Poly spectroscopic studies

Formaldehyde is produced and sold as water solutions containing variable amounts of methanol. These solutions are complex equiUbrium mixtures of methylene glycol, CH2(OH)2, poly(oxymethylene glycols), and hemiformals of these glycols. Ultraviolet spectroscopic studies (13—15) iadicate that even ia highly concentrated solutions the content of unhydrated HCHO is <0.04 wt%. 

It is difficult to establish the degree of polymerisation of materials (61) due to their insolubility, which prevents GPC analysis and standard spectroscopic studies. The important bathochromic shift of the Aonset observed in the series (34a) (496 nm)/(62) (600 nm) (Scheme 18)/poly(34a) (754 nm), suggests that (61) are oligomers. Note that electropolymerisation of monomers (40a) and... 

Crisp, S., Prosser, H. J. Wilson, A. D. (1976). An infra-red spectroscopic study of cement formation between metal oxides and aqueous solutions of poly(acrylic acid). Journal of Materials Science, 11, 36-48. 

The mechanism of anodic oxidation of CO at polycrystalline Au remains uncertain. Several groups have reported that the voltammetry of Au in acidic electrolytes is straightforward, with a well-formed oxidation wave/peak [Stonehart, 1966 Gibbs et al., 1977 Kita et al., 1985 Sun et al., 1999]. There is, however, no voltammetric evidence for the adsorption of CO on the Au surface, and spectroscopic studies indicate only a weak interaction of CO with poly crystalline Au surfaces in acidic solutions [Kunimatsu et al., 1986 Cuesta et al., 2003]. Moreover, there is little evidence for the formation of oxidizing species at the potential where the oxidation process is observed. Certainly, the oxidation of CO occurs at a potential over 500 mV less positive than that where bulk Au oxide is formed, and, indeed, the formation of this oxide strongly... 

The recent interest in substituted silane polymers has resulted in a number of theoretical (15-19) and spectroscopic (19-21) studies. Most of the theoretical studies have assumed an all-trans planar zig-zag backbone conformation for computational simplicity. However, early PES studies of a number of short chain silicon catenates strongly suggested that the electronic properties may also depend on the conformation of the silicon backbone (22). This was recently confirmed by spectroscopic studies of poly(di-n-hexylsilane) in the solid state (23-26). Complementary studies in solution have suggested that conformational changes in the polysilane backbone may also be responsible for the unusual thermochromic behavior of many derivatives (27,28). In order to avoid the additional complexities associated with this thermochromism and possible aggregation effects at low temperatures, we have limited this report to polymer solutions at room temperature. 

Sealants obtained by curing polysulfide liquid polymers with aryl bis(nitrile oxides) possess stmctural feature of thiohydroximic acid ester. These materials exhibit poor thermal stability when heated at 60°C they soften within days and liquefy in 3 weeks. Products obtained with excess nitrile oxide degrade faster than those produced with equimolar amounts of reagents. Spectroscopic studies demonstrate that, after an initial rapid addition between nitrile oxide and thiol, a second slower reaction occurs which consumes additional nitrile oxide. Thiohydroximic acid derivatives have been shown to react with nitrile oxides at ambient temperature to form 1,2,4-oxadiazole 4-oxides and alkyl thiol. In the case of a polysulfide sealant, the rupture of a C-S bond to form the thiol involves cleavage of the polymer backbone. Continuation of the process leads to degradation of the sealant. These observations have been supported by thermal analysis studies on the poly sulfide sealants and model polymers (511). 

Sakamoto A, Nakamura O, Tasumi M (2008) Picosecond time-resolved polarized infrared spectroscopic study of photoexcited states and their dynamics in oriented poly(p-phenylene-vinylene). J Phys Chem B 112 16437... 

The high rigidity of the catenane segments has been demonstrated by a temperature-dependent NMR spectroscopic study of the catenane monomers 44 and 46 [37, 52], Almost no temperature dependence was observed for the line shape of the spectra of the catenane monomers 44 and 46 whereas the temperature had a dramatic influence on the spectra of the unmethylated catenanes 41b,d and 42b,d [30, 37, 52, 56]. Therefore, the poly[2]catenanes 48 and 49 represent one extreme case where there is very little relative mobility of the macrocycles of the catenane segments. 

This is consistent with the relative ease of dissociation of poly(styryl)lithium in the presence of bases and also with the concentration dependence of enthalpy versus R plot (Fig. 4) with a break observed at an R value of ca. 1.0. These calorimetric results are also in agreement with the stoichiometric dependencies observed by Helary and Fontanille 92> from their kinetic and spectroscopic studies. For example, they reported that the UV wavelength of maximum absorption of poly(styryl)lithium shifted upon additions of TMEDA until an R value of 1.0 and then was constant. They also observed that TMEDA additions increased or decreased the rate of polymerization, depending on [PSLi] the increase or decrease in the rate leveled off at an R value of ca. 1.0. All... 

Homopolypeptides provide useful secondary structural models for spectroscopic studies on proteins and the ROA spectra of poly(L-lysine) in the three most important conformers are shown in Fig. 7.4. Poly(L-lysine) at alkaline pH... 

Journal of Applied Polymer Science 71, No.l, 3rd Jan. 1999, p.1-6 MICROWAVE PLASMA REACTIONS OF IMIDAZOLE ON POLY(VINYL CHLORIDE) SURFACES A SPECTROSCOPIC STUDY Schmitt B R Heung Kim Urban M W North Dakota State University... 

Anomalous Conformational Behavior of Short Poly(oxyethylene) Chains in Water An FT>IR Spectroscopic Study... 

Bulkin BJ, Lewin M, DeBlase EJ (1985) Conformational change, chain orientation, and crystallinity in poly (ethylene terapthalate) yams Raman spectroscopic study. Macromolecules 18 2587-2594... 

BLOOR Structural and Spectroscopic Studies of Poly diacetylenes... 

Kijima, M. Kinoshita, L Shirakawa, H. Spectroscopic study of soluble poly(2,5-dialkoxy-l,4-phenylene-alt-oligoethynylene)s. 5. Mol. Struct. 2000, 527, 279-283. 

Ohe C, Goto Y, Noi M, Arai M, Kamijo H, Itoh K (2007) Sum frequency generation spectroscopic studies on phase transitions of phospholipid monolayers containing poly(ethylene oxide) lipids at the air-water interface. J Phys Chem Bill 1693-1700... 

Cha H. J., Izumi T., Kokufuta E., Franck C. W. Spectroscopic studies of papain complexation with potassium poly(vinyl alcohol sulphate) ACS Polym. Preprints 1992 33 872-873. 

Li Y, Tanaka T (1990) Kinetics of swelling and shrinking of gels. J Chem Phys 92 1365-1371 Maeda Y (2001) IR spectroscopic study on the hydration and the phase transition of poly(vinyl methyl ether) in water. Langmuir 17 1737-1742... 

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