Preparation of Monodisperse Poly(N-Isopropylacrylamide) Microgels with β-Cyclodextrin Moieties

Submicron-sized monodisperse and spherical poly(N-isopropylacrylamide-co-glycidyl methacrylate)-β-cyclodextrin (PNG-CD) microgels with both thermo-responsive and molecular-recognition characteristics have been successfully fabricated via soap-free emulsion polymerization and subsequent chemical modification method. The thermo-responsivity of the microgels is based on the volume phase transition of poly(N-isopropylacrylamide) (PNIPAM) and the molecular-recognition property is based on the host-guest inclusion complexation of β-cyclodextrin (β-CD) units with specific guest molecules. The as-prepared microgels are characterized by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and dynamic light scattering (DLS) instrument. When β-CD is introduced onto the PNG-CD microgels, the volume phase transition temperature (VPTT) of resultant PNG-CD microgels shifts about 6 °C to a higher temperature in comparison with that of corresponding PNG microgels. When the β-CD units in PNG-CD microgels recognize 8-anilino-1-naphthal-enesulfonic acid ammonium salt (ANS) molecules in aqueous solution, the VPTT of PNG-CD microgels shifts around 3 °C negatively to a lower temperature. PNG-CD microgels present molecular-recognition induced swelling characteristics at fixed temperature. The results in this study provide valuable information for development of monodisperse and spherical dual thermo-responsive and molecular-recognition microgels which have potential applications in the fields of microscale molecular sensors and actuators and so on.