Correlation between gas transport properties and the morphology/dynamics of crystalline fluorinated copolymer membranes

The crystalline structure, dynamics, and gas transport properties (i.e., the gas permeability, gas diffusion coefficient, and gas solubility coefficient) of poly(tetrafluoroethylene-co-perfluoroethylvinylether) (PFA) membranes were systematically investigated via differential scanning calorimetry, wide/small/ultra-small-angle X-ray scattering, and quasielastic neutron scattering measurements. We evaluated the gas transport properties using a constant-volume/variable-pressure method. The gas permeability and the gas diffusion coefficient decreased with increasing crystallinity of the PFA membranes at crystallinities below 32%. However, in membranes with a crystallinity of 32% or greater, these parameters depended on the characteristics of the gas molecules, such as their kinetic diameter. The so-called long spacing period and the thickness of the crystalline/amorphous regions increased with crystallinity according to the small/ultra-small-angle X-ray scattering results. Furthermore, the quasielastic neutron scattering measurements indicated that the scattering law was well fitted to a sum of narrow and broad Lorentzian components. In particular, the narrow components, that is, the local motion of amorphous components and side chains, increased with crystallinity. These results suggest that large gas molecules could pass through the PFA membranes, assisted by the motion in the amorphous region. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45665.

[1]  M. Hasegawa,et al.  Spherulitic structures of poly [tetrafluoroethylene-co-(perfluoroalkyl vinyl ether)] , 2007 .

[2]  G. Kwak,et al.  Role of Local Dynamics in the Gas Permeability of Glassy Substituted Polyacetylenes. A Quasielastic Neutron Scattering Study , 2002 .

[3]  J. Dorgan,et al.  Gas permeation properties of poly(lactic acid) revisited , 2006 .

[4]  K. Nagai,et al.  Temperature Dependence on Gas Permeability and Permselectivity of Poly(lactic acid) Blend Membranes , 2009 .

[5]  R. Inoue,et al.  Relationship between the Local Dynamics and Gas Permeability of Para-Substituted Poly(1-chloro-2-phenylacetylenes) , 2012 .

[6]  Shuichi Sato,et al.  Gas Transport Properties and Crystalline Structures of Poly(lactic acid) Membranes , 2010 .

[7]  Christopher J. Ellison,et al.  Gas permeation and selectivity of poly(dimethylsiloxane)/graphene oxide composite elastomer membranes , 2016 .

[8]  B. Flaconneche,et al.  Permeability, Diffusion and Solubility of Gases in Polyethylene, Polyamide 11 and Poly (Vinylidene Fluoride) , 2001 .

[9]  Shuichi Sato,et al.  Analysis of permeability; solubility and diffusivity of carbon dioxide; oxygen; and nitrogen in crystalline and liquid crystalline polymers , 2010 .

[10]  B. Wunderlich,et al.  Single‐molecule single crystals , 1991 .

[11]  P. J. Lemstra,et al.  Structure versus properties relationship of poly(lactic acid). I. Effect of crystallinity on barrier properties , 2009 .

[12]  Alan S. Michaels,et al.  Solubility of gases in polyethylene , 1961 .

[13]  J. Drobny Technology of Fluoropolymers, Second Edition , 2008 .

[14]  C. Han,et al.  The effect of phase separation on crystal nucleation density and lamella growth in near-critical polyolefin blends , 2004 .

[15]  A. J. Lovinger,et al.  Chirality Constraints in Crystal−Crystal Transformations: Isotactic Poly(1-butene) versus Syndiotactic Polypropylene , 1998 .

[16]  R. Wrzalik,et al.  Characterization of structure and properties of polymer films made from blends of polyethylene with poly(4-methyl-1-pentene) , 2017 .

[17]  J. Frommer,et al.  Friction measurements on phase-separated thin films with a modified atomic force microscope , 1992, Nature.

[18]  J. Frommer,et al.  Force Microscopy Study of Friction and Elastic Compliance of Phase-Separated Organic Thin Films , 1994 .

[19]  S. Moon,et al.  Gas permeation resistance of various grades of perfluoroalkoxy–polytetrafluoroethylene copolymers , 2009 .

[20]  G. C. Sarti,et al.  Gas and Vapor Sorption, Permeation, and Diffusion in Poly(tetrafluoroethylene-co-perfluoromethyl vinyl ether) , 2005 .

[21]  Shuichi Sato,et al.  Correlation between interlamellar amorphous structure and gas permeability in poly(lactic acid) films , 2014 .

[22]  Takeshi Nakatani,et al.  AMATERAS: A Cold-Neutron Disk Chopper Spectrometer , 2011 .

[23]  A. Fujimori,et al.  Changes in Arrangement of Lamella and Fine Crystallite in Fluorinated "Crystalline" Transparent Fibers with Drawing , 2008 .

[24]  A. Fujimori,et al.  Changes in lamellar arrangement of crystalline and flexible fluorinated transparent films with drawing , 2010 .

[25]  V. Villani,et al.  Miscibility Study in Fluorinated Tetrafluoroethylene Copolymer−Copolymer Blends† , 2001 .

[26]  B. Améduri,et al.  Where is the glass transition temperature of poly(tetrafluoroethylene)? A new approach by dynamic rheometry and mechanical tests , 2013 .

[27]  M. Guiver,et al.  Advances in high permeability polymer-based membrane materials for CO2 separations , 2016 .

[28]  Takeshi Nakatani,et al.  Development Status of Software ``Utsusemi'' for Chopper Spectrometers at MLF, J-PARC , 2013 .

[29]  K. Nagai,et al.  Characterization and gas transport properties of poly(lactic acid) blend membranes , 2008 .