pH-Responsive cagelike porous polymer microspheres prepared via consecutive RAFT polymerization induced by γ-ray radiation

Abstract

Although RAFT polymerization in a homogeneous system has been widely studied, RAFT mediated polymerization on a solid–liquid surface has rarely been mentioned. In this work, a two-step consecutive RAFT polymerization of methyl methacrylate (MMA) and acrylic acid (AA) on the sulfonated polystyrene (SPS) microspheres dispersed in water was achieved under γ-ray radiation. As a result, poly(acrylic acid) (PAA)-grafted cagelike porous SPS/PMMA microspheres with distinct pH-responsive release properties have been fabricated. The RAFT mediated polymerization on the surface of porous microspheres has been discussed in detail based on the ¹H NMR spectra combined with the 2D ¹H–¹³C heteronuclear singular quantum correlation (HSQC) spectra. This work not only enriches the mechanism of heterogeneous surficial RAFT polymerization, but also indicates that γ-ray radiation induced RAFT mediated polymerization on a solid–liquid surface should be a practical technique for the fabrication of porous materials with subtle controllable surface properties.