Copolymers photoconductive

In order to obtain the desired photoconductive characteristics, toughness and adherence to the substrate it is usual to incorporate additives such as electron acceptors, plasticisers and primers. A typical electron acceptor is 2,4,7-trinitro-fluoronone, plasticisers include benzyltetraline and phenanthrene whilst as primers styrene-butadiene block copolymers (30-35% styrene) and styrene-maleic anhydride copolymers (5-30% maleic anhydride) are of use. 

On the other hand, the photoconductivity of a poly(vinyl chloride) copolymer and of sucrose benzoate each containing the leucobase of malachite green was characteristic of the dyestuff and independent of the polymeric host (137). This is similar to the behavior of conventional impurity semiconductors. However, a distinction must be drawn between an impurity which acts solely as an impurity providing an easier path to the conduction band, one which acts only as a plasticizer and one which may act as both impurity and plasticizer. 

These and similar copolymers exhibited photoconductivity in the visible region. The copolymer of N-vinylcarbazole with dinitrobenzoyl groups showed better photoresponse than PVK doped with chloranil158). 

The rationale for preparing this hybrid copolymer was to combine the desirable properties of polyaniline with those of polythiophene. For example, polythiophene has demonstrated thermo- and electrochromism, solvatochromism, luminescence, and photoconductivity while polyaniline has demonstrated reversible protonic dupability, excellent redox re-cyclability, and chemical stability. 

Loutfy et al. (1983) measured the photoconductivity of a series of squaraines dispersed in a styrene butylmethacrylate copolymer. The generation efficiencies were strongly field dependent. In most materials, a quadratic field dependence was observed. For MSQ, the results were in agreement with Tam. At high fields, the efficiency was approximately 0.70. 

The following photoconductive polymers can also be clarified as polymers of aromatic amines poly(N-vinylphenothiazine) and poly(N-vinylphenoxazine ° and poly(N-acrylodibenzazepine) ° Poly(N-vinylcarbazole) is basically a modified vinyldiphenylamine polymer . It has yet to be detemined if the transport characteristics of PVK with the diphenyl amino group forced into planarity are different from those of poly(N-vinyldiphenylamine) which would possess a greater freedom of rotation. The properties of PVK have been discussed in many articles and reviews [for example see Ref. ]. Several articles and patents have been published recently which deal with carbazole containing polymers other than PVK, and copolymers of N-vinylcarbazole with some other monomers. 

A photoconductive copolymer containing ca. 10 mol-% of V-vinylphthal-imide and the rest NVK can be prepared by free radical pol5mierization using AIBN in benzene solution. The polymer is precipitated by hexane, then purified by dissolution in a benzene/THF mixture, and then re-precip-itated from hexane. This process is repeated several times. The number average molecular weight of such a copolymer is in the range of 100,000 Dalton. ... 

The copolymers can be formed into photoconductive films useful in electrophotography by simple solvent casting and coating techniques. Typical solvents are THF and mixtures of toluene/cyclohexanone. The film thickness can be controlled by adjustment of the viscosity of the coating solution. 

Emission spectra upon the direct excitation of the 4-tert-butyl-benzoate moiety demonstrate that the benzoate group provides a highly efficient energy transfer to the carbazole groups. This fact suggests that the benzoate groups act as a photosensitizer in the photoconduction processes of the copolymers. 

Photoconductive Lithographic Printing Plate Assembly. NVK has been copolymerized with olefinic monomers possessing carboxylic acid, such as acrylic acid, methacrylic acid, fumaric acid, and, maleic anhydride, or carboxylic anhydride [7]. The acid functionality yields copolymers that are soluble in aqueous alkaline media. The copolymers are intended... 

Photoconductive polymers and copolymers were also synthesized by Haque et al. [249] from 2-(9-carbazolyl)-l-propenyl vinyl ether ... 

The material, however, did not turn out to be photoconductive. The photo-conductivity of copolymers was also investigated. Copolyacrylates with pendant donor and acceptor chromophores. 

The film prepared from the block copolymer is photoconductive suitable for apphcations in photovoltaic or electronic devices [164]. Similarly, random copolymers with similar donor and acceptor groups have also been disclosed [165]. Structures obtained from self-assembly possesses in selective solvents can be fixed by covalent linkages and the resulting nano-scaled materials conserve their structural identity also in nonselective solvents. Several synthetic... 

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