Composite Tectocapsules Containing Porous Polymer Microspheres as Release Gates

Porous and amphiphilic polymer microspheres were incorporated into polyurea capsules in order to control the release of the core solvents independently of wall formation. While nonpolar poly(divinylbenzene-55) microspheres were simply encapsulated along with the xylene core solvent, the amphiphilic poly(divinylbenzene-55-alt-maleic anhydride) microspheres, as well as maleic acid functionalized poly(divinylbenzene-55) microspheres, became embedded at the polyurea−water interface. Release of xylene from these microcapsules into air was monitored at room temperature and 50 °C. Release profiles change significantly upon addition of amphiphilic porous microspheres, with the release rates scaling with microsphere loading. Scanning transmission X-ray spectromicroscopy (STXM) indicates that the polyurea is largely excluded from the pores of the microspheres.