Angstrom-level repairs

Covalent Bonding As stated above, an ideal self-healing network should contain reactive species that are activated upon damage. The most commonly occurring reactive species in polymer networks are free radicals. Their affinity for reacting with other species is high in solutions, but lower in solid polymer networks. In spite of relatively longer lifetimes of free radicals in polymer networks, for two 

Chitin, one of the most abundantly available natural polysaccharides, can be readily modified by acetylation reactions to form chitosan (CHI) [37]. CHI was modified with the four-member oxetane (OXE), followed by cross-Hnking with trifunctional hexamethylene di-isocyanate (HDI) in the presence of polyethylene glycol to form heterogeneous cross-linked polyurethane (PUR) network. When there is mechanical damage of the network, self-repairing occurs upon exposure of the damaged area to UV radiation. While the reactions leading to network formation are shown 

HDFMA films containing 14 w/w% of y-Fe203 nanoparticles in the presence of oscillating magnetic field [51]. 

Relaxations and Shape Memories Mechanical deformations of synthetic materials 

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This chapter outlines recent advances in self-repairing of polymers that are related to autonomous heahng processes mastered by nature. Damages and repairs ranging from angstrom to milHmeter levels are discussed in terms of chemical reactions and physical processes governing the damage repairs. 

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