title: Synthesis and characterization of core-shell microspheres with double thermosensitivity.
abstract: We have synthesized doubly thermosensitive core-shell microspheres composed of chemically cross-linked poly(N-n-propyl acrylamide-co-styrene) (P(nPA-co-S)) with different styrene contents as the core and linear poly(N,N-diethyl acrylamide) (PDEA), poly(N-isopropyl acrylamide) (PiPA), or poly(N-isopropyl methacrylamide) (PiPMA) as the shells. The morphologies and swelling properties of the core and the core-shell microspheres have been studied. The P(nPA-co-S) copolymers have a similar volume phase transition temperature regardless of the styrene content, indicating a two-layer structure in the microspheres with a PS-rich inner core and a PnPA-rich outer layer resulting from soap-free emulsion polymerization in water. Upon the addition of the second shell composed of linear thermosensitive polymers, the core-shell microspheres display a two-step shrinking behavior when heated. The P(nPA-co-S) core exhibits a volume phase transition temperature at 13-15 degrees C, while the shells of PDEA, PiPA, and PiPMA have volume phase transition temperatures at 28, 32, and 42 degrees C, respectively. The core-shell microspheres are composed of three layers and possess two volume phase transition temperatures.
authors.affiliation: Département de Chimie, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec, Canada, H3C 3J7.
authors.forename: Yilong
authors.initials: Y
authors.lastname: Chen
authors.forename: Julien E
authors.initials: JE
authors.lastname: Gautrot
authors.forename: X X
authors.initials: XX
authors.lastname: Zhu
mesh_terms: D000042:Absorption; D000180:Acrylic Resins / Q000737:chemistry; D008863:Microspheres; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013696:Temperature; D014867:Water; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D011108:Polymers; D011137:Polystyrenes; D014867:Water; D000099166:Polyacrylamides