Synthesis of novel phosphinic acid-containing polymers

Three arylene difluoride monomers containing phosphine oxide (1), phosphinic acid (2), or phosphinate ester (3) groups were prepared and polymerized with bisphenol A to give novel poly-(arylene ether)s (4,5, and 6). The polymers obtained had moderate molecular weights (η_inh: 0.14-0.30 dL g^-1 in N-methylpyrrolidinone) and glass-transition temperatures (T_g: 102-200°C), depending on the phosphine group in the main chain. Using bis(4-fluorophenyl)sulfone as a comonomer improved the polymerization to give copolymers with higher solution viscosities. The stoichiometric investigation revealed that 7 mol % excess of fluoride monomer gave the highest molecular weight copolymer 8 with η_inh of 0.78 dL g^-1, which had a T_g of 176°C, a T_d10% of 432°C, and formed a hard film by casting from solution.