Sulfo-and carboxybetaine-containing polyampholytes based on poly(2-vinyl pyridine)s: Synthesis and solution behavior

We present the synthesis and characterization of zwitterionic homopolymers and copolymers based on poly(2-vinyl pyridine) (P2VP). Different molar masses as well as copolymer compositions of poly(styrene-co-2-vinyl pyridine) (P(2VP-co-S) were synthesized using RAFT (reversible addition fragmentation chain transfer) polymerization, followed by quaternization of the nitrogen atom by either 1,3-propanesultone (P2VPS, P(2VPS-co-S)) or ethyl-2-bromoacetate, followed by ester hydrolysis (P2VPC, P(2VPC-co-S)). The resulting materials were characterized using SEC, 1H and 13C NMR spectroscopy, elemental analysis, and zeta potential measurements. Degrees of functionalization ranging from 33 to 76% could be determined and both P2VPC and P2VPS exhibited good solubility over the entire pH-range. Upon incorporation of increasing amounts of styrene, aqueous solubility decreased and also UCST behavior could be observed in case of P(2VP56,S-co-S44).