Bouligand nanocomposites: Self-assembly of cellulose nanocrystals with a thermo-responsive polymer

Cellulose nanocrystals (CNCs) naturally self-assemble into helical structures that effectively deflect crack propagation and exhibit structural coloration based on the pitch. To further tune the structural coloration via environmental conditions, a thermoresponsive polymer poly(diethylene glycol methyl methacrylate) (PMEO2MA) was incorporated into CNC composites. Nanocomposite films of PMEO2MA-CNC with 0-30 mass % PMEO2MA loadings were prepared via controlled evaporation-induced self-assembly. As the polymer infiltrates CNCs' helical structure, the resulting films' reflectance wavelength transitions from blue to red. PMEO2MA-CNC nanocomposites exhibited reversible temperature responses in the solid-state between 26 degrees C and 29 degrees C under variable humidity conditions, demonstrating the tunability of the self-assembled films. Fluorescence lifetime imaging microscopy (FLIM) provided insights to polymer dynamics in response to temperature.