Interlocking, mechanical Subject

The versatility of this approach to interlocked molecules make it very attractive as a means towards nanoscale molecular machines in which the motions of the individual components are beginning to be translated into molecular logic operations and mechanical switches. We will return to this subject in the next chapter. 

Only lately have covalently linked species also become included in supramolecular structures since they are formed of particular building blocks, e.g. the Starburstjcascade dendrimers (see Chapter 6 of this volume). Moreover, the catenands and knots (as shown in Chapter 5) are not subject either to covalent or typical noncovalent bonds, although the latter are important in the formation step, but rest upon a mechanical interlock or coding. 

When subject to 90° peel test, adhesion values of 7-10 lbs/in have been obtained under ambient conditions. Interestingly, the adhesion after the solder float test retained 4-6 lbs/in. This high adhesion is believed to be primarily due to the mechanical interlocking facilitated by the textured Kapton polyimide. 

When an uncured but well dispersed filled rubber is subjected to solvent extraction, not all of the elastomer is recovered. The portion of rubber that is not extracted is called the bound rubber. The bound rubber layer results from a complex combination of physical adsorption, chemi-adsorption and mechanical interlocking. The surface activity of carbon black is related to the bound rubber. Wolff et alP have investigated the existence of the bound rubber layer and studied its characteristics. They measured the bound rubber layer for SBR filled with carbon black using NMR and the thickness of the bound rubber... 

Another problem is the fibre-matrix bond, which is based mostly on mechanical interlocking. For example, the surface of bamboo fibres should be subjected to special treatment like sand blow to increase its roughness. 

The actual bonding between the adhesive polymers and the wood polymers is attributed to a combination of three mechanisms mechanical interlocking, physical attraction, and covalent chemical bonding. The relative importance of these three mechanisms is still the subject of debate among adhesive chemists. 

The equivalent elastic modulus, Gip, for the mechanically interlocked interphase is calculated by assuming an isostress condition for the interphase, illustrated in Pig. 23.13. In other words, the adhesive and the adherend surface (projections) are subjected to the same level of shear stress, tjp, at the interphase, while the composite interfacial shear strain, yjp, is a volumetric weighted average of the adhesive and adherend strains, that is,... 

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