Synthesis and Characterization of New Styrene Main-Chain Polymer with Pendant Lactose Moiety through Urea Linkage

A simple and efficient method for the synthesis of lactose-based homopolymers from N-lactosyl-N ‘-(4-vinylbenzyl)urea or N ‘-lactosyl-N,N-methyl(4-vinylbenzyl)urea (5a, 5b) is described. Free radical polymerization of these new urea monomers proceeded smoothly in an aqueous solution using potassium persulfate (KPS) and N, N,N ‘ ,N ‘-tetramethylethylenediamine (TMEDA) as the initiating system and gave water-soluble homopolymers in good yields. These synthetic lactose-based polymers had molecular weights that ranged from 1.9 × 103 to 5.3 × 106 and low molecular weight polydispersities (M w/M n) (1.02−1.77) as determined by gel permeation chromatography (GPC). Thermal stability studies showed that these homopolymers had two-stage degradations related to the lactose moiety and the polystyrene main chain as well as similar T g's (6a at 134 °C, 6b at 133 °C) as determined by DSC, suggesting that the urea linkage increases the T g by hydrogen bonding. The present synthetic method is useful for the introduction of biologically important amino sugars into glycopolymers through a urea linkage.