Kinetic study of the "living" cationic polymerization of a galactose carrying vinyl ether. MALDI-TOF MS analysis of the resulting glycopolymers

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 H-1 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 H-1 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.