SYNTHESIS AND MECHANICAL-PROPERTIES OF INTERPENETRATING NETWORKS OF POLYHYDROXYBUTYRATE-CO-HYDROXYVALERATE AND POLYHYDROXYETHYL METHACRYLATE

Naturally occurring, biocompatible, and biodegradable polyhydroxybutyr ate-co-hydroxyvalerate (PHBV), and synthetic, non-degrading polyhydrox yethylmethacrylate (PHEMA) membranes were prepared and their mechanica l properties were studied. Their performances were compared with the i nterpenetrating networks (IPN) prepared by photopolymerization of HEMA in the presence of PHBV. The modulus of elasticity, failure stress an d failure strain indicated that the IPNs are viscoelastic with propert ies closer to PHEMA but much stronger than PHEMA homopolymers. Incorpo ration of PHBV (7, 14 and 22% I-IV) affected the mechanical properties positively. Increasing the PHBV content increased the modulus of elas ticity and failure stress nearly in all samples tested. PHBV (7, 14, a nd 22% HV, 300 mg) samples showed an approximately 17-30 fold increase in terms of modulus of elasticity and 7-10 fold increase in terms of failure stress. The scanning electron micrographs of the membranes sho wed that the PHEMA membranes are more porous than the PHBV membranes b ut the IPN structure displayed channels on the membrane surface indica ting that HEMA polymerization was achieved by using the PHBV as a scaf fold. With the use of the present technique, it is possible to synthes ize supramolecular structures from molecules that are not compatible a nd miscible with each other. (C) 1998 Published by Elsevier Science Lt d. All rights reserved.