DOI: 10.14457/tu.the.2019.524
title: Olefin metathesis of biorenewable resources–application of ruthenium catalysts

description: Concerns over the depleting fossil resources and increasing CO2 emissions are driving a strong interest in utilizing bio-renewable resources in the production of valuable synthesis materials. This research focuses on the synthesis of polyfunctional compounds, polyesters, and thermoset polymers from vegetable oils and its derivatives via olefin metathesis reactions using ruthenium-carbene catalysts. The research can be divided into three parts as follows.In the first part, cross-metathesis (CM) of unsaturated fatty acid methyl esters [methyl oleate (MO), methyl petroselinate (MP), and methyl erucate (ME), obtained from vegetable oils] with eugenol (obtained from clove oil) proceeded under green and mild conditions (in 2-propanol or ethanol at 50 ºC) in the presence of a ruthenium-carbene catalyst (called a second-generation Grubbs catalyst, G2). These metathesis reactions archived high conversion (&gt;90% of MO, MP) and selectivity (&gt;98%) even with low catalyst loading (0.1 mol % Ru). It believes that the CM reactions of UG with unsaturated fatty acid methyl esters open the route for the synthesis of a variety of polyfunctional compounds from renewable feedstocks.The second part is the development of bio-based polymers derived from vegetable oils via olefin metathesis polymerization. In this part, the renewable polyesters were synthesized by acyclic diene metathesis (ADMET) polymerization of α,ω-dienes, 4-allyl-2-methoxyphenyl 10-undecenoate (M1), prepared from bio-renewable eugenol and castor oil (undecenoate). The second-generation Grubbs catalyst (G2) afforded polymers with unimodal molecular weight distributions (Mn = 12700, Mw/Mn = 1.85). The polymerization of M1 in the presence of a triarm cross-linker, 5-formylbenzene-1,2,3-triyl tris(undec-10-enoate), also afforded polymers with certain uniform network structures. It thus believes that the present method approach is promising and should be applicable for the synthesis of polyesters from monomers prepared from bio-renewable resources.In the third part, bio-based thermoset polymers from norbornene-functionalized various plant oils (olive oil, rapeseed oil, and soybean oil) were prepared via ring-opening metathesis polymerization (ROMP) in the presence of G2 catalyst. Two norbornene-based crosslinking agents included petroleum-based norbornene and bio-based norbornene (norbornene-functionalized isosorbide, NB-IS) were used as crosslinkers. The catalyst loading determined to be most effective in this study was 0.5 %wt. The glass transition temperature (Tg) and storage modulus (E’) of the resulting bio-based thermoset films increased dramatically upon increasing catalyst loading due to the enhanced the crosslink density. The number of norbornene rings per triglyceride in the norbornene-functionalized plant oils significantly influenced on the crosslink density. Moreover, the addition of crosslinkers increased considerably the Tg and E’ values of all bio-based thermoset films. The results revealed that the bio-based norbornene crosslinker (NB-IS) is comparative to replace the petroleum-based norbornene in target to improve the thermo-mechanical properties of the bio-based thermoset films. These plant oil-based thermosets are potential promising environmentally friendly thermoset polymers.