Encapsulation of octadecane through crosslinking of cellulose nanofibrils at the interface of Pickering emulsion: Effect of ionic strength on cellulose assembly and capsule shell properties

Abstract

Emulsion interfacial polymerization is a versatile approach for the encapsulation of organic phase-change materials to improve their stability and prevent their elution and leakage. Herein, we report the successful octadecane encapsulation by the preparation of Pickering emulsions stabilized with carboxylated cellulose nanofibrils (CNF) at various ionic strengths of the dispersive medium. The stable capsule shells were obtained through the formation of amide bonds in the reaction with polymeric isocyanate dissolved in the oil phase. The addition of 5–200 mM NaCl resulted in different adsorption behaviors of carboxylated CNF, which led to an increase in capsule shell thickness (up to 530 nm), improved octadecane encapsulation efficiency (up to 78 %) and thermal stability, as well as reduced elution in organic medium with increasing ionic strength. The study presents a new strategy for the encapsulation of phase-change materials by surfactant-free emulsion interfacial polymerization into containers with defined and adjustable properties.