Macromolecular Rapid Communications, Vol.37, No.13, 1027-1032, 2016
High-T-g Thiol-Click Thermoset Networks via the Thiol-Maleimide Michael Addition
Thiol-click reactions lead to polymeric materials with a wide range of interesting mechanical, electrical, and optical properties. However, this reaction mechanism typically results in bulk materials with a low glass transition temperature (T-g) due to rotational flexibility around the thioether linkages found in networks such as thiol-ene, thiol-epoxy, and thiol-acrylate systems. This report explores the thiol-maleimide reaction utilized for the first time as a solvent-free reaction system to synthesize high-T-g thermosetting networks. Through thermomechanical characterization via dynamic mechanical analysis, the homogeneity and T(g)s of thiol-maleimide networks are compared to similarly structured thiol-ene and thiol-epoxy networks. While preliminary data show more heterogeneous networks for thiol-maleimide systems, bulk materials exhibit T(g)s 80 degrees C higher than other thiol-click systems explored herein. Finally, hollow tubes are synthesized using each thiol-click reaction mechanism and employed in low- and high-temperature environments, demonstrating the ability to withstand a compressive radial 100 N deformation at 100 degrees C wherein other thiol-click systems fail mechanically.