Caryophyllene as a Precursor of Cross-Linked Materials

This paper aims at the synthesis of a new type of elastomers from caryophyllene. The adopted strategy was to cross-link the polycaryophyllene, which was synthesized by ring-opening metathesis polymerization (ROMP). The polycaryophyllene obtained showed M_n = 2 x 10⁴ g.mol^-1 (Đ = 1.5) with a glass transition temperature (T_g) of -35 °C. On the first hand, thermal crosslinking was performed in the presence of organic peroxides or sulfur system. On the second hand, thiol-ene coupling initiated by UV-light at room temperature was also investigated as an alternative pathway to cross-link the polycaryophyllene. The materials obtained were analyzed by TGA, DSC, and DMA. The T_g of cross-linked polycaryophyllene could be easily modulated from -35 °C to a range between -25 and 10 °C by changing the type of cross-linking agent. The curing process led to the improvement of thermal stability ranging from 200 °C to around 340 °C. Finally, the network storage modulus varied from 1 to 100 MPa at room temperature.