Enormous-stiffness-changing polymer networks by glass transition mediated microphase separation

• Published in: Nature communications Vol. 13; no. 1; pp. 6821 - 8
• Main Authors: Chen, Lie, Zhao, Cong, Huang, Jin, Zhou, Jiajia, Liu, Mingjie
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.11.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/923/1027; 639/638/298/923/1028; Adaptability; Chemical bonds; Electronics; Flexible components; Glass transition; Humanities and Social Sciences; Ionic liquids; Lewis acid; Liquid phases; multidisciplinary; Phase diagrams; Phase separation; Polymers; Robotics; Science; Science (multidisciplinary); Soft robotics; Stiffness; Vitrification
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-34677-9

The rapid development of flexible electronics and soft robotics has an urgent demand for materials with wide-range switchable stiffness. Here, we report a polymer network that can isochorically and reversibly switch between soft ionogel and rigid plastic accompanied by a gigantic stiffness change from about 600 Pa to 85 MPa. This transition is realized by introducing polymer vitrification to regulate the liquid–liquid phase separation, namely the Berghmans’ point in the phase diagram of binary gel systems. Regulating the Lewis acid-base interactions between polymer and ionic liquids, the stiffness-changing ratio of polymer network can be tuned from 10 to more than 10 5 . These wide-range stiffness-changing ionogels show excellent shape adaptability and reconfigurability, which can enhance the interfacial adhesion between ionogel and electrode by an order of magnitude and reduce interfacial impedance by 75%. The development of flexible electronics and soft robotics demands materials with wide-range switchable stiffness. Here, the authors report a polymer network that can isochorically and reversibly switch between a soft ionogel and a rigid plastic accompanied by a large stiffness change.