Interpenetration self-penetration

There are a number of uninodal nets that are also self-penetrating, notably the (8,4) net (Figure 19a) and the (12,3) net (Figure 19b). A compound containing two interpenetrating self-penetrating (12,3) nets has even been reported. ... 

An interesting series of structures based on the rutile net illustrates the relationship between interpenetration and self-penetration. The compounds are constructed using octahedral metal ions and the trigonal ligands tcm [tricyanomethanide, C(CN) ] and dca [dicyanamide, N(CN)2 ]. It is important to note that dca is a smaller ligand than tcm. Thus, while the compounds M(tcm)2 have two interpenetrating rutile-related networks,the... 

Another self-penetrating network is the (12,3) net, of which two examples were recently reported. If interpenetrating networks can be related to catenanes and rotaxanes, then self-penetrating networks can be considered to be polymeric equivalents of molecular knots. 

Batten, S.R. Robson. R. Catenane and Rotaxane Motifs in Interpenetrating and Self-penetrating Coordination Polymers. In Molecular Catenanes, Rotaxanes and Knots, A Journey Through the World of Molecular Topology Sauvage, J.-P., Dietrich-Buchecker. C., Eds. Wiley-VCH Weinheim, 1999 77-105. 

Figure 4.38 (a) A two-fold three-dimensional interpenetrating network of Co(dca)2(pyrazine) and (b) part of a self-penetrating three-dimensional network Co(dca)(tcm). 

S. R. Batten and R. Robson, Catenane and rotaxane motifs in interpenetrating and self-penetrating coordination polymers, in Molecular Catenanes, Rotaxanes and Knots, a Journey Through the World of Molecular Topology, eds. J.-P. Sauvage and C. Dietrich-Buchecka-, WUey-VCH Ver-lag GmbH, Weinheim, 1999, pp. 77-106. 

The large voids formed by some single nets are seldom empty. Besides solvent molecules and counter ions, these voids can be filled with one or more additional nets. To be classified as interpenetrating, these nets should not be able to separate without breaking any bonds. Self-penetration on the other hand is a topological property of a single net (see for example section 6.2.1) and not dealt with in this chapter. 

There are a number of other forms of entanglement besides interpenetration (and self-penetration), which have received considerable interest in recent times. One such class of materials is the polyrotaxane or poly-threaded structures. These entanglements show great variety, partly because there are a number of different types of entanglement which can fall under this banner. 

With controllable strength of the self- and hetero-associated hydrogen, a molecular level penetrated semi-interpenetrating polymer networks (semi-IPNs) of ST-VPDMS with poly(N-vinylpyrrolidone) (PVPr) were prepared by condensation of the self-associated silanols.13... 

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