writer：Qiang Chen, Kun Xu, Wende Zhang, Chunlei Song, Pixin Wang
keywords：core-shell microgel
source：期刊
specific source：Colloid and Polymer Science. 287 (2009) 1339-1346.
Issue time：2009年
In this paper, well-defined temperature- and pH-sensitive core-shell microgels were synthesized by graft copolymerization in the absence of surfactant and stabilizer. The microgel particles consisted of poly (N-isopropylacrylamide (NIPAm)) core crosslinked with N, N′-methylene-bisacrylamide (MBA) and polyvinylamine (PVAm) shell. The effect of MBA content and NIPAm/PVAm ratio on microgel size was investigated. SEM showed that the microgels were spherical and had narrow particle-size distribution. TEM images of the microgels clearly displayed well-defined core-shell morphologies. Zeta-potential measurement further elucidated that the microgels possessed positively charged PVAm molecules on the microgel surface. Turbidity measurement and ¹H-nuclear magnetic resonance (NMR) experiments indicated that the VPTT of microgels was the same as the LCST of PNIPAm. ¹H-NMR experiments also inferred that the methyl proton of N-isopropylacrylamide appeared three peaks and responded to hydrogen-bonding interaction including polymer chain with water molecular, intramolecular interaction and intermolecular interaction, respectively.