Semi-IPN Membranes

Perfluorinated sulfonic acid polymers, such as Nafion membranes, were the most commonly used materials in practical systems for their high proton conductivity and extremely high oxidative stability. However, due to the poor dimensional stability, low mechanical properties of Nafion at high humidity and high temperature, and high cost, an essential need for cost-effective and reinforced substitutes with improved performance arises [193-195]. Nafion blended with the second component could not only reduce the cost, but also improve the mechanical properties and the dimensional stability. Recently, the reinforced composite membranes based on semi-interpenetrating polymer network (semi-IPN) structures of Nafion , polyimidazole (PI) [196-198], polybenzimidazole (PBI) [199], and poly(vinyIidene fluoride) (PVDF) [200] were reported. As shown in Fig. 2.35, the composite membranes with 

35 Semi-IPN structures of FPI/Nafion 212 composite membranes. (Reprinted with permission from Elsevier (2010). Copyright 2010 Elsevier [198].) 

Ledjeff-Hey, K., Heinzel, A. (1996) Critical issues and future prospects for solid polymer fuel cells. Journal of Power Sources, 61, 125-127. 

(a) Wall, L. (1972) Fluoropolymers, John Wiley Sons, Inc., New York, (b) Fiering, A. E. (1994) Fluoroplastics. In Banks, R.E., Smart, B., Tatlow, J.C. (Eds.) Organofluorine Chemistry Principles and Applications, Vol. 15, Plenum Press, New York, pp. 339-362. (c) Johns, K., Stead, G. (20(X)) Fluoroproducts— the extremophiles. Journal of Fluorine Chemistry, 104 (1), 5-18. (d) Scheirs, J. (Ed.) (1997) Modem Fluoropolymers, John Wiley Sons, Inc., New York, (e) Ajroldi, G. (1997) Stmcture and physical properties of some fluoropol3Tners. Chimica El Industria-Milano, 79, 483-488. 

(a) Hougham, G., Cassidy, P Jonhs, K., Davidson, T. (1999) Fluoropolymers, Kluvert, New York, pp. 233-276. (b) Schiraldi, D.A. (2006) Perfluorinated polymer electrolyte membrane durability. Journal ofMacronwlecular Scierwe, Part C Polymer Reviews, 46, 315-327. (c) Yoshitake, M., Watakabe, A. (2008) Perfluorinated ionic polymers for PEFCs (including supported PFSA). Advances in Polymer Science, 215, 127 155. 

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Semi-IPNs were prepared by the sol-gel technique through in situ polymerization of BMI in thermoplastic polyetherimide (PEI) as well as in polysulfone (PSF) (Kurdi and Kumar 2006). Structure and properties of semi-IPN membranes could be varied by controlling the thermoset BMI microdomain size interpenetrating within a thermoplastic polymer network. The size of this microdomain depended on the polymerization time of BMI and on the degree of thermoset/thermoplastic phase separation. These semi-IPN membranes showed an improved Tg but a decrease in their thermal stability and could be used for Oj-emiched-air applications where high selectivity is not required. At ambient temperature, it was possible to increase the permeance of semi-IPN membranes. 

FIG. 3.9 Synthesis of sPI- and poly(ethylene glycol) diacrylate-based semi-IPN membranes. 

Yu SH, Mi FL, Shyu SS et al (2006) Miscibility, mechanical characteristic and platelet adhesion of 6-O-carboxymethylchitosan/polyurethane semi-IPN membranes. J Membr Sci 276 68-80... 

Sergeyeva et al. [90,91] had introduced a very promising improvement by using an oligourethane-acrylate macromonomer in imprinting polymerization mixtures in order to increase the flexibility and mechanical stability of the membranes self-supported MIP membranes with a thickness between 60 and 120 pm could be prepared. Sreenivasan [92] had also addressed the problem of film stability, and a semi-IPN film was prepared by the polymerization of HEMA in a blend with polyurethane. 

Kundu PP, Kim BT, Ahn JE, Han HS, Shul YG (2007) Formation and evaluation of semi-IPN of Nafion 117 membrane for direct methanol fuel cell. 1. Crosslinked sulfonated polystyrene in the pores of Nafion 117. J Power Sources 171 86-91... 

C. C. Gryte and H. P. Gregor, Interpolymer Ultrafiltration Membranes Prepared from Poly(vinylidene Fluoride) and Poly(l-vinyl-3-methylimidazolium Iodide, J. Macromol. Sci.-Phys. B15(2), 183 (1978). Poly(vinyl imidazole)/poly(vinylidene fluoride)/epoxy semi-IPN. Ion exchange membrane. 

A. Rembaum and C. J. Wallace, Membrane Consisting of Polyquaternary Amine Ion Exchange Polymer Network Interpenetrating the Chains of Thermoplastic Matrix Polymer, U.S. Pat. 4,119,581 (1978). Anionic ion exchange membranes. Semi-IPNs. 

Semi-IPN based on collagen and poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) [15] Norfloxacin Membrane Tissue engineering, regenerative medicine of the skin... 

Fu et al. [124] prepared a series of novel covalent organic-inorganic hybrid proton-conductive membranes, each with a semi-interpenetrating polymer network (semi-IPN), for DMFC applications through polymer reactions and sol-gel method. A sulfonation reaction was produced as last step. The developed copolymer chains interpenetrated into the PVC matrix to form the semi-IPN structure, and the inorganic silica was covalently bound to the copolymers. 

Matsuguchi, M., Takahashi, H. (2006) Methanol permeability and proton conductivity of a semi-interpenetrating pol3Tner networks (IPNs) membrane composed of Nafion and cross-linked DVB. Journal of Membrane Scierwe, 281, 707-715. 

H. Czarczynska and W. Trochimczuk, Modification of Polyethylene Foil with Methacrylic Acid, Paper P-13 at the Fourth Bratislava lUPAC International Conference on Modified Polymers, their Preparation and Properties, July 1975. Semi-II IPNs using DVB. Selective ion exchange membranes. 

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