Crosslinking network of bio‐based bis‐functional epoxides derived from trans‐limonene oxide

The thiol-ene reaction between trans-limonene oxide (trans-LO) and ethane-1,2-dithiol in the presence of triethylborane affords a bio-based bis-functional epoxide (bis-trans-LO). The crosslinking reaction of bis-trans-LO with branched polyethyleneimine (BPEI; M-n = 600; BPEI600) at a feed ratio of bis-trans-LO/BPEI600 = 57/43 (wt/wt) yields the corresponding network polymer with T-d10 (10% thermal decomposition temperature) of 304.7 degrees C in 98% yield. In contrast, negligible amounts of network polymer are obtained by the reaction of bis-LO (bis-functional epoxide derived from cis and trans-LO) and BPEI600 regardless of the feed ratio. The mechanical strengths as measured by direct tensile tests of the network polymers derived from bis-trans-LO and BPEI600,1800 (M-n = 600 and 1800) were approximately 16 and 11 times higher than that of bis-LO and BPEI1800, respectively. The tensile shear strengths of the metal-to-metal adhesive bonds induced by bis-trans-LO and BPEI600,1800 were 9.5 and 14.1 MPa, respectively. DMA revealed that the storage modulus of the network polymer derived from bis-trans-LO and BPEI1800 in the rubber region was higher than that of the material prepared from bis-LO and BPEI1800, indicating higher crosslink density of the bis-trans-LO/BPEI1800 system. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019