Caryophyllene as a Precursor of Cross-Linked Materials

Abstract

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 Mn = 2 x 10 4 g.mol-1 (Đ = 1.5) with a glass transition temperature (Tg) of-35 °C. On the first hand, thermal cross-linking 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 Tg 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.

Polycaryophyllene as a Promising Plasticizer for Ethylene Propylene Diene Monomer Elastomers

“…The plasticized EPDM with Pcar@Sty#02 showed a slight difference in T g between the vulcanized and nonvulcanized counterpart (−50 and −53 °C, respectively). This might be due to the capability of Pcar to produce cross-linked networks by vulcanization and its increasing T g , as reported in a previous published work from our group …”

“…On the contrary, Pcar@Sty#02 was able to enhance considerably the elongation at break from 80 to 140%, suggesting the improvement of elastic properties and lowering the Young’s modulus. This effect may be due to the ability to cross-link as aforementioned elsewhere . A simplified model scheme describing the plasticizer–EPDM organization is displayed in Figure S12.…”

“…The synthesis of Pcar by classical ROMP was initially reported by Grau and Mecking and the resulting Pcar showed a molar mass of 20 × 10 3 g mol –1 and T g of −32 °C . We have more recently demonstrated that Pcar can be used as elastomer matrices . The study described the cross-linking Pcar by different pathways (traditional vulcanizationvia peroxide or sulfuror UV light-assisted thiol–ene) leading to elastomers with tuned thermomechanical properties.…”

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

“…Poly­(caryophyollene) can be made with molecular weights of up to 20 000 g/mol with dispersity values of 1.8–1.9 with a generation III Grubbs catalyst . Furthermore, the exocyclic bonds present in poly­(caryophyllene) can be cross-linked by various chemical strategies (e.g., thiol–ene reaction) to generate polymers with storage moduli between 1 and 100 MPa and an elongation until break of up to 360% …”

Ring-Opening Metathesis Polymerization for the Synthesis of Terpenoid-Based Pressure-Sensitive Adhesives

“…In other words, numerous (controlled) chain growth polymerization techniques can be used in combination with terpenes for the design of PSAs. On the other hand, while ring-opening metathesis polymerization (ROMP) allows for ultrafast synthesis of high molecular weight polymers on a multigram scale, the direct ROMP of terpenes is currently limited to δ-pinene, apopinene, caryophyllene, and humelene . These cyclic monomers carry a certain amount of ring strain, which makes direct ring-opening metathesis possible to obtain low dispersity polyterpenes with molecular weights up to 20 kDa.…”