Controlling network structure in degradable thiol-acrylate biomaterials to tune mass loss behavior

Degradable thiol-acrylate materials were synthesized from the mixed-mode polymerization of a diacrylate poly(ethylene glycol) (PEG) monomer with thiol monomers of varying functionalities to control the final network structure, ultimately influencing the material's degradation behavior and properties. The influence of the concentration of thiol groups and monomer functionality on the mass loss profiles were examined experimentally and theoretically. Mass loss behavior was also predicted for networks with varying extents of cyclization, PEG molecular weight, and backbone chain length distributions. Experimental results indicate that increasing the thiol concentration from 10 to 50 mol % shifted the reverse gelation time from 35 to 8 days and the extent of mass loss at reverse gelation from 75 to 40%. Similarly, decreasing the thiol functionality from 4 to 1 shifted the reverse gelation time from 18 to 8 days and the mass loss extent at reverse gelation from 70 to 45%.