Poly properties, third-order

The platinum poly-ynes show attractive physical properties, third-order optical non-linearity [107-109] and the formation of lyotropic liquid crystalline... 

LB films of CO-tricosenoic acid, CH2=CH—(CH2)2qCOOH, have been studied as electron photoresists (26—28). A resolution better than 50 nm could be achieved. Diacetylenic fatty acids have been polymerized to yield the corresponding poly (diacetylene) derivatives that have interesting third-order nonlinear optical properties (29). 

Third-order nonlinear optical properties of oriented poly(arylenevinylene) LB films... 

The area of molecular nonlinear optics has been rejuvenated by efforts to investigate three-dimensional multipolar systems, functionalized polymers as optoelectronic materials, near infrared optical parametric oscillators and related aspects.71 There have been some advances in chromophore design for second-order nonlinear optical materials 72 these include onedimensional CT molecules, octopolar compounds and organometallics. Some of the polydiacetylenes and poly(/>-phenylenevinylene)s appear to possess the required properties for use as third-order nonlinear optical materials for photonic switching.73... 

Conjugated polymers satisfy these requirements and have thus emerged as the most widely studied materials for their susceptability. Some of the examples of conjugated polymers, that have been studied for their third order NLO properties, are polydiacetylenes, poly-p-phenylenevinylenes and polythiophenes. However, CVD has only been used in the case of poly-p-phenylenevinylenes (PPV) [section 3.4], although values have not been reported. An excellent review of third order nonlinear optical properties of PPV in general, can be found in literature. Recently, McElvain et al. ° reported the values of CVD polyazomethines to be... 

Enzymatically synthesized polyphenol derivatives are expected to have great potential for electronic applications. The surface resistivity of poly(p-phe-nylphenol) doped with nitrosylhexafluorophosphate was around 105 Q.4a The iodine-labeled poly(catechol) showed low electrical conductivity in the range from 10 6 to 10 9 S/cm.48 The iodine-doped thin film of poly (phenol- co- tetradecyloxyphenol) showed a conductivity of 10 2 S/cm, which was much larger than that obtained in aqueous 1,4-dioxane.24a The third-order optical nonlinearity (%3) of this film was 10 9 esu. An order of magnitude increase in the third-order nonlinear optical properties was observed in comparison with that prepared in the aqueous organic solution. 

Poly(ferrocenylene vinylene) derivatives 68 with values of 3,000-10,000 and polydispersities of ca. 2.2-2.8 (determined by GPG) were synthesized in 1995 in high yields via a titanium-induced McMurry coupling reaction of the corresponding alkylferrocenyl carbaldehyde monomers (Equation (26)). " Gharacterization of these soluble polymers by NMR and IR revealed the presence of trans-Yinylcnc units. The UV-VIS spectra of the polymers are similar to those of the monomers and this indicates a fairly localized electronic structure in the former. The relatively limited electron localization is also reflected in the electrical and optical properties. For example, the values for iodine-doped conductivity a= 10 Scm ) and non-linear third-order optical susceptibility (x = 1-4 x 10 esu) are lower than those of linear conjugated polymers such as poly(l,4-phenylene-vinylene) (a = 2.5x 10 Scm" = 8 X 10 esu). 

Lu et al. have obtained poly(amic acid) side-chain polymers by polycondensation of benzoguanamine and pyromellitic dianhydride under microwave irradiation conditions [65-67]. The reactions were performed in a household microwave oven in which 100 mL DMF solution of 33 mmol benzoguanamine and an equimolar amount of pyromellitic dianhydride were stirred and irradiated for 1 h at 60 °C (Scheme 14.31). The resulting poly(amic acid) was precipitated from the solution and then modified to obtain side-chain polymers with fluorescent and third-order NLO properties. 

The intensity of the DFWM signal for the poly(l,6-heptadiyne)s increased linearly with intensity of the incident beam, as shown in Figure 10. From the direct comparison between the intercepts of the V axis of the polymers and the carbon disulfide reference. the values of the polymers were obtained. And also, as the concentration of the polymer solution was increased, the values of the polymers were increased (Figure 11). The third-order nonlinear optical properties were enhanced with an increase in the bulk of the substituents at the 4-position, which is in accord with the bathochromic shift of Amax in the UV—vis spectra. From these results, it was concluded that the incorporation of bulky substituents into the 4-position of 1,6-heptadiynes enforces the TT-conjugated polyene into the more planar conformation. resulting in a red shift and the increment of the values of the polymers. Recently, Schrock... 

The polymers having delocalized r-electron in the main chain have been expected to possess extremely large third-order optical susceptibility.However, such an extended jr-electron conjugation generally rendered the polymers insoluble and infusible as well, which has seriously limited the fabrication of practical NLO devices. Recently, it was reported that the third-order nonlinear optical properties of poly(l,6-heptadiyne)s which were environmentally stable, soluble, and processable. The third-order optical nonlinearities of poly(l,6-heptadiyne)s bearing NLO active chomophores were evaluated for the first time. The third-order nonlinear susceptibility... 

Solution properties indicate that the metal-poly(yne)s exist in a rod-like structure. They display lyotropic nematic mesophases [30] and form crystallites with a diameter of up to 50 nm [31]. Absorption and luminescence spectra of the polymers show that 7t-electron conjugation is expanded over the whole polymer chain, and third-order non-linear optical properties are exhibited. For polymer 7 good photocurrents were found in sandwich-diodes. 

B. P. Singh, P. N. Prasad, F. E. Karasz, Third-Order Non-hnear Optical Properties of Oriented Films of Poly(p-Phenylene Vinylene) Investigated by Femtosecond Degenerate Four Wave Mixing. Polymer 1988,29,1940-1942. 

Nonlinear optical properties of PTs which exhibit ultrafast responses and large nonlinearities attributed to one-dimensionality and delocalization of n-electrons along the polymer chains are also described [403,404]. Poly(4,4 -dipentoxy-2,2 -bithiophene) and poly(4,4 -dipentoxy-2,2 5, 2"-terthiophene) show a fast and high third-order nonlinearity [405]. Third-order nonlinearities depend on the nature of the polymer backbone and only slightly on the substituents [406], The optical transparency and the third-order optical nonlinearities can be tailored in random copolymers of 3-methylthiophene and methyl methacrylate [407]. A solution-processable thiophene copolymer with a side... 

J.-I. Lee, H.-K. Shim, G. J. Lee, and D. Kim, Synthesis of poly(2-methoxy-5-methyl-l,4-phenylene-vinylene) and its poly(l, 4-phenylenevinylene) copolymers electrical and third-order nonlinear optical properties. Macromolecules 28 4615 (1995). 

Arylene vinylene polymers, such as poIy(p-phenylene-vinylene) (PPV) and poly(2,5-thienyleneviryIene) (PTV) have been studied extensively over the past 10 years due to the relative ease of producing high quality thin films via the soluble precursor route [48-52]. PPVs in particular have been shown to be true multifunctional materials, displaying enhanced third-order NLO properties as well as applications as light-emitting diodes [53,54]. PPV pre-... 

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