1 Supporting Information Effect of stress on the molecular structure and mechanical properties of supercontracted spider dragline silks Qinglin Dong, §a Guangqiang Fang, §a Yufang Huang, b Linli Hu, a Jinrong Yao, a Zhengzhong Shao, a Shengjie Ling,* c and Xin Chen* a a State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, 200433, People’s Republic of China b Department of Material Science, Fudan University, Shanghai, 200433, People’s Republic of China c School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, People’s Republic of China § These authors contributed equally to this work. *Corresponding author: lingshj@shanghaitech.edu.cn (S.L.), chenx@fudan.edu.cn (X.C.) Electronic Supplementary Material (ESI) for Journal of Materials Chemistry B. This journal is © The Royal Society of Chemistry 2019