Controlled release in hard to access places by poly(methyl methacrylate) microcapsules triggered by gamma irradiation

Gamma irradiation was investigated as a triggering stimulus for the activation of poly(methyl methacrylate) (PMMA) microcapsules. PMMA was exposed to varying doses of irradiation and analyzed by differential scanning calorimetry, size-exclusion chromatography, and nuclear magnetic resonance. It was found that the glass transition temperature (T-g) of the polymer decreases at low irradiation doses. Additionally, T-g can be physically adjusted by adding a plasticizer, and both kinds of microcapsules were successfully prepared with non-plasticized and plasticized PMMA shell. Finally, impermeable microcapsules were shown to become permeable after irradiation and release an encapsulated cross-linker, which enables the remotely controlled formation of polydimethylsiloxanes in traditionally unavailable places. Therefore, the activation method has significant implications for industrial application. Copyright (C) 2015 John Wiley & Sons, Ltd.