Synthesis of narrow distribution polytetrahydrofuran

Abstract

Bulk polymerizations of tetrahydrofuran (THF) have been studied kinetically at reaction temperatures in the range −10 to +80°C using p-chlorophenyldiazonium hexafluorophosphate initiator. Initiation has been studied to enable selection of a ‘clean’ initiation condition (95°C for 4 min). Factors causing broadening of the molecular weight distribution are discussed, the main causes of such broadening being chain transfer reactions and concurrent initiation with propagation. These could be minimized by using a low reaction temperature (−10°C). Molecular weight distributions were measured by gel permeation chromatography. Propagation rate constants were determined and found to increase with increasing temperature according to an Arrhenius expression giving an activation energy of 51 kJ/mol. The method will produce monodisperse samples of THF polymer over a wide molecular weight range from 5 × 10 3 to 10 6.