Hydrogenation of poly(myrcene) and poly(farnesene) using diimide reduction at ambient pressure
Sharmaine B. Luk, Adrien Métafiot, Judith Morize, Emmanuel Edeh, Milan Marić
Abstract
Abstract Ambient pressure chemical hydrogenation using p ‐toluene sulfonyl hydrazide (TSH) via thermal diimide formation (N 2 H 2 ) permitted reduction of double bonds of poly(myrcene) (poly[Myr]) and poly(farnesene) (poly[Far]). Both pendent and backbone double bonds in poly(Myr) ( M n = 56 kg/mol) and poly(Far) ( M n = 62 kg/mol) synthesized by conventional free radical polymerization were hydrogenated to almost completion. Furthermore, TSH semi‐batch addition efficiently hydrogenated double bonds, while avoiding undesired autohydrogenation of diimides that occurred in batch mode. Thermal stability improved for hydrogenated poly(Myr) and poly(Far), where temperature at 10% weight loss ( T 10% ) increased from 188 to 404°C for poly(Myr) and from 310 to 379°C for poly(Far). T g s of poly(Myr) and poly(Far) also increased by about 10–25°C, indicating increased stiffness after hydrogenation. Finally, viscosities of poly(Myr) and poly(Far) were also increased after hydrogenation, and a greater increase was observed for poly(Myr) (by two orders of magnitude from 10 2 to 10 4 Pa s) due to its M n being much higher than its entanglement molecular weight. Poly(Far) viscosity only increased by 1.5 times after hydrogenation (~10 4 Pa s), comparable to the poly(Myr) after hydrogenation, suggesting unsaturated poly(Far) was more entangled than unsaturated poly(Myr) because of its longer side chains.