Polycatenane

Takata, T., Kihara, N. and Furusho, Y. Polyrotaxanes and Polycatenanes Recent Advances in Syntheses and Applications of Polymers Comprising of Interlocked Structures. Vol. 171, pp. 1-75. 

Polycatenanes, 17 60 Poly(y-caprolactone)dimethylacry, in shape-memory polymers, 22 357 Poly(y-caprolactone)/OMLS nanocomposite, 20 311 Poly(y-caprolactone) switching segment, in shape-memory polymers, 22 362-363 Polychlorinated biphenyls (PCBs),... 

Polycatenane complexes, 46 271-273 Polycatenasulfur, 18 304, 305 Polycobalticinium ligand systems, macrocyclic and acyclic, 39 134-140 Polydentate ligands, 32 56 with negative... 

The interest in macromolecular systems containing defined topological bonds, such as polyrotaxanes 7, multicatenanes 8, polycatenanes 9, poly[2]catenanes 10, and polymeric catenanes 11, is dual. First, these macromolecules represent daunting synthetic and characterization challenges which deserve attention in their own... 

The synthesis of polycatenanes requires, like the synthesis of catenanes, the preorientation of the macrocycle precursors into a favorable geometry before cycliza-tion (Scheme 4) [5], This pre-orientation is commonly achieved via a template, resulting from rc-donor-acceptor interactions, hydrogen-bonding, and coordination bonds [1-3, 5, 41], The use of a template in catenane synthesis is the subject of Chapters 4 and 6-8 and will not be treated further in this section. The aim of this section is to present the state of the art of the various synthetic approaches leading to the polycatenane polymers and networks. 

Conceptually, the macromolecular architecture of polycatenanes 9 bears many similarities to that of ladder polymers 15, depicted in Scheme 5. Therefore, certain similarities also exist between synthetic strategies leading to both polycatenanes 9 and ladder polymers 15. Conceptually, two synthetic routes may be envi-... 

Scheme 5. Pictorial representation of polycatenane 9 and of ladder-type polymer 15.

Scheme 6. The multifunctional polycondensation synthetic strategy to polycatenane.

The principle of the second synthetic approach to polycatenanes, i.e. stepwise polycondensation, has been proposed by Shaffer and Tsay, but not experimentally demonstrated [42, 43], This approach has the advantage over multifunctional polycondensation that a linear polymer is formed before cyclization (Scheme 7). However, the second step, which consists of the cyclization of n macrocycles along the polymer chain 19, is likely, again, to give rise to an undefined network, containing some rotaxane and catenane units 21, similar to the multifunctional polycondensation approach. 

An experimental attempt towards polycatenanes 9, based on a strategy related to the stepwise polycondensation approach, was reported in the seventies. Karagoumis et al. took advantage of the interface between a nonpolar phase (air, CC14) and a polar phase (H2O, Hg) to orient alkanes a,oj-disubstituted with polar groups (Scheme 9) [45], The successive addition of macrocycles of ring sizes 15-60 atoms and of difunctional species, susceptible to reaction with the a,o>disubstituted al-... 

Scheme 9. Synthetic strategy towards polycatenane according to Karagoumis [45].

Two outstanding forerunners of high molecular-weight polycatenanes are the [5]catenane 30, also named olympiadane, and the [7]catenanes 31 reported by Stoddart and coworkers (Scheme 10) [46, 49]. The synthetic strategy leading to... 

In this section the unprecedented oligocatenanes, i.e. the [5]- and [7]catenanes 30 and 31 and the scarce experimental approaches to high molecular-weight linear polycatenane 9 have been presented. No synthetic Olympic network 32 has been reported to date, although their DNA analogs are known. The next section is dedicated to a new type of macromolecular architecture, structurally related to polycatenane 9, i.e. poly[2]catenanes. 

---