Preparation of PVA-CS/SA-Ca²⁺ Hydrogel with Core-Shell Structure.

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Hydrogels are versatile hydrophilic polymers with broad applications.
• Developing advanced hydrogel structures is crucial for improved functionality, such as multi-substance loading.

Purpose of the Study:

• To prepare and characterize PVA-CS/SA-Ca²⁺ core-shell hydrogels with a bilayer structure.
• To investigate the factors influencing the swelling properties of these novel hydrogels.
• To optimize conditions for achieving a high swelling degree.

Main Methods:

• Core-shell hydrogels were synthesized by cross-linking polyvinyl alcohol (PVA) and chitosan (CS) for the core, and chelating sodium alginate (SA) with calcium ions (Ca²⁺) for the shell.
• Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used for structural and morphological characterization.
• Systematic studies were conducted to evaluate the impact of SA concentration, cross-linking time, and PVA/CS ratio on hydrogel properties.

Main Results:

• The successful formation of distinct core and shell structures in the PVA-CS/SA-Ca²⁺ hydrogels was confirmed.
• SA concentration and cross-linking time positively correlated with shell thickness.
• The PVA/CS mass ratio influenced core structure characteristics, with higher CS content enhancing the 3D network.
• Optimal conditions yielded a maximum swelling degree of 50 g/g.

Conclusions:

• PVA-CS/SA-Ca²⁺ core-shell hydrogels offer a promising platform for multi-substance loading due to their tunable bilayer structure.
• The swelling properties are controllable by adjusting SA concentration, cross-linking time, and the PVA/CS ratio.
• These findings provide a foundation for designing advanced hydrogels with tailored properties for specific applications.