title: Thermoreversible gelation of isotactic-rich poly(N-isopropylacrylamide) in water.
abstract: We report the experimentally determined phase diagram for an aqueous solution of isotactic-rich poly(N-isopropylacrylamide) (PNiPAM) composed of the sol-gel transition curve and the cloud-point curve. The meso diad content of isotactic-rich PNiPAM is 64%, and it is soluble in water at low temperatures, but undergoes a sol-to-gel transition with increasing temperature in the investigated concentration range of 1.8 wt. %-6.0 wt. %. With a further increase in temperature, the system becomes turbid. The gel formation and clouding behavior are thermally reversible. This is the first observation of thermoreversible gelation under the cloud-point temperature for an aqueous solution of PNiPAM. On the basis of the determined phase diagram, we carried out light scattering experiments to characterize the sol-gel transition behavior as a function of temperature.
authors.affiliation: Department of Physics, Tokai University, Hiratsuka 259-1292, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Nakano
authors.forename: Takao
authors.initials: T
authors.lastname: Ogiso
authors.forename: Rio
authors.initials: R
authors.lastname: Kita
authors.forename: Naoki
authors.initials: N
authors.lastname: Shinyashiki
authors.forename: Shin
authors.initials: S
authors.lastname: Yagihara
authors.forename: Masaru
authors.initials: M
authors.lastname: Yoneyama
authors.forename: Yukiteru
authors.initials: Y
authors.lastname: Katsumoto