1. Division of Advanced Fibro‐Science, Graduate School, Kyoto Institute of Technology, Matsugasaki, Sakyo‐ku, Kyoto 606‐8585, Japan
2. Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O‐okayama, Meguro‐ku, Tokyo 152‐8552, Japan
3. Kyoto Municipal Textile Research Institute, Karasuma‐dori, Kamigyo‐ku, Kyoto 602‐0898, Japan