Papers by Tomasz Martynski
Surface pressure-mean molecular area isotherms of Langmuir films of some liquid crystals with CN ... more Surface pressure-mean molecular area isotherms of Langmuir films of some liquid crystals with CN or --NCS terminal group as well as of their binary mixtures have been recorded. It was found that only the liquid crystals which molecules have CN group are able to form a stable monolayer at the air-water interface. Information about the molecular organization and intermolecular interaction in two dimensional layer has been obtained. Moreover, the miscibility or phase separation of two components in the mixtures of various compositions has been determined by using excess area criterion and surface phase rule.
Proceedings of Spie the International Society For Optical Engineering, Sep 1, 2005
Langmuir-Blodgett (LB) films formed of some discotic liquid crystals, namely 3,4,9,10-tetra-(n-al... more Langmuir-Blodgett (LB) films formed of some discotic liquid crystals, namely 3,4,9,10-tetra-(n-alkoxy-carbonyl)- perylenes, have been studied. The absorption and fluorescence spectra were recorded. The results obtained have led to conclusions about formation of dimers both in ground and excited states at the air-solid substrate interface. Moreover, information about the molecular arrangement in LB films has been obtained.
Liquid Crystals, 2002
ABSTRACT A study of dichroic dye-liquid crystal mixtures (guest-host systems) in monolayers forme... more ABSTRACT A study of dichroic dye-liquid crystal mixtures (guest-host systems) in monolayers formed at a gas-liquid interface (Langmuir films) and at a solid surface (Langmuir-Blodgett films) has been made. As a host 4- n -octyl-4′-cyanobiphenyl (8CB) or 4- n -pentyl-4″-cyano- p -terphenyl (5CT) were chosen, while three dichroic azo dyes with various molecular structures were used as guest species. The dyes were added to the liquid crystal matrices at a concentration corresponding to the whole range of molar fractions and the surface pressure-mean molecular area isotherms for Langmuir films were recorded. On the basis of the isotherms, conclusions about the molecular organization and the miscibility of the components in the ultrathin films were drawn. The Langmuir films were transferred onto the quartz plates at surface pressures below the collapse point. The polarized absorption spectra of the Langmuir-Blodgett films were recorded and information about the alignment and intermolecular interactions in the mixtures of the non-amphiphilic dichroic dyes and the liquid crystals with strongly polar terminal groups were obtained.
Http Dx Doi Org 10 1080 1358314x 2012 669223, Mar 26, 2012
Http Dx Doi Org 10 1080 02678290010010121, Aug 5, 2010
ABSTRACT Langmuir films of binary mixtures of the following liquid crystal materials: 4-octyl-4′-... more ABSTRACT Langmuir films of binary mixtures of the following liquid crystal materials: 4-octyl-4′-cyanobiphenyl (8CB) or 4-pentyl-4″-cyano-p-terphenyl (5CT) with 4-(trans-4'-octylcyclohexyl)isothiocyanatobenzene (8CHBT), trans-4-octyl(4′-cyanophenyl)cyclohexane (8PCH) or 4-octyl4′-isothiocyanatobiphenyl (8BT) were investigated. Surface pressure-mean molecular area isotherms were recorded at various mixture compositions. It was found that only liquid crystal materials for which the molecules have a terminal -CN group are able to form a stable monolayer at the air-water interface. Moreover, information about the miscibility or the phase separation of the two components in the mixures was obtained by using the excess area criterion and surface phase rules.
Zeitschrift für Naturforschung A, 2003
Two-component films of 4-octyl-4’-cyanobifenyl (8CB) and non-amphiphilic azo dye (1) at different... more Two-component films of 4-octyl-4’-cyanobifenyl (8CB) and non-amphiphilic azo dye (1) at different molar fractions were studied at the air-water interface on the basis of the surface potentialmean molecular area dependence recorded simultaneously with the surface pressure-mean molecular area isotherm. Conventional Langmuir technique was used to form 1/8CB (guest-host) films during reduction and expansion of an area occupied by the molecules. From the surface potential value the effective dipole moment in the first monolayer formed on the water was calculated. Moreover, the number of dipole moments directed to the air with respect to those directed towards the water was estimated. A model of the microscopic polar ordering of the molecules in 1/8CB films at the air-water interface is proposed.
Liquid Crystals: Optics and Applications, 2005
Langmuir-Blodgett (LB) films formed of some discotic liquid crystals, namely 3,4,9,10-tetra-(n-al... more Langmuir-Blodgett (LB) films formed of some discotic liquid crystals, namely 3,4,9,10-tetra-(n-alkoxy-carbonyl)- perylenes, have been studied. The absorption and fluorescence spectra were recorded. The results obtained have led to conclusions about formation of dimers both in ground and excited states at the air-solid substrate interface. Moreover, information about the molecular arrangement in LB films has been obtained.
Liquid Crystals Today, 2012
ABSTRACT Langmuir and Langmuir-Blodgett films of various dyes, namely derivatives of: 3,4,9,10-pe... more ABSTRACT Langmuir and Langmuir-Blodgett films of various dyes, namely derivatives of: 3,4,9,10-perylenetetracarboxylic acid, 3,4,9-perylenetricarboxylic acid, naphthalenebicarboxylic acid and naphthoylenebenzimidazole as well as of their mixtures with a liquid crystal were investigated. The dependence of the surface pressure -- on the mean molecular area for Langmuir films was measured, from which the molecular organization and the miscibility of components in the monomolecular layer at the air-water interface were determined. For Langmuir-Blodgett films the absorption and emission spectra were recorded and information about the spectral properties and molecular alignment of dyes and liquid crystals in ultrathin layers at solid substrates was obtained.
Organic Electronics, 2014
Using integrating sphere method we have determined the absolute photoluminescence quantum yield (... more Using integrating sphere method we have determined the absolute photoluminescence quantum yield (QY) of two perylene derivatives in ultra-thin films. Monomolecular and multilayer films were deposited onto quartz substrates by using Langmuir-Blodgett technique. The method adopted by us allows to evaluate QY with a high accuracy for samples having absorbance down to 0.01. The evaluated luminescence quantum yield of mono-and multilayers of two 3,4,9,10-tetra-(n-alkoxy-carbonyl)-perylenes was in the range of 7-12%.
Thin Solid Films, 2008
Langmuir-Blodgett (LB) films formed of some organic dyes, namely 3,4,9,10-tetra-(n-alkoxy-carbony... more Langmuir-Blodgett (LB) films formed of some organic dyes, namely 3,4,9,10-tetra-(n-alkoxy-carbonyl)-perylenes, and their mixtures with arachidic acid have been studied. The electronic absorption and fluorescence spectra were recorded. The results obtained have led to conclusions about formation of self-aggregates of dye molecules at the air-solid substrate interface. The absorption spectra have indicated that in the ground state some fraction of J-aggregates can be formed, whereas the fluorescence spectra have been dominated by the emission from excimer states.
Soft Materials, 2014
ABSTRACT The synthesis of perylene monoimide dye and the ability of Langmuir and Langmuir–Blodget... more ABSTRACT The synthesis of perylene monoimide dye and the ability of Langmuir and Langmuir–Blodgett (LB) films formation are reported. The perylene-like dye – n-butyl diester of N-(n-octyl)imide of perylene-3,4,9,10-tetracarboxylic acid and arachidic acid (AA) or thermotropic liquid crystal 4-octyl-4’-cyanobiphenyl (8CB) were used to compose mixtures of different mole fraction. The electronic absorption and emission spectra of the dye in diluted chloroform solution, a 10 μm thick liquid crystal sandwich cell, in the monomolecular film on water surface (in situ) and after deposition on quartz substrates were recorded. In the Langmuir and LB films the dye molecules reveal tendency to creation of self-aggregates what is reviled by significant broadening of the absorbance bands and changes in emission spectra. It has been shown that the molecules of the perylene dye under investigation exhibit a strong tendency to create H-types of aggregates in highly concentrated LB films. The emission spectra show the genuine excimer emission of the dye in the LB films. The AFM surface image of the pure dye monolayer showed that molecules form a two-level film with height of about 0.6 nm and 2.5 nm. Topographies of mixed monolayers with arachidic acid revealed three-level structures with circular domains of AA within the dye monolayer. From the highest analyses, a partial miscibility of the dye with arachidic acid (AA) is postulated. [Supplementary materials are available for this article. Go to the publisher's online edition of Soft Materials for the following free supplemental resource(s): Supplementary file.]
Liquid Crystals, 2006
Langmuir–Blodgett (LB) films of some dichroic dyes, namely derivatives of naphthalenebicarboxylic... more Langmuir–Blodgett (LB) films of some dichroic dyes, namely derivatives of naphthalenebicarboxylic acid and derivatives of naphthoylenebenzimidazole, and of their mixtures with mesogens: 4‐octyl‐4′‐cyanobiphenyl or 4‐pentyl‐4″‐cyano‐p‐terphenyl were prepared. Absorption and fluorescence studies using unpolarized and linearly polarized light were carried out. Both absorption and fluorescence spectra indicated the formation of aggregates of dye molecules in monomolecular layers. Moreover, it was found that dye molecules are more tilted to the quartz surface in LB films than to the plane of the air–water interface in Langmuir films.
Liquid Crystals, 1995
The polarized absorption spectra of eight dichroic dyes, alkyl derivatives of 4-amino-(N-ethylnap... more The polarized absorption spectra of eight dichroic dyes, alkyl derivatives of 4-amino-(N-ethylnaphthalimide) dissolved in the nematic liquid crystals 5CB and 6CHBT have been measured as a function of temperature. On the basis of these spectra, the guest order parameter has been evaluated. The influence of the alkyl chain length of the dye molecule on the molecular orientation has been examined. Moreover, the nematic-isotropic transition temperatures for the dye-liquid crystal mixtures have been determined. The experimental results have been compared in some detail with calculations made on the basis of the mean field theory for binary mixtures.
Liquid Crystals, 2002
ABSTRACT A study of dichroic dye-liquid crystal mixtures (guest-host systems) in monolayers forme... more ABSTRACT A study of dichroic dye-liquid crystal mixtures (guest-host systems) in monolayers formed at a gas-liquid interface (Langmuir films) and at a solid surface (Langmuir-Blodgett films) has been made. As a host 4- n -octyl-4′-cyanobiphenyl (8CB) or 4- n -pentyl-4″-cyano- p -terphenyl (5CT) were chosen, while three dichroic azo dyes with various molecular structures were used as guest species. The dyes were added to the liquid crystal matrices at a concentration corresponding to the whole range of molar fractions and the surface pressure-mean molecular area isotherms for Langmuir films were recorded. On the basis of the isotherms, conclusions about the molecular organization and the miscibility of the components in the ultrathin films were drawn. The Langmuir films were transferred onto the quartz plates at surface pressures below the collapse point. The polarized absorption spectra of the Langmuir-Blodgett films were recorded and information about the alignment and intermolecular interactions in the mixtures of the non-amphiphilic dichroic dyes and the liquid crystals with strongly polar terminal groups were obtained.
Liquid Crystals, 2002
ABSTRACT Langmuir films of binary mixtures of the following liquid crystal materials: 4-octyl-4′-... more ABSTRACT Langmuir films of binary mixtures of the following liquid crystal materials: 4-octyl-4′-cyanobiphenyl (8CB) or 4-pentyl-4″-cyano-p-terphenyl (5CT) with 4-(trans-4'-octylcyclohexyl)isothiocyanatobenzene (8CHBT), trans-4-octyl(4′-cyanophenyl)cyclohexane (8PCH) or 4-octyl4′-isothiocyanatobiphenyl (8BT) were investigated. Surface pressure-mean molecular area isotherms were recorded at various mixture compositions. It was found that only liquid crystal materials for which the molecules have a terminal -CN group are able to form a stable monolayer at the air-water interface. Moreover, information about the miscibility or the phase separation of the two components in the mixures was obtained by using the excess area criterion and surface phase rules.
Liquid Crystals, 2006
Langmuir films of members of two homologous series, the 4‐n‐alkyl‐4′‐cyanobiphenyls (nCB) for n =... more Langmuir films of members of two homologous series, the 4‐n‐alkyl‐4′‐cyanobiphenyls (nCB) for n = 2–14 and trans‐4‐n‐alkyl(4′‐cyanophenyl)cyclohexanes (PCHn) for n = 2–12, have been studied by recording surface pressure/area isotherms and by Brewster angle microscopy. It has been found that the compounds with very short chains (n⩽3) and very long chains (n>12 for nCB, n>10 for PCHn) are unable to form compressible monolayers at the air–water interface. Other members of both series can form stable Langmuir films, but both their rigidity and stability as well as the molecular packing vary with the alkyl chain length. The isotherms and BAM images imply that the organization of the liquid crystal molecules in the films is to some extent correlated with their ability to form corresponding mesophase in the bulk: nematogenic compounds tend to form rounded droplet‐like domains, whereas smectogenic compounds tend to form flat domains.
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Papers by Tomasz Martynski