Construction and properties of sequential dual thermal curing thiol-acrylate-epoxy 3D network

At room temperature, the differences in the reactivity of thiol-acrylate and thiol-epoxy catalyzed by tertiary amines are obvious and have controlled sequential curing characteristics. In this paper, a thiol-acrylate-epoxy sequential dual thermal curing system was constructed with pentaerythritol tetra(3-mercaptopropionate) (SH4), 1,4-bis[(2-oxiranylmethoxy)-methyl]-benzene (BOB) or 2,5-bis[(2-oxiranylmethoxy)-methyl]-furan (BOF), and 1,4-cyclohexanediylbis(methylene) diacrylate (CHDMDA), and the effect of hydrogen bonding on the curing process and properties of the system was investigated. FTIR, rheological analysis, DSC, DMA, universal material testing machine and hardness tester were used to characterize the thermal properties, rheological properties, mechanical properties and ambient temperature service period of the intermediate material after the first stage curing and the final material after the second stage curing. The results show that the presence of hydrogen bonding delays the dual curing reaction and improves the mechanical properties of final material. In addition, the rheological, thermal and mechanical properties of the two-stage materials produced by this sequential dual thermal curing system can be regulated, and the intermediate materials can maintain stable properties at room temperature for 24 h. Controlled sequential dual curing gives thermoset polymers easy complex shape processing molding, high performance, and a broader range of applications such as shape memory actuators and pressure sensitive adhesive films, breaking the limitations of thermoset plastics in shape design and processing. © 2022 Chemical Industry Press. All rights reserved.