Generation-dependent synthesis and reaction kinetics of octylsilane-cored hyperbranched polyesters

In this work, a series of octylsilane-cored hyperbranched polyesters (OSi-HBPs) of different generations (G1-G3) was successfully synthesized via one-pot polycondensation reaction using triethoxy-n-octylsilane as core and 2,2-Bis(hydroxymethyl)butyric acid as monomer. The structural evolution, reaction kinetics, and thermal properties of the synthesized HBPs were systematically investigated. The formation of ester linkages was confirmed through NMR and FTIR spectroscopy. Progress of the polymerization was monitored from the conversion of acid-to-ester peaks using FTIR, allowing the determination of optimum reaction time for each generation, viz. 6, 8, and 10 h for G1, G2 and G3, respectively. MALDI-TOF analysis confirmed molecular weight distribution and the formation of branched structure. Thermal characterization using TGA and DSC revealed a generation-dependent improvement in the thermal stability. Glass transition and degradation temperatures increased with higher generation, indicating enhancement in structural complexity. Despite a nearly constant degree of branching (~0.66), the molecular size, number of terminal groups, and structural complexity increase significantly with generation. Overall, this study provides a clear understanding of the synthesis, characterization, and reaction kinetics of OSi-HBP (G1-G3). • Octylsilane-cored hyperbranched polyesters was successfully synthesized. • Polymerization kinetics monitored via FTIR acid-to-ester conversion. • MALDI-TOF confirmed branched structure and molecular weight distribution. • Thermal stability improved with increasing HBP generation.