Microwave-assisted preparation of fatty acid esters based eco-friendly plasticizers for biologically-active thiazole-functionalized PVC

Two thiazole derivatives namely, ethyl 2-((4-hydroxyphenyl)amino)thiazole-4-carboxylate (A) and 4-(4-(4-chlorophenyl)thiazol-2-yl)amino) phenol (B) were prepared using Huntzich thiazole method. These derivatives were used to functionalize poly(vinyl chloride), to give two antimicrobial compounds PVC-A and PVC-B, respectively for possible use in biomedical applications. P1, P2, and P3 are three ethylene glycol esters of stearic, octanoic, and oleic fatty acids were prepared by microwave irradiation as an alternative to traditional phthalate plasticizers for the development of flexible and phthalate-free antimicrobial polymers. The chemical structures of the functionalized PVC samples were confirmed using FTIR and H-1 NMR spectroscopies. Thermal and photostability of PVC-A and PVC-B were determined by thermogravimetric analysis and gel permeation chromatography. The results revealed that the functionalized PVC had higher thermal and photo stabilities than the unmodified PVC. The effects of plasticizers on the thermal stability and mechanical properties of functionalized PVC samples, as well as plasticizer migration from the polymeric matrix, were studied. The physicochemical properties of the modified PVC were improved by adding the prepared fatty acids plasticizers. The extent of plasticizer migration from the polymeric matrix was less than that of diethylhexylphthalate, the reference plasticizer. The antibacterial activity of the two prepared thiazoles, their functionalized PVC samples, and PVC blended with the prepared thiazoles was tested against Gram+ve and Gram-ve bacteria as well as Candida albicans, a fungus strain. The antibacterial activity of the investigated samples revealed that all of the samples had a stronger inhibitory effect against the microorganisms that were tested.