Self healing materials can imitate the self-healing of human skin tissue and significantly improve the service life and safety of materials. Therefore, they are widely used in the fields of electronic skin, marine coatings, biomedicine and so on. However, in extreme environments such as extreme cold and supercooled sea, materials can not be repaired by themselves without any external energy stimulation (such as infrared, heating, etc.), which has been a problem unsolved in the field of self-healing materials. This is because when the existing healing materials are damaged in seawater, the water molecules will block the dynamic bond reconnection of the damaged interface of the materials; when the materials are damaged at low temperature, the dynamic characteristics of the chemical or physical bond in the materials will be significantly inhibited, and the polymer system will become crystal hard, lose the micro fluidity, so that the self-healing performance of the materials will be lost. Recently, the research group of Professor Zhang Lei, Department of Biochemistry, School of chemical engineering, Tianjin University, published research on a variety of self-healing materials for extreme environment on the internationally renowned academic journal Nature communications (nature Communications). Guo Hongshuang, Ph.D. student, School of chemical engineering, Tianjin University, is the first author of the paper, Professor Zhang Lei and young teacher Yang Jing are the corresponding authors, and the school of chemical engineering, Tianjin University is the first completion unit of the paper. The research was supported by "Qingdao Marine Science and technology pilot National Laboratory fund", the "excellent youth" fund of the State Fund Committee, the youth fund and the later projects of doctors. In this work, different hydrophilic groups that can form strong hydrogen bond and weak hydrogen bond are used to design and synthesize elastomer materials that can self heal rapidly under various extreme conditions (as shown in Fig. 1). The key point of the design is based on the cooperative interaction of multiple dynamic bonds, including strong cross-linked hydrogen bond (BNB – BNB), weak cross-linked hydrogen bond (IP – IP, IP – BNB or IP) and disulfide bond (s – s). These dynamic bonds are introduced into the main chain of polydimethylsiloxane (PDMS) polymer to spontaneously form a dynamic supramolecular polymer network pdms-ss-ip-bnb (Fig. 1a and b). In pdms-ss-ip-bnb, the function of strong hydrogen bond of hydrophilic group is mainly to endow the material with elasticity. The weak hydrogen bond dissipates the stress through reversible bond fracture and reconstruction. The double sulfur bond mainly endows the material with rapid repair and partial stress dissipation. Based on the synergistic effect of these dynamic keys, pdms-ss-ip-bnb has very high tensile property. When there is no notch damage, it can stretch to 14000% of its original length without fracture; when the material suffers notch damage, it can still stretch to 1300% of its original length. Figure 1. Molecular design of PDMS – SS – IP – BNB material with high tensile strength and self-healing ability under extreme conditions 2. All weather self-healing performance of PDMS – SS – IP – BNB. More importantly, pdms-ss-ip-bnb has "all-weather" self-healing performance. At room temperature, it can heal quickly within 10 minutes, and can bear 526 times of its own weight after healing. Under various extreme environmental conditions, such as underwater (self-healing efficiency of 93%), extremely low temperature (? 40 ° C), supercooled high concentration brine (? 10 ° C 30% NaCl solution, self-healing efficiency of 89%), and even in strong acid / alkaline environment (pH = 0 or 14, self-healing efficiency of 88% or 84%), all show excellent self-healing performance, as shown in Figure 2. This work is of great significance to realize the application of self-healing materials in marine engineering, polar, high altitude, industrial wastewater treatment and other extreme environments. Paper link: https://www.nature.com/articles/s41467-020-15949-8 author profile:
Zhang Lei, Professor, doctoral supervisor and head of Department of Biochemistry, School of chemical engineering, Tianjin University. He was selected into the "National Overseas Talent Plan", the "Excellent Youth Science Fund" of the National Natural Science Foundation of China, the "New Century Excellent Talent Support Plan" of the Ministry of education, the "young and middle-aged leading talents in scientific and technological innovation", "Hou Debang chemical Youth Award", "the first youth innovation expert of Tianjin", etc., and served as the Editorial Committee of the Journal of China chemical industry (English version). It has been committed to the development of new biocompatible hydrophilic molecules for many fields of biochemical industry, including artificial islets of Langerhans, cryopreservation of cells, antifreeze electronic skin materials, marine antifouling coatings, anti bacteria coatings, etc., by using the unique properties of hydrophilic molecules such as anti bioadhesion and anti freezing protection. Yang Jing, lecturer, School of chemical engineering, Tianjin University, was selected as a talent of the science and Technology Commission. Mainly engaged in cell preservation, bionic anti ice materials, flexible electronic skin materials and other fields. The home page of the research group: http://bpetc.tju.edu.cn/zhanglab.html the leading edge of polymer science has established "self-healing" and other communication groups, added small editors as friends (micro signal: polymer Xiang, please note: name unit Title Research direction), and invited to join the group.
Source: polymer science frontier
Statement: only on behalf of the author's personal point of view, the author's level is limited, if there is any unscientific, please leave a message below for correction!
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