Interconnected macropores cryogel with nano-thin crosslinked network regenerated cellulose

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Engineering

Background:

• Cellulose-based hydrogels are promising for various applications.
• Oil palm empty fruit bunch cellulose (EFBC) is an abundant, underutilized biomass resource.
• Sodium carboxymethylcellulose (NaCMC) is a widely used, water-soluble cellulose derivative.

Purpose of the Study:

• To synthesize and characterize hydrogels and cryogels from EFBC and NaCMC.
• To investigate the effect of the swelling phenomenon on the structural and physical properties of the resulting cryogels.
• To elucidate the relationship between swelling, microstructure, and re-swelling behavior.

Main Methods:

• Chemical crosslinking of EFBC and NaCMC with epichlorohydrin (ECH) to form hydrogels.
• Swelling of hydrogels in distilled water.
• Cryogel formation via freezing and freeze-drying of swollen hydrogels.
• Microscopic analysis using variable pressure scanning electron microscopy (VPSEM) to examine cryogel microstructure.
• Evaluation of swelling degree and re-swelling capacity.

Main Results:

• Successfully synthesized crosslinked hydrogels and cryogels from EFBC and NaCMC.
• VPSEM revealed nano-thin crosslinked network walls (24.31 ± 1.97 nm) and interconnected pores in the cryogels.
• The swelling phenomenon significantly influenced cryogel microstructure, including pore size, pore volume, and network wall thickness.
• Water content, swelling degree, and freeze-drying process were identified as key factors affecting cryogel properties and re-swelling.

Conclusions:

• The swelling process is critical in dictating the microstructure and properties of EFBC/NaCMC-based cryogels.
• The developed cryogels exhibit potential for applications requiring high water absorption and controlled release.
• Understanding the interplay between swelling and structural formation is essential for designing advanced cellulose-derived biomaterials.