title: Monodisperse microspheres with poly(N-isopropylacrylamide) core and poly(2-hydroxyethyl methacrylate) shell.
abstract: Monodisperse core-shell microspheres, composed of poly(N-isopropylacrylamide) (PNIPAM) core with thermo-responsive swelling/shrinking function and biocompatible poly(2-hydroxyethyl methacrylate) (PHEMA) shell with "open/close" switching function, have been successfully prepared by microfluidic emulsification, free-radical polymerization and atom transfer radical polymerization (ATRP). The effects of grafting time for the ATRP and polyvinyl alcohol (PVA) concentration inside the core on the thermo-responsive behavior of core-shell microspheres are investigated. For the core-shell microspheres prepared with PVA concentration of 2% (w/v) and grafting time of 2 h, the PNIPAM core is in the shrunken state and the solid PHEMA shell protect the whole PNIPAM core at temperatures above the volume phase transition temperature (VPTT); as environmental temperature decreases below the VPTT, the PNIPAM core swells dramatically and the PHEMA shell ruptures a large area. The thermo-responsive function of the core-shell microspheres is reversible and the appearance/recovery of PHEMA shell crack exhibits an "open/close" switching function. Such core-shell microspheres are highly attractive for developing drug delivery systems with both biocompatible and thermo-responsive characteristics.
authors.affiliation: School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China.
authors.forename: Ya-Lan
authors.initials: YL
authors.lastname: Yu
authors.forename: Rui
authors.initials: R
authors.lastname: Xie
authors.forename: Mao-Jie
authors.initials: MJ
authors.lastname: Zhang
authors.forename: Peng-Fei
authors.initials: PF
authors.lastname: Li
authors.forename: Lihua
authors.initials: L
authors.lastname: Yang
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Ju
authors.forename: Liang-Yin
authors.initials: LY
authors.lastname: Chu
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000180:Acrylic Resins; D008863:Microspheres; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013696:Temperature
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D011108:Polymers; C052970:poly-N-isopropylacrylamide; D011102:Polyhydroxyethyl Methacrylate