Enabling phase transition in pectin through green heterogeneous synthesis: Structural and thermal insights

Area of Science:

• Materials Science
• Polymer Chemistry
• Green Chemistry

Background:

• Flexible plastics market demands polymers with viscous flow processing capabilities.
• Natural polysaccharides like pectin require enhanced industrial processability to substitute synthetic plastics.

Purpose of the Study:

• To induce a phase transition in pectin through chemical modification for improved processability.
• To explore green heterogeneous synthesis using phosphoric acid for pectin modification.

Main Methods:

• Pectin was chemically modified using varying concentrations of phosphoric acid in an ethanol medium.
• Characterization involved Fourier Transform Infrared (FTIR) spectroscopy, solubility tests, X-ray diffraction (XRD), and thermal analysis.

Main Results:

• Formation of diester-phosphate crosslinks increased the degree of acyl esterification above 80%.
• Solubility decreased from 99.86% to 55.66%, and crystallinity reduced from 10% to 7% with increasing phosphoric acid.
• Modified pectin exhibited an endothermic peak (202–216°C) and shifted thermal degradation to lower temperatures (216–238°C).

Conclusions:

• Phosphoric acid treatment successfully modified pectin, creating crosslinks and altering its physical properties.
• A processing window (Tep–Td) was established for modified pectins, enabling viscous flow processing.
• This advancement offers a sustainable pathway for utilizing pectin as an alternative to synthetic plastics.