Synthesis, Characterization And Photogelation Of Polyethylene Glycols End-Capped With Vinylbenzyl Hydrophobias

Polyethylene glycols end-capped with vinylbenzyl (PEG-yB) with various molecular weight (PEG, Mn=~2k, 4k, 6k, 10k and 20k) were synthesized. The molecular weight and structure of PEG-VBs were characterized by 'RNIVIR, FT-LR and GPC with RI and UV dual detector. It turned out that the synthesized PEG-VB had very high double bond end-functionality.The self-association behaviors of PEG-VBs aqueous solution were investigated by a variety of techniques. The critical micelle concentration (cmc) of the solutions was determined by the surface tension, which was consistent with that determined by rheological measurements. Besides, We investigated the cloud-point of the PEG-VB aqueous solution and the impaction of different solvents on the aggregation ability of PEG-VBs. A model was developed to account for these results. In this model, the PEG-VBs form rosette-like micelles comprised of looped chains. At higher concentrations, larger structures are formed from further aggregation of these micelles.By UV photo-polymerizing hydrophobic domains self-formed in PEG-VB aqueous solution, hydro-gel membranes were prepared with a variety of concentrations and irradiation time. Swellability, mesh sizes, equilibrium volume fractions of the membranes and average molecular weights between crosslinks were found to be much influenced by molecular weight and aqueous solution concentration of VBPEGs, and irradiation time. On the basis of above results, a model to describe the structure of hydrogel membrane was developed. The relation of the mesh size of PEG-VB hydrogel membranes to the diffusivities of bovine serum albumin (BSA, Mw=~69O0) were determined.