Nonlinear optical properties copolymers

Nonlinear Optical Properties of COD/COT Copolymers and Polv-RCOTs... 

The third order nonlinear optical properties of monomers, polymers and copolymers were measured by DFWM in solution. The solutions of these materials were prepared in a solvent mixture of dimethyl formamide and methanol in the ratio 4 1 (v/v) at a concentration of 0.1% (w/v). The solvent mixture DMF MeOH (4 1) was used as a control. Measurements under identical conditions were made with carbon disulfide as the reference standard and this compound has a reported x value of 6.8 x 10 i3 esu (19). The schematic of the experimental setup is shown in Figure 2. 

Nonlinear optical properties of homopolymers and copolymers synthesized by enzyme-catalyzed reactions in monophasic media are given in Table 2. Aromatic monomers used for the polymerizations are aniline, aniline derivatives, and phenol derivatives. The table also gives x values of a number of monomers (used in the polymerization reactions) and solvent mixtures used to prepare polymer solutions for the measurements. In general, the third-order susceptibilities of all monomers and solvents tested are very low and are in the neighborhood of 10" esu. The values of the aromatic polymers obtained are three to five orders higher than the values of the monomers. Third-order nonlinear susceptibilities of homopolymers synthesized (by enzyme-catalyzed reactions) from aromatic amines such as aniline, benzidine, ethylaniline, propylaniline, butylaniline, and dimethy-... 

Table 3 gives the third-order nonlinear optical properties of bioengineered polymers prepared by enzyme-catalyzed polymerization using horseradish peroxidase in biphasic solvent systems. Water-immiscible solvents used for the biphasic media are benzene, chloroform, toluene, tetrahydrofuran, and isooctane. Third-order nonlinear optical properties of homopolymers and copolymers prepared in biphasic solvent systems are similar to those of polymers prepared in monophasic systems. The values of polyaromatic amines solutions measured at 532 nm are one to two orders higher than the x values observed with polyphenolic compounds. Third-order nonlinear optical properties of copolymers of aromatic amines with... 

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... 

The brief presents a systematic study of synthesis of optically active polymers. It discusses in detail about the syntheses of three different types of optically active polymers from helical polymers, dendronized polymers and other types of polymeric compounds. The brief also explains the syntheses of optically active azoaromatic and carbazole containing azoaromatic polymers and copolymers optically active benzodithiophene and optically active porphyrin derivatives. The final chapter of the brief discusses different properties of optically active polymers such as nonlinear optical properties, chiroptical properties, vapochromic behavior, absorption and emission properties, fabrication and photochromic properties. The intrinsic details of different properties of optically active polymers will be useful for researchers and industry personnel, who are actively engaged in application oriented investigations. 

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). 

The supramolecular structure of block co-polymers allows the design of useful materials properties such as polarity leading to potential applications as second-order nonlinear optical materials, as well as piezo-, pyro-, and ferroelectricity. It is possible to prepare polar superlattices by mixing (blending) a 1 1 ratio of a polystyrene)-6-poly(butadiene)-6-poly-(tert-butyl methacrylate) triblock copolymer (SBT) and a poly (styrene)-Apoly (tert-butyl methacrylate) diblock copolymer (st). The result is a polar, lamellar material with a domain spacing of about 60 nm, Figure 14.10. 

The nonlinear optical (NLO) susceptibilities of bioengineered aromatic polymers synthesized by enzyme-catalyzed reactions are given in Tables 2, 3, and 4. Homopolymers and copolymers are synthesized by enzyme-catalyzed reactions from aromatic monomers such as phenols and aromatic amines and their alkyl-substituted derivatives. The third-order nonlinear optical measurements are carried out in solutions at a concentration of 1 mg/mL of the solvent. Unless otherwise indicated, most of the polymers are solubilized in a solvent mixture of dimethyl formamide and methanol (DMF-MeOH) or dimethyl sulfoxide and methanol (DMSO-MeOH), both in a 4 1 ratio. These solvent mixtures are selected on the basis of their optical properties at 532 nm (where all the NLO measurements reported here are carried out), such as low noise and optical absorption, and solubility of the bioengineered polymers in the solvent system selected. To reduce light scattering, the polymer solutions are filtered to remove undissolved materials, the polymer concentrations are corrected for the final x calculations, and x values are extrapolated to the pure sample based on the concentrations of NLO materials in the solvent used. Other details of the experimental setup and calculations used to determine third-order nonlinear susceptibilities were given earlier and described in earlier publications [5,6,9,17-19]. 

As pointed out already in Section 2.5.5, low-molecular weight ferroelectric liquid crystals (FLCs) and FLCPs are attracting a lot of interest because of their potential for electro-optical applications. The polymers offer new possibilities, e.g., as elastomers for piezoelectric elements or by copolymerization [77, 78, 105] due to the formation of intrinsic mixtures between SmC mesogenic units and other comonomers. This leads to FLCPs combining several material properties which might be utilized for colored displays in the case of comonomers containing chromophores. For the differentiated evaluation of such copolymers with reference to the possible exploitation of nonlinear optical (NLO) properties, the interplay of the different orientation tendencies of the side-chain functionalities is of crucial importance [36,106]. 

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