Double networking mechanism

Nakayama A, Kakugo A, Gong JP, Osada Y, Takai M, Erata T, Kawano S (2004) High mechanical strength double-network hydrogel with bacterial cellulose. Adv Fund Mater 14 1124-1128... 

Gong, J.P., Katsuyama, Y., Kurokawa, T., Osada, Y. Double network hydrogels with extremely high mechanical strength. Adv. Mater. 15, 1155-1158 (2003)... 

Mott, P. H. and Roland, C. M. Mechanical and optical behavior of double network rubbers. A/dc-... 

FIGURE 15 Natural rubber sample on left is double network and on right is a conventional NR elastomer (a, b). Both are in a state of mechanical equilibrium (stress = 0). Nevertheless, as seen in (c), the double network transmits light through crossed polarizers, due to its inherent orientation. This is a violation of the stress optical rule, similar to that observed during creep recovery of uncrosslinked rubber. 

Results on double networks in the unswollen state generally track the behavior of single networks. Recent results, however, now indicate that swelling double networks gives gels that have extremely high mechanical... 

Santangelo, P. G. Roland, C. M., The Mechanical Behavior of Double Network Elastomers. Rubber Chem. Technol. 1994, 67, 359-365. 

Na, Y.-H. Kurokawa, T. Katsuyama, Y. Tsukeshiba, H. Gong, J. P. Osada, Y. Okabe, S. Karino, T. Shibayama, M., Structural Characteristics of Double Network Gels with Extremely High Mechanical Strength. Macromolecules 2004, 37, 5370-5374. 

Figure 15 Concept of biomimetic design of a tnodular cross-linker, based on double-looped UPy motifs, for enhancing network mechanical properties. (Reproduced from Ref. 45. American Chemical Society, 2007.)...

Gong JP, et al. Double-network hydrogels with extremely high mechanical strength. Adv Mater 2003 15(14) 1155. 

Figure 11.9 Mapping of bond cleavage in self-reporting chemiluminescent elastomers that are toughened ty sacrificial bonds, (a) Bis(adamantyl)-1,2-dioxetane breaks under a mechanical force, resulting in chemiluminescence. (b) Intensity-coloured images of polymer networks during crack propagation of notched samples and schematic depiction of bond breaking around the crack tip. SN, DN, TN label elastomers of different molecular architecture ( single network , double network and triple network ). The dashed line indicates the perimeter of the sample. Vertical lines are artefacts of the detector.

Jang, S. S., William, I., Goddard, A., et al. (2007) Mechanical and Transport Properties of the Poly(ethylene oxide)-Poly(acrylic acid) Double Network Hydrogel from Molecular Dynamic Simulations, J. Phys. Chem. B, 111, 1729-37. 

The motion of two kinds of polymer chains in the transient double network can be performed by the following different reputation mechanisms [8]. 

Santangelo PG, Roland CM (1994) The mechanical behavior of double network elastomers. Rubber Chem Technol 67(2) 359-365... 

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