摘要:

The orientation of chromophores (dipoles), introduced into polymer matrices covalently or dispersed molecularly, under the electric field (poling), has been discussed from thein situobservation of optical absorbance. The second harmonic generation of these polymer systems has also been observed. From depoling dynamics measurement, it is suggested that the orientational relaxation of chromophores due to thermal motion can be suppressed by the introduction of covalent bonding into the side chain, not the molecularly dispersion into the polymer matrix.

ISSN:1058-725X    

DOI:10.1080/10587259308032474

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This article provides a review on the experimental aspects of the alignment of nematic liquid crystal (NLC) in the pretilted homogeneous form in the sandwich cells; most of the contents of this paper are the results of research done by the authors in these few years. For simplicity and convenience, we used nematic liquid crystal (5CB) only; however, we have explored several polymer orientation films such as alkylbranched or alkylbranchless polyimide (PI), PI-Langmuir-Blodgett (LB) films, and those of polypyrrole. All these films were rubbed prior to assemble the cells except for some cases of PI-LB films. These films were characterized in terms of the atomic force microscope (AFM) observation and the optical retardation that are induced by the rubbing or unidirectional pulling up of the substrates in the LB process. Aligning capabilities of these orientation films for 5CB have been evaluated in terms of the texture of the NLC media, generation of pretilt angles, and temperature dependence of the anchoring strength (energies). Some results of this investigation is thought to partially contribute to provide several practical techniques for LCD technologies and to have some understanding the complicated surface anchoring phenomena.

ISSN:1058-725X    

DOI:10.1080/10587259308032475

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Novel sol-gel processed poly(l,4-phenylene vinylene) (PPV) and poly(2,5-disubstituted-l,4-phenylene vinylene)/silica composites were prepared by a soluble precursor technique. The two PPV derivatives included in this study were poly(2-bromo-5-methoxy-l,4-phenylene vinylene) and poly(2-butoxy-5-methoxy-1,4-phenylene vinylene). The spectral characteristics of these materials have been investigated using UV-visible and FT-IR spectroscopy. The densification process was studied by differential scanning calorimetry and thermal gravimetric analyzer. The third-order nonlinear susceptibility X(3)have been investigated for the polymers themselves and their sol-gel composites at 602nm using degenerate four-wave mixing (DFWM) technique. Relatively large X(3)values (4 × 10−10∼ 1 × 10−9esu) with a subpicosecond response were observed.

ISSN:1058-725X    

DOI:10.1080/10587259308032476

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Single crystals of new organic nonlinear optical materials,N-(2,4-dinitrophenyl)-1-chloro-3-phenyl-2-propanamine(DNCPA) andN-(5-nitro-2-pyridyl)leucinol(NPLO) have been grown by a seeded solution growth technique. Linear and nonlinear optical properties of these materials have been investigated. Angle-tuned type I and type II phase matching for frequency doubling of 1064 nm radiation at room temperature were achieved for DNCPA and NPLO crystals. The effective nonlinear coefficients weredeff= 0.13 pm/V (type I),deff= 1.1 pm/V (type II) for DNCPA anddeff= 40 pm/V (type I),deff= 3.0 pm/V (type II) for NPLO, respectively.

ISSN:1058-725X    

DOI:10.1080/10587259308032477

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The preparation and characteristics of the field-effect transistor (FET) based on plasma-polymerized pyrrole (PP-Py) are presented. The electric conductivity of PP-Py was 10−9S/cm and its value was significantly improved to the 10−6S/cm by the thermal treatment of PP-Py under nitrogen atmosphere. The PP-Py based FET displayed the typical enhancement-type FET properties with excellent source current (IDS)-drain voltage (VDS) characteristics at various gate voltages (VG). Field-effect mobility was found to be around 1.1 × 10−4cm2/V s, and the threshold voltage of FET performance was -1.2 volt.

ISSN:1058-725X    

DOI:10.1080/10587259308032478

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper summarizes the present status of materials science of conducting polymers relevant to the their technological applications. This paper also describes the development of solid electrolytic capacitors utilizing conducting-polymer thin films as a solid electrolyte. The capacitors are characterized by excellent frequency, temperature and life stabilities and have been put into commercial use in large quantity.

ISSN:1058-725X    

DOI:10.1080/10587259308032479

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We propose that the heavily doped polyacetylene is formed by the soliton-antisoliton pair condensation which is a mixed state of the delocalized charge carriers and the virtually bound states. With this proposal, the metallic conductivity and the temperature independent magnetic susceptibility as well as the infrared active vibrational modes (IRAV) observed in the heavily doped polyacetylene can be understood simultaneously. Furthermore, the persistence of the C˭C and C—C vibrational modes appeared in Raman spectra for the heavily doped polyacetylene can also be understood with this soliton-antisoliton condensed state model. The highest conductivity estimated from this phenomenological model is [sgrave]RT˭ 35,000 S/cm, consistent with the observed (and confirmed) maximum conductivity of the heavily doped polyacetylene.

ISSN:1058-725X    

DOI:10.1080/10587259308032480

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The 4,4′-bipyridinium ions formed ion-pair charge-transfer (CT) complexes with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate in organic solutions, microcrystalline films, Langmuir-Blodgett films, and polymer films. Reversible colour changes between pale yellow and blue due to photoinduced electron transfer upon excitation of an ion-pair CT band and thermal reverse reactions were observed, which we call the photoinduced electrochromism. The rate of reverse reactions markedly depended on temperature and microenvironments. The blue-coloured state was formed very rapidly by pulsed laser excitation, which was stored without decay below 0°C in polymer films. Such photoinduced electrochromism may be applied to a new high-speed and high-density optical memory.

ISSN:1058-725X    

DOI:10.1080/10587259308032481

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Dyes for optical recording systems such as laser optical recording systems, laser printing systems, cycolor and related systems, xerography and so on are reviewed. Infrared absorbing (IR) dyes are newly designed for laser optical recording systems such as DRAW and erasable type recording systems. The chemistry of IR dyes developed the new fields in dye chemistry. Many of functionalities in dye chromophores are newly developed for optical recording systems such as PHB and cycolor systems. New technology has developed new dye chemistry and new characteristics of dye chromophores advanced the technology for new optical recording systems.

ISSN:1058-725X    

DOI:10.1080/10587259308032482

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Diaminotriphenylamines4possessing four different substituents were newly synthesized, and introduced to polyamic acids6by the reaction with aliphatic tetracarboxylic dianhydride5. The LB films of polyimides8having triphenylamine units were fabricated on a glassy carbon electrode via the LB films of long chain alkylamine salts of6to measure cyclic voltammograms. The methoxy substituted triphenylamine afforded the lowest redox potential, that suggested the highest electron density on the nitrogen atom of the triphenylamine. The photoconductive devices (photodiodes) were constructed by the deposition of polyimides which possessed different chemical structure, i.e., triphenylamines as an electron donor (D), tetraphenylporphyrin as a sensitizer (S), and aromatic polyimide as an electron acceptor (A), giving polyimide LB multilayer films. Two types of photodiodes having E/D/S/A and E/A/S/D were prepared on the semitransparent gold electrodes (E). When the methoxy substituted triphenylamine was used as D layer, the highest photocurrent of 3 μA/cm2was obtained. The order of magnitude of photocurrent was in good agreement with the results of cyclic voltammometry. The dependence of numbers of D, S, and A layers on the photocurrent was examined by changing the number of each layer. It was found that the triphenylamine units had excellent electron donating ability and hole mobility, whereas the S and A layers did not transfer electron effectively.

ISSN:1058-725X    

DOI:10.1080/10587259308032483

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor