@article{ito_shiota_taniguchi_spontak_nagai_2020, title={Gas-separation and physical properties of ABA triblock copolymers synthesized from polyimide and hydrophilic adamantane derivatives}, volume={202}, ISSN={["1873-2291"]}, DOI={10.1016/j.polymer.2020.122642}, abstractNote={In this study, ABA triblock copolymers derived from 4,4’-(hexafluoroisopropylidene)-diphthalic anhydride-2,3,5,6-tetramethyl-1,4-phenylenediamine (6FDA-TeMPD; PI) and 3-hydroxy-1-adamantyl methacrylate (HAdMA) or 3,5-dihydroxy-1-adamantyl methacrylate (DHAdMA) have been synthesized via atom transfer radical polymerization to generate mechanically tough and thermally stable gas-separation membranes with composition-tunable transport properties. Due to the inherent thermodynamic incompatibility between the chemically dissimilar blocks, these two series of triblock copolymers appear microphase-separated. While the gas permeability coefficients of these triblock copolymer membranes are consistently lower than that of PI due to the reduced fractional free volume of HAdMA and DHAdMA, the solubility coefficients of the copolymers are higher than that of PI due presumably to specific interactions between the polar hydroxyl group(s) and penetrant gas molecules. These triblock copolymers synthesized from PI and hydrophilic adamantane derivatives constitute a new class of nanostructured polymeric materials possessing excellent thermomechanical properties in conjunction with designer gas-separation properties.}, journal={POLYMER}, author={Ito, Tsubasa and Shiota, Ryunosuke and Taniguchi, Naomi and Spontak, Richard J. and Nagai, Kazukiyo}, year={2020}, month={Aug} }
 @article{arnold_nagai_spontak_freeman_leroux_betts_desimone_digiano_stebbins_linton_et al._2002, title={Microphase-Separated Block Copolymers Comprising Low Surface Energy Fluorinated Blocks and Hydrophilic Blocks:  Synthesis and Characterization}, volume={35}, ISSN={0024-9297 1520-5835}, url={http://dx.doi.org/10.1021/ma0119631}, DOI={10.1021/ma0119631}, abstractNote={The synthesis and characterization of diblock and triblock copolymers produced by a two-component iniferter system is reported. These materials, designed for possible water treatment applications, consist of a hydrophilic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) block and a very low surface energy poly(1,1‘-dihydroperfluorooctyl methacrylate) (PFOMA) or poly(1,1,2,2-tetrahydroperfluorooctyl acrylate) (PTAN) block. Angle-dependent X-ray spectroscopy results and water contact angle measurements indicate that the surfaces of PDMAEMA-b-PFOMA diblock copolymers consist primarily of PFOMA. Transmission electron microscopy reveals that the block copolymers are microphase-separated, exhibiting either cylindrical or layered morphologies that do not change appreciably upon exposure to water. Both water uptake and water flux increase with increasing PDMAEMA content.}, number={9}, journal={Macromolecules}, publisher={American Chemical Society (ACS)}, author={Arnold, M. E. and Nagai, K. and Spontak, Richard and Freeman, B. D. and Leroux, D. and Betts, D. E. and Desimone, J. M. and Digiano, F. A. and Stebbins, C. K. and Linton, R. W. and et al.}, year={2002}, month={Apr}, pages={3697–3707} }
 @article{yampolskii_korikov_shantarovich_nagai_freeman_masuda_teraguchi_kwak_2001, title={Gas permeability and free volume of highly branched substituted acetylene polymers}, volume={34}, ISSN={["1520-5835"]}, DOI={10.1021/ma000628u}, abstractNote={Gas permeation, sorption, and structural properties of two highly branched polyacetylenes, poly[1-phenyl-2-[p-(triphenylsilyl)phenyl]acetylene] (PPhSiDPA) and poly[1-phenyl-2-[p-(triisopropylsilyl)phenyl]acetylene] (PPrSiDPA), are reported. Structurally, both polymers have much in common; however, their transport properties are quite different. PPhSiDPA has dramatically lower permeability coefficients than PPrSiDPA. For example, the O2 permeability coefficients of PPhSiDPA and PPrSiDPA are 12 × 10-10 and 230 × 10-10 cm3 (STP) cm/(cm2 s cmHg), respectively, at 22 °C. Gas solubility is very high in PPrSiDPA, similar to that observed in poly(1-trimethysilyl-1-propyne) (PTMSP), the most permeable polymer known. Gas solubility coefficients of PPhSiDPA are 2−3 times lower than those of PPrSiDPA. Free volume size and size distribution were characterized using positron annihilation lifetime (PAL) spectroscopy. Results from these studies (i.e., a bimodal size distribution of free volume elements and large free vol...}, number={6}, journal={MACROMOLECULES}, author={Yampolskii, YP and Korikov, AP and Shantarovich, VP and Nagai, K and Freeman, BD and Masuda, T and Teraguchi, M and Kwak, G}, year={2001}, month={Mar}, pages={1788–1796} }
 @article{arnold_nagai_freeman_spontak_betts_desimone_pinnau_2001, title={Gas permeation properties of poly(1,1 '-dihydroperfluorooctyl acrylate), poly(1,1 '-dihydroperfluorooetyl methacrylate), and poly(styrene)-b-poly(1,1 '-dihydroperfluorooctyl acrylate) block copolymers}, volume={34}, ISSN={["0024-9297"]}, DOI={10.1021/ma010355i}, abstractNote={The permeabilities of rubbery poly(1,1‘-dihydroperfluorooctyl acrylate) (PFOA), glassy poly(1,1‘-dihydroperfluorooctyl methacrylate) (PFOMA), and poly(styrene)-b-poly(1,1‘-dihydroperfluorooctyl acr...}, number={16}, journal={MACROMOLECULES}, author={Arnold, ME and Nagai, K and Freeman, BD and Spontak, RJ and Betts, DE and DeSimone, JM and Pinnau, I}, year={2001}, month={Jul}, pages={5611–5619} }
 @article{nagai_tanaka_hirata_nakagawa_arnold_freeman_leroux_betts_desimone_digiano_2001, title={Solubility and diffusivity of sodium chloride in phase-separated block copolymers of poly(2-dimethylaminoethyl methacrylate), poly (1,1'-dihydroperfluorooctyl methacrylate) and poly(1,1,2,2-tetrahydroperfluorooctyl acrylate)}, volume={42}, ISSN={["0032-3861"]}, DOI={10.1016/S0032-3861(01)00549-3}, abstractNote={Solubility and diffusivity of sodium chloride were determined in a series of dense films of phase-separated diblock and triblock copolymers composed of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and either poly(1,1′-dihydroperfluorooctyl methacrylate (PFOMA) or poly(1,1,2,2-tetrahydroperfluorooctyl acrylate) (PTAN). As the content of hydrophilic PDMAEMA increases in PDMAEMA-b-PFOMA films, total water uptake increases. The salt partition coefficient of these films increases with increasing PDMAEMA content and weight fraction of water in the PDMAEMA domains. In contrast, salt diffusivity is not monotonically correlated with PDMAEMA content and effective hydration. Triblock copolymers exhibit different values of total water uptake, total hydration, salt partition, and diffusion coefficients than those of diblock copolymers (PDMAEMA-b-PFOMA) at the same PDMAEMA concentration. The total water uptake of PFOMA-b-PDMAEMA-b-PFOMA copolymers is lower than that of PDMAEMA-b-PFOMA, while water uptake of PTAN-b-PDMAEMA-b-PTAN films is higher than that of PDMAEMA-b-PFOMA. Salt partition and diffusion coefficients increase monotonically with the amount of freezing water in the hydrophilic domains, suggesting that the state of water in the phase-separated block copolymers is an important factor influencing their salt uptake and transport properties.}, number={25}, journal={POLYMER}, author={Nagai, K and Tanaka, S and Hirata, Y and Nakagawa, T and Arnold, ME and Freeman, BD and Leroux, D and Betts, DE and DeSimone, JM and DiGiano, FA}, year={2001}, month={Dec}, pages={9941–9948} }
 @article{nagai_freeman_hill_2000, title={Effect of physical aging of poly(1-trimethylsilyl-1-propyne) films synthesized with TaCl5 and NbCl5 on gas permeability, fractional free volume, and positron annihilation lifetime spectroscopy parameters}, volume={38}, ISSN={["1099-0488"]}, DOI={10.1002/(SICI)1099-0488(20000501)38:9<1222::AID-POLB14>3.0.CO;2-P}, abstractNote={The effect of physical aging on the gas permeability, fractional free volume (FFV), and positron annihilation lifetime spectroscopy (PALS) parameters of dense, isotropic poly(1-trimethylsilyl-1-propyne) (PTMSP) films synthesized with TaCl5 and NbCl5 was characterized. As-cast films were soaked in methanol until an equilibrium amount of methanol was absorbed by the polymer. When the films were removed from methanol, film thickness initially decreased rapidly and was almost constant after 70 h in air for both catalysts. This timescale was much longer than the timescale for complete methanol desorption (ca. 5 h). From the film-thickness data, the reduction in FFV with time was estimated. For samples prepared with either catalyst, the kinetics of FFV reduction were well-described by a simple model based on the notion either that free-volume elements diffuse to the surface of the polymer film and are subsequently eliminated from the sample or that lattice contraction controls polymer densification. Methane permeability decreased rapidly during the first 70 h, which was the same timescale for the thickness change. The decrease in methane permeability was smaller in films prepared with NbCl5 than with TaCl5. The logarithm of methane permeability decreased linearly as reciprocal FFV increased, in accordance with free-volume theory. The PALS results indicate that the concentration of larger free-volume elements (as indicated by the intensity I4) decreased with aging time and that the other PALS parameters were not strongly influenced by aging. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1222–1239, 2000}, number={9}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Nagai, K and Freeman, BD and Hill, AJ}, year={2000}, month={May}, pages={1222–1239} }
 @article{dixon-garrett_nagai_freeman_2000, title={Ethylbenzene solubility, diffusivity, and permeability in poly(dimethylsiloxane)}, volume={38}, ISSN={["0887-6266"]}, DOI={10.1002/(SICI)1099-0488(20000601)38:11<1461::AID-POLB60>3.0.CO;2-H}, abstractNote={The pure-gas sorption, diffusion, and permeation properties of ethylbenzene in poly(dimethylsiloxane) (PDMS) are reported at 35, 45, and 55 °C and at pressures ranging from 0 to 4.4 cmHg. Additionally, mixed-gas ethylbenzene/N 2 permeability properties at 35 °C, a total feed pressure of 10 atm, and a permeate pressure of 1 atm are reported. Ethylbenzene solubility increases with increasing penetrant relative pressure and can be described by the Flory-Rehner model with an interaction parameter of 0.24 ± 0.02. At a fixed relative pressure, ethylbenzene solubility decreases with increasing temperature, and the enthalpy of sorption is -41.4 ± 0.3 kJ/mol, which is independent of ethylbenzene concentration and essentially equal to the enthalpy of condensation of pure ethylbenzene. Ethylbenzene diffusion coefficients decrease with increasing concentration at 35 °C. The activation energy of ethylbenzene diffusion in PDMS at infinite dilution is 49 ± 6 kJ/mol. The ethylbenzene activation energies of permeation decrease from near 0 to -34 ± 7 kJ/mol as concentration increases, whereas the activation energy of permeation for pure N 2 is 8 ± 2 kJ/mol. At 35 °C, ethylbenzene and N 2 permeability coefficients determined from pure-gas permeation experiments are similar to those obtained from mixed-gas permeation experiments, and ethylbenzene/N 2 selectivity values as high as 800 were observed.}, number={11}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Dixon-Garrett, SV and Nagai, K and Freeman, BD}, year={2000}, month={Jun}, pages={1461–1473} }
 @article{nagai_toy_freeman_teraguchi_masuda_pinnau_2000, title={Gas permeability and hydrocarbon solubility of poly[1-phenyl-2-[p-(triisopropylsilyl)phenyl]acetylene]}, volume={38}, ISSN={["0887-6266"]}, DOI={10.1002/(SICI)1099-0488(20000601)38:11<1474::AID-POLB70>3.0.CO;2-6}, abstractNote={The effects of film thickness, physical aging, and methanol conditioning on the solubility and transport properties of glassy poly[1-phenyl-2-[p-(triisopropylsilyl) phenyl]acetylene] are reported at 35 °C. In general, the gas permeability coefficients are very high, and this polymer is more permeable to larger hydrocarbons (e.g., C3H8 and C4H10) than to light gases such as H2. The gas permeability and solubility coefficients are higher in as-cast, unaged films than in as-cast films aged at ambient conditions and increase to a maximum in both unaged and aged as-cast films after methanol conditioning. For example, the oxygen permeability of a 20-μm-thick as-cast film is initially 100 barrer and decreases to 40 barrer after aging for 1 week at ambient conditions. After methanol treatment, the oxygen permeabilities of unaged and aged films increase to 430 and 460 barrer, respectively. Thicker as-cast films have higher gas permeabilities than thinner as-cast films. Propane and n-butane sorption isotherms suggest significant changes in the nonequilibrium excess free volume in these glassy polymer films due to processing history. For example, the nonequilibrium excess free volume estimated from the sorption data is similar for as-cast, unaged samples and methanol-conditioned samples; it is 100% higher in methanol-conditioned films than in aged, as-cast films. The sensitivity of permeability to processing history may be due in large measure to the influence of processing history on nonequilibrium excess free volume and free volume distribution. The propane and n-butane diffusion coefficients are also sensitive to film processing history, presumably because of the dependence of diffusivity on free volume and free volume distribution. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1474–1484, 2000}, number={11}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Nagai, K and Toy, LG and Freeman, BD and Teraguchi, M and Masuda, T and Pinnau, I}, year={2000}, month={Jun}, pages={1474–1484} }
 @article{nagai_freeman_cannon_allcock_2000, title={Gas permeability of poly(bis-trifluoroethoxyphosphazene) and blends with adamantane amino/trifluoroethoxy (50/50) polyphosphazene}, volume={172}, number={1-2}, journal={Journal of Membrane Science}, author={Nagai, K. and Freeman, B. D. and Cannon, A. and Allcock, H. R.}, year={2000}, pages={167–176} }
 @article{higuchi_yoshida_imizu_mizoguchi_he_pinnau_nagai_freeman_2000, title={Gas permeation of fullerene-dispersed poly(1-trimethylsilyl-1-propyne) membranes}, volume={38}, ISSN={["0887-6266"]}, DOI={10.1002/1099-0488(20000701)38:13<1749::AID-POLB80>3.0.CO;2-I}, abstractNote={Homogeneously fullerene-dispersed membranes were prepared under the conditions in which a 10 wt % poly(1-trimethylsilyl-1-propyne) solution containing 0.5 wt % fullerene was dried under a reduced pressure of 50 cmHg at 100 °C. UV-vis spectra and microscopic observations of the fullerene membranes indicated that the fullerene was homogeneously dispersed in the membranes. The permeability coefficients of 1-butene were found to be higher than those of n-butane in the fullerene membranes, although the permeability coefficients of olefin gases were nearly equal to those of paraffin gases having the same number of carbon in poly(1-trimethylsilyl-1-propyne) membranes containing no fullerene. Pressure dependence of permeability coefficients was clearly observed for the permeation of carbon dioxide, ethylene, ethane, 1-butene, and n-butane through the fullerene membranes, while no significant dependence was found for poly(1-trimethylsilyl-1-propyne) membranes except for the permeation of 1-butene and n-butane. The pressure dependence of the permeability was explained by the dual-mode sorption model. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1749–1755, 2000}, number={13}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Higuchi, A and Yoshida, T and Imizu, T and Mizoguchi, K and He, ZJ and Pinnau, I and Nagai, K and Freeman, BD}, year={2000}, month={Jul}, pages={1749–1755} }
 @article{merkel_bondar_nagai_freeman_pinnau_2000, title={Gas sorption, diffusion, and permeation in poly(dimethylsiloxane)}, volume={38}, ISSN={["0887-6266"]}, DOI={10.1002/(SICI)1099-0488(20000201)38:3<415::AID-POLB8>3.0.CO;2-Z}, abstractNote={The permeability of poly(dimethylsiloxane) [PDMS] to H2, O2, N2, CO2, CH4, C2H6, C3H8, CF4, C2F6, and C3F8, and solubility of these penetrants were determined as a function of pressure at 35 °C. Permeability coefficients of perfluorinated penetrants (CF4, C2F6, and C3F8) are approximately an order of magnitude lower than those of their hydrocarbon analogs (CH4, C2H6, and C3H8), and the perfluorocarbon permeabilities are significantly lower than even permanent gas permeability coefficients. This result is ascribed to very low perfluorocarbon solubilities in hydrocarbon-based PDMS coupled with low diffusion coefficients relative to those of their hydrocarbon analogs. The perfluorocarbons are sparingly soluble in PDMS and exhibit linear sorption isotherms. The Flory–Huggins interaction parameters for perfluorocarbon penetrants are substantially greater than those of their hydrocarbon analogs, indicating less favorable energetics of mixing perfluorocarbons with PDMS. Based on the sorption results and conventional lattice solution theory with a coordination number of 10, the formation of a single C3F8/PDMS segment pair requires 460 J/mol more energy than the formation of a C3H8/PDMS pair. A breakdown in the geometric mean approximation of the interaction energy between fluorocarbons and hydrocarbons was observed. These results are consistent with the solubility behavior of hydrocarbon–fluorocarbon liquid mixtures and hydrocarbon and fluorocarbon gas solubility in hydrocarbon liquids. From the permeability and sorption data, diffusion coefficients were determined as a function of penetrant concentration. Perfluorocarbon diffusion coefficients are lower than those of their hydrocarbon analogs, consistent with the larger size of the fluorocarbons. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 415–434, 2000}, number={3}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Merkel, TC and Bondar, VI and Nagai, K and Freeman, BD and Pinnau, I}, year={2000}, month={Feb}, pages={415–434} }
 @article{higuchi_agatsuma_uemiya_kojima_mizoguchi_pinnau_nagai_freeman_2000, title={Preparation and gas permeation of immobilized fullerene membranes}, volume={77}, ISSN={["0021-8995"]}, DOI={10.1002/(SICI)1097-4628(20000718)77:3<529::AID-APP8>3.0.CO;2-Y}, abstractNote={Fullerene-dispersed membranes were homogeneously prepared under the conditions in which a 10 wt % polystyrene solution containing 1 wt % fullerene was dried under a reduced pressure of 50 cmHg at room temperature. The fullerene membranes prepared with 1,2-dichlorobenzene were found to have the darkest color, and showed no evidence of fullerene crystals in their photomicrographs. UV-visible and infrared absorption spectra of the fullerene membranes showed fullerene bands, which indicated that the fullerene was homogeneously dispersed in the membranes. The permeability coefficients of pure nitrogen, oxygen, carbon dioxide, ethane, and ethylene were found to increase significantly in the fullerene membranes compared to those in the polystyrene membranes, although the ideal separation factors for oxygen/nitrogen and ethylene/ethane in the fullerene membranes (i.e., 4.3 and 1.7, respectively) were slightly less than the separation factors in the polystyrene membranes. The permeability increase originated from the increase in diffusion coefficients in the fullerene membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 529–537, 2000}, number={3}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Higuchi, A and Agatsuma, T and Uemiya, S and Kojima, T and Mizoguchi, K and Pinnau, I and Nagai, K and Freeman, BD}, year={2000}, month={Jul}, pages={529–537} }
 @article{toy_nagai_freeman_pinnau_he_masuda_teraguchi_yampolskii_2000, title={Pure-gas and vapor permeation and sorption properties of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] (PTMSDPA)}, volume={33}, ISSN={["1520-5835"]}, DOI={10.1021/ma991566e}, abstractNote={The pure-gas permeation and sorption properties of poly[1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene] [PTMSDPA] are presented and compared to those of poly(1-trimethylsilyl-1-propyne) [PTMSP], poly(4-methyl-2-pentyne) [PMP], and poly(1-phenyl-1-propyne) [PPP]. PTMSDPA is more permeable to large, condensable vapors (e.g., n-butane) than to small, permanent gases (e.g., hydrogen). Such behavior is also observed in PTMSP and PMP but not in PPP. PTMSDPA has lower fractional free volume (0.26) and gas permeabilities than PTMSP and PMP. However, relative to conventional glassy polymers, PTMSDPA is a highly permeable, high free volume, glassy material. For example, the oxygen permeability coefficient of PTMSDPA is 1200 × 10-10 cm3(STP)·cm/(cm2·s·cmHg) at 25 °C. As temperature increases, the permeability in PTMSDPA increases for light gases (helium, hydrogen, and nitrogen) and decreases for more condensable gases. In contrast, the permeabilities of PTMSP and PMP decrease with increasing temperature for both lig...}, number={7}, journal={MACROMOLECULES}, author={Toy, LG and Nagai, K and Freeman, BD and Pinnau, I and He, Z and Masuda, T and Teraguchi, M and Yampolskii, YP}, year={2000}, month={Apr}, pages={2516–2524} }
 @article{merkel_bondar_nagai_freeman_2000, title={Sorption and transport of hydrocarbon and perfluorocarbon gases in poly(1-trimethylsilyl-1-propyne)}, volume={38}, ISSN={["0887-6266"]}, DOI={10.1002/(SICI)1099-0488(20000115)38:2<273::AID-POLB1>3.0.CO;2-X}, abstractNote={Pure gas solubility and permeability of H2, O2, N2, CO2, CH4, C2H6, C3H8, CF4, C2F6, and C3F8 in poly(1-trimethylsilyl-1-propyne) (PTMSP) were determined as a function of pressure at 35°C. Permeability coefficients of the perfluorinated penetrants are approximately an order of magnitude lower than those of their hydrocarbon analogs, and lower even than those of the permanent gases. In striking contrast to hydrocarbon penetrants, PTMSP permeability to fluorocarbon penetrants decreases with increasing penetrant size. This unusual size-sieving behavior in PTMSP is attributed to low perfluorocarbon solubilities in PTMSP coupled with low diffusion coefficients relative to those of their hydrocarbon analogs. In general, perfluorocarbon penetrants are less soluble than their hydrocarbon analogs in PTMSP. The difference in hydrocarbon and perfluorocarbon solubilities in high free volume, hydrocarbon-rich PTMSP is much smaller than in hydrocarbon liquids and liquidlike polydimethylsiloxane. The low solubility of perfluorocarbon penetrants is ascribed to the large size of the fluorocarbons, which inhibits their dissolution into the densified regions of the polymer matrix and reduces the number of penetrant molecules that can be accommodated in Langmuir sites. From the permeability and sorption data, diffusion coefficients were calculated as a function of penetrant concentration. With the exception of H2 and the C3 analogs, all of the penetrants exhibit a maximum in their concentration-dependent diffusion coefficients. Resolution of diffusion coefficients into a mobility factor and a thermodynamic factor reveals that it is the interplay between these two terms that causes the maxima. The mobility of the smaller penetrants (H2, O2, N2, CH4, and CO2) decreases monotonically with increasing penetrant concentration, suggesting that the net free volume of the polymer–penetrant mixture decreases as additional penetrant is added to PTMSP. For larger penetrants mobility either: (1) remains constant at low concentrations and then decreases at higher penetrant concentrations (C2H6, CF4, and C2F6); (2) remains constant for all concentrations examined (C3H8); or (3) increases monotonically with increasing penetrant concentration (C3F8). Presumably these results reflect the varying effects of these penetrants on the net free volume of the polymer–penetrant system. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 273–296, 2000}, number={2}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Merkel, TC and Bondar, V and Nagai, K and Freeman, BD}, year={2000}, month={Jan}, pages={273–296} }
 @article{dixon-garrett_nagai_freeman_2000, title={Sorption, diffusion, and permeation of ethylbenzene in poly(1- trimethylsilyl-1-propyne)}, volume={38}, DOI={10.1002/(SICI)1099-0488(20000415)38:8<1078::AID-POLB8>3.0.CO;2-2}, abstractNote={The solubility, diffusivity, and permeability of ethylbenzene in poly(1-trimethylsilyl-1-propyne) (PTMSP) at 35, 45 and 55 °C were determined using kinetic gravimetric sorption and pure gas permeation methods. Ethylbenzene solubility in PTMSP was well described by the generalized dual-mode model with χ = 0.39 ± 0.02, b = 15 ± 1, and C′H = 45 ± 4 cm3 (STP)/cm3 PTMSP at 35 °C. Ethylbenzene solubility increased with decreasing temperature; the enthalpy of sorption at infinite dilution was −40 ± 7 kJ/mol and was essentially equal to the enthalpy change upon condensation of pure ethylbenzene. The diffusion coefficient of ethylbenzene in PTMSP decreased with increasing concentration and decreasing temperature. Activation energies of diffusion were very low at infinite dilution and increased with increasing concentration to a maximum value of 50 ± 10 kJ/mol at the highest concentration explored. PTMSP permeability to ethylbenzene decreased with increasing concentration. The permeability estimated from solubility and diffusivity data obtained by kinetic gravimetric sorption was in good agreement with permeability determined from direct permeation experiments. Permeability after exposure to a high ethylbenzene partial pressure was significantly higher than that observed before the sample was exposed to a higher partial pressure of ethylbenzene. Nitrogen permeability coefficients were also determined from pure gas experiments. Nitrogen and ethylbenzene permeability coefficients increased with decreasing temperature, and infinite dilution activation energies of permeation for N2 and ethylbenzene were −5.5 ± 0.5 kJ/mol and −74 ± 11 kJ/mol, respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1078–1089, 2000}, number={8}, journal={Journal of Polymer Science. Part B, Polymer Physics}, author={Dixon-Garrett, S. V. and Nagai, K. and Freeman, B. D.}, year={2000}, pages={1078–1089} }
 @article{nagai_watanabe_nakagawa_1999, title={Effect of aging on molecular motion in glassy polymer films containing bulky substituents}, volume={56}, ISSN={["0386-2186"]}, DOI={10.1295/koron.56.464}, abstractNote={かさ高い置換基を有するガラス状高分子 [ポリ (t-ブチルアセチレン) (PTBA) とポリ (ビニルトリメチルシラン) (PVTMS)] のフィルムの常温での真空保存によるスピン-格子緩和時間 (T 1) の変化を研究した. PTBAとPVTMSの主鎖の13CT1は, 側鎖の13CT1より大きな値を示した. またPTBAとPVTMSのフィルムを室温にて2週間真空中に保存した場合, PTBAとPVTMS共に保存前後の側鎖の13CT1と29SiT1の変化は観察されなかった. 一方, PTBAとPVTMSの主鎖の13CT1においては, 真空保存によりPTBAのCc [H-Cd =Cc-Cb (CaH3) 3] のT1は初期試料の値に対して9.6%の減少, そしてPVTMSのCc [H2Cc-Cb-Si (CaH3) 3] のT1は, 初期試料の値に対して5.8%の増加を示した. しかしながら主鎖のPTBAのCdとPVTMSのCbの真空保存前後のT1の変化は観察されなかった.}, number={7}, journal={KOBUNSHI RONBUNSHU}, author={Nagai, K and Watanabe, T and Nakagawa, T}, year={1999}, pages={464–467} }
 @article{merkel_bondar_nagai_freeman_yampolskii_1999, title={Gas sorption, diffusion, and permeation in poly(2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole-co-tetrafluoroethylene)}, volume={32}, ISSN={["0024-9297"]}, DOI={10.1021/ma990685r}, abstractNote={The solubility and permeability of H2, O2, N2, CO2, CH4, C2H6, C3H8, CF4, C2F6, and C3F8 in TFE/BDD87, a random copolymer prepared from 87 mol % 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole [BDD] and 13 mol % tetrafluoroethylene [TFE], are reported as a function of temperature and pressure. Sorption isotherms of all penetrants except hydrogen are concave to the pressure axis and are well-described by the dual-mode model. Hydrogen exhibits linear sorption isotherms. In contrast to previous results in hydrocarbon-rich polymers, the solubility of perfluorocarbon penetrants is higher in TFE/BDD87 than that of their hydrocarbon analogues. The solubility of all penetrants in TFE/BDD87 decreases with increasing temperature. Enthalpies of sorption become more negative as penetrant size increases. Fluorocarbon enthalpies of sorption at infinite dilution are significantly more exothermic than those of their hydrocarbon analogues, suggesting more favorable interactions between fluorocarbon penetrants and perflu...}, number={25}, journal={MACROMOLECULES}, author={Merkel, TC and Bondar, V and Nagai, K and Freeman, BD and Yampolskii, YP}, year={1999}, month={Dec}, pages={8427–8440} }
 @article{havelka-rivard_nagai_freeman_sheares_1999, title={Synthesis and characterization of poly[[1,1 '-biphenyl]-4,4 '- diyl[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]]}, volume={32}, number={20}, journal={Macromolecules}, author={Havelka-Rivard, P. A. and Nagai, K. and Freeman, B. D. and Sheares, V. V.}, year={1999}, pages={6418–6424} }