Supramolecular functional polymer

Supramoleciflar directed self-assembly of inorganic and inorganic-organic hybrid nanostructures has emerged as an active area of recent research. The recent advance shows a remarkable feasibihty to mimic natoal mineralization systems by a designed artificial organic template, where a supramolecular functional polymer can be directly employed as minerahzation template for the synthesis of novel inorganic nanoarchitectures [165] such as CdS helices [166] and hydroxyapatite (HAP) nanofibers [167]. 

Hydrogen bonding interactions are important for the development of selfassembling supramolecular materials, which are defined as materials in which monomeric units are reversibly bound via secondary interactions to form polymer-like stmctures that exhibit polymeric properties in solution as well as in bulk (Bmnsveld et al. 2001). Rotello used hydrogen bond functional polymers to direct the formation of large vesicles (lUian et al. 2000), reversibly attach polymers on... 

In this chapter we will focus on side chain functionalized supramolecular polymers as well as main chain noncovalent functionalized polymers, which are the two main areas of supramolecular polymers. We will initially discuss the design principles and methodology of side chain functionalization, in particular, multifunctionalization. In the later part of the chapter, we will discuss in detail two important applications of side chain functionalized supramolecular polymers. The first application involves the use of noncovalent interactions to yield highly functionalized materials, whereas the second application involves the reversible noncovalent cross-linking of polymers to yield responsive materials. 

Pollino JM, Week M. Supramolecular side-chain functionalized polymers synthesis and self-assembly behavior of polynorbornenes bearing Pd SCS pincer complexes. Synthesis 2002 9 1277-1285. 

Over the past 5 years, a number of researchers have started to explore and mimic these approaches in the laboratory. Enzyme-assisted formation of supramolecular polymers has several unique features. These include selectivity, confinement and catalytic amplification, which allow for superior control as observed in biological systems. These systems are finding applications in areas where supramolecular function is directly dictated by molecular order, for example in designed biomaterials for 3D cell culture, templating, drug delivery, biosensing, and intracellular polymerisations to control cell fate. Overall, biocatalytic production of supramolecular polymers provides a powerful new paradigm in stimuli-responsive nanomaterials. 

Chapters 1 through 4 feature work on supramolecular and polymer systems that function as sensors for a variety of chemical and biological targets. In Chapter 1, Rudzinski and Nocera give an exciting overview of research focusing... 

An interesting dimension of metal-coordinated self-assembly that is often ignored, or at least not exploited to its fullest extent, occurs when the resulting coordination complex is a charged species and, as such, in need of a counterion. This counterion itself presents yet another subtle instance of ionic self-assembly, which often is overshadowed by its partner, the coordination complex. The second multi-functional side-chain supramolecular polymer system is based on this simple but important concept [14, 106-111]. In 2003, Ikkala and coworkers reported a study in which they exploited (1) a side-chain functionalized polymer, poly(vinyl-pyridine), (2) metal-coordination self-assembly via a tridentate Zn2+ complex and (3) ionic self-assembly through functionalized counterions, i.e. dodecylbenzene-sulfonate ions, to form multiple self-assembled complexes which adopted a cylindrical morphology (Fig. 7.23) [112]. 

The examples represented here have demonstrated our increasing ability to design and to manipulate ever larger supramolecular systems and merge concepts from supramolecular and polymer chemistry. Yet we are still far Irom approaching the perfection and versatility and, most important, the functionality of biomolecules and their superstructures. Like in biology, macromolecules and the competition between macromolecular order and disorder will play a dominant role in the preparation of functional molecular devices and nanoscopic objects. 

Riihe J, Knoll W (2000) Functional Polymer Brushes. In Ciferri A (ed) Supramolecular polymers, Marcel Dekker... 

Functional polymers are macromolecules that have unique properties or uses. The properties of such materials are often determined by the presence of chemical functional groups that are dissimilar to those of the backbone chains. Examples are polar or ionic functional groups on hydrocarbon backbones or hydrophobic groups on polar polymer chains. Chemical heterogeneity on the polymer chains can le to enhanced reactivity, phase separation, or association. The ability of functional polymers to form self-assemblies or supramolecular stmctures is a further incentive. When the formation or dissociation of the self-assemblies is triggered by chemical or physical stimuli so called smart materials can result ... 

Keywords Supramolecular Networks Hydrogen Bonding Functional Polymers Viscoelasticity Phase Behavior Associating Polymers... 

Noro A, Ishihara K, Matsushita Y (2011) Nanophase-separated supramolecular assemblies of two functionalized polymers via acid-base complexation. Macromolecules 44 (16) 6241-6244... 

Partially Modified SPG One-Dimensional Host Toward the Supramolecular Functionalization of Guest Polymers... 

The findings clearly show that chemically modified SPG maintains its inherent ability as a one-dimensional host. The wrapping of the chemically modified SPG provides a novel strategy to create functional polymer composites in a supramolecular manner. Considering a general difficulty in introducing fimctional groups into the functional polymer backbones, the present system can be a new potential path to develop fimctional polymeric materials. 

They are expected to possess unique properties due to the lability of the non-covalent bonds, and, from a synthetic viewpoint, many of the usual molecular parameters that control the PLC characteristics can be more easily accessible. The latter include the length and type of spacer and tail, the type of mesogen, the type of polymer backbone, and the molar mass and polydispersity of the polymer. Additional molecular parameters are introduced in conjunction with the choice of functional groups. Furthermore, a number of useful functional polymers are available either commercially or through straightforward synthetic methods. It is also a simple matter to obtain a variety of supramolecular copolymer PLCs and network PLCs, as well as, in principle, a variety of other architectures. A number of examples of these aspects have been given in this review. 

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