Kinetic Study of the “Living” Cationic Polymerization of a Galactose Carrying Vinyl Ether. MALDI-TOF MS Analysis of the Resulting Glycopolymers

Abstract

The “living” cationic polymerization of a new saccharidic monomer, namely 1,2:3,4-di-O-isopropylidene-6-O-(2-vinyloxyethyl)-d-galactopyranose (GVE) has been investigated using acetaldehyde diethyl acetal/trimethylsilyl iodide as the initiating system in the presence of ZnCl2 as co-initiator. To determine if the process is living, the conversion was followed by dilatometry or by regularly withdrawing samples and analyzing them by 1H NMR. Fast polymerization occurred together with a nonlinear ln([M]0/[M] t) = f (t) plot indicating an apparent loss of active centers. Nevertheless, the 1H NMR- and SEC-determined molecular weights proved the absence of termination and transfer reactions during the polymerization process. MALDI−TOF mass spectrometry confirmed the absence of such side reactions and indicated a parallel initiation consecutive to the presence of water traces in the trimethylsilyl iodide solution. The nonlinear ln([M]0/[M] t) = f (t) plot was attributed to specific interactions between the saccharidic rings and ZnCl2 and/or the growing carbocations.