Selective localization of cellulose nanocrystals in the biodegradable poly (vinyl alcohol)/poly(epsilon-caprolactone) blend composites prepared by Pickering emulsions

Cellulose nanocrystal (CNC) particles were used as the solid emulsifier to stabilize poly(epsilon-caprolactone) (PCL) solution-in-poly(vinyl alcohol) (PVA) solution emulsions (oil-in-water), with the objective to prepare ternary nanocomposites using as-obtained Pickering emulsions as the templates. The morphology of emulsions and mechanical properties of nanocomposites were studied, aiming at establishing a convenient route to regulate selective localization of CNCs and multiphase structures. The results show that emulsion stability depend strongly on CNC loadings and PVA concentrations in continuous phase. The evolution of multiphase morphology of emulsions from locally coalesced droplet structure to interfacial saturation one, and finally to droplet-particle interfacial flocculation, shows scaling characteristics with increasing CNC loadings, and can be detected through rheological way. The interfacial localization makes CNCs show excellent reinforcement to ternary nano-composites because of their two-phase bridging effect. This work provides an interesting strategy of fabrication of the CNC reinforced polymer blend composites with controllable multiphase structures.