Synthesis and characterization of random hydrophilic/hydrophobic copolymers of styrene and D-lactose-O-vinylbenzylhydroxime

D-Lactose-O-(vinylbenzyl)oxime (LVO), prepared from α-D-lactose and [O-(vinylbenzyl)oxy]amine (1) was copolymerized with styrene (ST) in dimethylsulfoxide (DMSO)-toluene (1 : 1, v/v) at 65°C using 2,2′-azobisisobutyronitrile (AIBN) as a free radical initiator. The polymerization was rapid when using AIBN as the initiator. The resultant copolymers were characterized by elemental analyses, infrared, viscometry, TGA, DSC, and ¹H-NMR spectroscopy. The poly(ST-co-LVO) had an intrinsic viscosity in the range of 0.11-0.51 dL/g in DMSO at 30°C. The molecular weight was determined by gel permeation chromatography (GPC), and the molecular weight of the resulting polymers ranged from 2.11 × 10⁴ to 6.53 × 10⁷ with low polydispersities. The solubility of the copolymers with different monomer compositions in solvents of varied polarities was also studied. Incorporation of up to 65% (mol %) of lactose-based monomer onto polystyrene backbone led to a water-soluble polymer. Thermal behavior of the synthesized copolymers was evaluated by thermogravimetric analysis (TGA) and correlated very well with the polymer composition. Introduction of a pendant disaccharide compromised the thermal stability of the copolymer. The synthetic approach described in this report provides a route to prepare a novel disaccharide surfactant polymer with well-defined structures and hydrophilic/hydrophobic balances, by adjusting feed ratio of the lactose-based monomer (1) to styrene.