Stereoselective syntheses and properties of levoglucosenone-containing polymers linked with 1,4-butanedithiol and their application as organogels
摘要
Owing to the increase in global concern, the replacement of fossil fuel-derived plastics with biomass polymers has attracted the interest of many researchers in both academia and industry. Levoglucosenone (LGO; 1), which is a biomass compound obtained from cellulose in wood or waste paper, has been used as a feedstock for biomass polymers. We recently discovered the stereoselective formation of tricomponent polymers, including LGO fragments, dicarboxylic dihydrazides and aromatic dithiol. In this report, the syntheses and properties of their analogs using aliphatic dithiol instead of aromatic dithiol are reported. The LGO monomer linked with 1,4-butanedithiol was prepared by the addition of K2CO3. Polycondensation of the monomer with several dicarboxylic dihydrazides proceeded to form the corresponding polyhydrazones. All the C-S and C = N bonds were formed stereoselectively. The obtained polymers showed negative optical rotations, which were complementary to those of aromatic analogs. When the polymerization time increased, DMF-insoluble polymers were obtained, which formed organogels with DMF. The degree of swelling varied between 170% and 469% depending on the carbon number of the dicarboxylic dihydrazide. The elongation of the aliphatic carbon chains was assumed to promote intermolecular entanglement, and the resulting polymers were assumed to behave as network polymers despite the linear chains.