Narrowly Dispersed Molecularly Imprinted Polymer Microspheres with Photo- and Thermo-Responsive Template Binding Properties in Pure Aqueous Media by RAFT Polymerization

The facile and controlled synthesis of narrowly dispersed molecularly imprinted polymer (MIP) microspheres with both photo- and thermo-responsive template binding properties in pure aqueous media is described. Narrowly dispersed "living" core polymer microspheres with surface-immobilized dithioester groups were firstly prepared via reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization (RAFTPP). The polymer microspheres were then successively grafted with an azobenzene (azo)-containing MIP layer and thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) brushes via surface-initiated RAFT polymerization to provide the desired product. The successful grafting of the azo-containing MIP layer and PNIPAAm brushes was confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and static contact angle experiments. The attachment of an azo-containing MIP layer onto the "living" core polymer beads with a narrow size distribution allows the direct generation of narrowly dispersed photoresponsive core-shell MIP microspheres. Moreover, the introduction of PNIPAAm brushes onto the core-shell MIP microspheres has been shown to significantly improve their surface hydrophilicity leading to pure water-compatibility. Additionally, this modification confers thermo-responsive template binding properties upon the microspheres.