Preparation And Properties Of Silicone-Hydrogel Interpenetrating Polymer Network Materials

Poly(dimethylsiloxane) (PDMS) has been widely used and generated great interests as a biomaterial due to its good biocompatibility, stability, elasticity, and excellent oxygen permeability. Researchers have focused on developing materials applicable to artificial organs, soft tissue replacement and contact lens based on PDMS. However, one potential drawback of PDMS is its hydrophobicity. The limitations for its biomedical applications lie in the facts that proteins and lipids may tend to adsorb onto the native hydrophobic surface, pure PDMS may also cause a tissue adhesion and has a poor permeability to nutrients. In this paper, silicone-hydrogel interpenetrating polymer networks (IPNs) were prepared. The incorporation of second hydrophilic phase improves the surface wettability and endows the PDMS matrix with certain swellability for applications such as drug release and long time implantation.Composite IPNs PDMS and poly (2-hydroxyethyl methacrylate) (PHEMA) were prepared by monomer immersion method and influencing factors on hydrogel content were investigated. Improved surface wettability and swelling ability suggested the hydrogel component were present on the surface as well as in the bulk material. Hydrogel second network content in the IPN system can be optimized by addition of solvent during both PDMS curing procedure and subsequent hydrogel incorporation step to give better hydrophilicicty.Semi-interpenetrating polymer networks (semi-IPNs) based on PDMS and poly(vinyl alcohol) (PVA) were successfully prepared by crosslinking of the hydroxyl-terminated PDMS chains with tetraethylorthosilicate (TEOS) by a sol-gel process concomitant with the addition of different amounts of PVA into the system. Characterization of the PDMS/PVA semi-IPNs was carried out, thus reveals the relationships between the presence of PVA domains and the properties of resulting PDMS/PVA semi-IPNs.In order to pursue advantages such as easier implantation, better dispersion, and potential access to new implantation sites, a method to obtain PDMS/PHEMA IPN beads was developed. With further optimization, up to 43% PHEMA was incorporated into PDMS microspheres, offers an improved hydrophilicity and thus a reduced protein adsorption for long-term use. Furthermore, we found the PDMS/PHEMA IPN beads possess a hollow capsule-like structure, proposing their application as novel drug delivery vehicles.In recent years, porous implant materials have generated great interests, since the unique structures provide desired properties in practical applications. In our study, porous biphase silicone-hydrogel IPN films were synthesized by a template method. Surface modification of the CaCO3 microsphere templates improves their dispersibility, leading to an interconnected porous structure of obtained IPN films. Results showed that these porous IPN films exhibited higher swelling abilities, and thus higher drug loading capabilities than the corresponding nonporous, revealing their possibility to be used as materials for biomedical applications.