摘要:

The syntheses of novel side-chain liquid crystalline polyacrylates (LCPAs) containing siloxane spacers were carried out according to a convenient route by preparing alcohol compounds having a mesogenic group linked with a siloxane bond as key intermediates of the monomers. A relatively large mesogenic group was necessary to exhibit a mesophase in this system. The introduction of a siloxane spacer lowered the temperature range of mesophase of LCPAs resulting from the decrease of T, as compared with the corresponding LCPAs containing an alkylene spacer. It was also revealed that the chemical structure of spacer component played an important role for the assembly structure in the mesophase. g

ISSN:0267-8292    

DOI:10.1080/026782997208343

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An optically controlled electro-optic effect in nematic-discotic liquid crystals was discovered for the first time. The peculiarities of this effect are: (a) high photosensitivity observed in three different radial multiyne liquid crystal materials, allowing optically controlled transmission, i.e. giving the possibility of writing and reproducing optical images; (b) for one of these compounds (1a) the effect occurs at temperatures far below its melting point and even at room temperature.

ISSN:0267-8292    

DOI:10.1080/026782997208352

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Illumination of free-standing smectic films doped with azo dyes produces bubbles in the SmA phase; these cannot be observed in bulk samples. The bubbles appear in the films with some time delay after the beginning of illumination. This time delay depends linearly on (T where T is the smectic A-isotropic transition temperature. This dependence shows that IA illumination induces in the interior of the films a smectic A-isotropic phase transition. The SmC* in-plane director field configuration depends on the orientation of the polarization plane of the incident light. In the SmC* phase no bubbles are observed even on continuous illumination. T), IA

ISSN:0267-8292    

DOI:10.1080/026782997208361

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Using a radical copolymerization of 4-(4-cyanobiphenyl-4-yloxy)butyl acrylate and acrylic acid, a number of new liquid crystalline ionogenic copolymers capable of hydrogen bonding were synthesized. The formation of hydrogen bonds results in an invariant temperature interval of existence for the LC state (up to 52mol% of acrylic acid) and a rather sudden replacement of the nematic phase by the SmA phase with increase in content of acrylic acid (35 mol%) in copolymers.

ISSN:0267-8292    

DOI:10.1080/026782997208370

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The lamellar structure with chain foldings is formed from the main chain polyesters crystallized from the SmA phase. The lamellar spacing increases with a decrease in crystallization temperature. This trend is contrary to that observed in conventional polymers, and is explainable if the chain foldings exist at a thermodynamic equilibrium as an entropy effect in the preceding SmA phase.

ISSN:0267-8292    

DOI:10.1080/026782997208389

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Polymerization induced phase separation initiated by electron beam radiation has been used as a powerful method to obtain well defined PDLC films. Mixtures of different amounts of an aromatic polyester acrylate, an oligoether triacrylate and nematic liquid crystal material E7 were exposed to the electron beam radiation. The electro-optical properties strongly depend on the liquid crystal concentration and on the amount of the oligoether triacrylate in the prepolymer mixture, and are highly reproducible. An unusual enhancement effect of the electro-optical sensitivity was found for samples containing 28 weight per cent and 34 weight per cent of the oligoether triacrylate.

ISSN:0267-8292    

DOI:10.1080/026782997208398

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An optical method for investigating the dynamics in free-standing films of ferroelectric liquid crystals in the range 10 to 105 Hz by means of optical reflectivity is presented. The experimental results were obtained in the linear-response regime applying electric a. c. fields of strengths less than 16 V cm 1. By measuring the magnitude and phase of the dynamic reflectivity, a relaxation process was found at frequencies near 1 kHz originating from the Goldstone mode.

ISSN:0267-8292    

DOI:10.1080/026782997208406

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor