Marcin Kozanecki

Anisotropy in structural and physical properties in tetrathiafulvalene derivatives-based zone-cast layers as seen by Raman spectroscopy, UV-visible spectroscopy, and field effect measurements

We have studied anisotropy of thin layers of amphiphilic tetrathiafulvalene derivatives (TTF-4SCn, with n=12, 18, and 22) obtained by zone-casting technique. All the films show optical anisotropy, as seen by polarized optical microscopy and polarized UV-visible spectroscopy. By using polarized Raman spectroscopy an angular dependence of intensity of different vibrational modes in respect to the zone-casting direction was determined. It was found that intensities of the modes related to central and ring C=C vibrations in the TTF core depend very strongly on the angle between the zone-cast direction and polarization plane of incident laser light. Comparison of the deduced orientation of the molecules in one of the films (TTF-4SC18) with its crystal structure shows that the polarized Raman spectroscopy can be useful for controlling orientation of molecules in thin films (e.g., for online monitoring). Organic field effect transistors (OFETs), with channels oriented in parallel and perpendicularly to the zone-...

Micro-Raman study of nanodiamonds from Allende meteorite

We have studied the Raman spectroscopic signatures of nanodiamonds from the Allende meteorite in which some portions must be of presolar origin as indicated by the isotopic compositions of various trace elements. The spectra of the meteoritic nanodiamond show a narrow peak at 1326 cm −1 and a broad band at 1590 cm −1 . Compared to the intensities of these peaks, the background fluorescence is relatively high. A significant frequency shift from 1332 to 1326 cm −1 , peak broadening, and appearance of a new peak at 1590 cm −1 might be due to shock effects during formation of the diamond grains. Such changes may have several origins: an increase in bond length, a change in the electron density function or charge transfer, or a combination of these factors. However, Raman spectroscopy alone does not allow distinguishing between a shock origin of the nanodiamonds and formation by a CVD process as is favored by most workers.

Computational studies of intermolecular interactions in aqueous solutions of poly(vinylmethylether).

Thermo-responsive materials, such as poly(vinylmethylether) (PVME), attract a common attention because of their unique physical properties resulted from metastable equilibrium between various types of interactions. In this work Monte Carlo (MC) and quantum-mechanical (QM) methods were used to study excluded volume and electrostatic interactions respectively. The graining procedure of PVME-water system was proposed. Its implementation to MC calculations allowed to distinguish how two water fractions differ on dynamics. The QM calculations showed that the formation of cyclic clusters leads to the lengthening of the hydrogen bonds and consequently to higher energies in comparison to linear forms, which is crucial looking at an application of QM results to MC calculation considering thermal interactions.

Mesomorphism and photocuring processes of (2-hydroxypropyl)cellulose cinnamate

Mesomorphism and photocuring processes of (2- hydroxypropyl)cellulose cinnamate (CYPC) were investigated. The CYPC was synthesized in the course of estrification of (2-hydroxypropyl)cellulose (HPC) by cinnamoyl chloride. The chemical structure of CYPC was confirmed by IR and Raman spectroscopy. The substitution degree of HPC by cinnamoyl ester groups was calculated from 1H-NMR studies. The thermotropic mesomorphism of CYPC was confirmed by DSC, thermo-optical and X-ray investigations. The thermo-optical behaviors of CYPC tablet obtained under pressure and results of the dielectric spectroscopy investigations were interpreted in terms of the strong hydrophobic effect of the cinnamoyl ester groups. The cycloaddition of the cinnamoyl groups is initiated either by UV radiation or temperature, inside of the hydrophobic aggregates of the cinnamoyl ester groups. The chemical modification of the hydrophobic aggregates in the course of thermo- or photoaddition of the cinnamoyl ester groups slightly changes a molecular movement of the poly(saccharide) main chains of CYPC. However, these crossed aggregates can recover macromolecular orientation of CYPC from the isotropic state via the cooling of sample. These suggest that the hydrophobic aggregates after thermal or photochemical modification shows an anisotropic behavior.

The influence of selected NSAIDs on volume phase transition in poly(2-(2-methoxyethoxy)ethyl methacrylate) hydrogels

Hydrogels exhibiting Volume Phase Transition (VPT) are considered as useful biomaterials for the preparation of various drug delivery systems. Such hydrogels are commonly based on thermo-responsive polymers, such as poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMEO2MA), that have lower critical solution temperature (LCST) in aqueous solutions. In this work, PMEO2MA hydrogels were used as model systems to study the influence of encapsulated drugs, such as ibuprofen and salicylate sodium salts, on the temperature and dynamics of the VPT. Both thermo-optical analysis and differential scanning calorimetry have shown that the VPT becomes broader and shifts towards higher temperatures with increasing drug concentration. Three regimes of VPT in PMEO2MA gels were distinguished. The first two, related to the breaking of the strong water-polymer interactions and to the network collapse, slow down with increasing drug concentration. The last regime, corresponding to the slow diffusion of a residual solution from a collapsing network, becomes visible only for systems with high content of drug. Raman spectroscopy studies show that the observed effect is not connected to direct interactions between polymers and drugs. This suggests that the drug molecules are able to stabilise water-polymer interactions in thermo-responsive hydrogels. Consequently, they are able to modulate VPT and have a significant influence on the delivery process.

Micro - Raman Spectroscopy of Diamonds from JaH 054 and Sahara 98505 Ureilites, Statistic Research

In this paper Raman spectra of diamonds from two different ureilites, JaH 054 and Sahara 98505, were measured. Obtained results for both ureilites showed the Raman shift ranged between 1321 cm−1 and 1336 cm−1 for JaH 054 and between 1329 cm−1 and 1336 cm−1 for Sahara 98505. FWHM parameter (full width at half maximum) varied also in wide range especially for Sahara 98505. Raman imaging was done for JaH 054 sample and diamonds of different Raman shifts (1321 cm−1, 1328 cm−1, 1330 cm−1) were found in few tens μm sized area of carbon vein. Raman peaks of ureilitic diamonds were compared with literature data of laboratory diamonds produced under high pressure, under low pressure with MW PACVD method and with other ureilites. Presented research showed that even in highly shocked ureilites Raman shift versus FWHM parameter plots are similar with CVD diamonds for ureilites. However, the origin of diamonds in ureilites is not explained based on the obtained results, close coexistence of different diamonds in inves...

The anisotropy of poly(acrylic acid) in composites with liquid crystalline cellulose derivatives as seen by low-frequency Raman spectroscopy

Abstract The low-frequency Raman scattering (LFRS) was used in order to determine the orientation of poly(acrylic acid) in anisotropy composite with liquid crystalline [(propionyloxy)propyl]cellulose (PPC). The photopolymerisation of acrylic acid in the presence of PPC leads to the formation of the poly(acrylic acid) (pAA) anisotropic network. This anisotropy is stable even at temperatures higher than the temperature of the optical isotropisation of the PPC/pAA composite. The comparison of the LFRS and thermooptical data proves the hypothesis explaining of the reversibility of the optical birefringence in the PPC/pAA composites by formation, in a course of photopolymerisation of anisotropic pAA network.

Vibrational Spectroscopy in Analysis of Stimuli-Responsive Polymer–Water Systems

Over the last years, a rapid development in the material science, which is an answer to an increasing demand for functional, smart systems, has taken place. The recent progress in design, synthesis and characterization of stimuli-responsive polymer systems (SRPS) fits in this trend very well. However, extensive experiments, simulations as well as theoretical works are still conducted to deepen the knowledge about these systems, their complexity and diversity result in still insufficient understanding of some crucial phenomena. One of them is intermolecular interactions which change during swelling/deswelling processes, phase transitions (commonly leading to the phase separation) and loading or a release of various additives. Since the vibrational spectroscopy is considered to be the most powerful tool to study molecular interactions, this chapter presents various aspects related to the usage of vibrational spectroscopy in the field of SRPS.

Two-Step Procedure of Fly Ash Modification as an Alternative Method for Creation of Functional Composite

An appropriate filler is a key component required to achieve an useful composite with expected properties. Not only sophisticated types of filler, like graphene are popular, but also more common ones, like silica flour or fly ash because of their low costs. Besides production costs, adequate size and possibility of functionalization of particles surface to create stable bonds with a matrix are essential in filler selection. To create an useful filler for epoxy resin based composites with use of a waste material, namely fly ash, two-step procedure was proposed. In the first part, raw material was sieved and five different ranges of the filler size were obtained. After mechanical tests with fracture toughness, tensile strength and Young Modulus, as well thermal conductivity, the best size of the fly ash was chosen for further modification. During the second step, filler was modified with coupling agent [3-(2-aminoethylamino)propyl]trimethoxysilane in order to enhance the coupling between particular components of composite. Presence of the silane layer was confirmed with infrared spectroscopy and scanning electron microscopy measurements, whilst prepared epoxy composite filled with silanized fly ash was examined similarly as previous composites. Obtained results have proved the significant influence of size of a filler and bonding to the matrix on mechanical and thermal properties of fly ash-epoxy resin composite. Proposed simple method of fly ash modification is an environmentally friendly way for utilization of the fly ash. Moreover, it creates an alternative material applicable in electrical devices as functional composite.

Raman spectroscopy in investigation of rheometric processes

Studies of application of Raman spectroscopy in measurement of important parameters of rheometric process, including profile of oil film thickness and composition of oil/paste system, were carried out. The films of silicone oil AK106 (Wacker) extracted from ceramic paste AlOOH were subjects of investigations presented in this paper. Boundary between oil film and extruded paste is not regular and ambiguous during the extrusion process of ceramic paste in capillary rheometer. Moreover, the pastes are scattering materials, what makes determination of the film thickness by conventional optical methods difficult. Preliminary Raman measurements were made separately for oil and paste samples in range extending from 50 to 3500 cm-1. Determination of main Raman bands assigned to oil, ceramics and glass showed that Raman spectroscopy enables discernment of these materials. During the next step, studies were conducted for a model sample of the oil spread on the paste, using Raman microscope. This device was equipped with long-working-distance objective which should enable remote measurements through a borosilicate, view-port-window in the wall of capillary rheometry die. Two methods of Raman determination of the thickness were compared. Results of analysis and experimental works suggest that one of them can be applied for in-situ monitoring of the extrusion process.