Starch Hydrogel Films with Dual Cross-Linking: Structural and Functional Characterization

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Hydrogels are 3D polymeric networks with hydrophilic groups.
• Conventional cross-linking methods often lack eco-friendliness.
• Starch-based hydrogels are promising for various applications.

Purpose of the Study:

• To evaluate chemical cross-linking (Cc) with citric acid (CA) and physical cross-linking (Pc) for starch hydrogel films.
• To investigate the synergistic effects of a dual cross-linking approach.
• To assess the influence of cross-linking on hydrogel physicochemical properties.

Main Methods:

• Starch hydrogel films were prepared using varying concentrations of citric acid (0-2.5%).
• Films underwent chemical cross-linking (CA) and/or physical cross-linking (cooling/heating cycles).
• Analyses included structural, mechanical, thermal, morphological, hydration, and barrier property assessments.

Main Results:

• Chemical cross-linking with CA significantly stabilized the hydrogel matrix.
• At 0.5% CA, Cc reduced solubility more effectively than Pc.
• Higher CA concentrations (2.5%) led to reduced water uptake and increased network rigidity.
• Water vapor transmission rate decreased significantly with 1.5% CA in both Cc and Pc treatments.

Conclusions:

• Dual cross-linking offers a method to tailor starch/xanthan hydrogel properties.
• Eco-friendly cross-linking strategies are viable alternatives.
• Modified hydrogels show potential for biomedical and controlled-release applications.