Biodegradable polymers, derived from multifunctional hydroxyacids for slow release biomedical applications, were the objectives of this investigation. Poly((beta)-malic acid) was prepared by the ring opening polymerization of benzyl malolactonate, followed by hydrogenolysis of the resulting benzyl ester. Malolactonate ester monomers, including the methyl, ethyl, i-propyl, t-butyl, and benzyl esters, were prepared in 80 percent yields from aqueous solutions of the sodium salts of the various bromosuccinate esters utilizing a two phase system. Proper selection of the reaction temperature and the organic phase afforded high yields in short reaction times without the need for catalysts. Anionic, cationic, and organometallic initiators were used for the polymerizations. Anionic reactions gave the best results, but reactions with impurities and transfer to monomer during polymerization prevented the formation of living polymers, although molecular weights up to 50,000 were obtained. Conversion of poly(benzyl malolactonate) to poly((beta)-malic acid) was accomplished by catalytic hydrogenolysis at room temperature and atmospheric pressure. No backbone degradation occurred under these conditions. The effect of molecular weight, solvent, and catalyst on the rate of hydrogenolysis was studied. The polymers were characterized by spectroscopic techniques and thermal analysis. Biological-related evaluations to date, including toxicity and immunogenicity studies, are summarized.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-5790 |
| Date | 01 January 1983 |
| Creators | JOHNS, DOUGLAS BRIAN |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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