Mechanically Linked Poly [2]Rotaxanes Constructed Via Noncovalent Bond

The objects with mechanical interlocked structures are everywhere in our daily life. And when it comes to chemistry, we have defined mechanical bond, different from traditional covalent bonds, coordination or noncovalent bond, in which two or more molecular components become mechanically interlocked, one with another, and so on, in some manner or another. In addition, the fact that some weaker bonds ’live on’inside these mechanically interlocked molecules (MIMs) after their template directed synthesis give the molecules much’added value’when it comes to exploiting their physical and chemical properties. Mechanical bonds present chemists with the best of both worlds, which are the molecular and ’supramolecular’ ones,since they come with the robustness provided by covalent bonding throughout, yet contain therein all the intricacies and subtleties associated with coordinative and noncovalent bonding, rendering the molecules ideal for the control of function at the single molecule, the nanoscopic, the microscopic, and the macroscopic levels.Mechanically linked macromolecules, representing the marriage of interlocked molecules with traditional covalent polymers, have drawn considerate attentions due to their specific architectures and functionalities. As compared with the widely-reported main-chain poly[n]rotaxanes, embedment of mechanical bonds as integral parts of the polymer backbone is much more intriguing. Specifically, due to the impartment of unique rotational and elongational mobility to the polymeric chain, the resulting mechanically linked macromolecules could display fascinating thermal, mechanical and viscoelastic rheological properties. Therefore, we are desired to construct mechanical interlocked macromolecules. Based on our limited knowledge and ability, we have designed two types of main-chain poly[2]rotaxanes.In this paper, the first chapter summarizes some basic concepts of supramolecular chemistry and introduces some types of the mechanical interlocked macromoleculars. In the second chapter, we have been designed and synthesized mechanically linked poly[2]rotaxanes on the basis of the benzo-21-crown-7/secondary ammonium salt recognition motif, which are confirmed by GPC, IR and 1H NMR. The thermal and rheological properties for the resulting poly[2]rotaxanes display interesting thermal and rheological properties due to the integration of [2]rotaxane moieties into the polycaprolactone chains. The study would be advantageous for the further development of supramolecular materials with excellent mechanical behaviours. In the third chapter, we have successfully constructed mechanically linked poly[2]rotaxanes via the hierarchical self-assembly strategy.The integration of two noninterfering noncovalent recognition motifs facilitates chain extension of the B21C7-based [2]rotaxane monomer, demonstrating the capabilities to form self-standing films with preferable transparency and softness.