title: Unusual swelling of HPC in toluene forming a microspherical domain structure that causes Christiansen scattering coloration.
abstract: The unusual swelling behavior of hydroxypropyl cellulose (HPC) by toluene is described. At temperatures as high as 100 degrees C, toluene molecules can enter the HPC film up to the weight fraction of 55%; however, they are segregated from the HPC matrix and form microspherical domains. The size of the spherical domain is approximately 4.5 microm in diameter on average. Such an unusual swelling behavior is due to the amphiphilic nature of the HPC; HPC polymers rearrange to contact their hydrophobic group with toluene and confine the toluene molecules in spherical domains. Because of the similarity in refractive indices of the toluene microspherical phase and the HPC continuum phase, the swollen film shows a beautiful scattering color that is called the Christiansen filter effect.
authors.affiliation: Department of Polymeric and Organic Material, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Edo
authors.forename: Kento
authors.initials: K
authors.lastname: Okoshi
authors.forename: Sungmin
authors.initials: S
authors.lastname: Kang
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Tokita
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kaneko
authors.forename: Junji
authors.initials: J
authors.lastname: Watanabe