Modulating Thermal Stability and Flexibility in Chitosan Films with Neutral Polyol-Boric Acid Complexes

Area of Science:

• Materials Science
• Polymer Chemistry
• Biotechnology

Background:

• Bioplastics offer sustainable alternatives to traditional plastics.
• Chitosan, a biodegradable polymer, has potential in various applications.
• Controlling bioplastic properties is crucial for material design.

Purpose of the Study:

• To investigate the effect of boric acid and erythritol on chitosan properties.
• To understand the structure-property relationship in boron-modified chitosan.
• To explore the modulation of flexibility and thermal stability in chitosan bioplastics.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy for isomer identification.
• Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) for structural analysis.
• Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Dynamic Mechanical Analysis (DMA) for thermal and mechanical characterization.
• Scanning Electron Microscopy (SEM) for morphological studies.

Main Results:

• Neutral complexes of erythritol and boric acid were formed, primarily as 1,3-isomers.
• Increased aggregation and hydrogen bonding were observed between the boron complexes and chitosan's d-glucosamine units.
• Modulation of erythritol and boric acid concentrations successfully altered chitosan's flexibility and thermal stability.
• Characterization confirmed changes in structural, thermal, mechanical, and morphological properties.

Conclusions:

• Boron incorporation, via boric acid and erythritol complexes, offers a viable strategy to tune chitosan bioplastic properties.
• The observed changes in hydrogen bonding and aggregation correlate with enhanced material flexibility and thermal stability.
• This study provides insights into designing boron-modified bioplastics for specific applications.