Use in studies of polymers

Infra-red dichroism has been used in studies of polymer specimens in which the chain molecules are parallel to each other, to give evidence on the orientation of particular atomic groups. In nylon and polyvinyl alcohol (Ambrose, Elliott, and Temple, 1949), Terylene (Miller and Willis, 1953), and polytetrafluoroethylene (Liang and Krimm, 1956) the results are consistent with structures already established by X-ray methods. Turning to more complex structures not yet solved in detail by X-ray methods, infra-red dichroism has indicated that in cellulose... 

The SFM has been used in studies of polymer surfaces. Theoretical calculations (Abraham Batra, 1989 Ovemey, 1993) show that the SFM tip, operating in contact mode, can cause a significant distortion of the electronic and atomic stmcture of the measured materials. The SFM tip is therefore well suited as a micromechanical... 

Fluorescence quenching and NRET belong to popular fluorescence variants that have been exploited in a number of fields, including polymer and biopolymer research. NRET has been used in studies of polymer chain conformations [64-68], polymer miscibility [69-71], etc. Collision quenching, which reflects the accessibility of different quenchers, has been applied for testing the environment of pendant quenchers in polymer and biopolymer structures and associates [72-74]. Because the measurement is relatively simple, both techniques are benchmark fluorescence techniques in polymer science. Therefore, we could not avoid their use and, in spite of a number of review articles on that subject, we will briefly outline our results aimed at polymer self-assembly. 

The concept of the solubility parameter 6, which is frequently used in studies of polymer compatibility, is not always applicable. The solubility parameter is equal to the square root of the substance s cohesion energy density (6 = VDEC) and reflects only intermolecular interaction without accounting for the entropy factor. This parameter is an integral characteristic of only intermolecular interaction, and the components miscibility is determined by the presence of functional groups capable of specific interactions in the polymer molecules. This is why... 

Thermogravimetric analysis (Chapter 2), for example, has been used in studies of polymer degradation, activation energy, phase transitions, and also for the effect of antioxidants on polymer ageing and polymer lifetime studies. Coupling this technique with mass spectrometry (Chapter 3) enables further information to be obtained on the nature of polymer decomposition products, which accompany polymer weight changes. 

Chapter 1 covers experimental techniques widely used in studies of polymer crystalhzation. Chapter 2, Chapter 3, Chapter 4, and Chapter 5 are devoted to the structure of crystalline polymers and also to the kinetics of nucleation and growth of the crystaUine phase. Chapter 6 is focused on molecular modeling of polymer crystallization, whereas Chapter 7 describes overah crystalhzation kinetics, with special reference to the theories widely used in practice. Chapter 8 covers the subject of epitaxy. Chapter 9 is dedicated to melting of polymer crystals. Chapter 10, Chapter 11, and Chapter 13 describe the crystahization in copolymers, miscible and immiscible polymer blends, and also polymer composites. Chapter 12 is focused on phenomena related to the confinement of polymer chains. Chapter 14 describes the effect of flow on crystahization, and finally Chapter 15 covers the crystalhzation in processing conditions. 

Many other surfaces can be investigated by HREELS. As larger molecule and non-single-ciystal examples, we briefly describe the use of HREELS in studies of polymer surfaces. The usefiilness of HREELS specifically in polymer surface science... 

Liquid chromatography (LC) encompasses several techniques, which includes HPLC and SEC (sometimes referred to as GPC). Many variants of and developments from these techniques exist, and are used in the study and analysis of polymer degradation/oxidation. As discussed earlier, SEC is often coupled with MALDI-ToF-MS to facilitate the identification of the products of polymer degradation. SEC has also been coupled with mid-infrared detection and similarly used for studies of polymer degradation. SEC/GPC is discussed further below. 

Turbidity has proven to be especially useful in studies of protein polymerization, where one can demonstrate that the turbidity is directly proportional to the polymer mass concentration. This is illustrated in the following plot (Fig. 1) obtained for assembled microtubules. 

Casassa and Tagami (50) have given a theory for the partition of macromolecules, linear and branched, between a solution and cavities (such as the pores of a GPC gel). They have calculated elution volumes from their results, which agree closely with those derived from the hydrodynamic volume assumption this gives theoretical support to the use of hydrodynamic volume as a correlating parameter for branched polymers. This parameter has been used in studies of branching in polyethylene (Section 10). 

The method was used in studies of a fungal heterogalactan.150 The polysaccharide was subjected to successive tritylation, methylation, detritylation, p-toluenesulfonylation, reaction with sodium iodide, and, finally, reaction with sodium p-toluenesulfinate. The product was then treated with sodium methylsulfinyl carbanion in dimethyl sulfoxide, the product remethylated, and the polysaccharide material recovered by gel chromatography. The polymer was hydrolyzed, and the sugars in the hydrolyzate were analyzed, as the alditol acetates, by g.l.c.-m.s.1 The analysis revealed that —60% of the hexose residues that were unsubstituted at C-6 had been eliminated. As the product was still polymeric, it was concluded that these residues had constituted a part of side chains linked to a main chain of (1 — 6)-linked D-galactose residues. 

The above results are an example of the use of ARUPS in determining some details of polymer—polymer interfaces. To date, very few studies of polymer-polymer interfaces have been reported. As the abilities to obtain ordered polymer systems increase in the coming years, however, techniques such as ARUPS will be more and more useful in studies of such polymer—polymer interfaces73. 

Apart from salivary proteins, other proteins have been used in studies of kind mucin [56], gliadin [49], pl-glycosidase [32, 59], hemoglobin [60], and BSA [24, 35-37, 48, 61-64]. Other proteins have been used because of certain characteristics that make them similar to proline-rich proteins (PRPs), like casein [33, 65], gelatin [42, 49, 65-67], and polyproline [34, 66, 68]. Although it is not a protein, the polymer polyvinylpolypyrrolidone has also been used in these studies [68, 69]. 

A second major area in which the CD observed in a solute-polymer system has proven to be very useful in studies of the interactions has been for the particular instance where the polymer was an oligonucleotide. This area is also characterized by an extremely large literature, so in the present work we will restrict our focus on the CD induced in planar aromatic molecules which may or may not intercalate in the oligonucleotide structure. Perrin and Hart have reviewed the work performed prior to 1970 [67], and the focus of the current review will be on later works. 

Molecular dynamics (MD) simulations provide a detailed description of complex systems in a wide range of time and spatial scales.138 Simulations involve a statistical uncertainty component as the result of the finite length of the simulation.139 143 MD methods generate a series of time-correlated points in phase space by propagating a suitable starting set of coordinates and velocities according to Newton s second equation. This kind of computational simulations are useful in studies of time evolution of a variety of systems biological molecules, polymers, or catalytic materials, and in a variety of states crystal, aqueous solutions, or in the gas phase. 

NMR spectroscopy can be also used in investigations of polymer aggregates in solution, gels etc, i.e. in systems which are between liquids and solids. As an example, studies of the formation and structure of a stereo-complex of poly(methyl methacrylate) (PMMA) by Spevacek and Schneider (1974, 1975) can be mentioned. The formation of ordered associated structures of the stereo-complex upon mixing solutions of isotactic and syndio-tactic PMMA manifests itself by the broadening of all polymer lines and results in disappearance of HR-NMR signals wide-lines then can be detected. 

The analysis of van der Pauw can be used for arbitrary electrode arrangements on thin samples of anisotropic materials of any shape and has been widely used in studies of conjugated polymers, where only small and irregular samples are available. Four electrodes are attached, as shown in Fig. 5.19(d). The resistance values Ry and R2 are measured as for the Montgomery method. The volume resistivity is then calculated from these values as... 

The voltage-step method is, however, analogous to the TOF method and has been used in studies of semiconductive polymers. The theoretical transient current response is similar to that shown in the upper curve in Fig. 8.30(b). It rises from its initial value to a maximum and then falls away to a steady state... 

Polyimide was used as a model material in studies of polymer metal interfaces where metal layers were formed by metallization, plasma deposition, chemical vapor deposition, electrochemical deposition, etc In most of the cases studied, the interpenetration of metal was so good that the metal layer could not be removed by any other means but abrasion. An investigation of interface, determined that the metal particles were found in the surface layers in diminishing quantities perpendicular to the surface and not, as expected, in the form of a sharp borderline between the metal and polymer. Some difficulties exist when metallized polyimides are used for chip production. These diffuse layers of metals complicate design and performance due to the gradients of conductivity which they produce. 

The preceding analysis and review of the literature indicate a need for additional types of experiments to study triplet mobility in polymers. One experiment which has been particularly useful in studies of singlet energy migration in polymers, involves determination of the quenching of donor emission by a known mole fraction of a copolymerized luminescent quencher (26). We have extended this approach to the study of triplet states. The polymers chosen for study are homopolymers of isomeric acetonaphthyl methacrylates (aceto-NMA, 1). A related monomer, 2,4-diaceto-l-naphthyl... 

Since optical spectroscopy is widely and successfully used in studies of many polymerizations involving carbanionic living polymers, the values of Amax and of the respective molar absorbances of typical carbanionic living polymers are collected for the convenience of the reader in Tables 4 and 5. 

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