title: Stabile, thermoresponsive colloidal clusters: an unusual morphology of polymer dispersions.
abstract: A new class of colloidal polymeric particles consisting of polystyrene spheres grown in a poly(N-isopropyl acrylamide) precursor scaffold is synthesized via redox-initiated heterophase polymerization. The morphology and thermoresponsiveness of these assemblies is proven by electron microscopy investigations and temperature-dependent measurements of the change of both the speed of sound travelling through the dispersion and the hydrodynamic particle size. Electron microscopy (EM) micrographs (transmission and scanning EM as well cryo-scanning EM) prove the existence of colloidal clusters when the freeze-dried copolymer is redispersed in pure water. The clusters have a size of several micrometers, contain about 800 polystyrene particles with diameter below 100 nm, and show a highly reproducible thermoresponsive behavior with a lower critical solution temperature corresponding to that of pure poly(N-isopropyl acrylamide).
authors.affiliation: Max Planck Institute of Colloids and Interfaces, 14424, Potsdam, Germany.
authors.forename: Ran
authors.initials: R
authors.lastname: Yu
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hartmann
authors.forename: Klaus
authors.initials: K
authors.lastname: Tauer
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D002563:Cerium / Q000737:chemistry; D003102:Colloids / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013696:Temperature; D047392:beta-Cyclodextrins / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D003102:Colloids; D011108:Polymers; D011137:Polystyrenes; D047392:beta-Cyclodextrins; C052970:poly-N-isopropylacrylamide; D002563:Cerium; C031215:betadex
keywords: heterophase polymerization; particle morphology; thermoresponsiveness