Developing Water Barrier Coatings of Millimeter-Scale Hydrogel Capsules via Interfacial Initiated Ethyl Cyanoacrylate by In-Situ Polymerization

Abstract

The millimeter-scale capsules for oil encapsulation have been used successfully in food, cosmetic and pharmaceutical engineering. However, aqueous core capsules still have poor barrier properties and a short storage life. In this work, a rapid and mild coating method was applied on millimeter-scale calcium alginate aqueous core capsules (mm-CaSA-Caps). A layer of poly(ethyl-cyanoacrylate) (PECA) was coated on the surface of the mm-CaSA-Caps using interfacial polymerization. The PECA-coated mm-CaSA-Caps (PECA@CaSA-Caps) prepared in the trichloromethane maintained a spherical shape in wet and dry conditions. Compared with the mm-CaSA-Caps, the weight loss ratio of water in the PECA@CaSA-Caps decreased by 38.59%. The release rates of dye in PECA@CaSA-Caps greatly reduced in neutral (pH 7.0), alkaline (pH 10.0) and acidic (pH 1.0) conditions. This work provides a new way to improve the barrier properties and storage life of hydrogel capsules.