Sequence-Regulated Adhesion of Poly(diethyl glycolide- alt -β-butyrolactone) Synthesized via Enantiomorphic Site-Assisted Stereospecific Alternating Copolymerization

Abstract Biodegradable polyesters can be promising adhesives for their inherent biodegradability, yet their adhesive performance still requires substantial enhancement to meet practical demands. In this work, the alternating sequence effect on adhesive property was explored in the alternating copolymer of S,S-diethylglycolide (S,S-EG, derived from α-hydroxybutyric acid, i.e., α-ethyl-glycolic acid) and R-β-butyrolactone (R-BBL, derived from β-hydroxybutyric acid). However, the alternating copolymerization of these two monomers is still a challenge due to their distinct chemical structures and the inherent competition between cross-propagation and homopropagation. Herein, the successful alternating copolymerization of S,S-EG and R-BBL was reported with an alternating probability of 0.96 through an enantiomorphic site-assisted stereospecific alternating copolymerization strategy using new 1,1′-bi-2-naphthol (BINOL)-derived axially chiral yttrium complex catalysts. Remarkably, the lap-shear adhesion strength of the resulting copolyesters on stainless steel reaches a high level of 10.5 MPa, correlating positively with the increased regularity of the alternating sequence. This improvement can be attributed to the combined effects of interchain electrostatic interactions and viscoelastic behavior, which suggests that monomer sequence can also serve as a molecular parameter for regulating interfacial adhesion performance.