Vinylphosphonic Acid Homo- and Block Copolymers

• Published in: Macromolecular chemistry and physics Vol. 210; no. 22; pp. 1903 - 1914
• Main Authors: Wagner, Thomas, Manhart, Angelika, Deniz, Nesrin, Kaltbeitzel, Anke, Wagner, Manfred, Brunklaus, Gunther, Meyer, Wolfgang H.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 24.11.2009; WILEY‐VCH Verlag; Wiley
• Subjects: Anionic polymerization; Anions; Applied sciences; Block copolymers; block ratio; Exact sciences and technology; Molecular structure; Molecular weight; Monomers; Organic polymers; Physicochemistry of polymers; Polymerization; Polystyrene resins; Preparation, kinetics, thermodynamics, mechanism and catalysts; proof of blocking; proton conductivity; Styrenes; swelling behaviour; tacticity; Vinyl derivative copolymer; Temperature effect; Polymer solid electrolyte; Proton conductivity; proof of blocking; Anionic polymerization; Anionic copolymerization; block copolymers; Phosphorus copolymer; Electrical properties; swelling behaviour; Organic phosphonate; block ratio; molecular weight; Experimental study; Phosphorus polymer; Hydrolysis; Chemical modification; Humidity effect; tacticity; Preparation; Polyvinyl derivative; Moisture regain; Diblock copolymer; Styrene copolymer
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.200900284

Vinylphosphonic acid homo‐ and block copolymers with styrene have been prepared via anionic polymerization of dialkylvinylphosphonates (VPE) and subsequent hydrolysis of the precursor polyester with trimethylsilylbromide. Poly(vinylphosphonic acid) (PVPA) homopolymers with 4 200<$\overline M _{\rm w}$<814 000 have been obtained with vinyl‐diisopropyl‐phosphonate as monomer. With polystyryl anion as macroinitiator, AB block copolymers have been obtained with block compositions from approximately 9:2 to 3:7; however, the total molecular weights are limited to <10 000, due to solubility limitations. 1H DOSY NMR has been used to prove a real block‐type structure consisting of hydrophobic polystyrene and hydrophilic PVPA (PVPA‐b‐PS), which exhibits a phase‐separated morphology. It was found that the bulk proton conductivity does not change significantly with different molecular weights of the homopolymers, but is strongly dependant on the composition of the block copolymers. PVPA‐b‐PS with low PS content, behaves more or less like PVPA homopolymers, whereas PVPA‐b‐PS with a high PS content looses its conductivity when heated above the glass transition temperature of the PS phase. The swelling behaviour of the block copolymers differs significantly from that of PVPA homopolymers, when exposed to a humidified environment. Polymer electrolyte membranes (PEM) are the key to the function of low temperature fuel cells. Specifications for PEM are manifold and might best be fulfilled by phase separated block copolymers. The anionic synthesis and detailed characterization of homo‐ and block copolymers with poly(vinylphosphonic acid) (PVPA) are described, and the influence of macromolecular parameters on PEM specific properties are discussed.