Emergent hybrid mesophases in ternary mixtures of cellulose nanocrystals ‐ Pluronic micelles‐water

Abstract

Mixtures of nanometric rods and spherical micelles that are dominated by excluded volume (entropic) interactions tend to de-mix into sphere-and rod-rich mesophases.Here we report the observation of hybrid mesophases formed by mixtures of polymer-decorated sulfuric-acid-hydrolyzed cellulose nanocrystals (CNCs, rod-like particles), at high CNCs concentrations (7 wt%) where the native CNCs suspensions are at the bi-phasic (isotropic-chiral nematic) regime, and spherical micelles of the triblock-copolymers Pluronic F127 (and F108) in aqueous suspension. The polymers adsorb onto the CNCs particles, and at F127 concentrations above (10-18 wt%) the macroscopic phases of the hybrid mixture are transformed into mesoscopic droplets with a nanostructure that differs from that of the CNCs or the native Pluronics, as indicated by small-angle X-ray scattering. The observed phases preserve the chiral nematic nature of the CNCs phases with a shortened pitch, suggesting that coassembly of CNCs and self-assembling polymers may be used for engineering of emergent phases with emergent structures and properties.

Enantioselective disruption of cellulose nanocrystal self-assembly into chiral nematic phases in d-alanine solutions

“…38,45 Thus, the SAXS curves of CNCs suspended in D-alanine solutions do not show indications for surface adsorption, complexation, or condensation of the D-alanine molecules onto the CNCs particles. 45,46 Consistently, the surface charge, as measured via zeta-potential measurements (see Table S6 of the ESI †) (CNCs concentration of 0.1 wt%) in D-alanine, as well as in L-alanine suspensions, is similar to that of the native CNCs. This is very different from complexation with histidine, for example, that leads to charge neutralization of the CNCs.…”

Modulation of Tannic Acid on the Cholesteric Structure of Cellulose Nanocrystals

“…34 Polyanions, such as sodium polyacrylate (PAAS) 35 and poly[3-(potassium-4-butanoate) thiophene-2,5diyl] (PPBT), 36 decrease the pitch of the CNC liquid crystal phase. On the other hand, additives like polyvinyl alcohol (PVA), 37 Pluronic F127, 38 dextran, 39 xyloglucan, 40 gum arabic, 41 poly(ethylene glycol) (PEG), 39,42 and poly-(vinylpyrrolidone) (PVP) 43 affect phase separation through adsorption or depletion. They can induce changes in the anisotropic volume fraction and cholesteric pitch of the CNC suspension.…”