Thermoresponsive Gels Based on Cross-Linked Polymer-Grafted Cellulose Nanocrystals

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Stimuli-responsive hydrogels are crucial for advanced applications.
• Conventional hydrogels have limitations in tunable properties.
• Nanocomposite hydrogels offer enhanced control over network properties.

Purpose of the Study:

• To synthesize and characterize novel thermoresponsive, one-component nanocomposite hydrogels.
• To investigate the influence of copolymer grafting on CNCs for hydrogel formation.
• To understand the structure-property relationships governing the hydrogels' behavior.

Main Methods:

• Grafting thermoresponsive copolymers onto cellulose nanocrystals (CNCs) via atom-transfer radical polymerization.
• Formation of hairy nanoparticles (HNPs) with terminal olefin side chains.
• Cross-linking HNPs using UV-mediated thiol-ene click chemistry to create hydrogel networks.

Main Results:

• Successfully synthesized thermoresponsive nanocomposite hydrogels from copolymer-grafted CNCs.
• Demonstrated reversible Lower Critical Solution Temperature (LCST)-type swelling and deswelling behavior.
• Found that mechanical properties at low CNC loadings are primarily influenced by chain entanglement and solvation, not nanocrystal reinforcement.

Conclusions:

• Developed a novel method for creating one-component thermoresponsive nanocomposite hydrogels.
• The graft chemistry and architecture significantly influence the hydrogels' thermoresponsive and mechanical characteristics.
• These findings pave the way for designing advanced smart materials with tailored properties.