Making Nanocomposites of Hydrophilic and Hydrophobic Polymers Using Gas-Responsive Cellulose Nanocrystals

Generally, different surface-functionalized cellulose nanocrystals (CNC) are required for use as nanofillers in hydrophilic and hydrophobic polymers. In the present study, for the first time, a kind of "universal" nanofiller for polymer composites is demonstrated by using CNC grafted with a gas-responsive polymer. CNC are functionalized with pyrene-containing poly(2-(N,N-diethylaminoethyl)methacrylate) (CNC-g-PDEAEMA-Py). The reversible transport of the nanocrystals between phase-separated water and toluene is proved by nuclear magnetic resonance (¹ H NMR) and fluorescence spectroscopy. On the one hand, water-soluble poly(vinyl alcohol) (PVA) can be mixed with dispersed CNC upon CO₂ bubbling for making the PVA-CNC nanocomposite. On the other hand, after the transfer of CNC into the toluene solution upon N₂ bubbling, styrene-butadiene-styrene (SBS) triblock copolymer can be dissolved for the SBS-CNC nanocomposite. In both systems, CNC are well dispersed, having an effect on the mechanical and shape memory properties of SBS and PVA, respectively.