Polymerization and depolymerization of polyesters and polycarbonates using 1,1,3,3-tetramethyl guanidine as a catalyst for improved resource utilization

Abstract

Despite being biodegradable materials whose random disposal has no significant impact on the environment, finding new routes to recycle polyesters and polycarbonates under the current conditions of limited resources is of high importance. This study used 1,1,3,3-tetramethylguanidine (TMG) as a catalyst to test the polymerization of polylactide and poly(hexane-1,6-diol carbonate). In addition, the depolymerization of polylactide, poly-ε-caprolactone, polyvalerolactone, polyethylene terephthalate, and poly(bisphenol A carbonate) using TMG as a catalyst was investigated. In LA polymerization, various alcohols can be employed to initiate the reaction using TMG as a catalyst. When BnOH and poly(ethylene glycol) monomethyl ether-1900 were used as initiators, highly controlled LA polymerizations were observed. In addition, TMG could depolymerize PLA, PCL, PVL, PET, and PBAC in alcohol and water to produce alcoholysis products. Compared to depolymerization using 1,8-diazabicyclo[5.4.0]undec-7-ene and 1,5,7-triazabicyclo[4.4.0]dec-5-ene as catalysts, TMG exhibited an absolute advantage over PCL, PET, and PBAC depolymerization.