Degradable Poly(butylene-co-divanillyl adipate) with Intrinsic Free Radical Scavenging and Antibacterial Performance

Bioactive polyesters with antibacterial and free radical scavenging functionalities help inhibit the spread of bacteria and eliminate the inflammation, which are of great significance for improving human health. In this study, a bioactive and degradable polyester was designed. First, divanillyl alcohol (DA) was synthesized from vanillin, and the copolymerization of DA, butanediol, adipic acid, and isophorone diisocyanate was conducted to obtain three kinds of polymers: polybutylene adipate (PBA), poly(butylene-co-divanillyl adipate) (PBDA), and chain extended PBDA (named as PBDAU). The H-1 NMR and infrared spectra illustrated the successful synthesis of the polymers. Their T-g values are -30.5, -31.0, and -28.7 degrees C, respectively. Interestingly, PBDAU showed intrinsic free radical scavenging activity (RSA). The RSA efficiency of PBDAU can reach up to 100%, while PBDA has 78% and PBA shows no RSA. Furthermore, PBDAU showed inhibition of bacterial growth, especially for the Escherichia coli. The excellent free radical scavenging and antibacterial performance for PBDAU should be associated with the stabilization of phenoxy radicals (Ar-O-center dot), and the easily split-off H-center dot/H+, which will then couple with the free radicals, like "the eagle catches the mouse". Meanwhile, the polyesters can be degraded under both acidolysis and alkalinolysis conditions. This study is expected to contribute a solution to the synthesis of a bioactive and degradable polyester.