Dynamic Microcapsules with Rapid and Reversible Permeability Switching. (5th August 2018)

• Record Type: Journal Article
• Authors: Werner, Jörg G.; Deveney, Brendan T.; Nawar, Saraf; Weitz, David A.
• Is Part Of: Advanced functional materials. Volume 28:Number 39(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-08-05
• Subjects: actuation -- microcapsules -- microfluidics -- stimuli‐responsive capsules -- thiol–ene; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201803385
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Dynamic microcapsules are reported that exhibit shell membranes with fast and reversible changes in permeability in response to external stimuli. A hydrophobic anhydride monomer is employed in the thiol–ene polymerization as a disguised precursor for the acid‐containing shells; this enables the direct encapsulation of aqueous cargo in the liquid core using microfluidic fabrication of water‐in‐oil‐in‐water double emulsion drops. The poly(anhydride) shells hydrolyze in their aqueous environment without further chemical treatment, yielding cross‐linked poly(acid) microcapsules that exhibit trigger‐responsive and reversible property changes. The microcapsule shell can actively be switched numerous times between impermeable and permeable due to the exceptional mechanical properties of the thiol–ene network that prevent rupture or failure of the membrane, allowing it to withstand the mechanical stresses imposed on the capsule during the dynamic property changes. The permeability and molecular weight cutoff of the microcapsules can dynamically be controlled with triggers such as pH and ionic environment. The reversibly triggered changes in permeability of the shell exhibit a response time of seconds, enabling actively adjustable release profiles, as well as on‐demand capture, trapping, and release of cargo molecules with molecular selectivity and fast on‐off rates. Abstract : Dynamically responsive microcapsules with shells that exhibit a triggerable, rapid, and reversible hydrophobic‐to‐hydrophilic transition are obtained from water‐in‐oil‐in‐water double emulsion drops. The dynamic microcapsules quickly switch between their impermeable and permeable states without structural failure, triggered with pH or ionic environment, enabling actively adjustable release, as well as repeated capture, trapping, and release cycles of active substances with molecular selectivity.