Dynamic covalent bonds can be reversibly broken or formed under certain conditions, it may be used to control the cross-linked polymer with a viscoelastic purposes. At present, despite the great efforts have been made to develop new dynamic and chemical bonding of the catalyst to promote a variety of stimuli covalently adaptive network (CAN, covalent adaptable networks) exchange reaction in, but few studies have addressed other design factors can affect the material properties of conventional polymers. bottle brush polymers (bottlebrush polymers) is a covalent network adaptation ideal material because they can widen the available range of polymer physical properties. When physical or chemical bond with other substances elastic crosslinking, polymer non-dynamic network, since the networks and entanglement is reduced network density, the resulting bottle brush polymers abnormal soft elastomer, such flexibility in many emerging applications capacitive pressure sensor of high sensitivity, high dielectric actuator biomimetic materials and the like has advantages. However, bottle brush polymers typically by non-covalent cross-linking dynamically, these conventional methods can not achieve self-repair of the material, which is critical to reduce damage to the equipment or an analog bioremediation process.
the results of
Based on the above issue, Department of Materials, University of California, Department of Chemistry and Biochemistry and the Department of Chemical Engineering Professor Christopher M. Bates research group [123 ], we introduced a powerful synthetic platform that combines the advantages of the molecular architecture and adaptive covalent network, can be synthesized bottle the dynamic crosslinking ultra soft properties can be reconfigured by associative exchange key brush polymeric elastomer , these dynamic bottle brush polymers exhibit elastic> elongation at break of 300%, and still retain> 85% of the fracture toughness and after repeated annealing. Related outcomes to \”Dynamic Bottlebrush Polymer Networks: Self-Healing in Super-Soft Materials\” in the title, published in the \” JACS \”.
Graphic SolutionsAnalysis of the reaction scheme
1. Design and Synthesis of
a plurality of unique bottle brush polymers. Finally, with a diketone P4MCL hydroxyl side chain end and a Lewis acid catalyst, of the bottle brush crosslinked polymer precursor. The catalyst used in this step is retained after cross-linking in the material, and to facilitate dynamic key exchange by transesterification. 2. The characteristics of dynamic covalent bond
3. Mechanical properties
4. Healing and cyclability
In summary, researchers have introduced a new covalent adaptive network (the CAN), the polymer network includes a brush member carried by the bottle associated dynamic key exchange mechanism. Such dynamic network will find useful application in the self-healing properties of ultra-soft combination, such as next-generation sensors, drives and organizational simulation of biological material. The scope of covalent adaptive network expanded to include non-linear molecular structure, will create new opportunities in cross fields of chemistry, materials science and engineering. Article link: https: //pubs.acs.org/doi/10.1021/jacs.0c01467