@article{saraswat_kerstein_hsiao_2024, title={Creep and recovery in dense suspensions of smooth and rough colloids}, volume={68}, ISSN={["1520-8516"]}, url={https://doi.org/10.1122/8.0000722}, DOI={10.1122/8.0000722}, abstractNote={We report the effect of particle surface roughness on creep deformation and subsequent strain recovery in dense colloidal suspensions. The suspensions are composed of hard-spherelike poly(methyl methacrylate) smooth (S) and rough (R) colloids with particle volume fractions ϕS = 0.64 ± 0.01 and ϕR = 0.56 ± 0.01, corresponding to a distance of 3.0% and 3.4% based on their jamming volume fractions (ϕJS=0.66±0.01, ϕJR=0.58±0.01). The suspensions are subject to a range of shear stresses (0.01–0.07 Pa) above and below the yield stress values of the two suspensions (σyS=0.035Pa, σyR=0.02Pa). During creep, suspensions of rough colloids exhibit four to five times higher strain deformation compared to smooth colloids, irrespective of the applied stress. The interlocking of surface asperities in rough colloids is likely to generate a heterogeneous microstructure, favoring dynamic particle activity and percolation of strain heterogeneities, therefore resulting in higher magnitude of strain deformation and an earlier onset of steady flow. Strain recovery after the cessation of stress reveals a nonmonotonic recoverable strain for rough colloids, where the peak recoverable strain is observed near the yield stress, followed by a steep decline with increasing stress. This type of response suggests that frictional constraints between geometrically frustrated interlocking contacts can serve as particle bonds capable of higher elastic recovery but only near the yield stress. Understanding how particle roughness affects macroscopic creep and recovery is useful in designing yield stress fluids for additive manufacturing and product formulations.}, number={2}, journal={JOURNAL OF RHEOLOGY}, author={Saraswat, Yug Chandra and Kerstein, Eli and Hsiao, Lilian C.}, year={2024}, month={Mar}, pages={205–217} }
 @article{jani_farias_jain_houston_velev_santiso_hsiao_khan_2024, title={Isothermal Titration Calorimetry Reveals Entropy-Driven Bisphenol A Epoxy Resin Adhesion to Metal Oxide Surfaces}, volume={1}, ISSN={["1520-5835"]}, url={https://doi.org/10.1021/acs.macromol.3c02440}, DOI={10.1021/acs.macromol.3c02440}, abstractNote={Polymer-coated metals are ubiquitous in multiple industries as a corrosion protection strategy. Particularly in food and beverage packaging, bisphenol A (BPA)-based epoxy coatings provide an excellent barrier and strong adhesion to metals. There is, however, a need to design safer, alternative coatings with similar adhesion as BPA-epoxies due to environmental and health concerns associated with BPA. Limited critical information exists on epoxy-metal interactions and the effect of interfacial functional group concentration on overall adhesion due to the constraints of most experimental methods, which typically probe the interface only within a few nanometers in situ. Herein, we use isothermal titration calorimetry (ITC) and molecular dynamics simulations to characterize the thermodynamics of epoxy-metal oxide binding in the liquid phase and identify the influence of epoxy resin structure and metal oxide surface chemistry in dictating the binding process. Across a series of epoxy resins and three metal oxides, we reveal a previously unreported dominant role of entropy in the binding process, primarily facilitated by the release of bound solvent molecules from the epoxy/metal interface with possible contributions from dispersive OH–π interactions between the benzene rings of the resin and the –OH groups on the metal oxide surface. Enthalpy-favored hydrogen bonding between the –OH groups of the resin and the metal oxide plays a supporting role in the binding, with its participation dependent on the interfacial –OH group concentration. ITC therefore offers key molecular insights into the relative functional group contributions to the adhesion mechanism and informs the rational design of next-generation polymer coatings.}, journal={MACROMOLECULES}, author={Jani, Pallav K. and Farias, Barbara V. and Jain, Rakshit Kumar and Houston, Katelyn R. and Velev, Orlin D. and Santiso, Erik E. and Hsiao, Lilian C. and Khan, Saad A.}, year={2024}, month={Jan} }
 @article{farrell_jacob_truong_elbourne_kong_hsiao_dickey_tabor_2023, title={Compositional Design of Surface Oxides in Gallium-Indium Alloys}, volume={1}, ISSN={["1520-5002"]}, url={https://doi.org/10.1021/acs.chemmater.2c02696}, DOI={10.1021/acs.chemmater.2c02696}, abstractNote={Room-temperature liquid metal alloys encompass a highly versatile family of materials possessing a unique set of chemical, electronic, biological, and mechanical properties. The surface oxide of liquid metals has a direct influence on these properties and is often composed of one of the major alloy components (i.e., gallium or indium). However, this is not a foregone conclusion, as the identity of the surface oxide can be altered by the addition of minority elements into the liquid metal. Through judicious choice of a minority alloying metal, the composition of the oxide and therefore the resulting molten alloy’s properties are significantly modified. We demonstrate this by adding a small amount (∼5%) of several thermodynamically favorable alloying elements (X = Zn, Mg, Al) to eutectic gallium indium (EGaIn), resulting in a new class of alloys with designed surface oxide compositions that we term XGaIn. Using both STEM-EDS and XPS, XGaIn alloys are shown to form oxide layers enriched in the lowest-redox element as expected based on the thermodynamics of the alloy system. This approach is shown to be generalizable across both Ga and non-Ga-based liquid metal alloy compositions. XGaIn alloys with added Zn and Mg are shown to have strong antimicrobial activity, which has exciting implications for the development of flexible electronic medical devices and sensors.}, journal={CHEMISTRY OF MATERIALS}, author={Farrell, Zachary J. and Jacob, Alan R. and Truong, Vi Khanh and Elbourne, Aaron and Kong, Wilson and Hsiao, Lilian and Dickey, Michael D. and Tabor, Christopher}, year={2023}, month={Jan} }
 @article{sarker_jani_hsiao_rojas_khan_2023, title={Interacting collagen and tannic acid Particles: Uncovering pH-dependent rheological and thermodynamic behaviors}, volume={650}, ISSN={0021-9797}, url={http://dx.doi.org/10.1016/j.jcis.2023.06.209}, DOI={10.1016/j.jcis.2023.06.209}, abstractNote={Biomaterials such as collagen and tannic acid (TA) particles are of interest in the development of advanced hybrid biobased systems due to their beneficial therapeutic functionalities and distinctive structural properties. The presence of numerous functional groups makes both TA and collagen pH responsive, enabling them to interact via non-covalent interactions and offer tunable macroscopic properties.The effect of pH on the interactions between collagen and TA particles is explored by adding TA particles at physiological pH to collagen at both acidic and neutral pH. Rheology, isothermal titration calorimetry (ITC), turbidimetric analysis and quartz crystal microbalance with dissipation monitoring (QCM-D) are used to study the effects.Rheology results show significant increase in elastic modulus with an increase in collagen concentration. However, TA particles at physiological pH provide stronger mechanical reinforcement to collagen at pH 4 than collagen at pH 7 due to the formation of a higher extent of electrostatic interaction and hydrogen bonding. ITC results confirm this hypothesis, with larger changes in enthalpy, |ΔH|, observed when collagen is at acidic pH and |ΔH| > |TΔS| indicating enthalpy-driven collagen-TA interactions. Turbidimetric analysis and QCM-D help to identify structural differences of the collagen-TA complexes and their formation at both pH conditions.}, journal={Journal of Colloid and Interface Science}, publisher={Elsevier BV}, author={Sarker, Prottasha and Jani, Pallav K. and Hsiao, Lilian C. and Rojas, Orlando J. and Khan, Saad A.}, year={2023}, month={Nov}, pages={541–552} }
 @article{kotb_serfass_cagnard_houston_khan_hsiao_velev_2023, title={Molecular structure effects on the mechanisms of corrosion protection of model epoxy coatings on metals}, volume={7}, ISSN={2052-1537}, url={http://dx.doi.org/10.1039/d2qm01045c}, DOI={10.1039/d2qm01045c}, abstractNote={We investigate the role of the polymer network structure on the corrosion protection efficiency of thermoset epoxy coatings on metals as a prerequisite for the future design of safer alternatives to bisphenol A-based epoxy resins.}, number={2}, journal={Materials Chemistry Frontiers}, publisher={Royal Society of Chemistry (RSC)}, author={Kotb, Yosra and Serfass, Christopher M. and Cagnard, Alain and Houston, Katelyn R. and Khan, Saad A. and Hsiao, Lilian C. and Velev, Orlin D.}, year={2023}, pages={274–286} }
 @article{nabizadeh_nasirian_li_saraswat_waheibi_hsiao_bi_ravandi_jamali_2023, title={Network physics of attractive colloidal gels: resilience, rigidity, and phase diagram}, volume={1}, url={https://doi.org/10.48550/arXiv.2301.13027}, DOI={10.48550/arXiv.2301.13027}, abstractNote={Attractive colloidal gels exhibit solid-like behavior at vanishingly small fractions of solids, owing to ramified space-spanning networks that form due to particle-particle interactions. These networks give the gel its rigidity, and as the attraction between the particles grows, so does the elasticity of the colloidal network formed. The emergence of this rigidity can be described through a mean field approach; nonetheless, fundamental understanding of how rigidity varies in gels of different attraction strengths is lacking. Moreover, recovering an accurate gelation phase diagram based on the system's variables have been an extremely challenging task. Understanding the nature of these fractal clusters, and how rigidity emerges from their connections is key to controlling and designing gels with desirable properties. Here, we employ well-established concepts of network science to interrogate and characterize the network of colloidal gels. We construct a particle-level network, having all the spatial coordinates of colloids with different attraction levels, and also identify polydisperse rigid fractal clusters using a Gaussian Mixture Model, to form a coarse-grained cluster network that distinctly shows main physical features of the colloidal gels. A simple mass-spring model then is used to recover quantitatively the elasticity of colloidal gels from these cluster networks. Interrogating the resilience of these gel networks show that the elasticity of a gel (a dynamic property) is directly correlated to its cluster network's resilience (a static measure). Finally, we use the resilience investigations to devise [and experimentally validate] a fully resolved phase diagram for colloidal gelation, with a clear solid-liquid phase boundary using a single volume fraction of particles well beyond this phase boundary.}, author={Nabizadeh, M. and Nasirian, F. and Li, X. and Saraswat, Y. and Waheibi, R. and Hsiao, L.C. and Bi, D. and Ravandi, B. and Jamali, S.}, year={2023}, month={Jan} }
 @article{pradeep_wessel_hsiao_2022, title={Hydrodynamic origin for the suspension viscoelasticity of rough colloids}, volume={66}, ISSN={["1520-8516"]}, url={https://doi.org/10.1122/8.0000424}, DOI={10.1122/8.0000424}, abstractNote={We report the linear rheology for dense suspensions of sterically stabilized smooth and mesoscopically rough colloids interacting as hard particles. Small amplitude oscillatory measurements reveal that rough colloids at high volume fractions exhibit storage and loss moduli that are orders of magnitude greater than smooth colloids. Frequency-concentration superposition is used to collapse the viscoelasticity data onto a master curve, where shift factors suggest a more elastic microstructure and reduced cage volume for rough particles. A combination of the mode-coupling theory, hydrodynamic modeling, and the activated hopping theory shows that these rough particles with significantly reduced localization lengths tend to become trapped in their glassy cages for extended periods of time. High-frequency data show that rough colloids, but not smooth colloids, display a transition from a free-draining to a fully lubricated state above the crossover volume fraction and, furthermore, exhibit solidlike behavior. Scaling analyses support the idea that lubrication forces between interlocking asperities are enhanced, leading to rotational constraints and stress-bearing structures that significantly elevate the viscoelasticity of dense suspensions. The results provide a framework for how particle surface topology affects the linear rheology in applications such as coatings, cement, consumer products, and shock-absorbing materials.}, number={5}, journal={JOURNAL OF RHEOLOGY}, author={Pradeep, Shravan and Wessel, Alan and Hsiao, Lilian C.}, year={2022}, month={Sep}, pages={895–906} }
 @article{serfass_kotb_smith_houston_khan_velev_hsiao_2022, title={Microstructural Defects of Epoxy–Phenolic Polymers on Metal Substrates during Acidic Corrosion}, volume={4}, url={https://doi.org/10.1021/acsapm.1c01759}, DOI={10.1021/acsapm.1c01759}, abstractNote={This study uses confocal microscopy and image processing to investigate the microstructural changes of coating–metal systems immersed in a heated acidic bath. Unlike standard optical microscopy techniques, 3D confocal microscopy images can quantitatively reveal microscopic defects formed at early stages of cathodic delamination. The coatings are made of fluorescent epoxy–phenolic resins cured at high temperatures onto tinplate (T23) and tin-free steel (TFS) substrates. When the coated metal substrates are immersed in acetic acid, a series of microscopic corrosion events occur at the polymer–metal interface. These events are quantified by changes in the thickness distribution of the degraded samples relative to that of intact coatings. The degradation rate is highest for epoxy–phenolic polymers on TFS substrates, represented by multiple orders of magnitude increase in the number density of defect sites. Higher molecular weight coatings provide slightly better resistance against delamination. The coating thickness dictates the rate of oxygen diffusion and ion transport along the polymer–coating interface, where raised asperities serve as localized sites for metal oxidation and formation of alkaline species, leading to subsequent delamination of the cured polymers from the surfaces. The results show that the metal surface topology is as important as chemistry when designing the corrosion resistance of products containing acidic liquids, and that confocal microscopy is useful in quality control through early detection of mesoscale polymer failure.}, number={5}, journal={ACS Applied Polymer Materials}, author={Serfass, C.M. and Kotb, Y. and Smith, K.M. and Houston, K.R. and Khan, S.A. and Velev, O.D. and Hsiao, L.C.}, year={2022}, pages={3196–3204} }
 @article{kotb_cagnard_houston_khan_hsiao_velev_2022, title={What makes epoxy-phenolic coatings on metals ubiquitous: Surface energetics and molecular adhesion characteristics}, volume={608}, ISSN={["1095-7103"]}, DOI={10.1016/j.jcis.2021.09.091}, abstractNote={Wetting characteristics of epoxy and phenolic resins on metals depend on the molecular interactions between resins' functional groups and metal surface. Those interactions affect the practical adhesion strength of epoxy-phenolic coatings on metals. Estimation of the theoretical adhesion energies can reveal this system's microscopic adhesion mechanisms.Adhesion is estimated theoretically based on resins' wettability on metals, and experimentally through pull-off adhesion testing of cured coatings. The effect of various functional groups on adhesion is decoupled using epoxy and phenolic resins with different functionalities. To assess the impact of the metal passivation on adhesion, tinplated and tin-free steel substrates are used. Differences in their surface chemical composition and polarity are investigated using XPS.Theoretical adhesion results reveal a superior adhesion of epoxy compared to phenolic resins. Moreover, epoxy resins having a higher content of epoxide-to-hydroxyl groups show improved theoretical and practical adhesion. The importance of epoxides in driving resins' initial adhesion on metals is attributed to the formation of direct chemical bonds with active hydrogen on metal surfaces. The adhesion of coatings on tin-free steel is found to be higher than on tinplated steel. This is associated to the increased hydroxyl fraction on tin-free steel surface leading to more hydrogen bonds formation.}, journal={JOURNAL OF COLLOID AND INTERFACE SCIENCE}, author={Kotb, Yosra and Cagnard, Alain and Houston, Katelyn R. and Khan, Saad A. and Hsiao, Lilian C. and Velev, Orlin D.}, year={2022}, month={Feb}, pages={634–643} }
 @article{peng_serfass_hill_hsiao_2021, title={Bending of Soft Micropatterns in Elastohydrodynamic Lubrication Tribology}, volume={61}, ISSN={["1741-2765"]}, url={https://doi.org/10.1007/s11340-021-00715-8}, DOI={10.1007/s11340-021-00715-8}, number={6}, journal={EXPERIMENTAL MECHANICS}, author={Peng, Y. and Serfass, C. M. and Hill, C. N. and Hsiao, L. C.}, year={2021}, month={Jul}, pages={969–979} }
 @article{ko_truong_woo_dickey_hsiao_genzer_2021, title={Counterpropagating Gradients of Antibacterial and Antifouling Polymer Brushes}, volume={12}, ISSN={["1526-4602"]}, url={https://doi.org/10.1021/acs.biomac.1c01386}, DOI={10.1021/acs.biomac.1c01386}, abstractNote={We report on the formation of counterpropagating density gradients in poly([2-dimethylaminoethyl] methacrylate) (PDMAEMA) brushes featuring spatially varying quaternized and betainized units. Starting with PDMAEMA brushes with constant grafting density and degree of polymerization, we first generate a density gradient of quaternized units by directional vapor reaction involving methyl iodide. The unreacted DMAEMA units are then betainized through gaseous-phase betainization with 1,3-propanesultone. The gas reaction of PDMAEMA with 1,3-propanesultone eliminates the formation of byproducts present during the liquid-phase modification. We use the counterpropagating density gradients of quaternized and betainized PDMAEMA brushes in antibacterial and antifouling studies. Completely quaternized and betainized brushes exhibit antibacterial and antifouling behaviors. Samples containing 12% of quaternized and 85% of betainized units act simultaneously as antibacterial and antifouling surfaces.}, journal={BIOMACROMOLECULES}, publisher={American Chemical Society (ACS)}, author={Ko, Yeongun and Truong, Vi Khanh and Woo, Sun Young and Dickey, Michael D. and Hsiao, Lilian and Genzer, Jan}, year={2021}, month={Dec} }
 @article{rocklin_hsiao_szakasits_solomon_mao_2021, title={Elasticity of colloidal gels: structural heterogeneity, floppy modes, and rigidity}, volume={6}, ISSN={["1744-6848"]}, url={https://doi.org/10.1039/D0SM00053A}, DOI={10.1039/d0sm00053a}, abstractNote={Normal-mode analysis of experimentally measured colloidal gels reveals volume-fraction dependent structural heterogeneity that leads to floppy modes and a nonaffine–affine crossover as frequency increases.}, journal={SOFT MATTER}, author={Rocklin, D. Zeb and Hsiao, Lilian and Szakasits, Megan and Solomon, Michael J. and Mao, Xiaoming}, year={2021}, month={Jun} }
 @article{peng_serfass_kawazoe_shao_gutierrez_hill_santos_visell_hsiao_2021, title={Elastohydrodynamic friction of robotic and human fingers on soft micropatterned substrates}, volume={20}, ISSN={1476-1122 1476-4660}, url={http://dx.doi.org/10.1038/s41563-021-00990-9}, DOI={10.1038/s41563-021-00990-9}, abstractNote={The understanding of sliding friction for wet, patterned surfaces from first principles is challenging. While emerging applications have sought design principles from biology, a general framework is lacking because soft interfaces experience a multiphysics coupling between solid deformation and fluid dissipation. We investigate the elastohydrodynamic sliding of >50 patterned sliding pairs comprising elastomers, thermosets, and hydrogels, and discover that texturing induces a critical transition in the macroscopic friction coefficient. This critical friction scales universally, without any fitting parameters, with the reduced elastic modulus and the pattern geometry. To capture the frictional dissipation, we separate the flow curve into two regimes and account for the contributions of shear and normal forces applied by the fluid on the patterns. Our model combines Reynolds' equations and elastic deformation to provide physical insights that allow engineering of the elastohydrodynamic friction in a class of soft tribopairs using pattern geometry, material elasticity, and fluid properties.}, number={12}, journal={Nature Materials}, publisher={Springer Science and Business Media LLC}, author={Peng, Yunhu and Serfass, Christopher M. and Kawazoe, Anzu and Shao, Yitian and Gutierrez, Kenneth and Hill, Catherine N. and Santos, Veronica J. and Visell, Yon and Hsiao, Lilian C.}, year={2021}, month={Apr}, pages={1707–1711} }
 @article{adhikari_jani_hsiao_rojas_khan_2021, title={Interfacial Contributions in Nanodiamond-Reinforced Polymeric Fibers}, volume={125}, ISSN={["1520-5207"]}, url={https://doi.org/10.1021/acs.jpcb.1c03361}, DOI={10.1021/acs.jpcb.1c03361}, abstractNote={We study the interfacial energy parameters that explain the reinforcement of polymers with nanodiamond (ND) and the development of mechanical strength of electrospun ND-reinforced composites. Thermodynamic parameters such as the wettability ratio, work of spreading and dispersion/aggregation transition are used to derive a criterion to predict the dispersibility of carboxylated ND (cND) in polymeric matrices. Such a criterion for dispersion (Dc) is applied to electrospun cND-containing poly(vinyl alcohol) (PVA), polyacrylonitrile (PAN), and polystyrene (PS) fiber composites. The shifts in glass transition temperature (ΔTg), used as a measure of polymer/cND interfacial interactions and hence the reinforcement capability of cNDs, reveal a direct correlation with the thermodynamic parameter Dc in the order of PAN < PS < PVA. Contrary to expectation, however, the tensile strength of the electrospun fibers correlates with the Dc and ΔTg only for semicrystalline polymers (PAN < PVA) while the amorphous PS displays a maximum reinforcement with cND. Such conflicting results reveal a synergy that is not captured by thermodynamic considerations alone but also factor in the contributions of polymer/cND interface stress transfer efficiency. Our findings open the possibility for tailoring the interfacial interactions in polymer-ND fiber composites to achieve maximum mechanical reinforcement.}, number={36}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, publisher={American Chemical Society (ACS)}, author={Adhikari, Prajesh and Jani, Pallav K. and Hsiao, Lilian C. and Rojas, Orlando J. and Khan, Saad A.}, year={2021}, month={Sep}, pages={10312–10323} }
 @article{pradeep_nabizadeh_jacob_jamali_hsiao_2021, title={Jamming Distance Dictates Colloidal Shear Thickening}, volume={127}, ISSN={["1079-7114"]}, url={https://doi.org/10.1103/PhysRevLett.127.158002}, DOI={10.1103/PhysRevLett.127.158002}, abstractNote={We report experimental and computational observations of dynamic contact networks for colloidal suspensions undergoing shear thickening. The dense suspensions are comprised of sterically stabilized poly(methyl methacrylate) colloids that are spherically symmetric and have varied surface roughness. Confocal rheometry and dissipative particle dynamics simulations show that the shear thickening strength β scales exponentially with the scaled deficit contact number and the scaled jamming distance. Rough colloids, which experience additional rotational constraints, require an average of 1.5-2 fewer particle contacts as compared to smooth colloids, in order to generate the same β. This is because the surface roughness enhances geometric friction in such a way that the rough colloids do not experience a large change in the free volume near the jamming point. The available free volume for colloids of different roughness is related to the deficiency from the maximum number of nearest neighbors at jamming under shear. Our results further suggest that the force per contact is different for particles with different morphologies.}, number={15}, journal={PHYSICAL REVIEW LETTERS}, author={Pradeep, Shravan and Nabizadeh, Mohammad and Jacob, Alan R. and Jamali, Safa and Hsiao, Lilian C.}, year={2021}, month={Oct} }
 @article{smith_san-miguel_hsiao_2021, title={Local velocity of thermoresponsive colloidal gels in rate-driven flow}, volume={33}, ISSN={["1089-7666"]}, url={https://doi.org/10.1063/5.0042109}, DOI={10.1063/5.0042109}, abstractNote={The interplay between flow and attractive interactions in colloidal gels results in complex particle trajectories and velocity profiles that are not evident from bulk rheological measurements. We use high-speed confocal microscopy to investigate the local velocity of a low volume fraction (ϕ = 0.20) thermogelling nanoemulsion system as it flows through a cylindrical capillary at temperatures below and above the gel point. The nanoemulsions are composed of poly(dimethyl siloxane) droplets in a continuous phase of sodium dodecyl sulfate, de-ionized water, and a gelator molecule, poly(ethylene glycol diacrylate). The trajectories of fluorescent polystyrene tracer beads in the oil-rich domains are tracked using two-dimensional image processing. While the velocity profiles agree with those computed from rheometry measurements for nanoemulsion suspensions below the gel point temperature, increasing attractive interactions above the gel point results in statistically significant deviations. Specifically, the velocity measurements indicate a higher yield stress and a larger degree of shear thinning than expected from bulk rheology measurements, resulting in a more plug-shaped velocity profile as temperature and associated interdroplet attraction increase. These deviations from theoretical predictions are likely due to structural heterogeneity. Confocal microscopy images show that small, fluidized clusters are found in high shear rate regions near the capillary walls, while large dense clusters form in low shear rate regions closer to the center of the capillary.}, number={3}, journal={PHYSICS OF FLUIDS}, publisher={AIP Publishing}, author={Smith, Kristine M. and San-Miguel, Adriana and Hsiao, Lilian C.}, year={2021}, month={Mar} }
 @article{gao_krissanaprasit_miles_hsiao_labean_2021, title={Mechanical and Electrical Properties of DNA Hydrogel-Based Composites Containing Self-Assembled Three-Dimensional Nanocircuits}, volume={11}, ISSN={["2076-3417"]}, url={https://doi.org/10.3390/app11052245}, DOI={10.3390/app11052245}, abstractNote={Molecular self-assembly of DNA has been developed as an effective construction strategy for building complex materials. Among them, DNA hydrogels are known for their simple fabrication process and their tunable properties. In this study, we have engineered, built, and characterized a variety of pure DNA hydrogels using DNA tile-based crosslinkers and different sizes of linear DNA spacers, as well as DNA hydrogel/nanomaterial composites using DNA/nanomaterial conjugates with carbon nanotubes and gold nanoparticles as crosslinkers. We demonstrate the ability of this system to self-assemble into three-dimensional percolating networks when carbon nanotubes and gold nanoparticles are incorporated into the DNA hydrogel. These hydrogel composites showed interesting non-linear electrical properties. We also demonstrate the tuning of rheological properties of hydrogel-based composites using different types of crosslinkers and spacers. The viscoelasticity of DNA hydrogels is shown to dramatically increase by the use of a combination of interlocking DNA tiles and DNA/carbon nanotube crosslinkers. Finally, we present measurements and discuss electrically conductive nanomaterials for applications in nanoelectronics.}, number={5}, journal={APPLIED SCIENCES-BASEL}, author={Gao, Ming and Krissanaprasit, Abhichart and Miles, Austin and Hsiao, Lilian C. and LaBean, Thomas H.}, year={2021}, month={Mar} }
 @article{smith_hsiao_2021, title={Migration and Morphology of Colloidal Gel Clusters in Cylindrical Channel Flow}, volume={37}, ISSN={["0743-7463"]}, url={https://doi.org/10.1021/acs.langmuir.1c01287}, DOI={10.1021/acs.langmuir.1c01287}, abstractNote={We report the cluster-level structural parameters of colloidal thermogelling nanoemulsions in channel flow as a function of attractive interactions and local shear stress. The spatiotemporal evolution of the gel microstructure is obtained by directly visualizing the dispersed phase near the edge of a cylindrical channel. We observe the flow of the nanoemulsion gels in a range of radial positions (r) and shear stresses between 70 and 220 Pa, finding that the r-dependent cluster sizes are due to a balance between shear forces that yield bonds and attractive interactions that rebuild the inter-colloid bonds. In addition, the largest clusters appear to be affected by confinement and accumulate toward the central axis of the channel, resulting in a volume fraction gradient. Cluster size and volume fraction variabilities are most prominent when the attractive interactions are the strongest. Specifically, a distinct transition from sparse, fluidized clusters near the walls to concentrated, large clusters toward the center is observed. These two structural states coincide with a velocity-based transition from higher shear rates near the walls to lower shear rates toward the center of the channel. We find a compounding effect where larger gel clusters, formed under strong attractions and low shear stresses, are susceptible to shear-induced migration that intensifies r-dependent heterogeneity and deviations in the flow behavior from predictive models.}, number={34}, journal={LANGMUIR}, author={Smith, Kristine M. and Hsiao, Lilian C.}, year={2021}, month={Aug}, pages={10308–10318} }
 @article{williams_roh_jacob_stoyanov_hsiao_velev_2021, title={Printable homocomposite hydrogels with synergistically reinforced molecular-colloidal networks}, volume={12}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/s41467-021-23098-9}, DOI={10.1038/s41467-021-23098-9}, abstractNote={Abstract}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Williams, Austin H. and Roh, Sangchul and Jacob, Alan R. and Stoyanov, Simeon D. and Hsiao, Lilian and Velev, Orlin D.}, year={2021}, month={May}, pages={2834} }
 @article{pradeep_hsiao_2020, title={Contact criterion for suspensions of smooth and rough colloids}, volume={16}, ISSN={["1744-6848"]}, url={https://doi.org/10.1039/D0SM00072H}, DOI={10.1039/d0sm00072h}, abstractNote={We report a procedure to obtain the search distance used to determine the particle-particle contact in dense suspensions of smooth and rough colloids.}, number={21}, journal={SOFT MATTER}, author={Pradeep, Shravan and Hsiao, Lilian C.}, year={2020}, month={Jun}, pages={4980–4989} }
 @article{williams_roh_jacob_stoyanov_hsiao_velev_2020, title={Printable homocomposite hydrogels with synergistically reinforced molecular-colloidal networks}, url={https://doi.org/10.21203/rs.3.rs-110699/v1}, DOI={10.21203/rs.3.rs-110699/v1}, abstractNote={Abstract}, author={Williams, Austin and Roh, Sangchul and Jacob, Alan and Stoyanov, Simeon and Hsiao, Lilian and Velev, Orlin}, year={2020}, month={Dec} }
 @article{farias_hsiao_khan_2020, title={Rheological and Tribological Behavior of Gels and Emulsions Containing Polymer and Phospholipid}, volume={2}, ISSN={2637-6105 2637-6105}, url={http://dx.doi.org/10.1021/acsapm.0c00053}, DOI={10.1021/acsapm.0c00053}, abstractNote={Oil-in-water (O/W) emulsions are widely used in food, pharmaceutical, and personal care applications. These types of systems often contain hydrophobically modified polymers and phospholipids, where...}, number={4}, journal={ACS Applied Polymer Materials}, publisher={American Chemical Society (ACS)}, author={Farias, Barbara V. and Hsiao, Lilian C. and Khan, Saad A.}, year={2020}, month={Mar}, pages={1623–1633} }
 @article{cardenas-vasquez_smith_doolan_hsiao_2020, title={Shear-Induced Microstructural Variations in Nanoemulsion-Laden Organohydrogel Fibers}, volume={2}, ISSN={2637-6105 2637-6105}, url={http://dx.doi.org/10.1021/acsapm.9b00979}, DOI={10.1021/acsapm.9b00979}, abstractNote={We report the formation of solid composite hydrogel fibers with tunable mass transport kinetics using a continuous extrusion process, in which the length scales of hydrophobic microdomains are tune...}, number={2}, journal={ACS Applied Polymer Materials}, publisher={American Chemical Society (ACS)}, author={Cardenas-Vasquez, E. Daniel and Smith, Kristine M. and Doolan, Taylor J. and Hsiao, Lilian C.}, year={2020}, month={Dec}, pages={594–603} }
 @article{smith_hsiao_2020, title={The Formulator's Toolbox for Consumer Products}, volume={2020}, number={July}, journal={Chemical Engineering Progress}, author={Smith, K.M. and Hsiao, L.C.}, year={2020}, month={Jul}, pages={26–31} }
 @article{whitaker_varga_hsiao_solomon_swan_furst_2019, title={Colloidal gel elasticity arises from the packing of locally glassy clusters}, volume={10}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-019-10039-w}, abstractNote={Abstract}, journal={NATURE COMMUNICATIONS}, author={Whitaker, Kathryn A. and Varga, Zsigmond and Hsiao, Lilian C. and Solomon, Michael J. and Swan, James W. and Furst, Eric M.}, year={2019}, month={May} }
 @article{kass_cardenas‐vasquez_hsiao_2019, title={Composite double network hydrogels with thermoresponsive colloidal nanoemulsions}, volume={65}, ISSN={0001-1541 1547-5905}, url={http://dx.doi.org/10.1002/aic.16817}, DOI={10.1002/aic.16817}, abstractNote={Abstract}, number={12}, journal={AIChE Journal}, publisher={Wiley}, author={Kass, Lauren and Cardenas‐Vasquez, Ernesto Daniel and Hsiao, Lilian C.}, year={2019}, month={Nov}, pages={e16817} }
 @misc{hsiao_pradeep_2019, title={Experimental synthesis and characterization of rough particles for colloidal and granular rheology}, volume={43}, ISSN={["1879-0399"]}, DOI={10.1016/j.cocis.2019.04.003}, abstractNote={We review the experimental synthesis of smooth and rough particles, characterization of surface roughness, quantification of the pairwise and bulk friction coefficients, and their effect on the rheology of wet particulate flows. Even in the absence of interparticle attraction or cohesion, such types of flows are broadly ubiquitous, spanning enormous length scales ranging from consumer and food products to earth movements. The increasing availability of model frictional particles is useful to advancing new understanding of particulate rheology. Although hard-sphere particles remain the most widely studied system due to their simplicity, their rigid and frictionless nature cannot predict many of the complex flow phenomena in colloidal and granular suspensions. Besides a myriad of interparticle forces, the presence of tangential interparticle friction arising from either hydrodynamics or solid contacts of asperities is now thought to be responsible for commonalities in shear thickening and jamming phenomena at high volume fractions and shear stresses. The overall richness of the suspension mechanics landscape points to the reunification of colloidal and granular physics in the near future: one in which it may become possible to apply a universal set of physical frameworks to understand the flows of model rough particles across multiple spatiotemporal scales. This can only be accomplished by properly distinguishing between microscopic and bulk friction and by decoupling hydrodynamics and contact contributions within the context of experimental observations.}, journal={CURRENT OPINION IN COLLOID & INTERFACE SCIENCE}, author={Hsiao, Lilian C. and Pradeep, Shravan}, year={2019}, month={Oct}, pages={94–112} }
 @article{jacob_parekh_dickey_hsiao_2019, title={Interfacial Rheology of Gallium-Based Liquid Metals}, volume={35}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/acs.langmuir.9b01821}, DOI={10.1021/acs.langmuir.9b01821}, abstractNote={Gallium and its alloys react with oxygen to form a native oxide that encapsulates the liquid metal with a solid 'skin'. The viscoelasticity of this skin is leveraged in applications such as soft electronics, 3D printing and components for microfluidic devices. In these applications, rheological characterization of the oxide skin is paramount for understanding and controlling liquid metals. Here, we provide a direct comparison of the viscoelastic properties for gallium-based liquid metals and illustrate the effect of different subphases and addition of a dopant on the elastic nature of the oxide skin. The Du Noüy ring method is used to investigate the interfacial rheology of oxide skins formed by gallium-based liquid metal alloys. The results show that the oxide layer on gallium, eutectic gallium-indium, and galinstan are viscoelastic with a yield stress. Furthermore, the storage modulus of the oxide layer is affected by exposure to water or when small amounts of aluminum dopant are added to the liquid metals. The former scenario decreases the interfacial storage modulus of the gallium by 35-85% while the latter increases the interfacial storage modulus by 25-45%. The presence of water also changes the chemical composition of the oxide skin. Scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) suggest that a microstructural evolution of the interface occurs when aluminum preferentially migrates from the bulk to the surface. These studies provide guidance on selecting liquid metals as well as simple methods to optimize their rheological behavior for future applications.}, number={36}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Jacob, Alan R. and Parekh, Dishit P. and Dickey, Michael D. and Hsiao, Lilian C.}, year={2019}, month={Aug}, pages={11774–11783} }
 @article{hsiao_badruddoza_cheng_doyle_2017, title={3D printing of self-assembling thermoresponsive nanoemulsions into hierarchical mesostructured hydrogels}, volume={13}, ISSN={["1744-6848"]}, url={https://doi.org/10.1039/C6SM02208A}, DOI={10.1039/c6sm02208a}, abstractNote={Spinodal decomposition and phase transitions have emerged as viable methods to generate a variety of bicontinuous materials. Here, we show that when arrested phase separation is coupled to the time scales involved in three-dimensional (3D) printing processes, hydrogels with multiple length scales spanning nanometers to millimeters can be printed with high fidelity. We use an oil-in-water nanoemulsion-based ink with rheological and photoreactive properties that satisfy the requirements of stereolithographic 3D printing. This ink is thermoresponsive and consists of poly(dimethyl siloxane) droplets suspended in an aqueous phase containing the surfactant sodium dodecyl sulfate and the cross-linker poly(ethylene glycol) dimethacrylate. Control of the hydrogel microstructure can be achieved in the printing process due to the rapid structural recovery of the nanoemulsions after large strain-rate yielding, as well as the shear thinning behavior that allows the ink to conform to the build platform of the printer. Wiper operations are used to ensure even spreading of the yield stress ink on the optical window between successive print steps. Post-processing of the printed samples is used to generate mesoporous hydrogels that serve as size-selective membranes. Our work demonstrates that nanoemulsions, which belong to a class of solution-based materials with flexible functionalities, can be printed into prototypes with complex shapes using a commercially available 3D printer with a few modifications.}, number={5}, journal={SOFT MATTER}, author={Hsiao, Lilian C. and Badruddoza, Abu Zayed Md and Cheng, Li-Chiun and Doyle, Patrick S.}, year={2017}, month={Feb}, pages={921–929} }
 @article{cheng_hsiao_doyle_2017, title={Multiple particle tracking study of thermally-gelling nanoemulsions}, volume={13}, ISSN={["1744-6848"]}, url={https://doi.org/10.1039/C7SM01191A}, DOI={10.1039/c7sm01191a}, abstractNote={We demonstrate that, by tailoring the MPT probe surface chemistry, we can control the residence of probes in each domain in thermally-gelling nanoemulsions, thus allowing us to independently probe each phase at rising temperatures.}, number={37}, journal={SOFT MATTER}, author={Cheng, Li-Chiun and Hsiao, Lilian C. and Doyle, Patrick S.}, year={2017}, month={Oct}, pages={6606–6619} }
 @article{hsiao_jamali_glynos_green_larson_solomon_2017, title={Rheological State Diagrams for Rough Colloids in Shear Flow}, volume={119}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.119.158001}, abstractNote={To assess the role of particle roughness in the rheological phenomena of concentrated colloidal suspensions, we develop model colloids with varying surface roughness length scales up to 10% of the particle radius. Increasing surface roughness shifts the onset of both shear thickening and dilatancy towards lower volume fractions and critical stresses. Experimental data are supported by computer simulations of spherical colloids with adjustable friction coefficients, demonstrating that a reduction in the onset stress of thickening and a sign change in the first normal stresses occur when friction competes with lubrication. In the quasi-Newtonian flow regime, roughness increases the effective packing fraction of colloids. As the shear stress increases and suspensions of rough colloids approach jamming, the first normal stresses switch signs and the critical force required to generate contacts is drastically reduced. This is likely a signature of the lubrication films giving way to roughness-induced tangential interactions that bring about load-bearing contacts in the compression axis of flow.}, number={15}, journal={PHYSICAL REVIEW LETTERS}, author={Hsiao, Lilian C. and Jamali, Safa and Glynos, Emmanouil and Green, Peter F. and Larson, Ronald G. and Solomon, Michael J.}, year={2017}, month={Oct} }
 @article{hsiao_saha-dalal_larson_solomon_2017, title={Translational and rotational dynamics in dense suspensions of smooth and rough colloids}, volume={13}, ISSN={1744-683X 1744-6848}, url={http://dx.doi.org/10.1039/c7sm02115a}, DOI={10.1039/c7sm02115a}, abstractNote={We demonstrate that colloidal particles with surface roughness exhibit hindered rotational diffusion in quiescent dense suspensions.}, number={48}, journal={Soft Matter}, publisher={Royal Society of Chemistry (RSC)}, author={Hsiao, Lilian C. and Saha-Dalal, Indranil and Larson, Ronald G. and Solomon, Michael J.}, year={2017}, pages={9229–9236} }
 @article{hsiao_doyle_2015, title={Celebrating Soft Matter's 10th Anniversary: Sequential phase transitions in thermoresponsive nanoemulsions}, volume={11}, ISSN={1744-683X 1744-6848}, url={http://dx.doi.org/10.1039/c5sm01581b}, DOI={10.1039/c5sm01581b}, abstractNote={We report the coexistence of stress-bearing percolation with arrested phase separation in a colloidal system of thermoresponsive nanoemulsions spanning a broad range of volume fractions (0.10 ≤ ϕ ≤ 0.33) and temperatures (22 °C ≤ T ≤ 65 °C). Here, gelation is driven by short-range interdroplet polymer bridging at elevated temperatures. Direct visualization of the gel microstructure shows that nanoemulsions undergo a homogenous percolation transition prior to phase separation. Rheological characterization shows that both the percolated and the phase separated structures are capable of supporting a significant amount of elastic stress. As the system is heated, the sequential onset of these phase transitions is responsible for the unusual two-step increase in the linear viscoelasticity of the gels. In addition, we find that slowing the heating rate significantly reduces the elasticity of the gels at high temperatures. Our results suggest that the formation of metastable gelled states not only depends on the attraction strength and volume fraction of the system, but is also sensitive to the rate at which the attraction strength is increased.}, number={43}, journal={Soft Matter}, publisher={Royal Society of Chemistry (RSC)}, author={Hsiao, Lilian C. and Doyle, Patrick S.}, year={2015}, pages={8426–8431} }
 @article{hsiao_schultz_glaser_engel_szakasits_glotzer_solomon_2015, title={Metastable orientational order of colloidal discoids}, volume={6}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/ncomms9507}, DOI={10.1038/ncomms9507}, abstractNote={Abstract}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Hsiao, Lilian C. and Schultz, Benjamin A. and Glaser, Jens and Engel, Michael and Szakasits, Megan E. and Glotzer, Sharon C. and Solomon, Michael J.}, year={2015}, month={Oct} }
 @article{hsiao_solomon_whitaker_furst_2014, title={A model colloidal gel for coordinated measurements of force, structure, and rheology}, volume={58}, ISSN={0148-6055 1520-8516}, url={http://dx.doi.org/10.1122/1.4884965}, DOI={10.1122/1.4884965}, abstractNote={We introduce a model gel system in which colloidal forces, structure, and rheology are measured by balancing the requirements of rheological and microscopy techniques with those of optical tweezers. Sterically stabilized poly(methyl methacrylate) colloids are suspended in cyclohexane (CH) and cyclohexyl bromide (CHB) with dilute polystyrene serving as a depletion agent. A study of the optical trap strength, rheology, and microscopic structure of the gels as a function of CH/CHB solvent composition identifies the conditions for which these measurements can be applied to characterize gel properties. The results indicate that a solvent comprising 37% weight fraction CH (wCH = 0.37) provides sufficient refractive index contrast to enable optical trapping, while maintaining good confocal microscopy imaging quality and minimal sedimentation effects on the bulk rheology. At this condition, and at a depletant concentration c = 8.64 mg/ml (c/c* = 0.81), results from optical trapping in a dilute sample show that 50...}, number={5}, journal={Journal of Rheology}, publisher={Society of Rheology}, author={Hsiao, Lilian C. and Solomon, Michael J. and Whitaker, Kathryn A. and Furst, Eric M.}, year={2014}, month={Sep}, pages={1485–1504} }
 @article{hsiao_kang_ahn_solomon_2014, title={Role of shear-induced dynamical heterogeneity in the nonlinear rheology of colloidal gels}, volume={10}, ISSN={1744-683X 1744-6848}, url={http://dx.doi.org/10.1039/c4sm01375a}, DOI={10.1039/c4sm01375a}, abstractNote={We report the effect of flow-induced dynamical heterogeneity on the nonlinear elastic modulus of weakly aggregated colloidal gels that have undergone yielding by an imposed step strain deformation. The gels are comprised of sterically stabilized poly(methyl methacrylate) colloids interacting through short-ranged depletion attractions. When a step strain of magnitude varying from γ = 0.1 to 80.0 is applied to the quiescent gels, we observe the development of a bimodal distribution in the single-particle van Hove self-correlation function. This distribution is consistent with the existence of a fast and slow subpopulation of colloids within sheared gels. We evaluate the effect of incorporating the properties of the slow, rigid subpopulation of the colloids into a recent mode coupling theory for the nonlinear elasticity of colloidal gels.}, number={46}, journal={Soft Matter}, publisher={Royal Society of Chemistry (RSC)}, author={Hsiao, Lilian C. and Kang, Heekyoung and Ahn, Kyung Hyun and Solomon, Michael J.}, year={2014}, month={Oct}, pages={9254–9259} }
 @article{hsiao_newman_glotzer_solomon_2012, title={Role of isostaticity and load-bearing microstructure in the elasticity of yielded colloidal gels}, volume={109}, ISSN={0027-8424 1091-6490}, url={http://dx.doi.org/10.1073/pnas.1206742109}, DOI={10.1073/pnas.1206742109}, abstractNote={We report a simple correlation between microstructure and strain-dependent elasticity in colloidal gels by visualizing the evolution of cluster structure in high strain-rate flows. We control the initial gel microstructure by inducing different levels of isotropic depletion attraction between particles suspended in refractive index matched solvents. Contrary to previous ideas from mode coupling and micromechanical treatments, our studies show that bond breakage occurs mainly due to the erosion of rigid clusters that persist far beyond the yield strain. This rigidity contributes to gel elasticity even when the sample is fully fluidized; the origin of the elasticity is the slow Brownian relaxation of rigid, hydrodynamically interacting clusters. We find a power-law scaling of the elastic modulus with the stress-bearing volume fraction that is valid over a range of volume fractions and gelation conditions. These results provide a conceptual framework to quantitatively connect the flow-induced microstructure of soft materials to their nonlinear rheology.}, number={40}, journal={Proceedings of the National Academy of Sciences}, publisher={Proceedings of the National Academy of Sciences}, author={Hsiao, L. C. and Newman, R. S. and Glotzer, S. C. and Solomon, M. J.}, year={2012}, month={Sep}, pages={16029–16034} }
 @article{lehmann-ziebarth_heideman_shapiro_stoddart_hsiao_stephenson_milewski_ives_2005, title={Evolution of periodicity in periodical cicadas.}, volume={86}, ISSN={0012-9658}, url={http://dx.doi.org/10.1890/04-1615}, DOI={10.1890/04-1615}, abstractNote={Periodical cicadas present numerous puzzles for biologists. First, their period is fixed, with individuals emerging as adults precisely after either 13 or 17 years (depending on species). Second, even when there are multiple species of either 13- or 17-year cicadas at the same location, only one or rarely two broods (cohorts) co-occur, so that periodical cicada adults appear episodically. Third, the 13- or 17-year periods of cicadas suggest there is something important about prime numbers. Finally, single broods can dominate large areas, with geographical boundaries of broods remaining generally stable through time. While previous mathematical models have been used to investigate some of these puzzles individually, here we investigate them all simultaneously. Unlike previous models, we take an explicitly evolutionary approach. Although not enough information is known about periodical cicadas to draw firm conclusions, the theoretical arguments favor a combination of predator satiation and nymph competition as being key to the evolution of strictly fixed periods and occurrence of only one brood at most geographical locations. Despite ecological mechanisms that can select for strictly fixed periods, there seem to be no plausible ecological mechanisms that select for periods being prime numbers. This suggests that the explanation for prime-numbered periods, rather than just fixed periods, may reside in physiological or genetic mechanisms or constraints.}, number={12}, journal={Ecology}, publisher={Wiley}, author={Lehmann-Ziebarth, Nicolas and Heideman, Paul P. and Shapiro, Rebecca A. and Stoddart, Sonia L. and Hsiao, Chien Ching Lilian and Stephenson, Gordon R. and Milewski, Paul A. and Ives, Anthony R.}, year={2005}, month={Dec}, pages={3200–3211} }