Gel permeation chromatography characterization of the chain length distributions in thiol-acrylate photopolymer networks

Cross-linked, degradable networks formed from the photopolymerization of thiol and acrylate monomers are explored as potential biomaterials. The degradation behavior and material properties of these networks are influenced by the molecular weight of the nondegradable thiol-polyacrylate backbone chains that form during photopolymerization. Here, gel permeation chromatography was used to characterize the thiolpolyacrylate backbone chain lengths in degraded thiol-acrylate networks. Increasing thiol functionality from 1 to 4 increased the backbone molecular weight ((M) over bar (w)) (2.3 +/- 0.07)x10(4) Da for monothiol and (3.6 +/- 0.1)x10(4) Da for tetrathiol networks). Decreasing thiol functional group concentration from 30 to 10 mol% also increased the backbone lengths ((M) over bar (w)) (7.3 +/- 1.1)x10(4) Da for the networks containing 10 mol % thiol groups as compared to (3.6 +/- 0.1)x10(4) Da for 30 mol % thiol). Finally, the backbone chain lengths were probed at various stages of degradation, and an increase in backbone molecular weight was observed as mass loss progressed from 10 to 70%.