Modification of Polysiloxane Networks for Biocompatibility

Abstract

The hydrophobic characteristics of polysiloxane networks somewhat limit their wide applications in biomedical fields in spite of their many promising properties. In this paper, several surface and bulk modifications to bimodal poly(dimethylsiloxane) (PDMS) networks are described to improve surface hydrophilicity as well as biocompatibility. Surface modification methods employed were ultraviolet/ozone-induced grafting hydrophilic monomer polymerization, plasma induced-surface grafting polymerization, and surface direct chemical bonding. Bulk modifications were carried out by using hydrophilic block copolymers and cross-linkers having hydrophilic dangling chains, which also conferred high surface hydrophilicity. The experimental results showed that the surface hydrophilicity was greatly improved, i.e., there were decreases from a static water contact angle of about 105° in pristine PDMS to about 20° in poly(ethylene oxide)/PDMS amphiphilic conetworks having linear dangling chains consisting of 6–9 units. The hydrophilic nature lasted at least 30 days, especially in the case of the application of the hydrophilic cross-linker in the networks. Some other properties including mechanical behavior, equilibrium water swelling content, surface characteristics, and morphology were also investigated.

Keywords:

• Biocompatibility
• hydrophilicity
• polysiloxanes
• surface modification

Acknowledgments

It is a pleasure to acknowledge financial support provided JEM by the National Science Foundation through Grant DMR-083454 (Polymers Program, Division of Materials Research), and the use of some facilities in the Department of Electrical and Computer Engineering at the University of Cincinnati to measure values of the hydrophilicity.

Notes

Note. See references [16,17,48].