Magnetic microencapsulated phase change materials with an organo-silica shell: Design, synthesis and application for electromagnetic shielding and thermal regulating polyimide films

We have designed a type of dual-functional magnetic microcapsules containing a phase change material core and an organo-silica shell for the electromagnetic shielding and thermal regulating PI (polyimide) films. The magnetic microcapsules were synthesized through interfacial polycondensation in a reverse emulsion templating system. The resulting microcapsules show an interesting cup-like morphology as well as a well-defined core-shell structure. Their chemical compositions and crystalline structures were confirmed by Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction. The magnetic microcapsules not only achieved good phase-change performance and high energy-storage efficiency but also exhibited a superparamagnetic nature. PI/magnetic microcapsules hybrid films were fabricated through casting the poly(amic acid)/magnetic microcapsules mixtures onto glass plates followed by thermal imidization. The scanning electronic microscopy indicates a good interfacial adhesion between the PI matrix and magnetic microcapsules, resulting in a homogeneous dispersion of the microcapsules in the hybrid films accordingly. The hybrid films are also endowed with both temperature retention and microwave absorbing capabilities due to the introduction of magnetic microcapsules. With such a dual-functional feature, the PI-based hybrid films developed by this work show potential applications for the manufacture of microelectronic elements and electronic devices with anti-jamming and thermal regulating effectiveness.