Poly(3-hydroxyalkanoate)s functionalized with carboxylic acid groups in the side chain

Biodegradable polyesters represent an important class of materials, and one subset of these polymers are the bacterially produced poly(3-hydroxyalkanoate)s (PHA), a bacterially produced material. These polymers are very hydrophobic, and chemical methods to increase their hydrophilicity will ultimately lead to new applications. Many copolymers of PHA are known that contain simple, nonpolar functionality in the side chain, and we explored the conversion of side-chain olefins to carboxylic acids under conditions that minimize molecular weight degradation. With the use of osmium tetraoxide and oxone, the conversion proceeded to completion with little backbone degradation, which was confirmed with NMR, IR, and gel permeation chromatography (GPC). The solubility character of the polymer before and after reaction is very different, and several solvents were explored including acetone, tetrahydrofuran (THF), and water.