New comonomers in malic acid polyesters

Here, we report the synthesis of polyesters of l-malic acid, beta-cyclodextrin, and two other comonomers, resorcinol and salicylic acid that, involved in the polyester chain by direct polycondensation, could improve the antibacterial activity. The copolymers were characterized by thermal analysis, infrared spectroscopy as well as by specific optical rotation values. The thermogravimetric and differential scanning calorimetry (TG-DSC) measurement results showed the influence of the comonomers on the thermal stability of the copolymers, which was higher when ZnO was present in the reaction mixture. The FTIR spectra confirmed the presence of the comonomers in the polyesters and the influence of the ZnO on the products. The specific optical rotation values showed similar tendency, and the results were in accordance with those got by TG-DSC and FTIR techniques. In short, the zinc oxide helped not only in ester formation but improved the polyester stability. Results allowed elaboration of reproducible polyester synthesis with tailor-made characteristic.