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Biodegradable plastics are currently receiving much attention for use as a commodity consumed with ecological advantages over nondegradable ones. Biodegradability is well known for some kinds of polymers including natural polymers such as cellulose, chitin, lignin, and bacterially synthesized aliphatic polyesters, and chemically synthesized polymers such as aliphatic polyesters and polyvinyl alcohol. Among them, aliphatic polyesters are the most promising materials for fibers and resins [1,2].

Analysis of couplings by 2D HSQC, TOCSY, and HMBC spectroscopy enable the unambiguous and comprehensive assignments of the carbon and proton resonances of vinyl polymers [1–4].

The techniques of solid-state NMR have been still growing and now varieties of methods exist for the structure characterization. The multiple-quantum coherences are particularly useful in NMR for the precise analysis of the local structures in disordered as well as ordered polymers. In this chapter, we show some examples of the quantitative conformation characterization of disordered and amorphous solid polymers by the advanced solid-state multiple-quantum NMR spectroscopy.

Of the nuclei (^1H and ^13C), which both possess nuclear spin and are common to synthetic polymers, ^13C is by far the more sensitive NMR spin probe of polymer microstructure. ^13C NMR spectra suffer neither from a narrow dispersion of chemical shifts nor from extensive homonuclear, scalar spin-spin coupling, which both complicate the analyses of ^1H NMR spectra. It is the sensitivity of ^13C resonance frequencies or chemical shifts, δ^13C, to the micro structures of polymers, which makes ^13C NMR so useful as a structural probe.

Polymer blends and composites have emerged as technologically important advanced materials with mechanical, optical, and electrical applications. It has been shown that the properties of polymers can be improved with the addition of particles ranging in size from nanometers to microns. As the volume fraction becomes large or for composites with nanometer-sized particles, the fraction of interfacial material becomes large enough to influence the properties. In many nanocomposites, the improved properties are thought to result from the favorable properties of polymers at the interface.

Network polymers comprise one of the most important classes of polymeric materials, from both a theoretical and a commercial perspective. The linking together of macromolecular chains usually through permanent covalent bonds confers unique properties to network polymers. These may be increased modulus and elasticity, lower rates of creep, solvent resistance, high temperature stability, to name just a few. The applications of network polymers are thus myriad. Thermosetting resins comprise the majority of polymers used in structural applications. Crosslinkedpolyolefins are ubiquitous as automotive tyres, as a component of asphalt, as o-rings, sheeting, in clothing and footware and so on. In more recent times, chemically crosslinked networks are becoming important in the field of biomaterials, as supports for tissue growth and for drug delivery. Many other applications can be listed.

Individual structural units forming polymer molecules basically undergo their own local motions in different states although some of them may be cooperative motions. The modes and rates of the molecular motions are relatively well characterized in the crystalline state by solid-state NMR spectroscopy, but the analysis of the local motions in the noncrystalline state may not be straightforward because there are distributions in molecular motion associated with the noncrystalline structure. Several solidstate NMR analytical methods, which are summarized in Figure 3.1 in Ref. [1], have been already proposed and they are successfully applied to the characterization of different amorphous polymer materials. The outline of the characterization will be described in this contribution.

Chain dynamics in the crystalline region of semicrystalline polymers play an important role for bulk material properties such as mechanical strength, creep, drawability, crystallization process, and crystal transformation. Therefore, it is important to characterize chain dynamics in detail. 2D exchange NMR is a reliable tool for polymer dynamics analysis, because this method provides motional geometry and time-kinetic parameters quantitively. However, it is difficult to apply this sophisticated method for polymers with chemically complicated polymers in natural abundance. ID-MAS exchange NMR method is possible to give the same information, and has a great advantage of characterizing molecular dynamics for multi-functional groups of molecules without isotope labeling. In this contribution, we briefly explain ID-MAS exchange NMR, and their applications to slow dynamics of crystalline polymers with chemically complicated structures in natural abundance. We will show which part of polymer in the crystalline region contributes to mechanical property and what type of motions occur in the unstable crystalline form prior to crystal-crystal transformation.

Solid state ^2H NMR parameters are almost exclusively governed by the quadrupole interaction with electric field gradient (EFG) tensor at the deuteron site [1–3]. The EFG is entirely intramolecular in nature. Thus molecular order and mobility are monitored through the orientation of individual C-^2H bond direction. Therefore, ^2H NMR is a powerful technique of studying local molecular motions. It enables us to discriminate different types of motions and its correlation times over the wide frequency range. The side chain of a polypeptide have remarkable multiple motional freedom about multiple bonds, while the main chain forms the regular secondary conformation such as α-helix and β-sheet which are presumed to be a rigid structure. In this section, we focus on the dynamics of both side- and main-chains of synthetic polypeptides deuterated at several positions by solid state ^2H NMR.

Macroscopic properties of polymer blends are influenced by the degree of mixing among component polymers, that is, microscopic domain structure. The degree of mixing is related to how closely we look at the blend. The lower limitation of a characteristic space scale of a particular observation determines the detectable domain size in a miscible state, and affects the judgment of homogeneity. For most miscible polymer blends, in general, a single homogeneous phase is achieved by an interpolymer interaction and separates to two phases with distinct compositions and becomes heterogeneous when the temperature is beyond a critical point. Solid-state NMR provides very useful information to detect such a microscopic compositional change, especially less than 10–100 nm scale. Here, the interpolymer interaction, miscibility, and phase separation are mainly touched upon.