Interpenetrated structures

Copolymers (graft or block) made of immiscible sequences give rise to biphasic morphologies depending on the ratio of immiscible sequences (or of their lengths). Such possible microstructures are reported in Figure 33. A minor phase can be dispersed as nodules (spheres) or filaments (cylinders) while, when concentrations of both phases get similar, lamellar (interpenetrated) structures can appear. It should be noted that rather similar morphologies could also be found in (compatibilised) polymer blends. 

Three-Dimensional Double Interpenetrated Structures Fe(L)x[Ag(CN)2] Guest... 

By far the largest class of interpenetrating structures involves diamond-related nets. 2-Fold interpenetration in the case of Zn(CN)2 has already been considered and many examples varying in the degree of interpenetration from 2-fold to 9-fold are referred to in the comprehensive review [1]. The mode of 9-fold interpe-... 

As their structures define, polyrotaxanes are polymeric composites. Their ultimate properties are related both to the chemical compositions of the cyclic and backbone and to their relative proportions. However, because of its different topology relative to simple mixtures, the interpenetrated structure introduces new outcomes in terms of properties. Because the applications of materials rely on their properties, these aspects are incorporated into this section. 

Figure 9.34 Distribution of the topologies within the 301 interpenetrated structures observed in the CSD and ICSD (reproduced with permission of The Royal Society of Chemistry).

Figure 4. Anion-templated self-assembly ofpseudorotaxanes. Recognition of the anion by macrocycle results in the formation of an interpenetrated structure.

It is important to appreciate that these ditopic macrocycles contain a polyether moiety on one side and present a diamido motif on the other. Addition of a charged pyridinium cation to the substrate-free form of these macrocycles then generates a highly efficient receptor for chloride, presumably as the result of both template-induced organization and electrostatic effects. The further incorporation of hydro-quinone groups and polyether functionalities into the cyclic framework presumably contributes to the stabilization of the cationic pyridinium component within the final interpenetrated structure. Interestingly, while titration of the pyridinium cation building block alone revealed a preference for oxoanions, the final receptor-anion... 

During the same period, commercialization of thermoplastic starch polymer blends was pursued by Novamont, a division of the Ferruzzi Group of Italy.162-172 Their products, marketed under the trade name Mater-Bi, are typically comprised of at least 60% starch or natural additive and hydrophilic, biodegradable synthetic polymers.64,165 It is stated that these blends form interpenetrated or semi-interpenetrated structures at the molecular level. Properties of typical commercial formulations have properties similar to those in the range of low- and high-density PE. Blends of Mater-Bi products with biodegradable polyesters have been claimed for use as water impervious films.173... 

Figure 6. The triply interpenetrated structure formed by the 1 1.5 cocrystal oftrimesic acid and 4,4 -bipyridine.

The interpenetrating structure (Fig. 8.9) wherein the mobility originates can be described by the Q surface (discussed above). The long-range periodicity, which is a consequence of such a structural description, is relevant to tmderstand the cooperativity and the requirement of synchronisation of the movement of the individual myosin/actin. The phase/curvature approach to the structure of the muscle cell outlined here not only has a didactic value, but adds a new dimension to the discussion of function mechemisms. 

The isomorphous CugO and Ag20 are of unusual structure. The metal atoms have two collinear bonds and the oxygens four tetrahedral bonds in a cubic structure similar to that of cristobalite. The low co-ordination, 4 2, is indicative of covalence. The structure represented in Fig. 270 is not the complete picture. An identical framework, in which the structure shown is moved forward so that the oxygens marked A take up the positions B, interpenetrates it without cross-connection by M—O bonds. The interpenetrating structure is unique in crystal chemistry. Both oxides form solid solutions with the metal. 

Figure 1.3.6 The highly distorted diamondoid net observed in the 2-fold interpenetrated structure of SbCI3(p-diacetylbenzene) with a diamondoid cage in black (W. A. Baker, D. E. Williams, Acta Crystallogr., Sect. B 1978, 34, 1111) (left). The observed diamondoid cage (center) is compared with the undistorted adamantane cage as in diamond (right).

A survey of 301 interpenetrated structures in the CSD and ICSD was undertaken in 2004 which showed the distribution of structure types given in Figure 9.34. The 3D diamondoid net with its large adamantoid cavities proved to be by far the most common interpenetrated solid. For coordination polymers the highest degree of interpenetration is 10-fold and occurs for a silver(l) complex of... 

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