Environmentally responsive core/shell particles via electrohydrodynamic co-jetting of fully miscible polymer solutions.

Herein it is demonstrated that electrohydrodynamic co-jetting is not limited to Janus-type particles, but can also be used for the preparation of core/shell particles. Using side-by-side flow of miscible polymer solutions, electrohydrodynamic co-jetting offers an elegant and scalable route towards preparation of core/shell particles with otherwise difficult-to-prepare particle architectures, including particles with hydrophilic shell and core. Throughout this study, electrohydrodynamic co-jetting of aqueous solutions consisting of a mixture of PAAm-co-AA and PAA is used, and a range of different types of particles with distinct compartments are observed. Transition from Janus particles to core/shell particles appears to be caused by changes in the relative conductivity of the two jetting solutions. After crosslinking, the core/shell particles are stable in aqueous solution and exhibit reproducible swelling behavior while maintaining the original core/shell geometry. In addition, the pH-responsiveness of the particles is demonstrated by repeatedly switching the environmental pH between 1.3 and 12. Moreover, the core/shell particles show surprising uptake selectivity. For instance, a 450% increase in uptake of 6-carboxyfluorescein over rhodamine B base is found.