8 / 2021-05-12 23:34:39

Advanced microcapsule materials via cellulose nanocrystal stabilized Pickering emulsion as templates

Cellulose Nanocrystal,Pickering emulsion,microcapsule,phase change material

Microcapsules with core-shell structure are widely used in the field of medicine, buildings, textile, and so on^1-2. At present, microcapsules are generally fabricated via surfactant stabilized emulsions as templates. However, the abuse of synthetic surfactants has caused severe environmental pollution. The recovery of surfactant is costly and time-consuming. Moreover, the residues of surfactant have a huge negative effect on the properties of the products. Therefore, surfactant-free emulsions are significantly preferred especially in medicines, foods, and cosmetics. Pickering emulsions are surfactant-free emulsions stabilized by solid particles, which possess partially wettability with both oil and water phases^3-4. Compared to surfactant stabilized emulsions, Pickering emulsions are more stable, biocompatible, and sustainable. Cellulose nanocrystals (CNCs) are rod-like nanocellulose extracted from wood pulp by acid hydrolysis, and have been proven as outstanding Pickering emulsifiers^5-7. Due to the sustainability, biocompatibility, scalability, and excellent mechanical properties of CNC, CNC stabilized Pickering emulsions have attracted much attention in both academia and industry^{1, 3, 8}. In our studies, many kinds of advanced microcapsule materials with designed core-shell structure are fabricated With CNC stabilized Pickering emulsions as templates, such as hollow polymeric microcapsules with pH or temperature responsive properties via emulsion polymerization¹, silica colloidosomes via sol-gel method³, and polydopamine microcapsules via oxidization self-polymerization. The polymeric or silica microcapsules are promising in the field of drug encapsulation and control release. Moreover, CNC stabilized Pickering emulsions with phase change materials (PCMs) as oil phase are employed as templates to fabricated PCM microcapsules with CNC reinforced polystyrene or melamine resins as shells². The PCM microcapsules prevent the leakage of PCM during phase change and enhance the interfacial area between PCM and matrices. The PCM microcapsules are promising for energy-saving builds, smart textiles, and outdoor electric devices. In summary, CNC stabilized Pickering emulsion as template is a sustainable, low-cost, and facile approach to fabricate advanced microcapsule materials for a variety of applications.