Poly(N-vinylpyrrolidone)-polydimethylsiloxane amphiphilic ABA triblock copolymers

Triblock copolymers of N-vinylpyrrolidone (NVP) and polydimethylsiloxane (PDMS) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using two different types of difunctional telechelic PDMS-based dixanthate macroinitiators. The incorporation of PDMS into the triblock copolymers was evidenced by H-1 NMR spectroscopy and varied between 4 mol% and as high as 20 mol%, dependent on reaction time and monomer conversion. The copolymer homogeneity was characterized in terms of molecular weight distribution determined by GPC to estimate the level of control over the chain length. Monomodal molecular weight distributions were observed, and H-1 NMR spectroscopy indicated the copolymers had number average molecular weights (M-n) ranging between 28,000 and 160,000 g/mol. In addition, thin film phase separation and critical micelle concentrations for these copolymers were analyzed via transmission electron microscopy and surface tension measurements, respectively. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3387-3394