Hydrogenation of poly(myrcene) and poly(farnesene) using diimide reduction at ambient pressure

Abstract

Ambient pressure chemical hydrogenation using p‐toluene sulfonyl hydrazide (TSH) via thermal diimide formation (N2H2) permitted reduction of double bonds of poly(myrcene) (poly[Myr]) and poly(farnesene) (poly[Far]). Both pendent and backbone double bonds in poly(Myr) (Mn = 56 kg/mol) and poly(Far) (Mn = 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 (T10%) increased from 188 to 404°C for poly(Myr) and from 310 to 379°C for poly(Far). Tgs 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 102 to 104 Pa s) due to its Mn being much higher than its entanglement molecular weight. Poly(Far) viscosity only increased by 1.5 times after hydrogenation (~104 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.

Polymerization of Myrcene in Both Conventional and Renewable Solvents: Postpolymerization Modification via Regioselective Photoinduced Thiol–Ene Chemistry for Use as Carbon Renewable Dispersants

“…Hydrogenated PMy was obtained via reaction with p -toluenesulfonyl hydrazide (5 mol equiv for each myrcene unit) in an o -xylene solution under reflux at 144 °C for 6 h. 67 The resulting hydrogenation was high (>93%), confirmed by 1 H NMR ( Figure S16 ). TGA data showed increased thermal stability of the hydrogenated PMy as we expected ( Figure 4 ).…”

Toughening Poly(lactide) with Bio-Based Poly(farnesene) Elastomers

“…Therefore, to obtain PF samples with similar viscoelastic properties as poly­(isoprene) and poly­(butadiene) which could be used to rubber toughen PLA, a molecular weight of 50000 g/mol or higher is required. Conditions for the synthesis of PF have previously been developed by using several different approaches including anionic polymerization, redox free-radical polymerization in emulsion, nitroxide-mediated polymerization in miniemulsions and bulk, and free-radical polymerization (FRP) . However, only the FRP conditions are generally amenable to synthesize species with molecular weights greater than 50000 g/mol.…”

“…Here, slightly modified FRP conditions from Luk et al were employed to synthesize a suite of high molecular weight ( M n ’s of 58–63 kg/mol) farnesene-based polymers (Figure ). The hydrogenated derivative (HPF) has previously been shown to have higher thermal stability, a lower M e , and higher viscosity relative to its unsaturated counterpart (PF), , which are all more favorable characteristics of an elastomeric toughening agent for PLA and was therefore of interest here.…”

“…Here, slightly modified FRP conditions from Luk et al were employed to synthesize a suite of high molecular weight ( M n ’s of 58–63 kg/mol) farnesene-based polymers (Figure ). The hydrogenated derivative (HPF) has previously been shown to have higher thermal stability, a lower M e , and higher viscosity relative to its unsaturated counterpart (PF), , which are all more favorable characteristics of an elastomeric toughening agent for PLA and was therefore of interest here. With the goal of promoting an interfacial compatibilization reaction to achieve enhanced material properties, epoxy (PFGMA) and carboxylic acid (PFMAA) functionalized derivatives were also synthesized under the same conditions containing only modest amounts of compatibilizer groups (10 mol %).…”

“…farnesene monomer) instead of in bulk, and the reaction time was increased to 12 h. Poly­(farnesene- co -glycidyl methacrylate) (PFGMA) and poly­(farnesene- co -methacrylic acid) (PFMAA) were synthesized under analogous conditions by using 10 mol % of glycidyl methacrylate and methacrylic acid, respectively. Hydrogenated PF (HPF) was synthesized according to a previously reported procedure . Monomer conversions were calculated by using 1 H NMR as previously described .…”