Synthesis and Characterization of Thermoresponsive Hydrogels Based on N-Isopropylacrylamide (NIPAAm) and Novel Crosslinkers

Two sets of temperature responsive hydrogels were synthesized by free radical polymerization combining N-isopropylacrylamide (NIPAAm) with novel polyphenolic crosslinkers chrysin multiacrylate (ChryMA) and 4,4’-dihyroxybiphenyl multiacrylate (44BMA). The temperature response of the hydorgels was characterized by temperature dependent swelling studies and reversible swelling studies, and the lower critical solution temperature (LCST) was characterized through differential scanning calorimetry (DSC). Results showed that the incorporation of polyphenolic crosslinkers could decrease the swelling ratios of the hydrogels and shift their LCSTs to lower temperatures. Gels with different crosslinker contents exhibited different levels of temeprature responsiveness. Higher content gels had a broader phase transition and smaller temperature response, which could be attributed to the increased hydrophobicity introduced by the polyphenolic crosslinkers.

Research Supported by the National Science Foundation REU Program #EED-1460486