The objective of this work was to develop tough and glassy thiol-X network materials through the elimination of interchain ester linkages from their structures and by that extend the scope of thiol-X reaction implementations. To achieve the goal ester-free multifunctional thiols such as tetra(2-mercaptoethylene)-silane and 1,2,3-tris(3-mercaptopropylene)-1,3,5-triazyne-2,4,6-trion were synthesized and used in stoichiometric reactions with divinyl sulfone and/or hexamethylene diisocyanate. Further, thermoechanical properties of neat phosphine-catalyzed thiol-vinyl sulfone and thiol-vinyl sulfone-isocyanate networks fabricated in a controlled manner were reported, and a comparison with ester-containing thiol-acrylate step-growth networks was performed. It was shown that neat thiol-vinyl sulfone networks containing high weight fractions of sulfone groups exhibit significantly higher glass transitions temperatures (Tg) than structurally similar but ester-containing thiol-acrylate networks. Tgs as high as 112°C were achieved for ester-free thiol-Michael polymers (Fig. 1). It was also shown that the combination of sulfone and thiocarbamate structural effects generally shifted the Tg toward higher values and improved the materials’ toughness.

Thiol-vinyl sulfone and thiol-vinyl sulfone-isocyanate crosslinking reactions to generate glassy and tough network polymers

249th National Meeting (2015)

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