Influence of preparation procedure on polymer composition:: synthesis and characterisation of polymethacrylates bearing β-D-glucopyranoside and β-D-galactopyranoside residues

Methacrylate derivatives bearing beta -D-glucopyranoside and beta -D-galactopyranoside residues are synthesised by glycosylation of 2-hydroxyethyl methacrylate (HEMA) with 2,3,4,6-tetra-O-acetyl-alpha -D-glucopyranosyl bromide and 2,3,4,6-tetra-O-acetyl-alpha -D-galactopyranosyl bromide, respectively. beta -Selectivity in the glycosylation reactions is ensured by neighbouring-group participation of acetyl groups at O-2 in the glycosyl donors. 2-(2',3',4',6'-tetra-O -acetyl-beta -D-glucosyloxy) ethyl methacrylate (AcGlcEMA, 1a) was obtained as a crystalline solid and its crystal structure was determined by single-crystal X-ray diffraction. Deprotected polymers are synthesised in two parallel ways; either polymerisation of the protected monomers and subsequent deacetylation of the resulting polymers, or polymerisation of the previously deprotected monomers. The number- and weight-average relative molecular masses of both the protected and deprotected polymers are determined by size exclusion chromatography (SEC). Absolute molecular masses are obtained using the previously estimated refractive-index increments, dn/dc. It is found that polymerisation of deprotected monomers leads to polymers of well-defined composition, in contrast to the deacetylation of protected polymers.