Polyanhydride Networks from Thiol-Ene Polymerizations

Thiol-ene photopolymerization was used in the synthesis of elastomeric polyanhydrides Side reactions involving the addition of thiol to the anhydride were observed but take place at a much slower rate than photoinitiated thio-lene polymerization The thermomechanical properties, including the glass transition temperature (T-g) as well as tensile and compressive modulus, of the cross-linked material were studied using dynamic mechanical analysis T-g values ranged from -15 to approximately -50 degrees C and were dependent on the degree of cross linking The Young s and compressive modulus measurements confirm that these types of networks are a soft rubber like material at room and body temperature and become softer as the cross linking density is reduced The hydrophobicity/hydrophilicity of these networks was analyzed by water contact angle measurements The polyanhydrides were moderately hydrophobic, with water contact angle averages ranging from 82 degrees to 92 degrees This hydrophobicity, coupled with the high reactivity of the anhydride groups, results in the material eroding via the surface erosion mechanism