Synthesis and characterization of near-monodisperse electron acceptor homopolymers of 2-[(3,5-dinitrobenzoyl)oxy]ethyl methacrylate

Abstract

Homopolymers of 2-(trimethylsiloxy)ethyl methacrylate of degrees of polymerization from 5 to 50 were synthesized by group transfer polymerization in tetrahydrofuran (THF) using 1-methoxy-1-(trimethylsiloxy)-2-methyl propene as the initiator and tetrabutylammonium bibenzoate as the catalyst. These polymers were first converted to poly[2-(hydroxy)ethyl methacrylate]s by removal of the trimethylsilyl-protecting groups by acidic hydrolysis, and subsequently transformed to poly{2-[(3,5-dinitrobenzoyl)oxy]ethyl methacrylate}s by reaction with 3,5-dinitrobenzoyl chloride in the presence of triethylamine. Gel permeation chromatography in THF and proton nuclear magnetic resonance (1H NMR) spectroscopy in CDCl3 and d6 dimethyl sulfoxide were used to characterize the polymers in terms of their molecular weight and composition. The molecular weights were found to be close to the values expected from the polymerization stoichiometry and the molecular weight distributions were narrow, with polydispersity indices around 1.1. The hydrolysis and reesterification steps were found to be almost quantitative for all polymers. Differential scanning calorimetry and thermal gravimetric analysis were also employed to measure the glass transition temperatures (Tg's) and decomposition temperatures, which were determined to be approximately 80 and 320 °C, respectively.