SYNTHESIS AND CHARACTERIZATION OF POLYMER NETWORKS MADE FROM POLY(ETHYLENE OXIDE) AND POLYSILOXANE

In this paper, we describe the synthesis of copolymeric networks made from poly(ethylene oxide) (PEO) and a derivative of low-molecular-weight polydimethylsiloxane containing multiple glycidoxy functions (PGPMDMS). Upon addition of boron trifluoride etherate to homogeneous dichloromethane solutions of PEO and PGPMDMS, networks form via cationic ring opening of the glycidoxy groups, which add the terminal PEO hydroxyl and also homopolymerize. The molecular weight of PEO in the networks was varied from 690 to 17 700 and the PEO content was varied from 0 to 84 wt%. The reaction is sensitive to traces of water and the final network structure is affected by catalyst concentrations above 0.030 M. The networks containing PEO swell in water, and equilibrium swelling increases as the content of PEO increases. Equilibrium swelling does not increase with increases in PEO molecular weight because of intermolecular homopolymerization of PGPMDMS. Intentional oxidative degradation of the PEO component in these networks demonstrates that, for certain PEO-PGPMDMS compositions, a continuous PGPMDMS phase is formed. Because of the wide range of compositions that can be obtained, these networks are being used as a model system for studies on drug-releasing properties of hydrogels and on the blood compatibility of PEO-based materials. © 1990.