Supramolecular materials, dynamic materials by nature, are defined as materials whose components are bridged via reversible connections and undergo spontaneous and continuous assembly/disassembly processes under specific conditions. On account of the dynamic and reversible nature of noncovalent interactions, supramolecular polymers have the ability to adapt to their environment and possess a wide range of intriguing properties, such as degradability, shape-memory, and self-healing, making them unique candidates for supramolecular materials. In this critical review, we address recent developments in supramolecular polymeric materials, which can respond to appropriate external stimuli at the fundamental level due to the existence of noncovalent interactions of the building blocks.

Stimuli-responsive supramolecular polymeric materials.

Because of the importance of novel macrocycles in supramolecular science, interest in the preparation of these substances has grown considerably. However, the discovery of a new class of macrocycles presents challenges because of the need for routes to further functionalization of these molecules and good host–guest complexation. Furthermore, useful macrocylic hosts must be easily synthesized in large quantities. With these issues in mind, the recently discovered pillararenes attracted our attention. These macrocycles contain hydroquinone units linked by methylene bridges at para positions. Although the composition of pillararenes is similar to that of calixarenes, they have different structural characteristics. One conformationally stable member of this family is pillar[5]arene, which consists of five hydroquinone units. The symmetrical pillar architecture and electron-donating cavities of these macrocycles are particularly intriguing and afford them with some special and interesting physical, chemical, ...

Pillararenes, A New Class of Macrocycles for Supramolecular Chemistry

A review of stimuli-responsive shape memory polymer composites

In 2008, we reported a new class of pillar-shaped macrocyclic hosts, known as “pillar[n]arenes”. Today, pillar[n]arenes are recognized as key players in supramolecular chemistry because of their facile synthesis, unique pillar shape, versatile functionality, interesting host–guest properties, and original supramolecular assembly characteristics, which have resulted in numerous electrochemical and biomedical material applications. In this Review, we have provided historical background to macrocyclic chemistry, followed by a detailed discussion of the fundamental properties of pillar[n]arenes, including their synthesis, structure, and host–guest properties. Furthermore, we have discussed the applications of pillar[n]arenes to materials science, as well as their applications in supramolecular chemistry, in terms of their fundamental properties. Finally, we have described the future perspectives of pillar[n]arene chemistry. We hope that this Review will provide a useful reference for researchers working in th...

Pillar-Shaped Macrocyclic Hosts Pillar[n]arenes: New Key Players for Supramolecular Chemistry

Synthetic polymers containing metal centres are emerging as an interesting and broad class of easily processable materials with properties and functions that complement those of state-of-the-art organic macromolecular materials. A diverse range of different metal centres can be harnessed to tune macromolecular properties, from transition- and main-group metals to lanthanides. Moreover, the linkages that bind the metal centres can vary almost continuously from strong, essentially covalent bonds that lead to irreversible or 'static' binding of the metal to weak and labile, non-covalent coordination interactions that allow for reversible, 'dynamic' or 'metallosupramolecular', binding. Here we review recent advances and challenges in the field and illustrate developments towards applications as emissive and photovoltaic materials; as optical limiters; in nanoelectronics, information storage, nanopatterning and sensing; as macromolecular catalysts and artificial enzymes; and as stimuli-responsive materials. We focus on materials in which the metal centres provide function; although they can also play a structural role, systems where this is solely their purpose have not been discussed.

Functional soft materials from metallopolymers and metallosupramolecular polymers

A cross-linked supramolecular polymer network gel is designed and prepared, which shows reversible gel-sol transitions induced by changes in pH, temperature, cation concentration, and metal co-ordination. The gel pore size is controlled by the amount of cross-linker added to the system, and the material can be molded into shape-persistent, free-standing objects with elastic behavior. These features are all due to the dynamically reversible host-guest complexation and good mechanical properties of the cross-linked polymer network. No single organogel has previously been reported to possess all of these features, making this supramolecular gel an unprecedentedly intelligent soft material.

A Multiresponsive, Shape‐Persistent, and Elastic Supramolecular Polymer Network Gel Constructed by Orthogonal Self‐Assembly

A Dual-Responsive Supramolecular Polymer Gel Formed by Crown Ether Based Molecular Recognition

The topology of a polymer has a significant influence on its properties and functions, both in bulk and in solution. Therefore, the discovery of efficient methods to control polymer topology is very important. [1] The introduction of non-covalent interactions into traditional covalent polymers represents a novel approach for the control of polymer topologies, and has allowed the incorporation of reversible and switchable functionality into different macromolecular architectures. [2] However, this strategy usually requires the integration of specific molecular recognition motifs into polymer chains; such an approach suffers from problems such as the availability of suitable monomers and the poor efficiency of polymerization techniques that are tolerant to functional groups on the polymer. Conversely, supramolecular polymers that are assembled from low molecular weight monomers by non-covalent interactions, such as hydrogen bonding, [3] metal coordination, [4] and host–guest interactions, [5] have demonstrated traditional polymeric properties and are an important resource in the development of stimuliresponsive dynamic materials. [6] Until now, efforts to control the topology of supramolecular polymers have mainly been concerned with the conversion between the large-sized species and their corresponding monomers/oligomers; comparatively little effort has been devoted to the transformation between supramolecular polymers of different topologies. The desired recognition motifs can be conveniently introduced into the low-molecular-weight-monomers, thus avoiding the problems commonly associated with covalently linked polymer backbones, and thus leading to a more effective method for switching between different architectures. Herein, we present reversible switching between linear and cross-linked supramolecular polymers. That biological systems utilize multiple-interaction selfassembly to afford hierarchical and multifunctional systems [7]

Metal coordination mediated reversible conversion between linear and cross-linked supramolecular polymers.

Formation of a Cyclic Dimer Containing Two Mirror Image Monomers in the Solid State Controlled by van der Waals Forces

http://www.rsc.org/suppdata/cc/c1/c1cc11790d/c1cc11790d.pdf

Xia Ding

Papers

A Multiresponsive, Shape‐Persistent, and Elastic Supramolecular Polymer Network Gel Constructed by Orthogonal Self‐Assembly

A Dual-Responsive Supramolecular Polymer Gel Formed by Crown Ether Based Molecular Recognition

Metal coordination mediated reversible conversion between linear and cross-linked supramolecular polymers.

Formation of a Cyclic Dimer Containing Two Mirror Image Monomers in the Solid State Controlled by van der Waals Forces

Supramolecular polymer nanofibers via electrospinning of a heteroditopic monomer.