Sugars may be viewed as a chemical feedstock to produce new monomers, thermoplastics, thermosets, crosslinking agents and additives for a broad range of biomedical and commercial applications, including the replacement of bisphenol-A. Sugar based chemicals are attractive because they are biocompatible, are a renewable resource and may be made available at competitive pricing. Interest is focused on isosorbide and 2,5 furan dicarboxylic acid with chemical functionality compatible with many existing biomaterials chemistries. Stereo-chemical complexity and asymmetric reactivity enables the control of Tg, hydrophilicity and mechanical properties of novel biocompatible, biodegradable thermoplastics and thermosets which, in turn, allows the tailoring of properties for specific biomedical applications.
Isosorbide is derived from glucose by catalytic hydrogenation to sorbitol followed by dehydration. Furandicarboxylic acid can be made from fructose through the intermediate 5-hydroxymethylfurfural. Synthesis of isosorbide based hydroxy acid monomers with terephthalic acid or furandicarboxylic acid enables creation of stereoregular homopolymers with high Tg and mechanical properties. Incorporation of the isosorbide terephthalate monomers into PET has been demonstrated to raise the Tg of the polyester, which enables hot-filling. Modification of PLA or PCL with isosorbide based hydroxyacids is expected to affect cell attachment to the polyester as well as degradation rate.
Isosorbide diesters of epoxidized undecenoic acid and glycidyloxybenzoates demonstrate water absorption behavior comparable to bisphenol A glycidyl ether when crosslinked. A matrix of epoxies with varying levels of water absorption has been created by altering the number of isosorbide molecules and position of substituents. Presence of an ester bond in most of the epoxies renders them susceptible to hydrolysis and enzymatic degradation in vivo. Reacting each epoxy with isosorbide-based amine or carboxylic acid crosslinkers creates hydrogels with varying mechanical properties, water absorption behavior and degradation rates suitable for soft tissue engineering or drug delivery systems with controlled release of a pharmacologically active substance.
