Modifying network chemistry in thiol-acrylate photopolymers through postpolymerization functionalization to control cell-material interactions

Thiol-acrylate photopolymers often contain pendant, unreacted thiol groups even following complete reaction of the acrylate functional groups. The results presented herein demonstrate a high throughput method for quantifying pendant thiol group concentrations using FTIR spectra of thiol-acrylate microspot arrays. Using this technique, more than 25% of the original thiol groups were detected as pendant groups in microspots made from monomer solutions containing at least 40 mol % thiol functional groups. Subsequent modification reactions allowed postpolymerization tailoring of the network chemistry. The extent of modification was controlled by the concentration of the pendant thiols (ranging from 0.01 to 0.4M) and the duration of the modification reaction (0-10 min for photocoupling reactions, 0-24 h for Michael-type addition reactions). Further, when photocoupling was used to modify the networks, spatial and temporal control of the light exposure facilitated the formation of chemical patterns on the surface and throughout the material.