| Abstract: | Poly(styrene) nanospheres having poly(N-vinylisobutyramide)s (PNVIBA)s, which are structurally the same composition as well-known thermosensitive poly(N-isopropylacrylamide)s (PNIPAAm)s and show the thermosensitive property as well, on their surfaces were synthesized by the free radical polymerization of hydrophilic PNVIBA macromonomers and hydrophobic styrene with AIBN as a radical initiator in ethanol as a polar solvent and were characterized in regard to their thermosensitive properties. Both the NVIBA oligomers and PNVIBA macromonomers that we synthesized showed a lower critical solution temperature (LCST) at around 40°C, as was predicted by our previous research. The nanospheres were spherical in form and have a narrow size distribution. Their sizes could be controlled by varying the molecular weight of the macromonomers and the amount of it in feed. The size in the nanosphere became small above the LCST of the corresponding macromonomer, possibly due to thermosensitive shrinking of the PNVIBA on the nanosphere surface, while transmittance of its dispersion did not change at all at studied temperature range. The nanospheres having the PNVIBA on their surfaces, which response sharply to atmospheres such as dispersion temperature, can be significant and useful materials in technological and medical fields. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2581–2587, 1998 |
