Spectra of monomers and

The n.m.r. spectra of monomers and dimers of glycosaminoglycans have been recorded in solutions of ( H ldimethyl sulphoxide the NH- and OH-resonances were partially assigned.The temperature-dependence of the spectra suggests hydrogen bonding to the solvent with the exception of the C-4... 

UV/VIS-absorption spectra of monomer and polymer Circular dichroism of polymer Differential scanning calorimetry... 

Nicolet Instrument Corp. (Madison, WI), 15000 spectra of conunon chemical compounds Sadtler (BioRad Laboratories, Cambridge, MA), 1650 spectra of monomers and polymers AIST/STJ (Japan), 735 polymers and polymer additives and 125 dyes and pigments. 

A comparative analysis of the IR spectra of monomers under study and known model compounds (tetraalkylstannanes and unsaturated oxiranes) indicates corresponding shifts of absorption bands for the oxirane ring and the Sn—C bond. 

For NMR spectroscopic experiments, a thin film of pTrMPTrA was prepared by reacting a quantity of monomer and photoinitiator confined between glass plates with 1 mm separation. The polymerization conditions were the same as those for the photocalorimetry experiments. After 1 hour of UV exposure, the film was removed from the plates and ground to a fine powder using a mortar and pestle. A solid-state 13C NMR spectrum of the powder was obtained immediately, as described below. The remaining polymer powder was divided into two portions, one of which was stored under atmospheric conditions. The other portion was stored under N2. After one week, 13c spectra were again obtained for each of these polymer samples. Both samples were then heated to 280 °C in a vacuum oven and analyzed once more by 13C NMR spectroscopy. 

As for the homopolymers, dilute solution (1 x 10-4 M in toluene, isooctane or THF) spectroscopic studies were carried out over the temperature range of —70 to +80°C. The CD spectrum of 54 (Figure 4.39), containing 50% p-(S)-2-methylbutylphenyl-substituted monomer units, exhibits a positively signed Cotton effect (389 nm), almost coincident with the lowest energy main-chain electronic transition (or-or ) in the 20°C UV spectrum (394 nm). The CD spectra of 53 and 55 show similar features to that of 54, and the similarity... 

Fig. 2 Schematic representation of characteristic absorption (A) and fluorescence (F) spectra of H- and J-aggregates (marked as H and J, respectively) as compared to those of the monomer molecule (M). The dashed spectrum FH means that H-aggregates could be nonfluorescent...

Careful 1H and 13C NMR analyses were carried out for both monomers and polymers in order to prove the chemical structures of the polymers. The H NMR spectra of 50 and 52 are shown in Figure 8. As polymerization proceeded, an acetylenic proton peak at 2.0-2.2 ppm disappeared, while a new vinylic proton peak appeared broadly in the 6.8-7.2 ppm range. Since the new peak is weaker than those for the aromatic biphenyl rings and the two peaks are superimposed, it is hard to separate them clearly. The broad peaks at 2.6 and 3.4 ppm are assignable to the methylene protons and methine proton in the ring, respectively. 

Figure 9 exhibits the 13C NMR spectra of 50 and 52. The monomer has acetylenic carbon peaks at 70 and 82 ppm, but 52 does not show these peaks. Instead, the olefinic carbon peaks of the 52 backbone appear at 123 and 141 ppm, although the value for the quaternary carbon is very weak. The peak of the methylene carbon adjacent to the polymer backbone is shifted from 20 to 43 ppm on polymerization. 

Figure 4 shows the triplet EPR spectra of ZnTCP and [ZnTCP]2 recorded at 10 E (12). The spectra reflect the absence of axial symmetry (D s 3E) which is attributed to a Jahn-Teller effect (24). [ZnTCPl2 formation has little or no effect on D whereas the value of E is strongly reduced (cf. Table IT). By contrast, triplet EPR spectra of [ZnTPPS/ZnTTAP] (13) and [ZnTPPS]2 (11) show no evidence of a dimerization effect on E. In the case of ZnTPPS dimerization leads to a reduction in D (11). As is illustrated in Figure S, the triplet EPR spectrum of [ZnTPPS/ZnTTAP] is virtually indistinguishable from the spectra of the monomer precursors. 

Schaefer and Natusch have shown that for many synthetic high polymers in solution the NOE factors and relaxation times of carbon atoms in or near the main chains eire similcir (.2. In such cases the relative peak areas in the spectra obtained by the noise-decoupled and fast pulsing technique can be used as a good approximation for quantitative microstructure euialysis. However for our investigation of the polymerization of cyclic ethers we are frequently interested in the quantitative measurements of monomers and oligomers as well as the concentrations of the continuously growing polymeric species. Therefore, the assumption of Schaefer and Natusch is not applicable. 

Fig. 2 UV-Vis spectra of monomers EDOT and pyrrole, and polymers PEDOT, polypyrrole and PEDOT-co-polypyrrole. (Reprinted with permission from Bruno et al. [37]. 2006, American Chemical Society)...

Polymerization Kinetics and Cure Studies [2,4,25] Infrared spectra of monomers differ markedly from spectra of the polymers [2], As a consequence, it is possible to use infrared spectroscopy to follow the course of polymerization reactions and to simultaneously analyze the structure of the polymer [2]. 

A crystallographic study of MeZnS2CNEt2 (40) revealed that in the crystal phase, this complex exists in the dimeric [MeZnS2CNEt2]2 form. Unfortunately, no clear conclusion could be drawn about the structure of this compound in either the solution or the gas phase. Mass spectra of 40 and related compounds MeZnS2CNMe2 (41) and EtZnS2CNMe2 (42) contained peaks attributed to the M+ of the monomers and to the [Zn(dialkyldithiocarbamate)2] + ions". ... 

The chemical structure on the left shows one half of the (symmetrical) monomer in the top half and a possible curing structure with piperidine (bottom half) in the aromatic region. In the amorphous phase much of this detail is smoothed out, presumably by the distribution of molecular environments leading to a distribution of isotropic chemical shifts. The spectra of amorphous and polymerized phases are quite similar in the aromatic region 691... 

Figure 6.4 Variation in intensity of monomer and excimer emission spectra with concentration.

FIGURE 7. Absorption and emission spectra of polymer and monomer la in DMAc. 

Spectra of Monomeric Surfactant Solutions. The next step was to study alkyldimethylamine oxides having methylene chains of sufficient length such that the molecule is surface active. The FT-IR spectra of monomer solutions of CgAO at various degrees of protonation (Z) are shown in Figure 3. These spectra are much more complex than those of C AO due to the introduction of deformation modes of the CH2 and the terminal CH3 groups. 

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