Silicone rubber consists of cross-linked poly(dimethyl siloxane)(PDMS). Formation of the mesomorphic phase was found in silicone rubber that is highly stretched at room temperature. The mesomorphic phase is characterized by a pair of sharp equatorial reflections in the wide-angle X-ray diffraction (WAXD) pattern. At low temperature, the stretched silicone rubber crystallizes. The WAXD patterns from the crystallized silicone rubber exhibit totally different features depending on the draw ratio. The author successfully obtained single crystals of linear PDMS. Electron diffraction patterns of the single crystals indicate that at least four different crystal forms exist. The observed WAXD patterns and their peculiar transition scheme could be explained by the combination of the crystal forms.

Buckling instabilities in soft materials, specifically wrinkling, have led to the formation of unique surface patterns for a wide range of applications that are related to surface topography and its dynamic tuning. This article summarizes the fabrication of various wrinkle structures on a PDMS elastomer using 3D-streching method and application for SERS active surface on these structure with a metal deposition.

Typical silicones, including poly(dimethyl siloxane)(PDMS), are amorphous, but poly(tetramethyl-p-silphenylene-siloxane)(PTMPS) containing phenyl rings in the main chain is crystalline. A combination of in situ X-ray and NMR measurements during heating of PTMPS indicates that the molecular motion of the phenyl rings exhibits remarkable anisotropy even in the molten state, suggesting rigidity of the PTMPS molecules. Therefore, a melt-drawing technique could be successfully applied to PTMPS. The obtained melt-drawn PTMPS membrane is transparent but exhibits an excellent tensile modulus and strength of 1.7 GPa and 20 MPa, which are enough for various industrial applications. Similar introduction of phenyl rings in the main chain is also effective for property development of silicone elastomer. Blend films of PTMPS and silicone elastomer exhibits the characteristic phase separation, depending on the blending compositions. Such blend films give the remarkably higher tensile strength than the original silicone elastomer, due to the crystalline component.

This paper describes structural design of various polysiloxane-containing polymer membranes and their permselectivity for organic liquid mixtures in pervaporation. Morphology of microphase-separated membranes containing poly(dimethylsiloxane)(PDMS) strongly influenced their permselectivity in the separation of organic liquid mixtures. The analysis using various permeation models revealed that the continuity of the PDMS phase in the microphase separation governs the membrane permselectivity. This paper also focuses on simple surface modifications of polymer membranes by polymer additives and their effects on the permselectivity for organic liquid mixtures. The permselectivity of the surface-modified membranes was controlled without lowering the permeability by the simple surface modifications. Introduction of calixarene and ionic liquids into polysiloxane-containing polymer membranes enhanced their permselectivity for organic liquid mixtures. In addition, liquid crystalline polysiloxane membranes underwent drastic changes in permeation and separation properties at their nematic-isotropic phase transition temperatures. Our results suggest novel concepts for structural design of polymer membranes, that is, methods for controlling and enhancing the permselectivity of polymer membranes without lowering their permeability.

Polydimethylsiloxane (PDMS) is the typical material for catheter, although the excellent biocompatibility of PDMS, PDMS has some problems such as difficulty in coating and operability. We consider the introduction of an aromatic ring with sulfobetaine substituents into the main chain of PDMS to solve the problems. Poly(tetramethylsilphenylenesiloxane)(PTMS) is the representative polymer where an aromatic moiety is incorporated into the polysiloxane backbone, which would presumably improve the good properties of polysiloxane, especially the thermostability. It has been reported that the properties of poly(tetramethylsilarylenesiloxane) derivatives depend on the kind of arylene moiety, the substituted position of dimethylsilyl groups as well as the substituent, on the arylene moiety. Therefore, we examined the synthesis and physical properties of the multi-block copolymer based on polysiloxane with sulfobetaine substituents.

Wide angle X-ray diffraction (WAXD) mapping analysis around the crack tip of natural rubber filled with carbon black was carried out using an X-ray beam with 3 micro meter width to identify the strain-crystallized area. In the filled sample, crystallized area was found to be wider than the case of unfilled sample, even though the macroscopic draw ratio was the same. The preferential crystallization in the filled sample was explained by the enhanced draw ratio of the deformable rubber component, since carbon black and its surroundings are not deformed. A new technique that uses an attenuator in place of the beam stopper was developed to detect the beam intensity after passing through the sample. This new technique is useful when an ion chamber cannot be arranged between the sample and the detector for the detection of the beam intensity. By the new technique, enhanced local deformation around the crack tip was clarified.