Narrowly dispersed double-walled concentric hollow polymeric microspheres with independent pH and temperature sensitivity
writer：Guoliang Li, Chenlu Lei, C. H. Wang, E. T. Kang*, K. G. Neoh, Xinlin Yang*
keywords：Multi-layer microspheres; Distillation precipitation polymerization; Surface-initiated polymerization
source：期刊
specific source：Macromolecules, 41 (23), 9487-9490 (2008). DOI: 10.1021/ma801988a
Issue time：2008年
Nearly monodispersed silica/polymer multilayer hybrid composites and double-walled PMAA-PNIAPM concentric hollow polymeric microspheres with unique morphology and dual stimuliresponsive properties have been synthesized and characterized by FESEM, TEM, FT-IR, and EDX. The structures of polymer/silica multilayer hybrid microspheres and the double-walled hollow microspheres were shown to be well-defined. The respective
PMAA inner shell and PNIPAM outer shell in the unique hollow structure can respond independently to changing pH and temperature of the environment. The change in hydrodynamic diameter (Dh) of the PMAA inner shell arises from the Donnan osmotic
swelling, while the change in Dh of the PNIPAM outer shell is associated with the lower critical solution temperature behavior of the polymer. The doxorubicin-loaded PMAA-PNIAPM hollow microspheres exhibited temperature and pH-controlled release of
anticancer drug. The double-walled PMAA-PNIAPM concentric hollow microspheres, with their unique structures and dual (independent) stimuli-responsive properties, prepared in this work are expected to be useful for stimuli-controlled release of drugs and functional molecules, and for mimicking transport barriers in biological systems.