The behavior of hydrophobic-core/hydrophilic-shell structured microgels at an interface: from Mickering emulsion to colloidosomes with dual-level controlled permeability

Abstract

A bottom-up approach was employed to prepare colloidosomes with dual-level controlled permeability. Starting from the monodisperse poly-2,2,2-trifluoroethyl methacrylate (PTFMA) core, different sizes of microgels were obtained by introducing varying thicknesses of the poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AAc)) shell. The effects of the core on the mechanical properties of the microgels and their behavior at the oil/water interface in a Mickering emulsion were carefully studied. The colloidosomes were then obtained by “locking” the interfacial microgels in the Mickering emulsion. The release of the model drug FITC-Dex from colloidosomes was examined in selected media and the controllable release of the drug was achieved by adjusting the pH (coarse level) and the ratio of the shell to core size in the microgels (fine level). The dual-level controlled permeability of the colloidosomes enabled the high precision that is necessary for the pH triggered drug release system. It is the first demonstration of the control of the permeability of colloidosomes that can be achieved by controlling the size of the shell and core of the microgels to the core hydrophobicity and the shell hydrophilicity. Both the convenience and precision of the control of the permeability of colloidosomes were improved in this way due to the mature size control technology in the microgel syntheses.