Intrinsically functional polymers

The lUPAC definition for a functional polymer is a polymer that bears specified chemical groups or polymer that has specified physical, chemical, biological, pharmacological, or other uses which depend on specific chemical groups [3]. The functional polymers are of two basic types intrinsically and extrinsically functional polymer. Intrinsically functional polymers are where the polymers themselves offer a unique range of properties for different applications, while extrinsically functional polymers are those composite materials containing dispersed fine particles of a functional material, such as magnetite (FejO ), carbon black in a conventional polymer. 

This chapter concentrates on the design of efficient dipolar NLO chromophores and the different approaches for their incorporation in non-centrosymmetric materials, including guest-host polymer systems, chromophore-functionalized polymers (side-chain and main-chain), cross-linked chromophore-macromolecule matrices, dendrimers, and intrinsically acentric self-assembled chromophoric superlattices. The different architectures will be compared together with the requirements (e.g., large EO coefficient, low optical absorption, high stability, and processability) for their incorporation into practical EO devices. First, a brief introduction to nonlinear optics is presented. 

In the case of polymers or solid supports, intrinsic functionalities can sometimes be used as anchoring groups for the coupling with biomolecules. In other cases suitable functional groups must be introduced by substitution or activation. Several excellent reviews on the chemical modification of electrodes have covered all possibilities in this respect [250-254]. For special emphasis, modiflcation procedures are shown here that may play a role in electrochemical biosensor development on the basis of different electrode materials (Figure 14-16). 

Because of the strong coloration, depending on their state of oxidation, intrinsically conducting polymers have frequently been studied with SRRS [507, 508]. Molecular vibrations could be assigned based on various approaches. Most frequently band positions of the monomers and of already known oligomers were compared with those of the polymers. Alternatively, band positions were calculated based on an effective conjugation coordinate [509-516]. In a typical example shown in Fig. 5.84, SRR spectra of poly aniline are displayed as a function of electrode potential. 

Fig. 5 Films of intrinsically immiscible polymers with and without promotion by supramolecular linking, (a) Heterogeneous film of plain poly(butylmethacrylate) and polystyrene functionalized with 2,7-diamido-l,8-naphthyridine (DAN), (b) Transparent blend of poly(butylmethacrylate) functionalized with ureidoguanosine (UG) and polystyrene functionalized with DAN, thereby enabling quadruple hydrogen bonding of DAN and UG to facilitate polymer mixing. Reprinted with permission from [101]. Copyright 2006 American Chemical Society...

In this case, d is a fitting parameter relating to the width of the sigmoidal function, / polymer IS the mobiHty of the polymer alone, and max is the maximum achievable mobility in the blend. The latter will ideally be the intrinsic mobility of the high-mobility small molecule however, this is rarely the case. The aim is to achieve a i max that is greater than simply processing the small molecule with no polymer matrix This will also be lower than the intrinsic mobility due to the problems discussed earlier with thin-film formation of highly crystalline materials. 

Functional polymers appeared in the second half of the twentieth century. Although polyaniline was first described in the mid-nineteenth century by Henry Letheby and polypyrrole derivatives were reported to be electrically conducting in 1963 by B.A. Bolto et al. (1963), substantial progress was not made with intrinsically conducting polymers until the pioneering work of Hideki Shirakawa, Alan J. Heeger, and Alan MacDiarmid who reported similar high conductivity in oxidized iodine-doped polyacetylene in 1977 (Shirakawa 1977). For this research, they were awarded the 2000 Nobel Prize in Chemistry for the discovery and development of conductive polymers. ... 

Self-healing or restoration of lost functionalities without external help is a dream come true with self-healing polymers (Ai ssa et a/., 2012). Healing mechanisms can be extrinsic (the healing compound is isolated from the polymer matrix in capsules, fibers or nanocarriers) or intrinsic (the polymer chains temporarily increase mobility and flow to the damaged area) (Billiet et al, 2013) and are responsible for restoration of properties such as structural integrity (White et fll, 2001), surface aesthetics (Yao et a/., 2011), electrical conductivity (Tee et fl/., 2012), hydrophobicity and hydrophilicity (Ionov and Synytska, 2012), mechanical properties (Jones et al, 2013), etc. 

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