Thermal Transitions and Structural Characteristics of Poly(3,4-ethylenedioxythiophene/cucurbit[7]uril) Polypseudorotaxane and Polyrotaxane Thin Films.

Herein, we report the thermal transitions and structural properties of poly(3,4-ethylenedioxythiophene/cucurbit[7]uril) pseudopolyrotaxane (PEDOT∙CB7-PS) and polyrotaxane (PEDOT∙CB7-PR) thin films compared with those of pristine PEDOT. The structural characteristics were investigated by using variable-temperature spectroscopic ellipsometry (VTSE), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and atomic force microscopy (AFM). VTSE and DSC results indicated the presence of an endothermic process and glass transition in the PEDOT∙CB7-PS and PEDOT∙CB7-PR thin films. X-ray diffraction of PEDOT∙CB7-PS and PEDOT∙CB7-PR powders displayed the presence of interchain π-π stacking revealing a characteristic arrangement of aromatic rings in the internal structure of the crystallites. AFM imaging of PEDOT∙CB7-PS and PEDOT∙CB7-PR thin films exhibited significant differences in the surface topographies compared with those of PEDOT. A high degree of crystallization was clearly visible on the surface of the PEDOT layer, whereas the PEDOT∙CB7-PS and PEDOT∙CB7-PR thin films exhibited more favorable surface parameters. Such significant differences identified in the surface morphology of the investigated layers can, therefore, be clearly associated with the presence of surrounding CB7 on PEDOT skeletons.

Exploring the Influence of P3HT on PTCA Crystallization and Phase Behavior in Thin Films.

The thermal properties and alignment of crystallinity of materials in thin films play crucial roles in the performance and reliability of various devices, especially in the fields of electronics, materials science, and engineering. The slight variations in the molecular packing of the active layer can make considerable differences in the optical and thermal properties. Herein, we aim to investigate the tuning of the physical properties of a blended thin film of n-type small organic molecules of perylene-3,4,9,10-tetracarboxylic acid (PTCA-SMs) with the mixing of the p-type polymer poly(3-hexylthiophene) (P3HT). The resulting thin films exhibit an enhanced surface crystallinity compared to the pristine material, leading to the formation of long crystallites, and these crystallites are thermally stable in the solid state, as confirmed by X-ray diffraction (XRD), atomic force microscopy (AFM), and thermal analysis using variable-temperature spectroscopic ellipsometry (VTSE) and differential scanning calorimetry (DSC). We believe that the crystalline structure of the obtained P3HT/PTCA-SMs blends is a combination of edge-on and face-on orientations, which enable the potential use of this material as an active layer in organic electronics.

Variable Temperature Spectroscopic Ellipsometry as a Tool for Insight into the Optical Order in the P3HT:PC70BM and PC70BM Layers.

Two combined ellipsometric techniques-variable angle spectroscopic ellipsometry (VASE) and variable temperature spectroscopic ellipsometry (VTSE)-were used as tools to study the surface order and dielectric properties of thin films of a poly(3-hexylthiophene-2,5-diyl) (P3HT) mixture with a fullerene derivative (6,6-phenyl-C71-butyric acid methyl ester) (PC70BM). Under the influence of annealing, a layer of the ordered PC70BM phase was formed on the surface of the blend films. The dielectric function of the ordered PC70BM was determined for the first time and used in the ellipsometric modeling of the physical properties of the P3HT:PC70BM blend films, such as their dielectric function and thickness. The applied ellipsometric optical model of the polymer-fullerene blend treats the components of the blend as a mixture of optically ordered and disordered phases, using the effective medium approximation for this purpose. The results obtained using the constructed model showed that a layer of the ordered PC70BM phase was formed on the surface of the layer of the polymer and fullerene mixture. Namely, as a result of thermal annealing, the thickness of the layer of the ordered fullerene phase increased, while the thickness of the underlying material layer decreased.

Phase behavior of π-conjugated polymer and non-fullerene acceptor (PTB7-Th:ITIC) solutions and blends.

Phase diagrams of ternary π-bonded polymer (PTB7-Th) solutions were constructed as a function of molecular weight, temperature, and electron acceptor species (ITIC, PC61BM and PC71BM). For this purpose, the Flory-Huggins lattice theory was employed with a constant χ interaction parameter, describing a binodal, spinodal, tie line, and critical point. Then, the morphologies of the blends composed of highly disordered PTB7-Th and crystallizable ITIC were investigated by atomic force microscopy. Subsequently, the surface polarities of the PTB7-Th:ITIC thin films were examined by water contact-angle goniometer, exhibiting a transition at the composition of ~ 60 ± 10 wt.% ITIC. Furthermore, X-ray diffraction indicated the presence of ITIC's crystallites at ≥ 70 wt.% ITIC. Hence, the PTB7-Th:ITIC system was observed to undergo a phase transition at ~ 60-70 wt.% ITIC.

An Investigation of the Thermal Transitions and Physical Properties of Semiconducting PDPP4T:PDBPyBT Blend Films.

This work focuses on the study of thermal and physical properties of thin polymer films based on mixtures of semiconductor polymers. The materials selected for research were poly [2,5-bis(2-octyldodecyl)-pyrrolo [3,4-c]pyrrole-1,4(2H,5H)-dione-3,6-diyl)-alt-(2,2';5',2″;5″,2'''-quater-thiophen-5,5'''-diyl)]-PDPP4T, a p-type semiconducting polymer, and poly(2,5-bis(2-octyldodecyl)-3,6-di(pyridin-2-yl)-pyrrolo [3,4-c]pyrrole-1,4(2H,5H)-dione-alt-2,2'-bithiophene)-PDBPyBT, a high-mobility n-type polymer. The article describes the influence of the mutual participation of materials on the structure, physical properties and thermal transitions of PDPP4T:PDBPyBT blends. Here, for the first time, we demonstrate the phase diagram for PDPP4T:PDBPyBT blend films, constructed on the basis of variable-temperature spectroscopic ellipsometry and differential scanning calorimetry. Both techniques are complementary to each other, and the obtained results overlap to a large extent. Our research shows that these polymers can be mixed in various proportions to form single-phase mixtures with several thermal transitions, three of which with the lowest characteristic temperatures can be identified as glass transitions. In addition, the RMS roughness value of the PDPP4T:PDBPyBT blended films was lower than that of the pure materials.

Hybrid nanolayers of star polymers and silver nanoparticles with antibacterial activity.

The aim of this study was to obtain stable star polymer layers with incorporated silver nanoparticles (AgNPs) and to study the antimicrobial activity of these hybrid materials. In this work, a novel approach regarding the synthesis of AgNPs directly by the star polymer layer is presented. Nanolayers of poly(N,N'-dimethylaminoethyl methacrylate) and hydroxyl-bearing poly[oligo(ethylene glycol) methacrylate] (P(DMAEMA-co-OEGMA-OH)) stars, covalently bound with solid supports, were obtained through chemical reaction of hydroxyl groups in the star arms with substrate modified with imidazole derivative. Quantitative chemical composition analysis and tracking of the changes in the morphology and wettability after every step of surface modification confirmed the covalent attachment of stars with the support. In the next step, the polymer nanolayers were modified with AgNPs formed in situ using only amine groups of the star arms and followed by the crystal quartz microbalance (QCM). The analysis of the layer thickness and affinity to water, both with the shape, size and amount of silver incorporated into the layer, confirmed the efficacy of AgNPs formation. The amount of silver incorporated into layers was correlated with the molar masses of the grafted stars, and a possible location of AgNPs within layers was shown. The antibacterial activity tests of prepared nanolayers showed that obtained hybrid materials were highly effective against both gram-positive and gram-negative bacteria strains. This study shows that the obtained layers are promising as stable coatings for antibacterial applications.

Thermal Transitions in P3HT:PC60BM Films Based on Electrical Resistance Measurements.

In this paper, we present research on thermal transition temperature determination in poly (3-hexylthiophene-2,5-diyl) (P3HT), [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM), and their blends, which are materials that are conventionally used in organic optoelectronics. Here, for the first time the results of electrical resistance measurements are explored to detect thermal transitions temperatures, such as glass transition Tg and cold crystallization Tcc of the film. To confirm these results, the variable-temperature spectroscopic ellipsometry studies of the same samples were performed. The thermal transitions temperatures obtained with electrical measurements are well suited to phase diagram, constructed on the basis of ellipsometry in our previous work. The data presented here prove that electrical resistance measurements alone are sufficient for qualitative thermal analysis, which lead to the identification of characteristic temperatures in P3HT:PC60BM films. Based on the carried studies, it can be expected that the determination of thermal transition temperatures by means of electrical resistance measurements will also apply to other semi-conducting polymer films.

Temperature-Dependent Spectroscopic Ellipsometry of Thin Polymer Films.

Thin polymer films have found many important applications in organic electronics, such as active layers, protective layers, or antistatic layers. Among the various experimental methods suitable for studying the thermo-optical properties of thin polymer films, temperature-dependent spectroscopic ellipsometry plays a special role as a nondestructive and very sensitive optical technique. In this Review Article, issues related to the physical origin of the dependence of ellipsometric angles on temperature are surveyed. In addition, the Review Article discusses the use of temperature-dependent spectroscopic ellipsometry for studying phase transitions in thin polymer films. The benefits of studying thermal transitions using different cooling/heating speeds are also discussed. Furthermore, it is shown how the analysis and modeling of raw ellipsometric data can be used to determine the thermal properties of thin polymer films.

P3HT:PCBM blend films phase diagram on the base of variable-temperature spectroscopic ellipsometry.

In this work we present an in-depth study of the how the composition of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend films influences their phase transitions using variable-temperature spectroscopic ellipsometry. We demonstrate that this non-destructive method is a very sensitive optical technique to investigate the phase transitions and to determine the glass transition temperatures and melting crystallization points of the P3HT:PCBM blend films. By analyzing the influence of the temperature T on the raw ellipsometric data, we have identified a high sensitivity of the ellipsometric angle Δ at a wavelength of 280 nm to temperature changes. Characteristic temperatures determined from the slope changes of the Δ(T) plot appeared to be very good guess values for the phase transition temperatures.

The Effect of Aromatic Diimide Side Groups on the π-Conjugated Polymer Properties.

The presented study describes the method for the synthesis and characterization of a new class of conjugated copolymers containing a perylenediimide (PDI) and naphthalene diimide (NDI) side groups. The main conjugated backbone is a donor-acceptor polymer poly[3,6-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] containing thiophene and carbazole as donor units and benzothiadiazole as an acceptor unit. The presented compounds were synthesized in a multistep synthesis. The polymerization was carried out by Suzuki or Stille coupling reaction. Redox properties of the studied polymers were tested in different conditions. Electrochemical investigation revealed independent reduction of the main polymer chain and diimide side groups. UV-Vis spectroscopy revealed the overlap of two absorption spectra. The difference between the electron affinity of the polymer main chain and that of the diimides estimated electrochemically is approximately 0.3 eV.

Manufacturing and investigation of physical properties of polyacrylonitrile nanofibre composites with SiO2, TiO2 and Bi2O3 nanoparticles.

The aim of this study was to produce nanocomposite polymer fibres, consisting of a matrix of polyacrylonitrile (PAN) and a reinforcing phase in the form of SiO2/TiO2/Bi2O3 nanoparticles, by electrospinning the solution. The effect of the nanoparticles and the electrospinning process parameters on the morphology and physical properties of the obtained composite nanofibres was then examined. The morphology of the fibres and the dispersion of nanoparticles in their volume were examined using scanning electron microscopy (SEM). All of the physical properties, which included the band gap width, dielectric constant and refractive index, were tested and plotted against the concentration by weight of the used reinforcing phase, which was as follows: 0%, 4%, 8% and 12% for each type of nanoparticles. The width of the band gap was determined on the basis of the absorption spectra of radiation (UV-vis) and ellipsometry methods. Spectroscopic ellipsometry has been used in order to determine the dielectric constant, refractive index and the thickness of the obtained fibrous mats.

[Variant angina mimicking right ventricular infarction--a case report]. / Dlawica Prinzmetala o klinicznym przebiegu nasladujacym zawal prawej komory.

A case of a 59-year-old man with recurrent angina associated with ST-segment elevation in leads II, III, aVF and V4R-V6R, cardiogenic shock and complete atrio-ventricular block, is presented. Coronary angiography was normal. Therapy with calcium channel blockers was effective. Difficulties in the treatment of patients with variant angina are discussed.

Fast and slow torsade de pointes--electrocardiographic characteristics.

BACKGROUND: Clinical value of electrocardiographic features of torsade de pointes (TdP) has not yet been well established. AIM: To compare the mode of onset and ECG characteristics of slow (s-TdP) and fast (f-TdP) episodes of TdP. METHODS: 54 episodes of TdP recorded in 6 patients (5 females, one male, mean age 64.4 years) with acquired long QT syndrome were analysed. Baseline rate of TdP (V-V), ventricular rate variability (VRV), coupling interval (CI) at the onset of TdP, prematurity index (PI) and the first cycle length (FCL) were compared between 31 s-TdP (<200 beats/min) and 23 f-TdP (> or =220) episodes of TdP. RESULTS: Episodes of f-TdP were preceded by a significantly faster basal rhythm than s-TdP (R-R interval: 922 ms vs 1062 ms, p=0.03). QT interval was almost identical in both groups (517 ms vs 515 ms, NS, respectively). No significant differences were noted in the CI of the initiating beat (488 ms vs 472 ms, NS) nor in the PI (0.53 vs 0.47, NS). TdP was most frequently spontaneously terminated by a gradual slowing of the tachycardia rate; 58% of s-TdP and 39% of f-TdP episodes stopped in this way. An acceleration of ventricular rate before termination of TdP was noted in 32% of s-TdP and in 26% of f-TdP episodes. Episodes of f-TdP were longer than s-TdP episodes (mean of 19.7 vs 6.7 ventricular complexes per one episode, p=0.0003). There were significant differences in the VRV parameter (p=0.0005) and FCL (p=0.004) between both types of TdP. Faster TdP were characterised by lower ventricular rate variability (VRV - 19.5 msec) than s-TdP (VRV - 39.4 msec). Of 54 episodes of TdP, 9 (16.6%) degenerated into VF and required DC shock. Of 31 s-TdP episodes, one (3.2%) degenerated into VF compared with 8 (34.7%) episodes of f-TdP (p<0.04). CONCLUSIONS: Episodes of fast TdP were characterised by a longer duration, shorter first cycle of the arrhythmia and lower ventricular rate variability than episodes of slow TdP. Fast episodes of TdP were preceded by faster baseline rhythm before TdP. Faster TdP more frequently degenerated into VF than slower episodes.

[Acquired long QT syndrome with torsade de pointes in a patient with primary hypothyroidism]. / Nabyty zespól dlugiego QT z czestoskurczami typu torsade de pointes w przebiegu niedoczynnosci tarczycy.

A case of 78 year-old woman with primary hypothyroidism and atrial fibrillation treated with sotalol, complicated with cardiac arrest due to ventricular fibrillation (VF) and torsade de pointes (TdP) is presented. The QT interval was prolonged to 660 msec. Episodes of polymorphic ventricular tachycardia and VF recurred. Lidocaine, tosylate bretylate and betabloker successfully eliminated VF but short-lasting episodes of TdP were still present. Increased doses of hormonal substitution with thyroid hormones successfully eliminated malignant ventricular arrhythmias and normalised QT interval to 430 msec.