Synthesis Of Bio-based Polymers Through Click Chemistry And Characterization Of Corresponding Polymers

With the progress of the times,mankind is now facing a shortage of fossil resources and the consequent problems such as environmental pollution caused by it.Utilizing renewable biomass resources has great advantages in solving this problem.Lignocellulose is an important biomass resource.As one of the main components of lignocellulose,lignin can be transformed into various aromatic compounds including eugenol.Using these compounds derived from lignin to develop bio-based polymers is one of the effective ways to alleviate the oil crisis.This thesis uses eugenol as the raw material to design and prepare bio-based monomers and bio-based polymers,and study their structure and thermal properties,mainly including the following:On the one hand,using eugenol as a raw material,several polymerizable eugenol-based bisphenol monomers were synthesized by thiol-ene click reaction with dithiol.These bisphenol monomers replaced petroleum-based monomers and reacted with triphosgene,diacid chloride,and diisocyanate to prepare a series of bio-based polycarbonates,bio-based polyesters and bio-based polyurethanes.One of the polycarbonates and one of the polyesters were further oxidized to oxidize the sulfide bonds on the main chain to sulfones.The yield of these polymers were in the range of52%to 98%,and the molecular weight were ranging from 16000-60500 g/mol.TGA and DSC results showed the temperature with 5%weight loss in the range of 241-381~oC,and the T_g in the range of-9.1 to 35.0 ~oC.As the carbon chain of the dithiol segment grows,the thermal stability of the polymers were increasing,and the thermal stability of the polymers decreased after oxidation;the T_g of the polymers showed a downward trend,and the presence of rigid groups increased the Tg of the polymers.On the other hand,because isocyanate and its precursor phosgene have negative impact on human health,eugenol was used as raw material to synthesize eugenol-based cyclic carbonate compounds.Then several polymerizable eugenol-based bicyclic carbonate monomers were synthesized by thiol-ene click reaction between them and dithiol.The bio-based non-isocyanate polyurethane was prepared by reacting these bicyclic carbonate monomers and diamines.The yield of non-isocyanate polyurethanes reached 67-72%,and the molecular weight were ranging from 44400-46200 g/mol.TGA and DSC results showed the temperature with5%weight loss in the range of 334-339 ~o C,and the T_g in the range of 9.0-21.2 ~oC.As the carbon chain of the dithiol segment increases,the thermal stability of the polymers showed increasing trend,the Tg showed decreasing trend.