Cellulose nanocrystal thermal smart molecular brushes with upper critical aggregation temperature

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Cellulose nanocrystals (CNCs) are explored for tunable thermal properties.
• Grafting thermo-responsive polymers onto CNCs allows for critical temperature regulation.
• Surface modification of CNCs is key to controlling their thermal transition behavior.

Purpose of the Study:

• To synthesize and characterize thermo-responsive polymer-grafted CNCs.
• To investigate the effect of surface molecular brushes on CNC thermal transition.
• To develop CNC-based materials with tunable upper critical aggregation temperature (UCAT) for biomedical applications.

Main Methods:

• Surface-initiated reversible addition-fragmentation chain transfer polymerization for grafting.
• Quaternization of poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) to poly-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (PDMAPS).
• Modification with poly(ethylene glycol) methacrylate to create CNC-PDMAPS-mPEG.
• Characterization using UV-Vis spectroscopy and dynamic light scattering.

Main Results:

• CNC-PDMAEMA aggregated above 70°C; CNC-PDMAPS aggregated below 31°C.
• Thermo-responsive behavior shifted from lower to upper critical aggregation temperature (UCAT).
• CNC-PDMAPS-mPEG exhibited UCAT regulated to approximately 37°C, near human body temperature.
• Materials showed minimal structural changes and substance encapsulation/release capabilities.

Conclusions:

• Surface molecular brush modification effectively controls CNC thermal stimulus-responsive type and transition point.
• Developed CNC-based materials with tunable UCAT near physiological temperatures are promising.
• These thermo-responsive CNCs hold significant potential for diverse biomedical applications.