@article{zhai_koh_vogt_simon_2024, title={Kinetics of nanoconfined benzyl methacrylate radical polymerization}, ISSN={["2642-4169"]}, DOI={10.1002/pol.20230332}, abstractNote={Abstract}, journal={JOURNAL OF POLYMER SCIENCE}, author={Zhai, Chunhao and Koh, Yung P. and Vogt, Bryan D. and Simon, Sindee L.}, year={2024}, month={Feb} }
 @article{pallaka_simon_2024, title={The glass transition and enthalpy recovery of polystyrene nanorods using Flash differential scanning calorimetry}, volume={160}, ISSN={["1089-7690"]}, DOI={10.1063/5.0190076}, abstractNote={The glass transition (Tg) behavior and enthalpy recovery of polystyrene nanorods within an anodic aluminum oxide (AAO) template (supported nanorods) and after removal from AAO (unsupported nanorods) is studied using Flash differential scanning calorimetry. Tg is found to be depressed relative to the bulk by 20 ± 2 K for 20 nm-diameter unsupported polystyrene (PS) nanorods at the slowest cooling rate and by 9 ± 1 K for 55 nm-diameter rods. On the other hand, bulk-like behavior is observed in the case of unsupported 350 nm-diameter nanorods and for all supported rods in AAO. The size-dependent Tg behavior of the PS unsupported nanorods compares well with results for ultrathin films when scaled using the volume/surface ratio. Enthalpy recovery was also studied for the 20 and 350 nm unsupported nanorods with evolution toward equilibrium found to be linear with logarithmic time. The rate of enthalpy recovery for the 350 nm rods was similar to that for the bulk, whereas the rate of recovery was enhanced for the 20 nm rods for down-jump sizes larger than 17 K. A relaxation map summarizes the behavior of the nanorods relative to the bulk and relative to that for the 20 nm-thick ultrathin film. Interestingly, the fragility of the 20 nm-diameter nanorod and the 20 nm ultrathin film are identical within the error of measurements, and when plotted vs departure from Tg (i.e., T - Tg), the relaxation maps of the two samples are identical in spite of the fact that the Tg is depressed 8 K more in the nanorod sample.}, number={12}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Pallaka, Madhusudhan R. and Simon, Sindee L.}, year={2024}, month={Mar} }
 @article{koh_fondren_denton_simon_mckenna_2022, title={Amorphization and Crystallization of Hexanitroazobenzene (HNAB) Using Conventional DSC and Flash DSC}, ISSN={["1521-4087"]}, DOI={10.1002/prep.202100366}, abstractNote={Abstract}, journal={PROPELLANTS EXPLOSIVES PYROTECHNICS}, author={Koh, Yung P. and Fondren, Zachary T. and Denton, Aric A. and Simon, Sindee L. and McKenna, Gregory B.}, year={2022}, month={Aug} }
 @article{lopez_koh_zapata-hincapie_simon_2022, title={Composition-dependent glass transition temperature in mixtures: Evaluation of configurational entropy models}, ISSN={["1548-2634"]}, DOI={10.1002/pen.26018}, abstractNote={Abstract}, journal={POLYMER ENGINEERING AND SCIENCE}, author={Lopez, Evelyn and Koh, Yung P. and Zapata-Hincapie, John A. and Simon, Sindee L.}, year={2022}, month={May} }
 @article{tian_koh_orski_simon_2022, title={Dodecyl Methacrylate Polymerization under Nanoconfinement: Reactivity and Resulting Properties}, ISSN={["1520-5835"]}, DOI={10.1021/acs.macromol.1c01724}, abstractNote={The effect of nanoconfinement on the free radical polymerization of dodecyl methacrylate (DMA) with di-tert-butyl peroxide (DtBP) initiator is investigated over a wide temperature range from 110 to 190 °C using differential scanning calorimetry. The reaction shows a distinct induction time, which decreases as temperature increases, with an activation energy that is the same, albeit, of opposite sign, as that for dissociation of the initiator. The rate of reaction increases with increasing temperature and is higher in nanopores than in bulk conditions, with an Arrhenius temperature dependence at temperatures lower than 160 °C and an activation energy that is approximately 10% lower in the nanoconfined cases than for bulk. The higher reaction rate and lower activation energies in the nanopores are presumably due to specific interactions between the monomer and the native silanol groups on the pore surface. The enhancement of the reaction rate is found to be inversely related to the length of the alkyl group and the water contact angle comparerd data for several poly(n-alkyl methacrylate) studied previously. For bulk and nanoconfined DMA polymerizations, the molar mass increases as temperature decreases with a cross-linked product obtained at temperatures below 170 °C. The gel fraction increases as temperature decreases and is nearly 80% at 110 °C. In the nanopores, the molar mass is smaller compared to that in bulk conditions at high temperatures. The results can be described by a simplified recursive model.}, journal={MACROMOLECULES}, author={Tian, Qian and Koh, Yung P. and Orski, Sara V and Simon, Sindee L.}, year={2022}, month={Sep} }
 @article{pallaka_bari_simon_2022, title={Origin of the broad endothermic peak observed at low temperatures for polystyrene and metals in Flash differential scanning calorimetry}, volume={62}, ISSN={["1548-2634"]}, DOI={10.1002/pen.26102}, abstractNote={Abstract}, number={9}, journal={POLYMER ENGINEERING AND SCIENCE}, author={Pallaka, Madhusudhan R. and Bari, Rozana and Simon, Sindee L.}, year={2022}, month={Sep}, pages={3059–3069} }
 @article{sakib_koh_simon_2022, title={The absolute heat capacity of polymer grafted nanoparticles using fast scanning calorimetry}, ISSN={["1548-2634"]}, DOI={10.1002/pen.26078}, abstractNote={Abstract}, journal={POLYMER ENGINEERING AND SCIENCE}, author={Sakib, Nazam and Koh, Yung P. and Simon, Sindee L.}, year={2022}, month={Jul} }
 @article{zhao_grassia_simon_2021, title={Mobility of Pressure-Densified and Pressure-Expanded Polystyrene Glasses: Dilatometry and a Test of KAHR Model}, volume={54}, ISSN={["1520-5835"]}, DOI={10.1021/acs.macromol.1c00983}, abstractNote={The structural recovery of pressure-densified (PDG) and, for the first time, pressure-expanded (PEG) glasses are experimentally investigated using pressurizable dilatometry. Both glasses show early devitrification on heating, indicating that these glasses have more mobility, compared to the conventional isobarically formed glass. The Kovacs–Aklonis–Hutchinson–Ramos (KAHR) model of structural recovery is able to reasonably predict the behavior of the pressure-expanded glass, but the KAHR model fails with the pressure-densified glass. The results suggest two limitations of the model: (i) the structural recovery is assumed to depend on the instantaneous liquid state and (ii) the same relaxation kinetics are assumed for the temperature and pressure perturbations. Modification of the KAHR model, allowing the departure from equilibrium, δ, to initially depend on the liquid state that the glass came from and to evolve toward the state that the glass is going to, improves the ability of the model to predict the early devitrification for the pressure-densified glass. Another modification of the KAHR model, allowing the temperature and pressure perturbations to relax independently of one another, results in effectively capturing the increased thermal expansion coefficient of glass lines during heating, as well as a “memory”-like aging behavior, for the pressure-densified glass.}, number={18}, journal={MACROMOLECULES}, author={Zhao, Xiao and Grassia, Luigi and Simon, Sindee L.}, year={2021}, month={Sep}, pages={8352–8364} }
 @article{zhao_cheng_koh_kelly_mckenna_simon_2021, title={Prediction of the Synergistic Glass Transition Temperature of Coamorphous Molecular Glasses Using Activity Coefficient Models}, volume={18}, ISSN={["1543-8392"]}, DOI={10.1021/acs.molpharmaceut.1c00353}, abstractNote={The glass transition temperature (Tg) of a binary miscible mixture of molecular glasses, termed a coamorphous glass, is often synergistically increased over that expected for an athermal mixture due to the strong interactions between the two components. This synergistic interaction is particularly important for the formulation of coamorphous pharmaceuticals since the molecular interactions and resulting Tg strongly impact stability against crystallization, dissolution kinetics, and bioavailability. Current models that describe the composition dependence of Tg for binary systems, including the Gordon-Taylor, Fox, Kwei, and Braun-Kovacs equations, fail to describe the behavior of coamorphous pharmaceuticals using parameters consistent with experimental ΔCP and Δα. Here, we develop a robust thermodynamic approach extending the Couchman and Karasz method through the use of activity coefficient models, including the two-parameter Margules, non-random-two-liquid (NRTL), and three-suffix Redlich-Kister models. We find that the models, using experimental values of ΔCP and fitting parameters related to the binary interactions, successfully describe observed synergistic elevations and inflections in the Tg versus composition response of coamorphous pharmaceuticals. Moreover, the predictions from the NRTL model are improved when the association-NRTL version of that model is used. Results are reported and discussed for four different coamorphous systems: indomethacin-glibenclamide, indomethacin-arginine, acetaminophen-indomethacin, and fenretinide-cholic acid.}, number={9}, journal={MOLECULAR PHARMACEUTICS}, author={Zhao, Xiao and Cheng, Sixue and Koh, Yung P. and Kelly, Brandon D. and McKenna, Gregory B. and Simon, Sindee L.}, year={2021}, month={Sep}, pages={3439–3451} }