Hyperbranched polyglycidol grafted with rosin by a natural catalyst under ultrasound: Synthesis, characterization and antimicrobial activity

This study aimed to apply a novel green polymerization process to produce a new copolymer with potential antimicrobial activity for industrial application. The glycidol was polymerized into hyperbranched polyglycidol (HPG) polymer which in turn has been esterified with rosin to produce hyperbranched copoly(glycidol-Rosin) (HPGR), a new co-polymer. The process used Maghnite-H+, a montmorillonite silicate sheet clay, as an eco-catalyst and ultrasound was applied to enhance the interaction during polymerization. Different catalyst amounts were tested to assess their effects on the polymerization process. Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) were used to analyze the polymer products. The antimicrobial activity of HPGR was assessed against six human standard microbial strains using the agar disc diffusion method. The catalyst percentage of 10% resulted in the best yield for HPGR (35%). Thermogravimetric Analysis (TGA) revealed a best thermal stability of HPGR compared to that of HPG. The HPGR co-polymer displayed the best antibacterial activity against Klebsiella pneumonia, Bacillus cereus, Staphylococcus aureus, and Escherichia coli, producing inhibition zones of 12.33 ± 0.57, 11.00 ± 1.00, 10.66 ± 1.15, and 10.33 ± 1.15 mm, respectively. The hyperbranched copoly(glycidol-Rosin), an eco-catalyst-synthesized co-polymer, displayed interesting physical and antimicrobial properties for industrial application.