Green Synthesis of Urethane‐Linked Tamarind Seed Xyloglucan: Thermal Stability, Antibacterial Properties, and DFT Study

Abstract

This study presents a feasible, one‐pot synthesis approach for the preparation of a composite biopolymer material derived from tamarind seed xyloglucan (XG) by utilizing isocyanate chemistry. Through a facile reaction process, urethane bonds are formed in XG, resulting in the formation of a crosslinked network. FTIR spectra confirm the successful urethane link formation in XG via the OH‐NCO reaction, and CHN analysis provides insights into the elemental composition. The synthesized XG‐urethane composite (U‐XG) exhibits enhanced thermal stability compared to native XG, with an enhanced degradation temperature (T5%) of 276°C (XG marked T5% at a lower temperature of 163°C). The optimized geometric structure, hydrogen bond types, and hydrogen bond strength of the synthesized U‐XG are computationally studied by density functional theory (DFT) at the B3LYP/6‐31G(d,p) level. This study also investigates the antibacterial efficacy of both XG and U‐XG against a panel of pathogenic bacteria, including gram‐positive bacteria such as S. aureus and S. epidermidis, as well as gram‐negative E. coli. The U‐XG demonstrates superior antibacterial activity against S. epidermidis compared to pristine XG. This research showcases the feasibility of a one‐pot synthesis approach for preparing urethane‐linked XG with enhanced thermal properties and superior antibacterial activity, offering promising prospects for biomedical and antimicrobial applications.