Repeatable molecularly recyclable semi-aromatic polyesters derived from lignin

The design of molecularly recyclable polymers contributes to a possible solution to the end-of-use issue of polymeric materials and gives a closed-loop approach toward a circular materials economy. The biobased semi-aromatic polyesters (e.g., poly(phloretic acid), poly(dihydroferulic acid), and poly(dihydro-sinapinic acid)), described in this paper, can be derived entirely from biomass (mainly lignin). The described polyesters exhibit thermal properties similar to those of certain commodity polymeric materials. These polyesters with ligno-phytochemicals as monomer have so far demonstrated complete and almost infinite molecular recyclability with a loss of total mass less than 5% per cycle. Moreover, molecular weight and thermal properties (T_g, T_m, and T_cryst) of the tenth generation polymeric material are identical to those of the first generation.