Nondestructive Light-Initiated Tuning of Layer-by-Layer Microcapsule Permeability

Abstract

A nondestructive way to achieve remote, reversible, light-controlled tunable permeability of ultrathin shell microcapsules is demonstrated in this study. Microcapsules based on poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI) star polyelectrolyte and poly(sodium 4-styrenesulfonate) (PSS) were prepared by a layer-by-layer (LbL) technique. We demonstrated stable microcapsules with controlled permeability with the arm number of a star polymer having significant effect on the assembly structure: the PMETAI star with 18 arms shows a more uniform and compact assembly structure. We observed that in contrast to regular microcapsules from linear polymers, the permeability of the star polymer microcapsules could be dramatically altered by photoinduced transformation of the trivalent hexacyanocobaltate ions into a mixture of mono- and divalent ions by using UV irradiation. The reversible contraction of PMETAI star polyelectrolyte arms and the compaction of star polyelectrolytes in the presence of multivalent counterions are considered to cause the dramatic photoinduced changes in microcapsule properties observed here. Remarkably, unlike the current mostly destructive approaches, the light-induced changes in microcapsule permeability are completely reversible and can be used for light-mediated loading/unloading control of microcapsules.

Layer-by-layer Nanoarchitectonics: Invention, Innovation, and Evolution

“…361 LbL microcapsules of poly{[2-(methacryloyloxy)ethyl]-trimethylammonium iodide} star polyelectrolyte and PSS were first prepared. The star polyelectrolyte with 18 arms possesses a compact assembly structure.…”

Bifunctional ultraviolet/ultrasound responsive composite TiO2/polyelectrolyte microcapsules

“…The first approach is to use polyelectrolytes (PEs) with either photo-responsive or photo-cleavable groups as the layer material. 13 Examples included LbL microcapsules containing azobenzene using poly[1-[4-(3-carboxy-4-hydroxyphenylazo)-benzenesulfonamid o]-1,2-ethanediyl, sodium salt] (PAZO) and poly(diallyldimethyl ammonium) chloride (PDADMAC) as the assembling materials, and the UV responsiveness was achieved by UV induced isomerization of PAZO. 14,15 However, such an approach is constrained by the building materials and PEs where special groups have to be used.…”

Bio-inspired controlled release through compression–relaxation cycles of microcapsules

“…Considerable effort has been devoted to achieving this goal via incorporation of functional materials or nanoparticles into the microcapsule shell to control the release of the contents of the microcapsules through the application of an external stimulus, 1-3 such as pH, 4-7 temperature, [8][9][10] light, [11][12][13] ultrasound, [14][15][16][17] glucose 18,19 and magnetic field, [20][21][22] at the appropriate time. Significant progress has been achieved to develop such controlled release methods; however, methods with better controllability are still in demand.…”