Dehydration-Induced Chain Entanglement for Tough, Low-Hysteresis, Double-Network Hydrogels.

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Highly entangled hydrogels exhibit superior mechanical properties due to dense physical cross-links.
• Current fabrication methods using concentrated solutions limit scalability and practical use.

Purpose of the Study:

• To develop a facile dehydration-induced entanglement approach for fabricating double-network hydrogels.
• To achieve programmable entanglement density and enhance mechanical properties.

Main Methods:

• Synthesized a single-network hydrogel via UV polymerization of acrylamide (AAm) and carboxymethyl chitosan (CMCS).
• Induce dense intermolecular entanglements through controlled dehydration, stabilized by secondary CMCS cross-linking.

Main Results:

• Achieved tensile strength of 798 kPa and toughness of 1.98 × 10^3 J·m^-2, an 11-fold and 10-fold increase, respectively.
• Demonstrated synergistic interplay between covalent networks and physical entanglements for optimal stiffness-toughness balance.

Conclusions:

• The dehydration-induced entanglement method offers a robust platform for high-performance hydrogel design without complex processing.
• The resulting hydrogels are suitable for flexible electronics, wound dressings, and drug delivery systems.