Development of high-performance starch-chitosan films reinforced by hyperbranched polyester from triethanolamine and...

This study reports a hyperbranched poly(ester amine) (TMA) synthesized via melt polycondensation of triethanolamine and maleic anhydride, and its application as a modifier for starch/chitosan (SC) films. Fourier-transform infrared spectroscopy (FTIR), ¹³C nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and liquid chromatography-mass spectrometry (LC-MS) confirmed the synthesis of TMA (weight-average molecular weight, Mw = 44,215 Da; polydispersity index, PDI = 1.94). Low loadings of TMA (1.25-5.00 wt% based on SC dry weight) were incorporated into the SC matrix to evaluate its effects on film properties. Results showed that 3.75 wt% TMA significantly enhanced tensile strength from 3.71 to 10.97 MPa while maintaining elongation at break (128.59% to 138.12%). Thermogravimetric analysis (TGA) revealed slight reductions in thermal stability. Antioxidant activity increased in a dose-dependent manner, with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) scavenging improving from 29.83% to 76.42% and ferric reducing antioxidant power (FRAP) values rising from 13.35 to 86.68 μmol FeSO₄/g at 5.00 wt%. TMA loadings of 1.25-3.75 wt% maintained water contact angle and moisture uptake, while 2.50 wt% minimized both water vapor and oxygen permeability. FTIR, X-ray diffraction (XRD), differential scanning calorimetry (DSC), ¹H NMR, circular dichroism (CD), and scanning electron microscopy (SEM) revealed that TMA incorporation disrupted native SC hydrogen bonding while inducing new hydrogen-bonding interactions between SC and TMA, leading to an increased strong/weak H-bond ratio and reduced crystallinity in the matrix, yielding a compact, homogeneous microstructure. This study provides a promising strategy for developing high-performance sustainable materials for potential food packaging applications.