Synthesis and polymerization of acrylic monomers with hydrophilic long side groups. Oxygen transport through water swollen membranes prepared from these polymers

Abstract

[EN] The synthesis and characterization of tetraethyleneglycol acrylate (TTEGA) and tetraethyleneglycol diacrylate are described. Radical polymerization reactions of TTEGA were carried out at different temperatures and the curves of conversion against time, obtained by using dilatometric techniques, allowed the determination of k(p)/k(t)(1/2), where k(p) and k(t) are, respectively, the propagation and termination rate constants. The values found for this ratio were comparatively much higher than those reported in the literature for other acrylic monomers. The polymer, poly(tetraethyleneglycol acrylate), is soluble in water, exhibits low glass transition temperature (-45 degrees C) and the percentage of syndiotactic dyads in the chains lies in the vicinity of 65 +/- 5%, a value normally found in similar polymers. Both poly(tetraethyleneglycol acrylate-co-tetraethyleneglycol diacrylate) and poly(triethyleneglycol acrylate-co-triethyleneglycol diacrylate) membranes were prepared by radical polymerization of the corresponding monomers and a small quantity of diacrylic esters. Electrochemical techniques were used to evaluate oxygen transport through these membranes swollen in water. The apparent values of both the permeability and diffusion coefficients are unusually large as a consequence of a high swelling degree of these membranes. Although the solubility coefficient of oxygen in the swollen hydrogels is larger than in water, restrictions in the diffusion path caused by the polymer matrix decrease the diffusion coefficient of the gas to ca one-third of its value in water.