Vegetable Oil-based Epoxide Monomers:Synthesis And Copolymerization With Anhydride And CO₂

Biomass-based polymers have been received much attention due to the advantages in the environmental protection and resource conservation.In this study,several vegetable oil-based polycarbonates were synthesized by the copolymeration of cyclic anhydride and/or CO₂with vegetable oil-based epoxide which were prepared from10-undecenoic acid(a biobased fatty acid derived from castor oil).The resulting biobased polycarbonates with C=C double bonds could be post-polymerization modified by mercaptan with long alkyl chain through thiol-ene click reaction and the comb-like polymer with variable phase transition temperature have been achieved.This provides a feasible approach for the high value-added utilization of vegetable oil.The main conclusions are as follows:1.Two vegetable oil based epoxide monomer,oxiran-2-ylmethyl 10-undecenoate(OYU)and epoxide methyl 10-undecenoate(EMU),were synthesized from 10-undecenoic acid cracked by castor oil.It was found that the yield was increased by 23%by recrystallization instead of vacuum distillation method in the preparation of OYU.2.The copolymers of EMU/CO₂ and OYU/CO₂(POYUC)were synthesized under the catalysis of zinc glutarate(Zn GA)and double metal cyanide(DMC),respectively.The effects of reaction temperature,time and the amount of DMC catalyst on POYUC were studied.The results displayed that terminal OYU monomer with high reactivity,which could achieve 100%conversion(m(OYU):m(DMC)=10000:1,110?,t=1 h).In addition,P-1 polymer dissolved in petroleum ether and P-2 polymer precipitated in petroleum ether were obtained respectively by using DMC to catalyze OYU,PO and CO₂.¹H NMR and GPC curves indicated that the content of carbonate and the molecular weight(M_n)of P-2 were higher than P-1.With the feed ratio of PO/OYU increasing,the mass fraction of P-2 increased from 26.7% to 95.5%.3.Comb-like POYUC-g-R polymers with different side chain lengths were synthesized by grafting mercapto functional monomers to the alkyl side chains of POYUC polymers through a thiol-ene click reaction.It was found that the decrease of molecular weight of POYUC caused by the UV light-mediated the breaking of ether linkage in the polymer chain in the grafting reaction.The melting temperature(T_m)and enthalpy(?H_m)of POYUC-g-R respectively increased from-15.0 ? and 34.1 J/g to 69.3 ? and 108.5 J/g with the increase of alkyl side chain length from 10 to 28.Moreover,the alkyl side chains were arranged in the form of hexagonal(?_H)crystals indicated by XRD.