Room-Temperature Direct Polymerization of Glycerol via Ultrasonication

A study was conducted on the synthesis of glycerol polymerization using ultrasonic (USG) technology. Although ultrasonication has been widely applied in various chemical processes, its role in glycerol polymerization remains insufficiently explored. In this study, polymerization was conducted under initial room-temperature conditions for 150 min using 4 wt% NaOH as a catalyst at an ultrasonic power of 300 W, corresponding to a cumulative energy input of 427,182 J. The process yielded a product with a molecular weight of 697.53 g/mol and a degree of polymerization (DP) of 7.52. FTIR analysis confirmed ether bond formation through characteristic C–O–C stretching bands in the 1033–1210 cm−1 region, while the broad O–H band at 3284 cm−1 indicated the presence of residual hydroxyl groups consistent with hyperbranched architectures. 1H-NMR spectroscopy further verified polymer formation, evidenced by the emergence of a doublet resonance at δ 3.68–3.69 ppm corresponding to ether linkages and the shift of the hydroxyl proton signal from δ 5.11 ppm in glycerol to δ 4.45–4.79 ppm in the polymer. Quantitative analysis using the Fréchet equation yielded a Degree of Branching (DB) of 0.57, characteristic of a well-defined hyperbranched architecture. This high DB ensures a dense periphery of hydroxyl groups, promoting excellent water solubility and versatile functionalization potential.