Studies on Structural Responses in Sphere-Forming Triblock Copolymers Subjected to Stress Fields

球状ミクロ相分離構造を形成するトリブロック共重合体に応力場を印加した時の構造応答に関する研究

2017-03-24

2017-03-24

Block copolymers are well known to form microphase separated structure with a variety of morphologies, such as sphere, cylinder, lamella, and double-gyroid, depending on volume fraction and molecular weight. When ABA-typed triblock copolymer chains composed of glassy (A) and rubbery (B) block chains form glassy spherical-microdomains within the rubbery matrix, the triblock copolymer film can be used as a thermoplastic elastomer film. Since the shape of spherical microdomains is completely isotropic, the mechanical property of the film is irrespective of the stretching direction (SD). As for the case that glassy cylinders in the rubbery matrix oriented parallel to a certain direction, the mechanical property becomes anisotropic due to the anisotropy in the shape of glassy cylinders. Since such an unique property is a potential resource for an unique production, there has been a lot of studies aiming highly oriented cylinders parallel to the film surface. In Chapter 1, I demonstrate significant progress in the orientation of cylindrical microdomains by utilizing the morphological transition from sphere to cylinder. In Chapter 2, I show an attempt to orient the cylinders parallel to SD of the triblock copolymer film by utilizing the morphological transition, induced by a thermal annealing of the film under stretched state. Although the methodology was found to fail for controlling the cylinder orientation, strain-induced deformation of glassy spheres was, interestingly, indicated. The deformation behavior of the glassy spheres was examined for several kinds of triblock copolymer films by conducting simultaneous measurements of stress-strain curve and two-dimensional small-angle X-ray scattering (2d-SAXS), and time-resolved 2d-SAXS measurements. It was found that the extent of the deformation was clearly dependent on both the strain of specimens and the size of glassy spheres, and the deformation proceeded with time for the films under stretched state. These findings are discussed in Chapter 3 and 4 in details.

博士（工学）

京都工芸繊維大学

14303甲第840号

http://hdl.handle.net/10212/2397

jpn

ETD

Thesis or Dissertation

Thesis