@article{patel_hunt_lin-gibson_bencherif_spontak_2005, title={Tunable CO2 transport through mixed polyether membranes}, volume={251}, ISSN={["1873-3123"]}, DOI={10.1016/j.memsci.2004.11.003}, abstractNote={Gas-separation membranes composed of polyethers such as poly(ethylene glycol)diacrylate (PEGda) or poly(propylene glycol)diacrylate (PPGda) exhibit high CO2 solubility selectivity, which makes them attractive for use in H2 and air purification. In this work, we investigate the factors governing CO2 and H2 transport in mixed polyether matrices. Addition of semicrystalline poly(ethylene oxide)s to amorphous PEGda lowers the net CO2 permeability and CO2/H2 selectivity due to crystal formation. Gas permeation through the amorphous fraction, however, remains unaffected, confirming the existence of a molecular weight limit below which the entire membrane participates in gas transport. The permeabilities of CO2 and H2, as well as their activation energy of permeation, in miscible PEGda/PPGda blends follow the linear rule of mixtures over the temperature range explored. Incorporation of amine moieties employed in liquid membranes into either the PEGda matrix during crosslinking or the PEG backbone generally reduces CO2/H2 selectivity but occasionally improves CO2 permeability.}, number={1-2}, journal={JOURNAL OF MEMBRANE SCIENCE}, author={Patel, NP and Hunt, MA and Lin-Gibson, S and Bencherif, S and Spontak, RJ}, year={2005}, month={Apr}, pages={51–57} }
 @article{patel_zielinski_samseth_spontak_2004, title={Effects of pressure and nanoparticle functionality on CO2-selective nanocomposites derived from crosslinked poly(ethylene glycol)}, volume={205}, ISSN={["1521-3935"]}, DOI={10.1002/macp.200400356}, abstractNote={Abstract}, number={18}, journal={MACROMOLECULAR CHEMISTRY AND PHYSICS}, author={Patel, NP and Zielinski, JM and Samseth, J and Spontak, RJ}, year={2004}, month={Dec}, pages={2409–2419} }
 @article{patel_spontak_2004, title={Gas-transport and thermal properties of a microphase-ordered poly(styrene-b-ethylene oxide-b-styrene) triblock copolymer and its blends with poly(ethylene glycol)}, volume={37}, ISSN={["0024-9297"]}, DOI={10.1021/ma049975k}, abstractNote={Block copolymers are under growing consideration as precursor materials for use in a wide variety of emerging nanotechnologies. While these materials can serve as ordered templates in the preparation of nanoporous membranes, they can also be designed for use as dense nanostructured polymer membranes exhibiting chemical specificity. In the present work, we explore the properties of a poly(styrene-b-ethylene oxide-b-styrene) (SEOS) triblock copolymer and its blends with poly(ethylene glycol) (PEG) as reverse-selective membranes due to their unusually high CO2 affinity. The permeability of CO2 measured as a function of blend composition, PEG molecular weight, and temperature is consistently found to exceed that of any other gas (H2, N2, or O2) examined here. Addition of PEG eventually results in a composition-dependent transition from an alternating lamellar to polyether-continuous morphology, as evidenced by both gas-transport and thermal properties, and a systematic variation in crystallinity that depends ...}, number={8}, journal={MACROMOLECULES}, author={Patel, NP and Spontak, RJ}, year={2004}, month={Apr}, pages={2829–2838} }
 @article{patel_spontak_2004, title={Mesoblends of polyether block copolymers with poly(ethylene glycol)}, volume={37}, ISSN={["1520-5835"]}, DOI={10.1021/ma0356257}, abstractNote={Mesoblends are conveniently generated by sorbing a parent homopolymer into a microphase-separated triblock or higher-order multiblock copolymer swollen by a block-selective solvent. These nonequilibrium systems afford a viable route by which to produce, in systematic fashion, novel copolymer/homopolymer blends as well as explore homopolymer transport and solubility within a molecularly confined polymer environment. In the present work, we have imbibed poly(ethylene glycol) (PEG) differing in molecular weight into a model poly(styrene-b-ethylene oxide-b-styrene) (SEOS) triblock copolymer and a commercial poly(amide-b-ethylene glycol) (AEG) multiblock copolymer. Solvent quality and solution concentration are found to have a profound effect on PEG solubility in both copolymers, whereas PEG molecular weight over the range 100−4600 is generally less influential. Transmission electron microscopy reveals the spatial distribution of amorphous PEG within the SEOS copolymer matrix, and complementary differential sc...}, number={4}, journal={MACROMOLECULES}, author={Patel, NP and Spontak, RJ}, year={2004}, month={Feb}, pages={1394–1402} }
 @article{patel_aberg_sanchez_capracotta_martin_spontak_2004, title={Morphological, mechanical and gas-transport characteristics of crosslinked poly(propylene glycol): homopolymers, nanocomposites and blends}, volume={45}, ISSN={["1873-2291"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-3342879397&partnerID=MN8TOARS}, DOI={10.1016/j.polymer.2004.06.024}, abstractNote={Linear polyethers possess unusually high CO2 solubility and, hence, selectivity due to the presence of accessible ether linkages that can interact with the quadrupolar moment of CO2 molecules. In this work, membranes derived from crosslinked poly(propylene glycol) diacrylate (PPGda) oligomers differing in molecular weight (M), as well as PPGda nanocomposites containing either an organically-modified montmorillonite clay or a methacrylate-terminated fumed silica are investigated and compared with highly CO2-selective poly(ethylene glycol) diacrylate (PEGda) homopolymer and nanocomposite membranes previously reported. The rheological and permeation properties of PPGda depend sensitively on M, with the elastic modulus decreasing, but CO2 permeability and CO2/H2 selectivity increasing, with increasing M. Incorporation of either nanofiller into PPGda enhances the elastic modulus and reduces the gas permeability in the resultant nanocomposites without strongly affecting CO2/H2 selectivity. Blending PPGda and PEGda prior to chemical crosslinking yields binary membranes that exhibit intermediate gas-transport properties accurately described by a linear rule of mixtures.}, number={17}, journal={POLYMER}, author={Patel, NP and Aberg, CM and Sanchez, AM and Capracotta, MD and Martin, JD and Spontak, RJ}, year={2004}, month={Aug}, pages={5941–5950} }
 @article{patel_miller_spontak_2003, title={Highly CO2-permeable and selective polymer nanocomposite membranes}, volume={15}, ISSN={["0935-9648"]}, DOI={10.1002/adma.200304712}, abstractNote={As technologies turn to more efficient routesto remove CO2from mixed gas streams for H2or air purification, new cost‐effective multifunctional materials are needed for the separation processes. Here, hybrid poly(ethylene glycol)/fumed silica nanocomposite membranes exhibiting high CO2/H2selectivity (> 11) and CO2permeability (∼ 83 Barrer), as well as robust mechanical properties and optical clarity, are reported (see Figure).}, number={9}, journal={ADVANCED MATERIALS}, author={Patel, NP and Miller, AC and Spontak, RJ}, year={2003}, month={May}, pages={729–733} }
 @article{stevens_thongruang_patel_smith_spontak_2003, title={Solvent-facilitated homopolymer sorption in swollen block copolymer matrices}, volume={36}, ISSN={["1520-5835"]}, DOI={10.1021/ma0215868}, abstractNote={Homopolymer sorption in microphase-ordered block copolymers can provide insight into the factors governing transport of chain molecules in dense nanostructured environments, as well as yield novel nonequilibrium materials. Here, we examine the sorption of homopolymer B (hB) in ABA triblock copolymers swollen in a B-selective solvent. Gravimetric analysis reveals that the solubility of hB (ShB) varies linearly with solution concentration (C) and that (∂ShB/∂C)T depends on the molecular weight of the B midblock (MB). These data also show that the effective diffusion coefficient of hB is ∼10-8 cm2/s, independent of MB.}, number={9}, journal={MACROMOLECULES}, author={Stevens, JE and Thongruang, W and Patel, NP and Smith, SD and Spontak, RJ}, year={2003}, month={May}, pages={3206–3209} }
 @article{roberge_patel_white_thongruang_smith_spontak_2002, title={Block copolymer/homopolymer mesoblends: Preparation and characterization}, volume={35}, ISSN={["1520-5835"]}, DOI={10.1021/ma0115747}, abstractNote={Miscible block copolymer/homopolymer blends are typically prepared from homogeneous solutions in a nonselective solvent. During solvent removal and subsequent annealing, the molecular species comprising such blends organize in such fashion as to lower the system free energy and ideally attain thermodynamic equilibrium. In this work, we investigate nonequilibrium triblock copolymer/homopolymer (ABA/hB) blends generated by diffusing hB molecules from a hB-selective solvent into a lamellar ABA copolymer. Since the copolymer is already microphase-ordered during homopolymer incorporation, we refer to such blends as mesoblends. The mass uptake of hB is found to be strongly dependent on homopolymer molecular weight (MhB), with the maximum solubility scaling as MhB-1. An induction period that scales as MhB1/2 is also observed. Transmission electron microscopy reveals that the morphology of these mesoblends appears to be perforated lamellar, which, in some cases, transforms to cylindrical upon annealing. Dynamic m...}, number={6}, journal={MACROMOLECULES}, author={Roberge, RL and Patel, NP and White, SA and Thongruang, W and Smith, SD and Spontak, RJ}, year={2002}, month={Mar}, pages={2268–2276} }