@article{shamsi_wells_yan_dickey_spontak_2024, title={Thermoplastic Elastomers and Their Physical Gels Electrospun into Tunable Microfibrous Nonwoven Mats: Structure Formation and Property Enhancement}, volume={9}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202314013}, abstractNote={Abstract Thermoplastic elastomers (TPEs) based on styrenic block copolymers constitute excellent examples of self‐networking macromolecules that are employed in a wide range of contemporary technologies as molded parts. In such applications, these TPEs exist as dense (nonporous) films or other shapes. Here, it is first demonstrated that a series of commercial TPEs possessing comparable compositions can be electrospun from solution to form microfibers that are arranged into nonwoven mats that are breathable. An important consideration for microfiber formation is the copolymer molecular weight, which regulates i) the viscosity of the parent solution prior to electrospinning, ii) the ability of these copolymers to self‐assemble during electrospinning, iii) the microfiber morphology, and iv) the mechanical properties of the resultant microfibers. The addition of a midblock‐selective aliphatic oil to these TPEs yields thermoplastic elastomer gels (TPEGs), wherein the copolymer morphology and mechanical properties become highly composition‐tunable. Electrospinning TPEGs from a binary oil+solvent solution introduces a micelle inversion mechanism that begins with an oil‐rich micellar core and ends with a styrene‐rich micellar core, required for network stabilization, as the solvent dries during microfiber solidification. This work has implications for the production of controllably low‐modulus microfibrous materials possessing modestly improved toughness but exceptional extensibility and enhanced optical transparency.}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Shamsi, Mohammad and Wells, Kacie M. and Yan, Jiaqi and Dickey, Michael D. and Spontak, Richard J.}, year={2024}, month={Sep} }
 @article{dai_guo_deng_deng_yan_spontak_2023, title={Carbon molecular-sieve membranes developed from a Troger's base polymer and possessing superior gas-separation performance}, volume={680}, ISSN={["1873-3123"]}, DOI={10.1016/j.memsci.2023.121731}, abstractNote={Carbon molecular-sieve membranes possess tremendous practical advantages over unary polymer membranes by providing high gas-separation performance levels, coupled with excellent mechanical and chemical stability. Improving their overall effectiveness greatly expands the competitiveness of this class of membranes. In the present study, carbon membranes are fabricated from a Tröger’s base polymer as the precursor. By optimizing the carbonization conditions, the gas-separation performance of the resultant membranes are significantly enhanced. Under optimized conditions, a H2 permeability of up to 1135 Barrer is achieved, with a corresponding H2/CH4 selectivity of 1170 and a CO2/CH4 selectivity of 238. While increasing the operating temperature slightly reduces the selectivity, it still remains in the high-separation region. Overall, the measured separation performance levels for H2-related separations, i.e., H2/CH4, H2/N2 and H2/CO2, all substantially exceed the Robeson upper bound. Moreover, the CO2/CH4 separation efficacy also lies above the 2019 upper bound, indicating that the carbon membranes developed in the present work are versatile and promising for many different gas-separation applications.}, journal={JOURNAL OF MEMBRANE SCIENCE}, author={Dai, Zhongde and Guo, Hongfang and Deng, Jing and Deng, Liyuan and Yan, Jiaqi and Spontak, Richard J.}, year={2023}, month={Aug} }
 @article{yan_lee_smith_spontak_2021, title={Morphological Studies of Solution-Crystallized Thermoplastic Elastomers with Polyethylene Endblocks and a Random-Copolymer Midblock}, volume={9}, ISSN={["1521-3927"]}, DOI={10.1002/marc.202100442}, abstractNote={AbstractStyrenic thermoplastic elastomers (TPEs) in the form of triblock copolymers possessing glassy endblocks and a rubbery midblock account for the largest global market of TPEs worldwide, and typically rely on microphase separation of the endblocks and the subsequent formation of rigid microdomains to ensure satisfactory network stabilization. In this study, the morphological characteristics of a relatively new family of crystallizable TPEs that instead consist of polyethylene endblocks and a random‐copolymer midblock composed of styrene and (ethylene‐co‐butylene) moieties are investigated. Copolymer solutions prepared at logarithmic concentrations in a slightly endblock‐selective solvent are subjected to crystallization under different time and temperature conditions to ascertain if copolymer self‐assembly is directed by endblock crystallization or vice versa. According to transmission electron microscopy, semicrystalline aggregates develop at the lowest solution concentration examined (0.01 wt%), and the size and population of crystals, which dominate the copolymer morphologies, are observed to increase with increasing aging time. Real‐space results are correlated with small‐ and wide‐angle X‐ray scattering to elucidate the concurrent roles of endblock crystallization and self‐assembly of these unique TPEs in solution.}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, author={Yan, Jiaqi and Lee, Byeongdu and Smith, Steven D. and Spontak, Richard J.}, year={2021}, month={Sep} }
 @article{peddinti_downs_yan_smith_ghiladi_mhetar_tocchetto_griffiths_scholle_spontak_2021, title={Rapid and Repetitive Inactivation of SARS-CoV-2 and Human Coronavirus on Self-Disinfecting Anionic Polymers}, volume={8}, ISSN={["2198-3844"]}, DOI={10.1002/advs.202003503}, abstractNote={AbstractWhile the ongoing COVID‐19 pandemic affirms an urgent global need for effective vaccines as second and third infection waves are spreading worldwide and generating new mutant virus strains, it has also revealed the importance of mitigating the transmission of SARS‐CoV‐2 through the introduction of restrictive social practices. Here, it is demonstrated that an architecturally‐ and chemically‐diverse family of nanostructured anionic polymers yield a rapid and continuous disinfecting alternative to inactivate coronaviruses and prevent their transmission from contact with contaminated surfaces. Operating on a dramatic pH‐drop mechanism along the polymer/pathogen interface, polymers of this archetype inactivate the SARS‐CoV‐2 virus, as well as a human coronavirus surrogate (HCoV‐229E), to the minimum detection limit within minutes. Application of these anionic polymers to frequently touched surfaces in medical, educational, and public‐transportation facilities, or personal protection equipment, can provide rapid and repetitive protection without detrimental health or environmental complications.}, number={11}, journal={ADVANCED SCIENCE}, author={Peddinti, Bharadwaja S. T. and Downs, Sierra N. and Yan, Jiaqi and Smith, Steven D. and Ghiladi, Reza A. and Mhetar, Vijay and Tocchetto, Roger and Griffiths, Anthony and Scholle, Frank and Spontak, Richard J.}, year={2021}, month={Jun} }
 @article{dai_zhu_yan_su_gao_zhang_ke_parsons_2020, title={An Advanced Dual-Function MnO2-Fabric Air Filter Combining Catalytic Oxidation of Formaldehyde and High-Efficiency Fine Particulate Matter Removal}, volume={30}, ISSN={["1616-3028"]}, url={https://doi.org/10.1002/adfm.202001488}, DOI={10.1002/adfm.202001488}, abstractNote={AbstractComprehensive treatment of indoor contaminants such as volatile organic compounds (VOCs) and fine particulate matter (PM2.5) using transition metal oxide catalysts or functional fibrous filters has gained substantial attention recently. However, coupling VOC oxidation catalysts into high‐performance filter systems remains a challenge. Herein, an overall solution to strongly bind manganese dioxide (MnO2) nanocrystals onto polypropylene (PP) nonwoven fabrics is provided. For the first time, uniform heterogeneous nucleation and growth of MnO2 onto PP nonwoven fabrics using intermediate inorganic nucleation films, including Al2O3, TiO2, and ZnO, formed conformally on the fabrics via atomic layer deposition (ALD) are demonstrated. How different ALD thin films influence the crystallinity, morphology, surface area, and surface oxygen species of the MnO2 grown ALD‐coated PP fibers is further investigated. In addition to uniformity and integrity, ZnO thin films give rise to MnO2 crystals with the largest fraction of available surface oxygen, enabling 99.5% catalytic oxidation of formaldehyde within 60 min. Moreover, the metal oxide filters provide excellent PM removal efficiencies (ePM), achieving ePM2.5 90% and ePM10 98%, respectively, making the approach an outstanding method to produce fully dual‐functional filtration media.}, number={42}, journal={ADVANCED FUNCTIONAL MATERIALS}, publisher={Wiley}, author={Dai, Zijian and Zhu, Jie and Yan, Jiaqi and Su, Jiafei and Gao, Yunfei and Zhang, Xing and Ke, Qinfei and Parsons, Gregory N.}, year={2020}, month={Oct} }
 @article{dai_lee_shi_wang_barton_zhu_yan_ke_parsons_2020, title={Fabrication of Freestanding Metal Organic Framework Predominant Hollow Fiber Mat and Its Potential Applications in Gas Separation and Catalysis}, url={https://doi.org/10.1039/C9TA11701F}, DOI={10.1039/c9ta11701f}, abstractNote={Freestanding MOF predominant hollow fiber mats are fabricatedviaan oxide-to-MOF conversion approach. The unique hollow fiber mats show promising potential in CO2adsorption, CO2/N2separation, and VOC abatement applications.}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Dai, Zijian and Lee, Dennis and Shi, Kaihang and Wang, Siyao and Barton, Heather F and Zhu, Jie and Yan, Jiaqi and Ke, Qinfei and Parsons, Gregory N}, year={2020} }
 @article{yan_yan_tilly_ko_lee_spontak_2020, title={Ionic Complexation of Endblock-Sulfonated Thermoplastic Elastomers and Their Physical Gels for Improved Thermomechanical Performance}, volume={2}, DOI={10.1016/j.jcis.2020.02.007}, abstractNote={Thermoplastic elastomers (TPEs) composed of nonpolar triblock copolymers constitute a broadly important class of (re)processable network-forming macromolecules employed in ubiquitous commercial applications. Physical gelation of these materials in the presence of a low-volatility oil that is midblock-selective yields tunably soft TPE gels (TPEGs) that are suitable for emergent technologies ranging from electroactive, phase-change and shape-memory responsive media to patternable soft substrates for flexible electronics and microfluidics. Many of the high-volume TPEs used for these purposes possess styrenic endblocks that are inherently limited by a relatively low glass transition temperature. To mitigate this shortcoming, we sulfonate and subsequently complex (and physically crosslink) the endblocks with trivalent Al3+ ions. Doing so reduces the effective hydrophilicity of the sulfonated endblocks, as evidenced by water uptake measurements, while concurrently enhancing the thermomechanical stability of the corresponding TPEGs. Chemical modification results, as well as morphological and property development, are investigated as functions of the degree of sulfonation, complexation and TPEG composition.}, journal={Journal of Colloid and Interface Science}, publisher={Elsevier BV}, author={Yan, Jiaqi and Yan, Shaoyi and Tilly, Joseph C. and Ko, Yeongun and Lee, Byeongdu and Spontak, Richard J.}, year={2020}, month={Feb} }
 @article{tiedemann_yan_barent_spontak_floudas_frey_register_2020, title={Tapered Multiblock Star Copolymers: Synthesis, Selective Hydrogenation, and Properties}, volume={5}, DOI={10.1021/acs.macromol.0c00645}, abstractNote={Two series of well-defined multiblock four-arm tapered star copolymers with “arms” of the type poly(styrene)-block-poly(isoprene-grad-styrene), (SI/S)4, were synthesized on a multigram scale with s...}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Tiedemann, Philipp and Yan, Jiaqi and Barent, Ramona D. and Spontak, Richard J. and Floudas, George and Frey, Holger and Register, Richard A.}, year={2020}, month={May} }
 @article{deng_dai_yan_sandru_sandru_spontak_deng_2019, title={Facile and solvent-free fabrication of PEG-based membranes with interpenetrating networks for CO2 separation}, volume={570}, ISSN={["1873-3123"]}, DOI={10.1016/j.memsci.2018.10.031}, abstractNote={For nearly two decades, membranes derived from polyethers have served as promising candidate materials for CO2 separation. Due to the inherent tendency of high-molecular-weight poly(ethylene oxide) (PEO) to crystallize and thus reduce its CO2 permeability, prior studies have focused on membranes produced from low-molecular-weight poly(ethylene glycol) (PEG). In this work, a novel series of cross-linked PEG-based membranes composed of interpenetrating polymer networks has been generated through the use of amine-terminated Jeffamine and multiple acrylate-functionalized cross-linkers in a facile, solvent-free, two-stage reaction. Evidence of cross-linked interpenetrating polymer networks formed by aza-Michael addition and acrylate polymerization is confirmed by real-time fourier-transform infrared spectroscopy. In addition, we systematically investigate the thermal stability, mechanical properties and water sorption of these multicomponent membranes. Corresponding CO2 and N2 transport properties, evaluated by single-gas permeation tests, are found to depend on both the chemical nature of the cross-linkers and the ratio of the interpenetrating networks. Moreover, free PEG dimethyl ether has been added into the optimized cross-linked matrix at different loading levels to further enhance gas-transport properties.}, journal={JOURNAL OF MEMBRANE SCIENCE}, publisher={Elsevier BV}, author={Deng, Jing and Dai, Zhongde and Yan, Jiaqi and Sandru, Marius and Sandru, Eugenia and Spontak, Richard J. and Deng, Liyuan}, year={2019}, month={Jan}, pages={455–463} }
 @article{dai_deng_aboukeila_yan_ansaloni_mineart_baschetti_spontak_deng_2019, title={Highly CO2-permeable membranes derived from a midblock-sulfonated multiblock polymer after submersion in water}, volume={11}, DOI={10.1038/s41427-019-0155-5}, abstractNote={AbstractTo mitigate the effect of atmospheric CO2 on global climate change, gas separation materials that simultaneously exhibit high CO2 permeability and selectivity in gas mixtures must be developed. In this study, CO2 transport through midblock-sulfonated block polymer membranes prepared from four different solvents is investigated. The results presented here establish that membrane morphology and accompanying gas transport properties are sensitive to casting solvent and relative humidity. We likewise report an intriguing observation: submersion of these thermoplastic elastomeric membranes in liquid water, followed by drying prior to analysis, promotes not only a substantial change in membrane morphology, but also a significant improvement in both CO2 permeability and CO2/N2 selectivity. Measured CO2 permeability and CO2/N2 selectivity values of 482 Barrer and 57, respectively, surpass the Robeson upper bound, indicating that these nanostructured membranes constitute promising candidates for gas separation technologies aimed at CO2 capture.}, number={1}, journal={NPG Asia Materials}, publisher={Springer Science and Business Media LLC}, author={Dai, Zhongde and Deng, Jing and Aboukeila, Hesham and Yan, Jiaqi and Ansaloni, Luca and Mineart, Kenneth P. and Baschetti, Marco Giacinti and Spontak, Richard J. and Deng, Liyuan}, year={2019}, month={Oct} }
 @article{yan_spontak_2019, title={Toughening Poly(lactic acid) with Thermoplastic Elastomers Modified by Thiol–ene Click Chemistry}, volume={7}, DOI={10.1021/acssuschemeng.9b01657}, abstractNote={Due primarily to the inherent brittleness of poly(lactic acid) (PLA), numerous studies have sought to improve the mechanical properties (e.g., fracture toughness) of PLA for a wide range of contemporary applications. In this study, we report a facile method by which to prepare esterified poly[styrene-b-(ethylene-alt-propylene)-b-styrene] (eSEPS) as a toughening agent for PLA through the use of thiol–ene click chemistry. The effects of adding 1 to 30 wt % eSEPS on the thermomechanical properties and morphological characteristics of PLA/eSEPS blends have been systematically investigated. Since eSEPS copolymers are more thermodynamically compatible with PLA than their parent partially hydrogenated SIS copolymer, we find a measurable reduction in the thermal properties of PLA from thermal calorimetry and enhanced dispersion of eSEPS within the PLA matrix according to electron microscopy. Considerable boosts in mechanical properties such as toughness (∼60 MJ/m3) and elongation at break (∼470%) are about 16× an...}, number={12}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Yan, Jiaqi and Spontak, Richard J.}, year={2019}, month={May}, pages={10830–10839} }
 @article{deng_yan_tilly_deng_mineart_spontak_2018, title={Incorporation of Metallic Species into Midblock-Sulfonated Block Ionomers}, volume={39}, ISSN={["1521-3927"]}, DOI={10.1002/marc.201800427}, abstractNote={AbstractBlock ionomers can, in the same fashion as their neutral block copolymer analogs, microphase‐order into various nanoscale morphologies. The added benefit of a copolymer possessing a charged species is that the resultant block ionomer becomes amphiphilic and capable of imbibing polar liquids, including water. This characteristic facilitates incorporation of metallic species into the soft nanostructure for a wide range of target applications. In this study, the nonpolar and polar constituents of solvent‐templated midblock‐sulfonated block ionomers (SBIs) are first selectively metallated for complementary morphological analysis. Next, four different salts, with cationic charges ranging from +1 to +3, are introduced into three hydrated SBIs varying in their degree of sulfonation (DOS), and cation uptake is measured as a function of immersion time. These results indicate that uptake generally increases with increasing salt concentration, cationic charge, and specimen DOS. Swelling and nanoindentation measurements conducted at ambient temperature demonstrate that water uptake decreases, while the surface modulus increases, with increasing cationic charge. Chemical spectra acquired from energy‐dispersive X‐ray spectroscopy (EDS) confirm the presence of each of the ion‐exchanged species, and corresponding EDS chemical maps reveal that the spatial distribution of these species is relatively uniform throughout the block ionomer films.}, number={22}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, publisher={Wiley}, author={Deng, Jing and Yan, Jiaqi and Tilly, Joseph C. and Deng, Liyuan and Mineart, Kenneth P. and Spontak, Richard J.}, year={2018}, month={Nov} }