Modulating superabsorbent polymer properties by adjusting the amphiphilicity

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Amphiphilicity is crucial for polysaccharide-based superabsorbent polymers (SAPs).
• Hydrophilicity enhances freeze-dried SAPs, but evaporative-dried SAPs may behave differently.
• Carboxymethyl cellulose (CMC) is a widely used polysaccharide for SAPs.

Purpose of the Study:

• To investigate the effect of amphiphilicity on the swelling and mechanical properties of evaporative-dried CMC-based SAP films.
• To synthesize CMC-based SAP films using diglycidyl ether crosslinkers with varying amphiphilicity.
• To establish structure-property relationships for optimizing evaporative-dried SAP performance.

Main Methods:

• Synthesis of CMC-based SAP films using four diglycidyl ether crosslinkers with different chain lengths and amphiphilicities.
• Structural and physiochemical characterization of the synthesized films.
• Evaluation of swelling capacity and mechanical properties (tensile strength, Young's Modulus).

Main Results:

• Contrary to freeze-dried polymers, increased hydrophobicity in evaporative-dried CMC films enhanced swelling.
• Hydrophobic moieties reduced inter-chain hydrogen bonding during drying, lowering hornification and entropy for water uptake.
• Optimized poly(propylene glycol)-CMC polymer achieved 182 g/g swelling capacity.
• Glycerol-CMC films exhibited tensile strength of 39 MPa and Young's Modulus of 4.0 GPa.

Conclusions:

• Amphiphilicity plays a key role in tuning the properties of evaporative-dried CMC-based SAPs.
• Hydrophobic crosslinking is a viable strategy to improve swelling in evaporative-dried cellulose hydrogels.
• These materials show potential as low-cost, high-performance swellable films for various applications.