Bochinski, Jason R. and Clarke, Laura I.}, year={2013}, month={Sep}, pages={7352–7362} }
 @article{viswanath_maity_bochinski_clarke_gorga_2013, title={Thermal Annealing of Polymer Nanocomposites via Photothermal Heating: Effects on Crystallinity and Spherulite Morphology}, volume={46}, ISSN={["1520-5835"]}, DOI={10.1021/ma401855v}, abstractNote={Metal nanoparticles embedded within polymeric systems can act as localized heat sources, facilitating in situ polymer processing. When irradiated with light resonant with the nanoparticle’s surface plasmon resonance (SPR), a nonequilibrium electron distribution is generated which rapidly transfers energy into the surrounding medium, resulting in a temperature increase in the immediate region around the particle. This work compares the utility of such photothermal heating versus traditional heating in gold nanoparticle/poly(ethylene oxide) nanocomposite films, crystallized from solution and the melt, which are annealed at average sample temperatures above the glass transition and below the melting point. For all temperatures, photothermally annealed samples reached maximum crystallinity and maximum spherulite size faster. Percentage crystallinity change under conventional annealing was analyzed using time–temperature superposition (TTS). Comparison of the TTS data with results from photothermal experiments...}, number={21}, journal={MACROMOLECULES}, author={Viswanath, Vidya and Maity, Somsubhra and Bochinski, Jason R. and Clarke, Laura I. and Gorga, Russell E.}, year={2013}, month={Nov}, pages={8596–8607} }
 @article{thoppey_gorga_bochinski_clarke_2012, title={Effect of Solution Parameters on Spontaneous Jet Formation and Throughput in Edge Electrospinning from a Fluid-Filled Bowl}, volume={45}, ISSN={["1520-5835"]}, DOI={10.1021/ma301207t}, abstractNote={The process of edge electrospinning relies on forming electric-field-induced instabilities (i.e., jets) in a polymer solution bath which act as sources for nanofiber production. As such, it depends...}, number={16}, journal={MACROMOLECULES}, author={Thoppey, Nagarajan M. and Gorga, Russell E. and Bochinski, Jason R. and Clarke, Laura I.}, year={2012}, month={Aug}, pages={6527–6537} }
 @article{maity_bochinski_clarke_2012, title={Metal Nanoparticles Acting as Light-Activated Heating Elements within Composite Materials}, volume={22}, DOI={10.1002/adfm.201201051}, abstractNote={Abstract}, number={24}, journal={Advanced Functional Materials}, publisher={Wiley}, author={Maity, Somsubhra and Bochinski, Jason R. and Clarke, Laura I.}, year={2012}, month={Aug}, pages={5259–5270} }
 @article{thoppey_bochinski_clarke_gorga_2011, title={Edge electrospinning for high throughput production of quality nanofibers}, volume={22}, ISSN={["1361-6528"]}, DOI={10.1088/0957-4484/22/34/345301}, abstractNote={A novel, simple geometry for high throughput electrospinning from a bowl edge is presented that utilizes a vessel filled with a polymer solution and a concentric cylindrical collector. Successful fiber formation is presented for two different polymer systems with differing solution viscosity and solvent volatility. The process of jet initiation, resultant fiber morphology and fiber production rate are discussed for this unconfined feed approach. Under high voltage initiation, the jets spontaneously form directly on the fluid surface and rearrange along the circumference of the bowl to provide approximately equal spacing between spinning sites. Nanofibers currently produced from bowl electrospinning are identical in quality to those fabricated by traditional needle electrospinning (TNE) with a demonstrated ∼ 40 times increase in the production rate for a single batch of solution due primarily to the presence of many simultaneous jets. In the bowl electrospinning geometry, the electric field pattern and subsequent effective feed rate are very similar to those parameters found under optimized TNE experiments. Consequently, the electrospinning process per jet is directly analogous to that in TNE and thereby results in the same quality of nanofibers.}, number={34}, journal={NANOTECHNOLOGY}, author={Thoppey, N. M. and Bochinski, J. R. and Clarke, L. I. and Gorga, R. E.}, year={2011}, month={Aug} }
 @article{maity_downen_bochinski_clarke_2011, title={Embedded metal nanoparticles as localized heat sources: An alternative processing approach for complex polymeric materials}, volume={52}, ISSN={["1873-2291"]}, DOI={10.1016/j.polymer.2011.01.062}, abstractNote={Metal nanoparticles were utilized as heating elements within nanofibers to demonstrate an alternative approach to thermally process nanostructured polymeric materials. In the photothermal process, resonant light excites the surface plasmon of the nanoparticle and the absorbed energy is converted into heat due to electron-phonon collisions. This heating is efficient and strongly localized, generated from the nanometer-sized metal particles embedded within the polymer. Composite polyethylene oxide (PEO) nanofibers, containing differing concentrations and types of nanoparticles, were fabricated by electrospinning and irradiated by a low intensity laser tuned specifically to the metal nanoparticle surface plasmon absorbance; aggregation of fibers, loss of fibrous structure, and ultimately, complete melting were observed. The photothermal response to irradiation increased with nanoparticle concentration as long as particle aggregation was avoided. Pure PEO nanofibers, or those containing metal nanoparticles possessing a non-resonant surface plasmon, were also irradiated but no melting occurred, demonstrating the controllable specificity of this approach.}, number={7}, journal={POLYMER}, author={Maity, Somsubhra and Downen, Lori N. and Bochinski, Jason R. and Clarke, Laura I.}, year={2011}, month={Mar}, pages={1674–1685} }
 @article{stevens_skau_downen_roman_clarke_2011, title={Finite-size effects in nanocomposite thin films and fibers}, volume={84}, ISSN={["1550-2376"]}, DOI={10.1103/physreve.84.021126}, abstractNote={Monte Carlo simulations of finite-size effects for continuum percolation in three-dimensional, rectangular sample spaces filled with spherical particles were performed. For samples with any dimension less than 10-20 times the particle diameter, finite-size effects were observed. For thin films in the finite-size regime, percolation across the thin direction of the film gave critical volume fraction (p(c)) values that differed from those along the plane of the film. Simulations perpendicular to the film for very thin samples resulted in p(c) values lower than the classical limit of ∼29% (for spheres in a three-dimensional matrix) which increased with film thickness. For percolation along thin films, while holding film thickness constant, p(c) increased with increasing sample size, which is a modification of the finite-sized scaling effect for cubic samples. For samples with a large aspect ratio (fibers) and a finite-sized cross-sectional area, the critical volume fraction increased with sample length, as the sample became quasi-one-dimensional. The results are discussed in the context of adding volume along or perpendicular to the percolation direction. From an experimental perspective, these findings indicate that sample shape, as well as relative size, influences percolation in the finite-size regime.}, number={2}, journal={PHYSICAL REVIEW E}, author={Stevens, D. R. and Skau, E. W. and Downen, L. N. and Roman, M. P. and Clarke, L. I.}, year={2011}, month={Aug} }
 @article{ramaswamy_clarke_gorga_2011, title={Morphological, mechanical, and electrical properties as a function of thermal bonding in electrospun nanocomposites}, volume={52}, ISSN={["1873-2291"]}, DOI={10.1016/j.polymer.2011.05.023}, abstractNote={Poly lactic acid (PLA) was electrospun with various concentrations of multi-wall carbon nanotubes (MWNT) and thermal bonding was utilized as a post-processing treatment to improve the mechanical and electrical properties of the nanofibrous mats. Thermally bonded fiber–fiber junctions were observed with scanning electron microscopy. An increase in either the strength or modulus of the PLA mats both with and without MWNTs was observed; the maximum modulus and maximum strength occur at different treatment conditions. The electrical conductivity of the MWNT loaded mats showed significant improvement after treatment just below the composite melting point.}, number={14}, journal={POLYMER}, author={Ramaswamy, Sangeetha and Clarke, Laura I. and Gorga, Russell E.}, year={2011}, month={Jun}, pages={3183–3189} }
 @article{hutchison_brown_mooster_reed_schmidt_clarke_wybourne_2011, title={Nanoscale Patterns of Metal Nanoparticles Chemically-Assembled on Biomolecular Scaffolds: Assembly, Stability and Electron Transport Properties}, volume={582}, DOI={10.1557/proc-582-h11.1}, abstractNote={ABSTRACT}, journal={MRS Proceedings}, publisher={Cambridge University Press (CUP)}, author={Hutchison, James E. and Brown, Leif O. and Mooster, Jana L. and Reed, Scott M. and Schmidt, Mary E. and Clarke, Laura I. and Wybourne, Martin N.}, year={2011}, month={Mar} }
 @article{wybourne_clarke_berven_hutchison_brown_mooster_2011, title={Room Temperature Single Electron Charging in Gold Nanoparticle Networks Formed on Biopolymer Templates}, volume={582}, DOI={10.1557/proc-582-h13.4}, abstractNote={ABSTRACT}, journal={MRS Proceedings}, publisher={Cambridge University Press (CUP)}, author={Wybourne, M.N. and Clarke, L. and Berven, C.A. and Hutchison, J.E. and Brown, L.O. and Mooster, J.L.}, year={2011}, month={Mar} }
 @article{mccullen_mcquilling_grossfeld_lubischer_clarke_loboa_2010, title={Application of Low-Frequency Alternating Current Electric Fields Via Interdigitated Electrodes: Effects on Cellular Viability, Cytoplasmic Calcium, and Osteogenic Differentiation of Human Adipose-Derived Stem Cells}, volume={16}, ISSN={["1937-3392"]}, url={https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/20367249/?tool=EBI}, DOI={10.1089/ten.tec.2009.0751}, abstractNote={Electric stimulation is known to initiate signaling pathways and provides a technique to enhance osteogenic differentiation of stem and/or progenitor cells. There are a variety of in vitro stimulation devices to apply electric fields to such cells. Herein, we describe and highlight the use of interdigitated electrodes to characterize signaling pathways and the effect of electric fields on the proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs). The advantage of the interdigitated electrode configuration is that cells can be easily imaged during short-term (acute) stimulation, and this identical configuration can be utilized for long-term (chronic) studies. Acute exposure of hASCs to alternating current (AC) sinusoidal electric fields of 1 Hz induced a dose-dependent increase in cytoplasmic calcium in response to electric field magnitude, as observed by fluorescence microscopy. hASCs that were chronically exposed to AC electric field treatment of 1 V/cm (4 h/day for 14 days, cultured in the osteogenic differentiation medium containing dexamethasone, ascorbic acid, and β-glycerol phosphate) displayed a significant increase in mineral deposition relative to unstimulated controls. This is the first study to evaluate the effects of sinusoidal AC electric fields on hASCs and to demonstrate that acute and chronic electric field exposure can significantly increase intracellular calcium signaling and the deposition of accreted calcium under osteogenic stimulation, respectively.}, number={6}, journal={TISSUE ENGINEERING PART C-METHODS}, author={McCullen, Seth D. and McQuilling, John P. and Grossfeld, Robert M. and Lubischer, Jane L. and Clarke, Laura I. and Loboa, Elizabeth G.}, year={2010}, month={Dec}, pages={1377–1386} }
 @article{crowe-willoughby_stevens_genzer_clarke_2010, title={Investigating the Molecular Origins of Responsiveness in Functional Silicone Elastomer Networks}, volume={43}, ISSN={["1520-5835"]}, DOI={10.1021/ma100470w}, abstractNote={Dielectric, calorimetric, and dynamic mechanical measurements were performed to delineate the types and dynamic rates of molecular scale motion in modified poly(vinylmethyl siloxane) (PVMS) stimuli-responsive networks, where pendent groups of the form -S-(CH2)n-OH were chemically attached to the vinyl moiety of PVMS. The glass transition temperature (Tg) for the unsubstituted PVMS network matches that previously reported for linear PVMS indicating that the flexibility of the polymer chains is unaffected by the network cross-linking. In contrast, Tg increases with the introduction of pendent groups of the type -S-(CH2)n-CH3 or -S-(CH2)n-OH, where n is 2, 6, or 11, as the different groups constrain the siloxane backbone to differing degrees. The macroscopic response time and amplitude, as previously measured bydynamic contactangle,arecorrelated withtheobservedglass transition temperatures. Onecon- clusion is that the flexibility of the network and the interactions between pendent groups affect responsiveness.}, number={11}, journal={MACROMOLECULES}, author={Crowe-Willoughby, Julie A. and Stevens, Derrick R. and Genzer, Jan and Clarke, Laura I.}, year={2010}, month={Jun}, pages={5043–5051} }
 @article{thoppey_bochinski_clarke_gorga_2010, title={Unconfined fluid electrospun into high quality nanofibers from a plate edge}, volume={51}, ISSN={["0032-3861"]}, DOI={10.1016/j.polymer.2010.07.046}, abstractNote={We demonstrate an easily-implemented, edge-plate geometry for electrospinning and produce high quality nanofibers from unconfined polymer fluids. We show that for electrospinning in general, the electric field gradient, not just the electric field amplitude, is a critical parameter for successful self-initiated jetting. Considering a single spinning site, the edge-plate configuration resulted in the same or a higher fabrication rate as traditional needle electrospinning, while producing nanofibers similar in quality (diameter, diameter distribution, and collected mat porosity); moreover, this novel configuration operates without the possibility of clogging and has high potential for scale-up. We analyze the fundamental physical processes which underlie edge-plate electrospinning, including electric field, working distance, and feed rate dependence and the resultant changes to the linear and whipping regions, and thus to the fiber diameter. We conclude that the edge-plate configuration functions in a remarkably similar manner to traditional needle electrospinning.}, number={21}, journal={POLYMER}, author={Thoppey, Nagarajan Muthuraman and Bochinski, Jason R. and Clarke, Laura I. and Gorga, Russell E.}, year={2010}, month={Oct}, pages={4928–4936} }
 @article{garland_lee_baer_clarke_2009, title={Growth Dynamics and Morphology of Oleic Acid Vapor-Deposited on a Silica Surface}, volume={113}, ISSN={["1932-7447"]}, DOI={10.1021/jp8068514}, abstractNote={The vapor deposition of oleic acid onto silica surfaces at 25% relative humidity and temperatures ranging from 60 to 80 °C is found to proceed in three stages: (I) rapid formation of monolayer-high islands of approximately 100 nm diameter on timescales of a few minutes; (II) relatively little growth over timescales of tens to hundreds of minutes; and (III) a linear increase in apparent thickness as a function of time, characterized by the formation of multilayer islands on time scales of thousands of minutes. The rate of growth in region III is faster at higher temperatures. This growth process is analyzed in the context of the transition from two-dimensional to three-dimensional island growth at submonolayer coverage observed for metal vapor deposition on oxide surfaces. At a relative humidity of 94%, with several layers of water molecules present on the silica surface, the oleic acid wets the surface rather than forming discrete islands.}, number={6}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Garland, Eva R. and Lee, Amy D. and Baer, Tomas and Clarke, Laura I.}, year={2009}, month={Feb}, pages={2141–2148} }
 @article{mccullen_ramaswamy_clarke_gorga_2009, title={Nanofibrous composites for tissue engineering applications}, volume={1}, ISSN={1939-5116}, url={http://dx.doi.org/10.1002/wnan.39}, DOI={10.1002/wnan.39}, abstractNote={Abstract}, number={4}, journal={Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology}, publisher={Wiley}, author={McCullen, Seth D. and Ramaswamy, Sangeetha and Clarke, Laura I. and Gorga, Russell E.}, year={2009}, month={May}, pages={369–390} }
 @article{ojha_stevens_stano_hoffman_clarke_gorga_2008, title={Characterization of electrical and mechanical properties for coaxial nanofibers with poly(ethylene oxide) (PEO) core and multiwalled carbon nanotube/PEO sheath}, volume={41}, ISSN={["1520-5835"]}, DOI={10.1021/ma702634a}, abstractNote={The present work focuses on the electrical and mechanical characterization of nanocomposite fibers having core−sheath (or bicomponent) morphologies. Owing to their unique mechanical and electrical properties, multiwalled carbon nanotubes (MWNTs) have been utilized in the nanocomposite construction. Submicron diameter nanofibers (200–300 nm) with core−sheath morphology were fabricated from a polymer/MWNT solution and collected in random mats. By constraining the MWNTs to the sheath, significant increases in the mechanical properties were observed at lower MWNT concentrations when compared to mats made from single-layer fibers. The electrical properties of the core−sheath mats showed similar gains, having a critical weight percent more than 10 times lower than that of the single-layer mats.}, number={7}, journal={MACROMOLECULES}, author={Ojha, Satyajeet S. and Stevens, Derrick R. and Stano, Kelly and Hoffman, Torissa and Clarke, Laura I. and Gorga, Russell E.}, year={2008}, month={Apr}, pages={2509–2513} }
 @article{scott_stevens_bochinski_clarke_2008, title={Dynamics within Alkylsiloxane Self-Assembled Monolayers Studied by Sensitive Dielectric Spectroscopy}, volume={2}, ISSN={["1936-0851"]}, DOI={10.1021/nn800543j}, abstractNote={Self-assembled monolayers are a ubiquitous laboratory tool and have been the subject of many experimental investigations which have primarily focused on static properties of full coverage monolayers, with the maximum density and ordering possible. In this work, dynamics within low density, planar siloxane self-assembled monolayers are studied utilizing highly sensitive dielectric spectroscopy. Dilute, disordered films were intentionally fabricated in order to study the widest range of possible motions. At low coverage, an interacting relaxation is observed, which has similar dynamics to polyethylene-like glass transitions observed in phase-segregated side-chain polymers, despite the rigidity of the substrate and the constraint of ethyl groups in relatively short chains. As density is increased, a second local relaxation, previously observed in three-dimensional SAMs and associated with rotation within a small segment of the alkyl chain, is also observed.}, number={11}, journal={ACS NANO}, author={Scott, Mary C. and Stevens, Derrick R. and Bochinski, Jason R. and Clarke, Laura I.}, year={2008}, month={Nov}, pages={2392–2400} }
 @article{ojha_stevens_hoffman_stano_klossner_scott_krause_clarke_gorga_2008, title={Fabrication and characterization of electrospun chitosan nanofibers formed via templating with polyethylene oxide}, volume={9}, ISSN={["1526-4602"]}, DOI={10.1021/bm800551q}, abstractNote={Chitosan is an abundantly common, naturally occurring, polysaccharide biopolymer. Its biocompatible, biodegradable, and antimicrobial properties have led to significant research toward biological applications such as drug delivery, artificial tissue scaffolds for functional tissue engineering, and wound-healing dressings. For applications such as tissue scaffolding, formation of highly porous mats of nanometer-sized fibers, such as those fabricated via electrospinning, may be quite important. Previously, strong acidic solvents and blending with synthetic polymers have been used to achieve electrospun nanofibers containing chitosan. As an alternative approach, in this work, polyethylene oxide (PEO) has been used as a template to fabricate chitosan nanofibers by electrospinning in a core-sheath geometry, with the PEO sheath serving as a template for the chitosan core. Solutions of 3 wt % chitosan (in acetic acid) and 4 wt % PEO (in water) were found to have matching rheological properties that enabled efficient core-sheath fiber formation. After removing the PEO sheath by washing with deionized water, chitosan nanofibers were obtained. Electron microscopy confirmed nanofibers of approximately 250 nm diameter with a clear core-sheath geometry before sheath removal, and chitosan nanofibers of approximately 100 nm diameter after washing. The resultant fibers were characterized with IR spectroscopy and X-ray diffraction, and the mechanical and electrical properties were evaluated.}, number={9}, journal={BIOMACROMOLECULES}, author={Ojha, Satyajeet S. and Stevens, Derrick R. and Hoffman, Torissa J. and Stano, Kelly and Klossner, Rebecca and Scott, Mary C. and Krause, Wendy and Clarke, Laura I. and Gorga, Russell E.}, year={2008}, month={Sep}, pages={2523–2529} }
 @article{stevens_downen_clarke_2008, title={Percolation in nanocomposites with complex geometries: Experimental and Monte Carlo simulation studies}, volume={78}, ISSN={["2469-9969"]}, DOI={10.1103/physrevb.78.235425}, abstractNote={The development of nanocomposites (a matrix, often polymeric, enhanced by a particle with a nanometer-sized dimension) has expanded dramatically in recent years with a particular focus on materials with complex microstructure and nanostructure. Such composites rely on formation of a connected network of particles throughout the sample volume in order to enhance the polymer's mechanical and electrical properties. From a fundamental perspective, this network formation will be governed by a percolation process within the constrained geometry of the particular microstructure. In this paper, the percolation process within a particular complex nanostructure, namely, a mat of electrospun nanofibers with fiber size of $\ensuremath{\approx}100\text{ }\text{nm}$ and high porosity, is studied via continuum Monte Carlo simulations, where the sample geometry (fiber and particle sizes, orientation, and sample porosity) is matched to the mats utilized in our previous experimental work. A good agreement between experimental and computational results is observed. Simulations of spherical dopant in uniform samples, with zero, one, or two sample dimensions similar in size to the particle, were completed to explore the effects of confinement, in particular within a single fiber. These results were compared and contrasted with those from porous fibrous mats to determine the influence of porosity on the critical volume fraction. The results indicate that percolation in fibrous mats occurs via pathways that include sections of many fibers rather than being contained within single fibers which span the sample. The detailed dependence of critical volume fraction on porosity and the sensitivity to fiber number and width is discussed.}, number={23}, journal={PHYSICAL REVIEW B}, author={Stevens, D. R. and Downen, L. N. and Clarke, L. I.}, year={2008}, month={Dec} }
 @article{garland_rosen_clarke_baer_2008, title={Structure of submonolayer oleic acid coverages on inorganic aerosol particles: evidence of island formation}, volume={10}, ISSN={["1463-9084"]}, DOI={10.1039/b718013f}, abstractNote={A series of submonolayer deposition studies of oleic acid on both hydrophobic and hydrophilic surfaces has shown that oleic acid self-associates into islands rather than uniformly covering the surfaces. The studies were performed by vapor deposition on 1.6 mum diameter polystyrene aerosol particles as well as on polystyrene and silica surfaces. The surfaces were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), ellipsometry and contact-angle goniometry. After timescales of minutes to hours of vapor deposition at 70 degrees C, the oleic acid arranged itself in the form of islands with diameters of about 100 nm. Many of the islands are 25-30 A high, suggesting that the oleic acid sits vertically on the surface. The surface structure of oleic acid on particles is expected to impact on several atmospherically relevant properties such as the reactivity of the oleic acid and the hygroscopicity of the particles.}, number={21}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, author={Garland, Eva R. and Rosen, Elias P. and Clarke, Laura I. and Baer, Tomas}, year={2008}, pages={3156–3161} }
 @article{mccullen_stevens_roberts_clarke_bernacki_gorga_loboa_2007, title={Characterization of electrospun nanocomposite scaffolds and biocompatibility with adipose-derived human mesenchymal stem cells}, volume={2}, number={2}, journal={International Journal of Nanomedicine}, author={McCullen, S. D. and Stevens, D. R. and Roberts, W. A. and Clarke, L. I. and Bernacki, S. H. and Gorga, R. E. and Loboa, E. G.}, year={2007}, pages={253–263} }
 @article{mccullen_stano_stevens_roberts_monteiro-riviere_clarke_gorga_2007, title={Development, optimization, and characterization of electrospun poly(lactic acid) nanofibers containing multi-walled carbon nanotubes}, volume={105}, ISSN={["1097-4628"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000247576000079&KeyUID=WOS:000247576000079}, DOI={10.1002/app.26288}, abstractNote={Abstract}, number={3}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={McCullen, Seth D. and Stano, Kelly L. and Stevens, Derrick R. and Roberts, Wesley A. and Monteiro-Riviere, Nancy A. and Clarke, Laura I. and Gorga, Russell E.}, year={2007}, month={Aug}, pages={1668–1678} }
 @article{mccullen_stevens_roberts_ojha_clarke_gorga_2007, title={Morphological, electrical, and mechanical characterization of electrospun nanofiber mats containing multiwalled carbon nanotubes}, volume={40}, ISSN={["1520-5835"]}, DOI={10.1021/ma061735c}, abstractNote={This work focuses on the development of electrically conducting porous nanocomposite structures by the incorporation of multiwalled carbon nanotubes (MWNT) into electrospun poly(ethylene oxide) (PEO) nanofibers. Electron microscopy confirmed the presence of individual aligned MWNT encapsulated within the fibers and showed fiber morphologies with diameters of 100−200 nm. Electrical conductance measurements of the random nanofiber mats showed that by increasing the concentration of MWNT we were able to produce porous nanocomposite structures with dramatically improved electrical conductivity. Above a percolation threshold of 0.365 ± 0.09 MWNT weight percent (wt %) in PEO the conductance increased by a factor of 1012 and then became approximately constant as the concentration of MWNT was further increased. Because of this percolation threshold, for a 1 wt % loading of MWNT, the conductivity is essentially maximized. Mechanical testing confirmed that the tensile strength did not change, and there was a 3-fold...}, number={4}, journal={MACROMOLECULES}, author={McCullen, Seth D. and Stevens, Derrick R. and Roberts, Wesley A. and Ojha, Satyajeet S. and Clarke, Laura I. and Gorga, Russell E.}, year={2007}, month={Feb}, pages={997–1003} }
 @article{horansky_clarke_winston_price_karlen_jarowski_santillan_garcia-garibay_2006, title={Dipolar rotor-rotor interactions in a difluorobenzene molecular rotor crystal}, volume={74}, DOI={10.1103/physrevb.74.054306}, abstractNote={In this paper, we characterize the rotational dynamics and observe rotor-rotor interactions within a crystalline, three-dimensional array of dipolar molecular rotors. The rotating portion of each rotor molecule consists of a dipolar fluorine-substituted phenyl group. The phenyl rotors are connected by acetylene linkages to bulky triphenyl methyl groups which are held rigid in the crystal lattice. These custom synthesized rotor molecules allow control over the molecular spacing in the lattice, the dipole strength, and the rotational hindrance, thus permitting formation of systems with rapid thermal rotation and strong dipole-dipole interactions, which is of interest for studying new phases and collective phenomena. Dielectric and H NMR spectroscopy measurements are used to map the rotational potential, and to explore the influence of rotor-rotor interactions. Interactions due to dipole-dipole effects are studied using a Monte Carlo simulation, while contributions from steric interactions between rotors are investigated using molecular mechanics methods. Both contributions are needed explain the dielectric spectroscopy results.}, number={5}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Horansky, Robert D. and Clarke, Laura I. and Winston, Erick B. and Price, John C. and Karlen, Steven D. and Jarowski, Peter D. and Santillan, Rosa and Garcia-Garibay, Miguel A.}, year={2006}, month={Aug} }
 @article{kottas_clarke_horinek_michl_2005, title={Artificial Molecular Rotors}, volume={36}, DOI={10.1002/chin.200532283}, abstractNote={Abstract}, number={32}, journal={ChemInform}, publisher={Wiley}, author={Kottas, Gregg S. and Clarke, Laura I. and Horinek, Dominik and Michl, Josef}, year={2005}, month={Aug} }
 @misc{kottas_clarke_horinek_michl_2005, title={Artificial molecular rotors}, volume={105}, ISSN={["1520-6890"]}, DOI={10.1021/cr0300993}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTArtificial Molecular RotorsGregg S. Kottas, Laura I. Clarke, Dominik Horinek, and Josef MichlView Author Information Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, and Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 Cite this: Chem. Rev. 2005, 105, 4, 1281–1376Publication Date (Web):April 13, 2005Publication History Received8 September 2004Published online13 April 2005Published inissue 1 April 2005https://doi.org/10.1021/cr0300993Copyright © 2005 American Chemical SocietyRequest reuse permissionsArticle Views11805Altmetric-Citations1065LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (4 MB) Get e-AlertscloseSUBJECTS:Energy,Molecular structure,Molecules,Phenyls,Pyrroles Get e-Alerts}, number={4}, journal={CHEMICAL REVIEWS}, author={Kottas, GS and Clarke, LI and Horinek, D and Michl, J}, year={2005}, month={Apr}, pages={1281–1376} }
 @article{horansky_clarke_price_khuong_jarowski_garcia-garibay_2005, title={Dielectric response of a dipolar molecular rotor crystal}, volume={72}, DOI={10.1103/physrevb.72.014302}, abstractNote={We report the results of the dynamics of a three dimensional lattice of dipolar molecular rotors where the unit cells consist of a dipolar phenylene ring rotating about an axle stabilized by stationary triphenyl groups. The molecules are synthesized such that the lattice may be customized to elicit novel and useful physical phenomena. Using dielectric spectroscopy and 2 H NMR, we demonstrate rapid thermal rotation of the molecular rotors in the solid state, and characterize the depth and asymmetry of the rotational potential. Calculations show that rotor-rotor interactions are weak in this structure, and the rotational potential is dominated by steric interactions between each rotary element and the nonrotating portions of neighboring molecules.}, number={1}, journal={Physical Review B}, publisher={American Physical Society (APS)}, author={Horansky, Robert D. and Clarke, Laura I. and Price, John C. and Khuong, Tinh-Alfredo V. and Jarowski, Peter D. and Garcia-Garibay, Miguel A.}, year={2005}, month={Jul} }
 @article{berven_wybourne_clarke_longstreth_hutchison_mooster_2002, title={Background charge fluctuations and the transport properties of biopolymer-gold nanoparticle complexes}, volume={92}, DOI={10.1063/1.1506399}, abstractNote={The room temperature electrical characteristics of biopolymer-gold nanoparticle complexes show threshold behavior, periodic conductance features, and current–voltage scaling that together indicate the nonlinear transport is associated with single electron charging. Repeated measurements over a period of up to 80 h showed the characteristics change with time. The current–voltage scaling behavior is found to be time independent, while the position of the conductance features shifted randomly over periods of many hours. We show that the time dependence is consistent with a fluctuating background charge distribution and can be understood within the framework of the orthodox model of single electron transport that is modified to account for the relatively large self-capacitance of the nanoparticles.}, number={8}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Berven, C. A. and Wybourne, M. N. and Clarke, L. and Longstreth, L. and Hutchison, J. E. and Mooster, J. L.}, year={2002}, month={Oct}, pages={4513–4517} }
 @article{berven_clarke_mooster_wybourne_hutchison_2001, title={Defect-Tolerant Single-Electron Charging at Room Temperature in Metal Nanoparticle Decorated Biopolymers}, volume={13}, DOI={10.1002/1521-4095(200101)13:2<109::aid-adma109>3.3.co;2-p}, abstractNote={Gold nanoparticles assembled on a biopolymer template (see Figure) between metal electrodes on an insulating substrate are shown to exhibit unambiguous single electron charging effects that are found to depend on the nanoparticle properties and the geometrical contraints imposed by the biopolymer. The results support the idea of using nanoparticles in conjuction with biomolecular organization to produce nanoscale systems with defect-tolerant current–voltage behavior.}, number={2}, journal={Advanced Materials}, publisher={Wiley}, author={Berven, C. A. and Clarke, L. and Mooster, J. L. and Wybourne, M. N. and Hutchison, J. E.}, year={2001}, month={Jan}, pages={109–113} }
 @article{berven_clarke_mooster_wybourne_hutchison_2001, title={Defect-Tolerant Single-Electron Charging at Room Temperature in Metal Nanoparticle Decorated Biopolymers}, volume={13}, DOI={10.1002/1521-4095(200101)13:2<109::aid-adma109>3.0.co;2-y}, abstractNote={The last three decades have seen a dramatic decrease in the size of microelectronic devices, with the number of devices on a microchip doubling about every eighteen months. As device feature sizes shrink towards quantum scales, this evolution is facing serious technical, fundamental, and economic challenges. To address these issues a number of revolutionary departures from the conventional semiconductor device paradigm are currently being investigated. In particular, nanostructures, in which single electron tunneling and charging effects can be exploited for device applications, (e.g., in quantum cellular automata and organic thin-film transistors) are receiving much attention. The effects of single-electron charging on electron transport in lithographically-defined nanostructures is well-documented. In general, nanostructures at the limits of electron-beam lithography (ca. 15 nm) are too large to achieve clear singleelectron effects at room temperature. Alternative approaches to achieve these effects at room temperature include silicon nanocrystal floating gate devices and focused ion beam deposited structures. Another involves assemblies of metal or semiconductor nanoparticles that have well-defined dimensions down to the molecular scale. At these sizes the inherent capacitance of the system is small enough that single-electron effects are manifest at room temperature. An added advantage is that the chemical nature of these building blocks makes possible the parallel chemical assembly of particle arrays from individual particles with precisely tuned physical properties. In order to utilize nanoparticle building blocks, or even to explore their electrical properties, it is important to be able to assemble and make electrical contact to them. Considerable progress has been made toward the rational assembly of extended nanoparticle arrays, and transport measurements perpendicular to the plane of the arrays have been performed using scanning probe microscopy and thin film electrode sandwich arrangements. Measurements that probe lateral transport (in the plane of the array) in two-dimensional films and patterned arrays such as lines are important for designing planar device applications. Given the finite yield of the chemical assembly process, defects will exist in these arrays and might be expected to adversely influence the transport properties. Although the importance of defect tolerance in chemically-assembled nanoscale electronic circuits has been discussed in the context of other systems, the potential of near room temperature experiments on patterned nanoparticle arrays to probe the defectand disorder-sensitivity remains largely unexplored. Here we present the room-temperature electrical behavior of gold nanoparticles assembled on a biopolymer template deposited between metal electrodes on an insulating substrate. The assemblies were prepared using a straightforward procedure that involves only wet chemical methods. Unambiguous single-electron charging effects are observed that can be understood in terms of the nanoparticle properties and the geometrical constraints imposed by the biopolymer. These results support the idea of using nanoparticles in conjunction with biomolecular organization to achieve nanoscale systems with novel, defect-tolerant current±voltage behavior. Networks of gold nanoparticles were fabricated between the fingers of gold interdigitated array (IDA) electrodes (15 or 2 lm gap) by electrostatic assembly of carboxylic acid modified gold nanoparticles onto the amino side chains of the biopolymer poly-L-lysine (PLL). A thin film of PLL (MW = 54 000 amu) is initially deposited from aqueous methanol containing the alpha-helical form of its hydrobromide salt. The exposed side chains of the dried film were subsequently deprotonated by soaking in dilute base. The 11-mercaptoundecanoic acid-stabilized gold nanoparticles were assembled onto the biopolymer from an organic solvent. The metal-core radius was determined to be 0.7 ± 0.2 nm (±30 %) by transmission electron microscopy (TEM), and the diameter of the core and ligand shell together is estimated to be 4.2 nm. The average length of an extended PLL chain is ca. 30 nm. Current±voltage (I±V) measurements were performed at room temperature with the samples in an electrically shielded vacuum chamber. Control measurements were made on the bare electrodes and again after the PLL had been deposited and deprotonated. The I±V characteristics of the deprotonated PLL and the bare surface were linear (ohmic) without any structure, as shown by curve I in Figure 1a. Importantly, these two sets of control data were indistinguishable, which shows that to within experimental uncertainty the surface conductance of the glass substrate was unaffected by the deprotonated PLL. In contrast, when decorated with nanoparticles, the samples exhibited pronounced nonlinear I±V characteristics, as shown by curve II in Figure 1a. After subtraction of the linear I±V behavior measured before PLL decoration, to within the measurement accuracy the electrical characteristics showed a region of zero conductance at low voltages. The onset of current is characterized by a threshold voltage, VT,}, number={2}, journal={Advanced Materials}, publisher={Wiley}, author={Berven, C. A. and Clarke, L. and Mooster, J. L. and Wybourne, M. N. and Hutchison, J. E.}, year={2001}, month={Jan}, pages={109–113} }
 @article{berven_wybourne_clarke_hutchison_brown_mooster_schmidt_2000, title={The use of biopolymer templates to fabricate low-dimensional gold particle structures}, volume={27}, DOI={10.1006/spmi.2000.0852}, abstractNote={Abstract We report the current–voltage characteristics of gold nanoparticle–biopolymer networks at room temperature. The characteristics have features that are indicative of single-electron charging in ordered, one-dimensional chains of nanoparticles. From capacitance estimates and numerical simulations, we argue that the observed electrical behavior is related to the low size dispersion of the nanoparticles and the uniformity of the biopolymer lengths imbedded within the network.}, number={5-6}, journal={Superlattices and Microstructures}, publisher={Elsevier BV}, author={Berven, C.A. and Wybourne, M.N. and Clarke, L. and Hutchison, J.E. and Brown, L.O. and Mooster, J.L. and Schmidt, M.E.}, year={2000}, month={May}, pages={489–493} }
 @article{wybourne_hutchison_clarke_brown_mooster_1999, title={Fabrication and electrical transport characteristics of low-dimensional nanoparticle arrays organized by biomolecular scaffolds}, volume={47}, DOI={10.1016/s0167-9317(99)00147-1}, abstractNote={We report the use of a biopolymer scaffold in the nanofabrication of low-dimensional arrays of gold nanoparticles. The room-temperature current-voltage dependence shows threshold behavior characteristic of Coulomb-blockade. Above threshold the current varies linearly with voltage which suggests one-dimensional behavior. Capacitance estimates are consistent with transport through a disordered chain containing a minimum of 200 nanoparticles.}, number={1-4}, journal={Microelectronic Engineering}, publisher={Elsevier BV}, author={Wybourne, M.N. and Hutchison, J.E. and Clarke, L. and Brown, L.O. and Mooster, J.L.}, year={1999}, month={Jun}, pages={55–57} }
 @article{clarke_wybourne_brown_hutchison_yan_cai_keana_1999, title={Room-temperature Coulomb-blockade-dominated transport in gold nanocluster structures}, volume={13}, DOI={10.1088/0268-1242/13/8a/033}, abstractNote={In this paper we discuss the near-room-temperature electrical transport characteristics of structures made from ligand-stabilized metal clusters. The structures show threshold behaviour, nonlinear current-voltage characteristics and radio-frequency-induced plateaux consistent with Coulomb-blockade-dominated transport in disordered arrays of metal dots. Samples having triphenylphosphine and octadecanethiol ligand shells are found to have a 3 orders of magnitude difference in current above threshold. We discuss a possible explanation for this observation.}, number={8A}, journal={Semiconductor Science and Technology}, publisher={IOP Publishing}, author={Clarke, L and Wybourne, M N and Brown, L O and Hutchison, J E and Yan, M and Cai, S X and Keana, J F W}, year={1999}, month={Jan}, pages={A111–A114} }
 @article{wybourne_clarke_yan_cai_brown_hutchison_keana_1997, title={Coulomb-Blockade Dominated Transport in Patterned Gold-Cluster Structures}, volume={36}, DOI={10.1143/jjap.36.7796}, abstractNote={ 
   In this paper we present the fabrication and near-room temperature electrical transport    properties of structures made from the gold-cluster material  Au55[P(C6H5)3]12Cl6. We discuss the    use of electron-beam lithography to define the structures laterally and compare the direct current-voltage characteristics of non-patterned and patterned structures. In both cases non-linear    behavior is observed with features that are consistent with Coulomb blockade dominated    transport in disordered arrays of clusters. Radio frequency induced plateaus in the current-voltage characteristics demonstrate coherent tunneling. Finally, we show that other ligand    stabilized gold-cluster materials can be used to form ordered gold-cluster arrays. 
   }, number={Part 1, No. 12B}, journal={Japanese Journal of Applied Physics}, publisher={Japan Society of Applied Physics}, author={Wybourne, Martin N. and Clarke, Laura and Yan, Mingdi and Cai, Sui X. and Brown, Leif O. and Hutchison, James and Keana, John F.W.}, year={1997}, pages={7796–7800} }
 @article{clarke_wybourne_yan_cai_keana_1997, title={Transport in gold cluster structures defined by electron-beam lithography}, volume={71}, DOI={10.1063/1.120568}, abstractNote={The near-room temperature current-voltage (I-V) characteristics of small structures made from the metal-cluster material Au55[P(C6H5)3]12Cl6 were studied. It is shown that these electron-beam defined structures have highly nonlinear characteristics with features, including a threshold voltage and scaling behavior, which are consistent with Coulomb charging of individual Au55 cores in a disordered array. Applied radio frequency signals introduce plateaus in the I-V characteristics, which demonstrates the presence of coherent tunneling in these cluster systems.}, number={5}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Clarke, L. and Wybourne, M. N. and Yan, Mingdi and Cai, S. X. and Keana, J. F. W.}, year={1997}, month={Aug}, pages={617–619} }