@article{pratchayanan_yang_lewis_thoppey_anthamatten_2017, title={Thermomechanical insight into the reconfiguration of Diels-Alder networks}, volume={61}, ISSN={["0148-6055"]}, DOI={10.1122/1.4997580}, abstractNote={Relating thermoreversible bond kinetics to temperature and mechanical stress is essential to for the ongoing development of melt-processable, reconfigurable networks. Here, we apply the dynamic mechanical analysis methods to study the kinetics and equilibrium behavior of dynamic polymer networks above their gel point. Thermoreversible Diel–Alder (DA) adducts are installed as linking groups to create well-defined poly(caprolactone) networks. Stress relaxation studies at various strains are performed to differentiate how temperature and stress influence the rate of bond breaking, i.e., the rate of the retro-DA reaction. The resulting thermal activation energies of stress relaxation are nearly independent of applied stress over the experimental range studied. The forward, more sluggish, DA reaction is studied by continuously monitoring the response in Young's modulus (E′) following different temperature reductions. Equilibrium values of E′ are used to establish the temperature dependence of the DA equilibriu...}, number={6}, journal={JOURNAL OF RHEOLOGY}, author={Pratchayanan, Danaya and Yang, Jeh-Chang and Lewis, Christopher L. and Thoppey, Nagarajan and Anthamatten, Mitchell}, year={2017}, month={Nov}, pages={1359–1367} }
 @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{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{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{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} }