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In this paper results of a study of mechanical, optical and electrical properties of thin films made of multiwall carbon nanotubes (MWCNT) of various types were reported. The MWCNT films were obtained on quartz substrates using the Langmuir-Schaefer (LS) method. A gradual increase in transmittance was recorded with decreasing diameters of MWCNT used. Moreover, a blue shift of the π-plasmon band position was observed with increasing MWCNT diameter. In all tested films, anisotropy of electrical surface resistivity was revealed, which was more pronounced for MWCNT of low diameters, except for the MWCNT sample of the smallest diameters. Results of oscillatory barrier measurements of various MWCNT films at the air water interface were used to calculate the complex compression and shear moduli. It is worth emphasizing that the values of these moduli were obtained for the first time for carbon nanotubes films. Moreover, the obtained results allowed identification of the main factor blocking the alignment process, which turned out to be the shear loss tangent.

The Langmuir and Langmuir-Blodgett techniques have been widely used for nearly a century for the production of molecular thin layers with controlled packing and intermolecular distances. Unfortunately, the Langmuir layers of non-amphiphilic molecules have unstable and unrepeatable parameters. The addition of chemical compounds such as liquid crystals can stabilize and prevent aggregation in the Langmuir layer. The aim of the study was to obtain and characterize Langmuir and Langmuir-Blodgett layers of selected dithiophene diketopyrrolopyrrole (DPP) derivatives and to improve their parameters by forming mixtures with 4‑octyl‑4′‑cyanobiphenyl (8CB). Two DPPs with alkyl chains symmetrically and asymmetrically attached to pyrrole unit were chosen for the investigation. The Langmuir layer of the asymmetrical DPP was unstable over time. For the symmetrically functionalized DPP, after transferring onto solid substrates, agglomerates formation was clearly seen. For DPPs/8CB mixtures, a significant improvement in stability over time was achieved. The confocal microscopy investigation revealed almost complete removal of agglomerate structures in the symmetrical DPP with 8CB. The results proved the miscibility of components at air/water interface and the stabilizing effect of 8CB on DPPs layers. Furthermore, the addition of 8CB forces DPP J-type aggregation in the Langmuir film. Above all, the stable layers with repeatable parameters, made of indistinctly amphiphilic DPP dyes, were shown to form at the air/water interface and on solid substrates.

Biotechnological use of probiotic microorganisms involves providing them with appropriate conditions for growth, but also protection against environmental changes caused by an exchange of the medium, isolation of metabolites, etc. Therefore, the research on effective immobilization of probiotic microorganisms should be focused in this direction. The present study aimed to evaluate the effectiveness of an innovative hybrid immobilization system based on electrospun nanofibers and alginate hydrogel. The analyses carried out included the study of properties of the initial components, the evaluation of the degree and durability of cell immobilization in the final material, and their survival under stress conditions. Effective binding of microorganisms to the hydrogel and nanofibers was confirmed, and the collected results proved that the proposed biocomposite is an efficient method of cell protection. In addition, it was shown that immobilization on electrospun nanofibers leads to the preservation of the highest cell activity and the least cell growth restriction as compared to free or lyophilized cells only. The completed research opens new perspectives for the effective immobilization of microorganisms of significant economic importance.

In the mucoadhesive drug delivery systems the controlling mechanism is initiated by the wetting and swelling of the polymer matrix. In view of the above, the aim of our study was to analyze the effect of model saliva and gastric fluids on the wetting properties and sorption of selected mucoadhesive (Carbopol 974P NF, HEC) and film-forming (Kollidon VA 64) polymers as well as their blends. We considered two types of examined materials: individual polymers and their blends in the form of powders as well as in the form of compressed discs (blanc tablets). The contact angle measurements for powders were performed according to the Washburn method, using the capillary rise technique, whereas the sessile drop method was applied to the compressed discs of mucoadhesive polymers. The surface energy was determined by the OWRK method. The influence of composition of the polymer blends and pH of model fluids on the wetting properties and sorption of the polymer formulations was evaluated. Moreover, significant differences in the morphology, surface roughness and surface properties of mucoadhesion polymers considered were discussed.

Novel electrospun poly(methyl methacrylate)/polyaniline electrospun fibres were produced, characterised, modified, and used as a support for laccase immobilisation by two methods: adsorption and covalent binding. Effective deposition of laccase by both methods was confirmed by FTIR and CLSM results. Nevertheless, the main objective of the study was to select the most favourable immobilisation conditions and prepare heterogeneous biocatalysts with the best possible catalytic properties. The highest relative activity of enzymes immobilised by adsorption and covalent binding were obtained after 1 h of immobilisation using laccase solution at a concentration of 1 mg/mL, at pH 5 and 25 °C. It was found that the immobilised enzymes, which were present in amounts of 110 mg/g and 185 mg/g for systems with adsorbed and covalently bonded laccase respectively, exhibited slightly lower substrate affinity, and in consequence also a lower maximum reaction rate, than the free enzyme. The stability of laccase improved significantly upon immobilisation: both heterogeneous biocatalysts retained over 80% relative activity even after 10 repeated catalytic cycles and 30 days of storage. The obtained systems were used for decolourisation of Remazol Brilliant Blue R dye from a model aqueous solution, resulting in removal efficiencies of 87% and 58% using adsorbed and covalently bonded laccase, respectively. The described approach to the removal of textile dye from model solution is significant for the sustainable and environmentally friendly decolourisation of various compounds from wastewater.

An improved Langmuir method is described and applied to produce transparent, conductive and flexible single layer of multiwall carbon nanotubes. This paper presents properties of multiwall carbon nanotubes spread on water subphase and in a form of Langmuir–Schaefer layers on a quartz plate and on flexible polymeric foil. The results show very high homogeneity of the monolayers on a very large area obtained with the use of the proposed modified Langmuir method and indicate their relatively high radiation transmission and electrical conductivity. Laser scanning confocal and scanning electron microscopic images of the layers are presented. The microscopic visualization of the nanolayers is supported by spectroscopic studies (transmittance, photoacoustics) in the range from ultraviolet to mid-infrared. Moreover, electric measurements (current versus voltage characteristics) of the carbon material on the polymeric foil are presented. The obtained results of the investigated multiwall carbon nanotubes are discussed in a view of potential application in optoelectronics.

Liquid-crystalline perylene-3,4,9,10-tetra-(n-hexylester) forms characteristic dendritic or flower-like structures at room temperature when it is deposited on a hydrophilic glass substrate using the zone-casting technique. It was found that such unique structures were not possible to be created simply by recrystallisation of this dye from a liquid-crystalline columnar phase. On the basis of the observations using a confocal microscope and the study of wide angle X-ray scattering (WAXS) as well as the analysis of the absorption and fluorescence spectra, some conclusions, concerning the molecular organisation in the dendritic structure, are drawn. Based on the research, one can assume that the dendrites are formed by columnar molecular aggregates with the column axes parallel to the substrate. Such an organisation of the molecules can be interesting from the point of view of organic electronics.

The properties of Langmuir monolayers and Langmuir–Blodgett as well as Langmuir–Schaefer films formed by two open-cage polyhedral oligomeric silsesquioxanes (POSS): 1,3,5,7,9,11,14-hepta-isooctyltricyclo [7.3.3.15,11] heptasiloxane-endo-3,7,14-triol (TSiO-POSS) and 1,3,5,7,9,11-octaisobutyltetracyclo [7.3.3.15,11] octasiloxane-endo-3,7-diol (DSiB-POSS) were studied. Both compounds were shown to form stable monolayers at the air/water interface. The morphology of the monolayers was visualized with a Brewster Angle Microscopy (BAM). The results obtained indicated that TSiO-POSS molecules formed dimers whereas in the case of DSiB-POSS was found the network structure, which was seen on the water/air interface as well as on L-S and L-B thin films. The difference in the interfacial behavior of POSS considered results from alkyl chains length and number of hydroxyl groups in the POSS molecule. The formation of network structure and presence of POSS dimers after transfer of the films on the solid substrates were reported.

Correction for ‘The influence of diameter of multiwalled carbon nanotubes on mechanical, optical and electrical properties of Langmuir–Schaefer films’ by Karol Rytel et al., Phys. Chem. Chem. Phys., 2020, DOI: 10.1039/d0cp03687k.

The paper deals with spectroscopic characterization of a core/shell CdSe/ZnS quantum dot and phthalocyanines substituted with butyl and octakis(octyloxy) peripheral groups: zinc (II) and copper (II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine, zinc (II) and copper (II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine in chloroform as well as in a form of 2D Langmuir monolayers. The isotherms of surface pressure as a function of the mean area per molecule are examined and the in-situ absorption study of the Langmuir monolayer is also studied. The influence of the substituents attached to the phthalocyanine macroring and of the presence of the quantum dot on dye spectroscopic properties (absorption and fluorescence) is shown. Molecular arrangement of the molecular skeleton of the phthalocyanines on water substrate is evaluated. A comparison of the in-situ absorption of the phthalocyanine monolayers and electronic absorption spectra of the dyes in chloroform supports the existence of dye aggregates in the monolayer. Interaction between the phthalocyanine dyes and CdSe/ZnS quantum dot observed as dot fluorescence quenching is also discussed.

The bichromophoric systems comprising of corrole and fullerene units and representing one of the rare cases of elaborate structures based on corrole have been studied with the use of photophysical methods. The dyad displays spectroscopic properties which are the superposition of the component spectra, indicating a very weak electronic coupling. Excitation of the corrole unit leads to charge redistribution. The results of UV–vis absorption and fluorescence and also fluorescence kinetics suggest the presence of charge separation. It was shown that light absorption of the corrole–fullerene dyad is better fitted to the sunlight spectrum than porphyrin. Electron paramagnetic resonance investigations suggest partial spin density redistribution at low temperature between corrole and fullerene in the dyad. Quantum chemical calculations support experimental results.

The IR reflection–absorption spectra of Langmuir–Blodgett (LB) layers of the functionalized fullerenes: C 60 -fused N-methylpyrrolidine-5-(dodecyl)thiophene ( 1 ) and C 60 -fused N-methylpyrrolidine-5-(12-bromododecyl)thiophene ( 2 ) were investigated. It was shown that thin films of functionalized fullerenes are ordered and characteristic parts of the molecules are oriented. Their orientation was evaluated with a simple spectroscopic method. It was stated that bromine atom at the end of aliphatic chain of the sample 2 strongly influences the chain orientation. Similarly, the sulphur atom in the thiophene ring causes some bend of its plane.

This article deals with results concerning the study of interacting dyes which are able to create weak interdimers. Two groups of organic systems: phthalocyanines (di-ethanol-amine and di-octane-amine) and pyridyl porphyrins (zinc, copper, and free-base) covalently linked to polyethylene glycol (PEG) in water and organic solvents (dioxane, dimethylsulfoxide) were investigated. Absorption, fluorescence, and photoacoustics were used as experimental methods but particular attention was paid to light-induced optoacoustic spectroscopy to follow the dye’s triplet population and triplet thermal relaxation to study intermolecular interactions. It has been shown that even the weak interactions of the organic dyes under study is not detectable by absorption and only slightly by fluorescence is it possible to follow interactions by complementary photothermal methods. The results obtained for selected phthalocyanines and covalent porphyrin–polymer samples evidently show that the light-induced optoacoustic experiment is a perfect tool in the detection of weakly interacting aggregates.

The paper deals with thermodynamic and spectroscopic characterization of Langmuir layers of phthalocyanines substituted with different peripheral groups: copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine, copper(II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine, copper(II) tetrakis(4-cumylphenoxy)phthalocyanine. The isotherms, compressibility and stability of the Langmuir layers are investigated. Molecular arrangement of the molecular skeleton on water substrate is also evaluated. The essential influence of the substituents attached to the phthalocyanine macroring on dye thermodynamic properties is shown. The in-situ absorption of the phthalocyanine monolayers and electronic absorption spectra of dye solution in chloroform support existence of aggregates which architecture depends on the dye molecular structure.

The paper deals with spectral studies (IR absorption, IR reflection–absorption, Raman scattering, and electronic absorption) of Langmuir–Blodgett layers of selected fullerene–thiophene dyads; some information on preparation and properties of the layers are also given. The spectra were recorded with unpolarised and polarised light (p-polarisation and s-polarisation) to receive data on orientation of the dyads with respect to the solid substrate and on interaction of the dyads with gold substrates. The comparison of the dyad spectra suggests redistribution of charges in both moieties of the dyads after films deposition on the substrate. We have shown that the polarised reflection–absorption spectra of the thin films are strongly dependent on the light polarisation. From the analysis of the data on the basis of the results obtained from various spectral methods it was concluded that the Langmuir–Blodgett layers are ordered and some parts of the dyads are oriented.

Electronic absorption and IR reflection–absorption spectra in non-polarized and in polarized light for lead porphyrin as well as magnesium and lead phthalocyanine dyes when deposited in the form of Langmuir–Blodgett (LB) nanolayers on solid inorganic surfaces (quartz, semiconductor and metal) were measured. Some IR bands of the Langmuir–Blodgett dye layers’ spectra show frequency shifts and changes in the relative intensities as well as in half widths when compared with the vibrational features of powdered dyes dispersed in KBr pellets, which were used as references. The FT-IR spectroscopic examination of the Langmuir–Blodgett layers allowed to estimate electron redistribution at the interface between dye layer and solid substrates. The Langmuir–Blodgett films of different thicknesses (3, 5, 10 layers) were studied at various angles of IR beam incidence and different light polarizations. The most spectacular results were obtained for the grazing incidence (80°) and films of 5 layers for dyes on the Au substrate. The IR spectroscopy was supported with electronic absorption studies (UV–vis) to follow interaction at interface between the dye layers and the substrates as well as to evaluate linear dichroism and to determine arrangement of molecules in the Langmuir–Blodgett films. Molecular arrangement in the Langmuir–Blodgett layers was discussed. It was shown that the dye molecular planes are rather randomly oriented in the Langmuir–Blodgett films with a tendency that the Q y and Q x transition moments in the phthalocyanine macroring are slightly directed along the y -axis (Langmuir–Blodgett dipping direction) and the x -axis direction, respectively.

The spectral and thermodynamic properties of bacteriochlorophyll c and dipalmitoylphosphatidylcholine in binary mixed monolayers have been investigated. The model system of biological membrane was built up of a mixture of phospholipids and pigments dissolved in chloroform, at several mole ratios. The isotherms of these samples were recorded and then the monomolecular layers on quartz plate were produced. For the Langmuir layer obtained on the air–water interface the thermodynamic parameters were calculated. Additionally, by means of the absorption spectroscopy methods in natural and polarized light, pigment–pigment and pigment–lipid interactions were studied. The information about the average surface per molecule, aggregation properties and the molecular orientation of pigments in Langmuir–Blodgett layers, was obtained.

Langmuir and Langmuir–Blodgett (LB) films formed of some fluorescent dyes, namely three derivatives of naphthalenebicarboxylic acid and one derivative of naphthoylenebenzimidazole as well as of their mixtures with arachid acid and liquid crystal 4-octyl-4′-cyanobiphenyl (8CB) have been studied. Surface pressure and surface potential versus mean molecular area isotherms for Langmuir films were recorded and information about intermolecular interactions at the air–liquid interface were obtained. Absorption spectra in situ for Langmuir films and both absorption and fluorescence spectra for LB films were recorded. Additionally, in order to analyze the spectra in wide range of a dye concentration some absorption and fluorescence measurements of dyes dissolved in 8CB were performed in sandwich cells. The results obtained from spectroscopic studies have led to conclusions about the formation of self-aggregates by dye molecules.

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.

Langmuir films of various dyes, namely derivatives of 3,4,9,10-perylenetetracarboxylic acid and 3,4,9-perylenetricarboxylic acid, derivatives of naphthalenebicarboxylic acid and derivatives of naphthoylenebenzimidazole were investigated. Surface pressure–mean molecular area isotherms were recorded from which the alignment of the molecules in a monomolecular layer at the air–water interface was determined. It was found that both the stability and the rigidity of the monolayer are strongly affected by the molecular structure of the side groups substituted on the skeleton of the molecule.

Langmuir (L) and Langmuir–Blodgett (LB) films of some 3,4,9,10-tetra-( n -alkoxy-carbonyl)-perylenes have been studied. On the basis of the surface pressure–mean molecular area isotherms, the molecular alignment on the air–water interface has been estimated. The optical spectroscopic study of the LB films has allowed conclusions to be drawn about the arrangement of the molecules on the quartz slides. The fluorescence spectra of the LB films of the perylene-derivatives investigated have revealed the formation of excited dimers.

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 ...

The paper deals with spectroscopic characterization of metallic phthalocyanines (Pc’s) (indium and gallium) complexed with chlorine and substituted with four benzyloxyphenoxy peripheral groups in bulk systems, 2D Langmuir monolayers and Langmuir–Blodgett nanolayers. An influence of the molecular structure of dyes (the presence of metal and of substitutes attached to the phthalocyanine macroring) on the in situ measurements of light absorption is reported. Molecular arrangement of the phthalocyanine molecular skeleton in the Langmuir monolayers on water substrate and in the Langmuir–Blodgett nanolayers is evaluated. A comparison of the light absorption spectra of the phthalocyanine monolayers with the spectra of the dyes in solution supports the existence of dye aggregates in the monolayer. It was shown that the type of dye aggregates (oblique and H types) depends markedly on the dye molecular structures. The NIR-IR, IR reflection–absorption and Raman spectra are also monitored for Langmuir–Blodgett nanolayers in non-polarized and polarized light. It was shown that the dye molecules in the Langmuir–Blodgett layers are oriented nearly vertically with respect to a gold substrate.

The adsorption properties of surfactant mixtures containing two types of quaternary derivatives of lysosomotropic substances: alkyl N,N-dimethylalaninates methobromides and alkyl N,N-dimethylglycinates methobromides were studied. Quantitative and qualitative description of the adsorption process was carried out on the basis of experimentally obtained equilibrium surface tension isotherms. The results indicated that most of the systems studied revealed synergistic effect both in adsorption and wetting properties. In vitro studies on human cancer cells were undertaken and the data obtained showed that the mixtures suppressed the cancer cells’ proliferation more effectively than individual components. Results of preliminary research on the interaction of catanionic mixtures with phospholipids suggested a possibility of a strong penetration of cell membranes by the mixtures investigated.

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.