Entanglement polyrotaxanes

Gibson and coworkers also found that the melt viscosity of a polymer is also altered by the formation of a polyrotaxane [19], Poly(ester rotaxane) 60 containing 42C14 as the cyclic component had a melt viscosity equivalent to that of the parent polyester with 2.5-fold higher molecular weight. This result clearly indicates that there is less chain entanglement in the polyrotaxane than in the backbone polymer by itself. 

Importantly, it was observed that in the case of polymers lacking end-blocking groups, dethreading of maerocycles was not significant. This result was interpreted in terms of chain-macrocycle entanglements in the polyrotaxane, the macrocycle being trapped in random coils of the backbone [40]. 

Not only poly-pseudo-rotaxanes but also polyrotaxanes should be considered trivial topological entanglements, extending the concepts developed for the related molecular entities. By means of ideal continuous deformations we could separate the components of any finite portion of a polyrotaxane. How-... 

It may be noted that besides chemical crosslink formation we can achieve the physical linking of macromolecules (Fig. 6) where the effect on propoties could be just as important as in chemical aosslinking and entanglements. The pertinence of such a procedures may be demonstrated by the synthesis of polyrotaxanes [197] in which a cyclic oligomer of ethylene oxide is absorbed on macromolecules of polyami (Scheme 1)... 

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. 

Figure 21 Polyrotaxanes with rotaxane-based ligands (a) a trivial entanglement (b) a nontrivial entanglement -...

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