Conversion of Alcoholic Concentration Variations into Mechanical Force via Core–Shell Capsules

Abstract

Conversion of chemical signals into mechanical force is very important for implementation of stimuli-responsive hydrogels. We design a core–shell hydrogel capsule that can translate the variations of alcohol concentration into mechanical force. Oil-in-water-in-oil (O/W/O) emulsions are prepared with microfluidic technique and serve as templates for the synthesis of the core–shell capsules. The oil core is ejected from the capsule by the mechanical force generated from the deswelling of the capsule membrane upon increasing the alcohol concentration at a certain temperature below the lower critical solution temperature. The influences of alcohol concentration and temperature on the deswelling process of capsule membranes are investigated systematically. The deswelling rate also plays an important role in the ejection of the oil core. These demonstrations of conversion of alcohol concentration variations into mechanical force provide proof that these core–shell capsules can function as both sensors and actuators of alcohols