Biobased unsaturated polyesters containing trans-2-butene-1,4 -diol and various dicarboxylic acids: Synthesis, characterization, and thermo-mechanical properties

Trans -2-butene-1,4-diol ( t B), a renewable unsaturated monomer prepared from erythritol, is a promising building block for future biobased unsaturated polyesters. Herein, a series of biobased unsaturated polyesters based on t B and eight linear α, ω-diacids was explored by melt-polycondensation. Under the optimized reaction conditions, the alkene bonds of t B were intact in the polyester backbones with no isomerization or saturation side reactions taking place during the polymer synthesis even without a radical quencher adding. Surprisingly, the synthetic unsaturated polyesters reached high weight average molecular weight ( M w ) up to 93.0 kDa. These results indicated that t B was an ideal unsaturated monomer used for the synthesis of biobased unsaturated polyesters with well-defined structure. Moreover, the structure–property relationships of the unsaturated polyesters were discussed via studying the effect of chain length on crystalline and thermo-mechanical properties. The result of tensile test manifested that t B performed better than 1, 4-butanediol in improving the tensile stress of polyesters. Among the synthetic polyesters, poly( trans -butene suberate)(P t BSu), poly( trans -butene sebacate) (P t BSe), and poly( trans -butene dodecanedioate) (P t BDo) gave T m of 61.2−78.5 °C, satisfactory crystalline property, and exhibited comparable or even better tensile properties compared with most industrial aliphatic polyesters. Overall, t B was a promising candidate for replacing petroleum-based monomers for the preparation of unsaturated polyesters with superior thermomechanical properties. • High molecular-weight unsaturated polyesters were prepared based on the biobased trans -2-butene-1, 4-diol. • The polyesters show excellent thermomechanical property, satisfactory crystalline property and broad processing window. • The physical properties of the polyesters could be effectively regulated by changing the chain length of diacids.