Poly pristine

Polyacetylene is considered to be the prototypical low band-gap polymer, but its potential uses in device applications have been hampered by its sensitivity to both oxygen and moisture in its pristine and doped states. Poly(thienylene vinylene) 2 has been extensively studied because it shares many of the useful attributes of polyacetylene but shows considerably improved environmental stability. The low band gap of PTV and its derivatives lends itself to potential applications in both its pristine and highly conductive doped state. Furthermore, the vinylene spacers between thiophene units allow substitution on the thiophene ring without disrupting the conjugation along the polymer backbone. 

The evolution of the XPS C(ls), S(2p), and Al(2p) core level lines, upon A1 deposition onto poly(3-octylthiophene) films (P30T), is shown in Figure 5-15 [84. The S(2p) spectrum for the pristine polymer consists of two components, S(2p 1/2) and S(2p.v2), due to spin-orbit coupling. 

The XPS S(2p) core level spectra recorded during the stepwise deposition of copper onto poly(3-hcxyllhiophenc), or P3HT [88] are shown in Figure 5-17. The S(2p) spectrum at the lop correspond to the pristine system. On increasim copper... 

Poly(styrene-fc-butadiene) copolymer-clay nanocomposites were prepared from dioctadecyldimethyl ammonium-exchanged MMT via direct melt intercalation [91]. While the identical mixing of copolymer with pristine montmorillonite showed no intercalation, the organoclay expanded from 41 to 46 A, indicating a monolayer intercalation. The nanocomposites showed an increase in storage modulus with increasing loading. In addition, the Tg for the polystyrene block domain increased with clay content, whereas the polybutadiene block Tg remained nearly constant. 

Fig. 67 Schematic of phase behaviour for blend of novolac epoxy resin with nearly symmetric poly(methyl acrylate-co-glycidylmelhacrylate)-0-polyisoprene. Ordered L can be swollen with up to about 30% of resin before macroscopic phase separation occurs, producing heterogeneous morphologies containing various amounts of L, C, worm-like micelles and pristine epoxy. At lower concentrations, disordered worm-like micelles transform into vesicles in dilute limit. According to [201]. Copyright 2003 Wiley...

The pristine and doped poly-phenylene sulfide may be used for light energy conversion to the electrical one. The efficiency coefficient is of the order 0.01-0.2% for various lightwaves, fill factor 0.07-0.20. The characteristics are better than ones for doped TNF PVC. 

The amorphous poly(541), poly(540), and poly(539) pristine films exhibited structureless absorption bands at 416, 423, and 438 nm, respectively, which are significantly blue shifted compared with the lowest vibrational band of P3HT ( 640 nm) (04MM6306 07AM833 08JA3030). On the other hand, the more crystalline poly(543), poly (542), poly(545), and poly(544) pristine films exhibited more structured, red-shifted absorption bands with a shoulder or a vibrational band corresponding to the lowest vibronic transition at 635, 612, 633, and 640 nm, respectively, which is more comparable to that of... 

Poly(541) pristine films of this polymer exhibited a photoinduced transient absorption band at around 700 nm. The transient signal decayed monoexponentially with a lifetime of 7 (is under Ar atmosphere, accelerating to 1.5 (is under O2 atmosphere. These transient bands are assigned to Ti > T transitions of polymer triplet excitons (3P ) formed in the amorphous polymer pristine films. 

The poly(542) pristine film, representative of the more crystalline polymers, exhibited a broader transient photoinduced absorption band around 900-1000 nm. This transient optical density decayed rapidly on the... 

The inclusion of 5 wt% PCBM [l-(3-methoxycarbonyl)propyl-l-phe-nyl-[6,6]C6i] in the spin-coating solutions resulted in efficient polymer emission quenching for all the polythiophenes studied. The transient absorption spectra of the amorphous poly(541)/PCBM blend film. At 10 ps exhibited an absorption peak around 700 nm, similar to that observed for the poly(541) pristine film. The shape of the transient spectrum varied with time, with the absorption peak shifting from 700 nm at 10 is to 900 nm for time delays >100 (is, demonstrating the formation of two distinct transient species in the blend film. The monoexponential lifetime was t = 8 (is under Ar atmosphere and significantly shortened under 02 atmosphere. Monoexponential phase is therefore assigned to the decay of poly(541) triplet excitons. 

Monomer 44a was also found to electropolymerize on indium-tin-oxide (ITO) under potential-sweep conditions (Figure 33). The resulting film poly-44a) can be electrically doped by oxidation, as was demonstrated by UV/Vis spectroelectrochem-istry (oxidative dotation leads to a broad absorption band beyond 1000 nm). We found that on irradiation with a 500 W incandescent lamp the pristine film (at 0 mV vs. Ag/AgCl) gave rise to the formation of the VHF form poly-44b). Under thermal conditions, the DHA spectrum could be restored (Figure 34). 

Table 2 Relative3 Peak Areas 5 of the Fragments Observed for the Low (a) and High ((3) Temperature Features in the Temperature Programmed Desorption of PC-d6 Adsorbed on Pristine Au(poly) at ca. 120 K...

Several organics, e.g. pristine poly(3-octylthiophene), polyfluorene, bifunctional spiro compounds and polyphenyleneethynylene derivative, have been used for fabricating photOFETs. Responsivity as high as 0.5-1 A/W has been achieved in some of these transistors. We have already discussed the bulk heterojunction concept in Chapter 5. The bulk heterojunctions are fabricated using acceptor materials with high electron affinity (such as C<5o or soluble derivatives of C6o) mixed with conjugated polymers as electron donors. PhotOFETs based on conjugated polymer/fullerene blends are expected to show... 

As was mentioned above, conjugated organic polymers in their pristine state, are electrical insulators or, at best, semi-conductors. Their conductivity can be increased by orders of magnitude by a doping process. In the "doped" state, the backbone of a conducting polymer consists of a delocalised 7i-system. Early in the twenty-first century Schon et al. (2001) discovered super-conduction in solution cast doped regioregular poly(3-hexylthio-phene) at temperatures below 2.35 K The appearance of superconductivity seems to be... 

Numerous other studies on the nanotube nanocomposites have been reported which demonstrate other properties like optical, morphological, fiber surface properties etc. Saini et al. (52) measured the UV absorption spectra of the poly(3-hexylthiophene) (P3HT) and its nanocomposites with varying amounts of nanotubes. The absorption band for pristine P3HT was observed at 505 nm which shifts toward the higher wavelength region on the addition of nanotubes... 

Poly(ethylene)/ZCHS nanocomposites were prepared via melt blending using established methods (7). Poly(ethylene) nanocomposites were prepared by mixing x g of the additive with (100- x g) of pristine poly(ethylene) to achieve x % mass fractions. Melt blending was then performed on a Brabender mixer for 10 minutes at a temperature of about 130°C and speed of 60 rpm. The prepared nanocomposites are identified as PE/ZCHS-5 and PE/ZCHS-10 for 5% and 10% loadings respectively. A reference sample of pure poly(ethylene) was prepared by following the same procedure in the absence of additive. 

The utility of classical antioxidants such as hindered amines, phenols, and nitrones for the stabilization of pristine polyacetylene (29), poly(methyl acetylene) (30), and poly(l,6-heptadiyne) (31) has been examined. Poly(methyl acetylene), although dopable to only low conductivities (10" S/cm), has similar oxidative behavior to polyacetylene and serves as a good model for other polyenes. In general, the improvement in stability of poly(methyl acetylene) was limited, but combinations of hindered phenols and hydroperoxide scavengers resulted in a factor of 5 decrease in the oxidation rate (30) as monitored by the appearance of IR absorption bands attributable to carbonyl groups. These degradation rates are still too high for the use of these polyenes in an unprotected environment. The compatibility of such stabilizers with the dopants commonly used for polyacetylene was not studied. 

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