OXIDATION OF THIOL-ENE POLYMERS FOR THERMOMECHANICAL PROPERTY MODIFICATION

Post-polymerization modification of thermomechanical properties is a useful approach to help address the limitations due to the inherently anisotropic nature of thermosetting materials used for 3D-printing applications. Bulk synthesis of thiol-ene chemistries combined with a crosslinking agent can form low cure-stress thermosetting polymers which enable high-temperature applications that are not possible with traditional thermoplastics. While the oxidation of thioether linkages to sulfone linkages has been studied previously, the use of thioether oxidation has not been applied to investigate thermomechanical property changes in thiol-ene systems.

The oxidation process was tested on different thiol-ene copolymers with varied chain lengths and crosslinking agent percentage for different time durations. The oxidized polymers were hypothesized to have higher T_g values and be stronger due to the rigidity of the S=O bonds formed in thioethers by oxidation. Results confirm the hypothesis and demonstrate the potential for practical use of the post-polymerization oxidation protocol to produce 3D-printed parts with improved mechanical load bearing characteristics.