Synthesis and characterization of linear asymmetrical poly(propylene oxide) diol

Abstract

AbstractLinear asymmetrical poly(propylene oxide) was synthesized through four‐step reactions: selective benzylation, alcohol exchange reaction, propylene oxide anionic polymerization, debenzylation. One terminal of the asymmetrical polymer chains is alcohol hydroxyl and the other is phenol hydroxyl. It was characterized with infrared (IR) and 1H Nuclear Magnetic Resonance (1H‐NMR). Peaks at 1.11, 3.38, and 3.53 ppm were attributed to side groups (OCH2CH(CH3)), backbone units (OCH2CH(CH3)) and (OCH2CH(CH3)) of poly(propylene oxide), respectively. Molecular weight and molecular weight distribution were measured with 1H‐NMR and laser light scattering (LLS), which showed that the linear asymmetrical poly(propylene oxide) was mono‐disperse (PDI = 1.02–1.07). Then, its carbamate reaction with phenyl isocyanate was studied; the reaction rate constants for phenol hydroxyl and alcohol hydroxyl of poly(propylene oxide) were k1 = 0.209 mol L−1 min−1 and k2 = 0.051 mol L−1 min−1. There was a great reactivity difference for two types of hydroxyls in asymmetrical poly(propylene oxide), contrasting to the single carbamate reaction rate constant of symmetrical poly(propylene oxide) (k3 = 0.049 mol L−1 min−1). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010