Preparations of Tough and Conductive PAMPS/PAA Double Network Hydrogels Containing Cellulose Nanofibers and Polypyrroles oleh Cheng-Wei Tu, Fang-Chang Tsai, Jem-Kun Chen, Huei-Ping Wang, Rong-Ho Lee, Jiawei Zhang, Tao Chen, Chung-Chi Wang, Chih-Feng Huang