One pot synthesis and gelation studies of amphiphilic triblock polyurethanes

Abstract

This article shows a generalized synthetic strategy to make amphiphilic ABA type triblock polyurethane (PU) in a SINGLE reaction pot. This is achieved by condensation polymerization between a hydrophobic diol and a di-isocyanate in the presence of a polyethylene glycol monomethyl ether (Mw = 2000 or 5000 g mol−1) as mono-functional impurity. Using different ratios of the three reactants with a fixed parameter such that the total concentration of –OH = isocyanate, a series of PUs are produced with both the ends capped with PEG. These polymers show facile gelation ability in solvents like dimethyl formamide, dimethyl sulfoxide, and dimethyl acetamide by H-bonding interaction among the urethane groups. A comprehensive structure–property relationship study reveals importance of the right balance between the weight fractions of the soft and hard segments in self-assembly and efficient gelation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2502–2508