Polyrotaxanes branched

A polyrotaxane with a dendrimer-like structure is known [60]. Based on the observation that [3-CD and sodium deoxycholate (NaDC) 54 forms a 2 1 host guest complex in water, Tato et al. constructed hyperbranched polyrotaxanes 55 by slowly reacting triply branched receptor 53 containing P-CD and NaDC... 

Dendritic Polyrotaxanes Incorporating Ring Components at Branching Points Type lll-B... 

Fig. 19. (a) Divergent and (b) convergent synthesis of dendritic polyrotaxanes with mechanical branching units... 

Fig. 21. Dendritic polyrotaxanes with mechanical branching units containing covalently linked bis-dendrons and a core imit fused to polyether macrocycles...

By careful design, two CDs were also incorporated per pendant group (57) with poly(methyl methacrylate) backbones [102]. In polyrotaxane 58, pendant branched chains were threaded with CDs (one per branch) [97,101]. The chemical composition of the branched arm was very similar to that in 56. 

All the polyrotaxanes discussed thus far are based on linear backbones. Viewing new properties and applications of branched and cross-linked polymers, three-dimensional polyrotaxanes will surely be interesting in terms of both topology and potential applications. Gong and Gibson extended the hydrogen-bonding theo-... 

Figure 14. Preparation of branched or cross-linked polymer via the formation of side-chain polyrotaxanes.

Figure 17. Reversible process for branched or cross-linked polyrotaxanes.

The ring topology is the potential to form unique polymer structures. Like linear polymers, cyclic polymers not only can be branched or cross-linked, but also can form non-covalently linked structures based on their loop topology. These are referred to as topological polymers, including rotaxane, catenane, threaded rings, and rings threaded by network chains. Recently, much attention has been paid to how their particular properties not only differ from linear polymers, but also how they differ from a component of an interlocked polymer system, such as polycatenanes and polyrotaxanes. 

Besides simple rotaxanes and catenanes, a great variety of more complex systems have been synthesized, including branched [n]rotaxanes [26a], [n]rotaxanes bearing dendritic stoppers [26b], catenanes composed by two, three, five, or seven interlocked macrocycles [26c,e], polyrotaxanes and polycatenanes [2-6, 8], catenanes with very special shapes [27], rotocatenanes [28], pretzelanes [29], and knots [4], Some of these compounds are shown in Figure 8. 

Polymers are normally classified into four main architectural types linear (which includes rigid rod, flexible coil, cyclic, and polyrotaxane structures) branched (including random, regular comb-like, and star shaped) cross-linked (which includes the interpenetrating networks (IPNs)) and fairly recently the dendritic or hyperbranched polymers. I shall cover in some detail the first three types, but as we went to press very little DM work has been performed yet on the hyperbranched ones, which show some interesting properties. (Compared to linear polymers, solutions show a much lower viscosity and appear to be Newtonian rather than shear thinning [134].) Johansson [135] compares DM properties of some hyperbranched acrylates, alkyds. and unsaturated polyesters and notes that the properties of his cured resins so far are rather similar to conventional polyester systems. 

Buschmann et al. were the first to prepare a polyrotaxane containing cucurbituril by cleverly adapting interfacial polymerization conditions to the requirements of the water-soluble pseudorotaxane monomer. Polymers in which cucurbituril has been threaded onto the side chain in a pseudorotaxane fashion have been reported by Kim et al. Cucurbituril has also been integrated into a branched polymer structure. Through the functionalization of the surface of a dendrimer with a diamine motif, Kim et al. achieved the threading of CB[6] onto it, leading to a pseudorotaxinated surface architecture. ... 

The architectures of polymers synthesized using ROMP generally fall under four broad categories linear, cross-linked, branched, and dendritic. Linear polymers, as the name implies, possess chains that extend in one dimension, and encompass flexible coils, rigid rods, cycles, and polyrotaxanes, which can all be related to a string. Flexible coils may be imagined as a... 

Macromolecules incorporating repeating units connected by covalent bonds are widespread in nature [1], Synthetic procedures for the construction of their artificial counterparts are well established [2], Furthermore, the properties of these unnatural macromolecules are now rather well understood and, indeed, polymeric materials have found applications in numerous branches of science and technology [2], In recent years, synthetic chemists have learned how to introduce mechanical bonds (Fig. 1) into small molecules. Mechanically interlocked rings, as well as wheels mechanically trapped onto axles, can be constructed efficiently to afford molecular compounds, named catenanes and rotaxanes, respectively.t Metal coordination [18-32], donor/acceptor interactions [33-43], hydrogen bonds [44-64] and/or hydrophobic interactions [65-78] between appropriate components have all been employed to template the formation of these exotic molecules. Making the transition from simple catenanes and rotaxanes to their macromolecular counterparts—namely, polycatenanes and polyrotaxanes. 

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