Determination of molecular weight of poly(methyl methacrylate) by deuteriwn nmr and its reliability

Abstract

The number average molecular weight Mn of the PMMA prepared by the living polymerization with CH3(CD3)2CMgBr was determined by the absolute method using deuterium NMR. The Mn value agreed well with that determined by proton NMR, based on the intensity ratio of the signal due to the methoxy group in monomeric units to the signal due to the CH3(CD3)2C– group at the left (initiating) end of chain. The results showed that Mn up to 105 can be determined reliably by deuterium NMR spectroscopy, when the experimental conditions are carefully arranged. © 1990 The Society of Polymer Science, Japan.