Microcapsules based self-healing materials have been applied in restoring mechanical properties, optical properties, conductivity, inhibiting corrosion, etc. In most cases, mechanical activation is required to deliver protective payloads, whereas targeted spatial and temporal delivery of core materials triggered by non-mechanical means remains challenging. Here we show an internal phase separation approach to fabricate multi-responsive core/shell microcapsules using cyclic poly(phthalaldehyde) (cPPA) as shell wall. cPPA is a rising material for stimuli responsive systems with applications in photolithography, controlled release and transient electronics packaging. Degradation of cPPA in organic acid/base is rapid. To expand the triggering conditions, we incorporate acid generators in encapsulation, resulting in acid, UV, and thermal responsive shell walls. Release behavior has been directly visualized using optical microscope and scanning electron microscope. Smooth microcapsule exterior surface erodes after exposing to triggering condition, releasing core materials onto the substrates. Release rate profiles of microcapsules are quantified from UV-vis spectroscopy, <sup>1</sup>H NMR and/or GC-MS using a model core material, hexadecane. Over 90% payload is released within 24h in 1M HCl solution. Ongoing and future work involves optimization in fabricating microcapsules, developing shell wall with different responsiveness and expanding application areas in self-healing coatings, Li battery, electrical devices, etc.

Fabrication and applications of multiresponsive cyclic poly(phthalaldehyde) microcapsules prepared by internal phase separation

251st National Meeting (2016)

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