Graft copolymers having hydrophobic backbone and hydrophilic branches. xvi. Polystyrene microspheres with poly(N-isopropylacrylamide) branches on their surfaces: size control factors and thermosensitive behavior

✍ Scribed by Ming-Qing Chen; Takeshi Serizawa; Mitsuru Akashi

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 375 KB
• Volume: 10
• Category: Article
• ISSN: 1042-7147
• DOI: 10.1002/(sici)1099-1581(199901/02)10:1/2<120::aid-pat781>3.0.co;2-g

✦ Synopsis

Thermosensitive monodisperse particles were prepared with diameters of 0.3±1.8 mm, and which consisted of polystyrene core and poly(N-isopropylacrylamide) branches on their surfaces by the free radical copolymerization of polyNIPAAm macromonomers and styrene in ethanol or ethanol/water mixtures. The styrene monomer concentration [St], steric stabilizer (polyNIPAAm macromonomer) concentration [S], initiator concentration [I], polymerization temperature and the percentage of water in the reaction medium affected the final microsphere size. The microsphere size in diameter (D n ) follows the relationship D n G[St] 0.75 [S] À0.76 [I] À0.13 . The dynamic size of microspheres decreased with increasing temperature in the dispersion solution. The effects of lyophilization and external temperature on the morphology of microspheres were analysed by means of transmission electron micrograph (TEM). The exterior environment did not seem to affect their morphology.