bluuebunny/crossref_metadata_2025_split huggingface dataset:
Swelling Deswelling Behavior of PS‐PNIPAAM Copolymer Particles and PNIPAAM Brushes Grafted from Polystyrene Particles & Monoliths
Authors: Mittal Vikas , Matsko Nadejda B. , Butté Alessandro , Morbidelli Massimo 
Published: May 2008

AbstractTwo sets of emulsion particles have been synthesized. In the first set, surfactant free emulsion was used to directly synthesize PS‐PNIPAAM copolymer particles. In the second set, polystyrene particles with an ATRP initiator shell were first synthesized and subsequently grafted with PNIPAAM brushes. Swelling/deswelling behavior of both sets of particles was studied with respect to temperature and time. Monoliths with two different porosities were also formed by grafting and crosslinking of PNIPAAM chains on the aggregated particles and characterized. In all cases, swelling kinetics is sufficiently fast to use these supports for separation driven by temperature changes only. However, hindrance and cross‐linking is sensibly reducing the material performance.magnified image
Sonochemical Synthesis of Magnetic Protein Container for Targeted Delivery
Authors: Han Yongsheng , Radziuk Darya , Shchukin Dmitry , Moehwald Helmuth 
Published: May 2008

AbstractA new targeted delivery system was developed in this paper by depositing magnetic NPs on protein containers which were prepared by sonicating oil in a protein solution. The deposition was conducted by layer‐by‐layer technique and monitored by zeta potential measurement. Such prepared samples can be targeted delivery in an external magnetic field. The hydrophobic dye TPP, as a model of drug, was loaded in the containers by dissolution in the oil phase before sonication. The containers loaded with dye are stable and can sustain the deposition treatment without loss of dye due to the protection of protein nanoshells.magnified image
Structure–Reactivity Correlation in “Click” Chemistry: Substituent Effect on Azide Reactivity
Authors: Golas Patricia L. , Tsarevsky Nicolay V. , Matyjaszewski Krzysztof 
Published: May 2008

AbstractAn investigation was conducted into substituent effects on azide reactivity during CuI‐catalyzed click reactions by reacting a variety of model azides with propargyl alcohol in DMF‐d7 using CuBr as catalyst, and monitoring conversions via 1H NMR. The model azides utilized for this investigation were selected due to structural similarity with the end groups of polymers typically employed in azide‐alkyne cycloadditions including polystyrene, poly(methyl acrylate), poly(methyl methacrylate), and polyacrylonitrile. Reactivities of alkyl azides depend on both the electronic properties of the substituent and steric congestion around the end group. The fastest reactions were observed for azides with electron‐withdrawing substituents and less sterically congested end groups.magnified image
The Introduction of Pyrrolotetrathiafulvalene into Conjugated Architectures: Synthesis and Electronic Properties
Authors: Kanibolotsky Alexander L. , Forgie John C. , Gordeyev Sergey , Vilela Filipe , Skabara Peter J. , Lohr Jan E. , Petersen Bo M. , Jeppesen Jan O. 
Published: May 2008

AbstractA series of new conjugated copolymers incorporating the redox‐active pyrrolo‐TTF unit has been synthesised. The properties of the polymers have been investigated by cyclic voltammetry and electronic absorption spectroscopy, revealing that the pyrrolo‐TTF behaves very differently to its thieno‐TTF variant. In comparison to thieno analogues, the band gaps of the new polymers are wider than expected due to a decrease in the polarizability of the heteratom (nitrogen vs. sulfur) and steric interactions between repeat units. Whilst the pyrrolo‐TTF units are stronger electron donors than thieno‐TTFs in related structures, the two redox active elements of the new polymers (TTF and conjugated chain) function independently under oxidative conditions.magnified image
Micro‐Raman and Tip‐Enhanced Raman Spectroscopy of Carbon Allotropes
Authors: Hoffmann Günter G. , de With Gijsbertus , Loos Joachim 
Published: May 2008

AbstractSummary: Raman spectroscopic data are obtained on various carbon allotropes like diamond, amorphous carbon, graphite, graphene and single wall carbon nanotubes by micro‐Raman spectroscopy, tip‐enhanced Raman spectroscopy and tip‐enhanced Raman spectroscopy imaging, and the potentials of these techniques for advanced analysis of carbon structures are discussed. Depending on the local organisation of carbon the characteristic Raman bands can be found at different wavenumber positions, and e.g. quality or dimensions of structures of the samples quantitatively can be calculated. In particular tip‐enhanced Raman spectroscopy allows the investigation of individual single wall carbon nanotubes and graphene sheets and imaging of e.g. local defects with nanometer lateral resolution. Raman spectra of all carbon allotropes are presented and discussed.
Planar Array Transient Infrared Spectroscopy: A New Tool for the Time‐Resolved Analysis of Polymers
Authors: Pellerin Christian 
Published: May 2008

AbstractSummary: Planar array infrared spectroscopy (PA‐IR) was used for the first time to record transient infrared (TIRS) spectra. In proof‐of‐concept experiments, it was demonstrated that PA‐TIRS can record high quality spectra of common polymeric samples. It was shown the this new technique allows acquiring spectra in as little as 17 ms, opening the door to high speed, real‐time monitoring applications.
Spectroscopical Investigation of Ski Base Materials
Authors: Fischer Jorg , Wallner Gernot M. , Pieber Alois 
Published: May 2008

AbstractSummary: Raman spectroscopy was applied to perform a comprehensive morphological analysis of polyethylene (PE) ski base materials at different processing levels. The morphological characterization included determination and evaluation of Raman spectra and examination of the crystallinity values by differential scanning calorimetry (DSC). A good agreement between Raman and DSC crystallinity fractions was obtained, thus corroborating the Raman spectroscopy approach. While for the PE grade with the lowest average molar mass no significant morphological changes due to processing from the raw material via the extruded film to the post‐treated film was found, higher molar mass PE grades exhibited a decrease of crystallinity, but an increase of the amorphous fraction along the process chain.
Investigation of Lignins by FTIR Spectroscopy
Authors: Derkacheva Olga , Sukhov Dmitry 
Published: May 2008

AbstractSummary: Applying special computer mathematical treatments to increase resolution of experimental spectra there were established a set of stable characteristic bands for isolated softwood lignins. In the 740–1620 cm−1 spectral range the band maximum positions did not change but values of bandwidths and peak intensities were varied in limits 15% and 32%. After analysis of the infrared spectra of 30 investigated samples a softwood lignin spectral model was constituted. This model allowed to clear discrepancies in the bands parameters of different mild isolated (lignins of Bjorkman, Pepper and Freudenberg), dioxane and technical lignin spectra. It was helpful for studying lignin structure changes during degradation procedures.
Solid‐State NMR Studies of Polysaccharide Systems
Authors: Spěváček Jiří , Brus Jiří 
Published: May 2008

AbstractSummary: Two polysaccharide systems were studied by solid‐state NMR methods: (i) Chitin/glucan complexes. The 13C NMR spectra have shown that in samples isolated from the mushroom Pleurotus sp., the glucan content was always higher in stems than in pilei. While carbonyl lineshape in complex isolated from Aspergillus niger mycelium shows similar hydrogen bonding as in neat chitin, a significantly higher amounts of hydrogen bonding between carbonyl groups of chitin and hydroxy groups of glucan was found in complexes isolated from Pleurotus sp. (ii) Biodegradable starch/polycaprolactone (PCL) blends. From the relaxation times T1(H) and T1ρ(H) it follows that blends starch/PCL, starch/ester oligomers and starch formate/ester oligomers are phase‐separated even on the scale 20–110 nm. On the contrary, starch formate/PCL blend is phase‐separated on the scale 1–9 nm but homogeneously mixed on the scale 20–90 nm. Therefore formylation of starch significantly improves its miscibility with PCL.
Phase Behaviour of Poly(styrene‐co‐methacrylic acid)/ Poly(styrene‐co‐N,N‐dimethylacrylamide)/Poly(styrene‐co‐4‐vinylpyridine) Ternary Blends by DSC and FTIR
Authors: ElMiloudi Khaled , Djadoun Said 
Published: May 2008

AbstractSummary:we have investigated by DSC and FTIR the miscibility and phase behaviour of binary and ternary blends of different ratios of poly(styrene‐co‐methacrylic acid) containing 15 mol% of methacrylic acid (SMA15) with poly(styrene‐co‐N,N‐dimethylacrylamide) containing 17 mol% of N,N,‐dimethylacrylamide (SAD‐17) and poly(styrene‐ co‐4‐vinylpyridine) containing 15 mol% of 4‐vinylpyridine. SMA15 is miscible with both SAD17 and S4VP15 and interacts more strongly with S4VP15 than with SAD17 as evidenced by the positive deviations from linear average line observed with these blends and the appearance of new bands in the 1800–1550 cm−1 region. This behaviour is known as ΔK effect. The FTIR study confirms that though the specific intermolecular interactions that occurred with each pair of the SMA15/S4VP15 and SMA15/SAD17 binary components are of different strength, they still exist in the ternary blend. Even though the three binary polymer pairs are individually miscible, the ternary system of SMA15/S4VP15/SAD17 exhibits only partial miscibility with small loop of immiscibility due to a significant ΔK effect. These results obtained by DSC and FTIR are in a fair agreement with theoretical prediction applying the Painter‐Coleman association model.
In situ Fluorescence Study of Swelling, Sorption and Desorption Processes in and out of PAAm Gels
Authors: Evingur Gulşen Akın , Karslı Kadir , Pekcan Onder 
Published: May 2008

AbstractSummary: Small molecule sorption and desorption in and out of polyacrylamide (PAAm) gels were studied at various temperatures. Pyranine (Py) dissolved in water used as a probe. Fluorescence emission intensity, Ip from Py was monitored for studying sorption and desorption processes. Scattered light intensities, Isc from PAAm gel was also monitored to observed structural variations during sorption and desorption process. Li‐Tanaka model was applied to produce the swelling time constants, τc and sorption coefficients, Dc for the swelling processes. On the other hand, sorption and desorption processes were studied and coefficients were produced by using Fickian model. Related activation energies were also calculated from the corresponding physical processes.
Development of Methods to Determine the Infrared‐Optical Properties of Polymer Films
Authors: Oreski Gernot , Tscharnuter Daniel , Wallner Gernot M. 
Published: May 2008

AbstractSummary: In this paper, two methods for the determination of infrared optical properties of thick polymer films, based on FTIR spectroscopy, were implemented and used. Complex index of refraction data were generated for various ethylene copolymer films. Transmittance and reflectance spectra were measured in the mid infrared range using a gold‐coated 100 mm‐diameter integrating sphere. For the investigated films n and k values ranging from 1.3 to 1.6 and from 10−4 to 0.25 were determined, respectively. Regarding n, a good agreement was obtained for both methods, the transmittance/reflectance procedure (T/R method) used for transparent and semitransparent regions, and Single Substractive Kramers‐Kronig (SSKK) algorithm applied for non‐transparent regions. The highest k values were determined for the CH2 stretching vibration. The k values are dependent on comonomer content and film thickness. The combination of both methods allows for an accurate determination of n and k in the entire IR region relevant for solar application.
Monitoring of the Sol‐Gel Synthesis of Organic‐inorganic Hybrids by FTIR Transmission, FTIR/ATR, NIR and Raman Spectroscopy
Authors: Fischer D. , Pospiech D. , Scheler U. , Navarro R. , Messori M. , Fabbri P. 
Published: May 2008

AbstractSummary: The sol‐gel synthesis of organic‐inorganic hybrids based on triethoxysilane‐ terminated poly(ethylene oxide) and tetraethylorthosilicate was monitored in‐situ using three spectroscopic methods (FTIR/ATR, Raman, NIR). These spectroscopic methods allow in‐situ monitoring of the evolution of hybrid materials starting from the modification of the polymer and the early steps of hydrolysis up to the network formation. By application of 29Si solid‐state NMR spectroscopy the assignment and quantification of the Raman bands to different end groups and different cross‐linking states was made. The sol‐gel reaction was also followed by in‐line NIR spectroscopy. A multivariate data analysis was accomplished to obtain a conversion‐time curve. Furthermore, we investigated spin‐coated films on wafers using FTIR transmission spectroscopy.
Optical Spectra of Polygermane/Mesoporous Silica Nanocomposites
Authors: Ostapenko Nina , Kozlova Nata , Suto Shozo , Nanjo Masato , Mochida Kunio 
Published: May 2008

AbstractSummary: The monitoring of poly(di‐n‐hexylgermane) (PDHG) optical spectra in a variety of structures ranging from a bulk film to a nanosize polymer confined into a nanopore of SBA‐15 was performed using the fluorescence and fluorescence excitation spectra in the temperature range from 5 to 240 K as well as the absorption and FTIR spectra at room temperature. The observed data were compared with those obtained for poly(di‐n‐hexylsilane). It was shown that PDHG film absorption and fluorescence spectra strongly depend on the polymer thickness and consist of a number of bands which were assigned to centers with different amount of trans‐ and gauche‐ conformers of the polymer chains. Conformations of the polymer chains found in a thin film and in a 10 nm pore are similar while differing from the conformations of a thick film. Optical spectra of the confined PDHG are blue‐shifted relative to those of a thin film. The PDHG polymer chain conformation becomes disordered with the decrease of the polymer film thickness and the nanopore size from 10 to 6 nm.
Assessment of Beam Damage in Polymers Caused by in situ ESEM Analysis using IR Spectroscopy
Authors: Zankel Armin , Chernev Boril , Brandl Christian , Poelt Peter , Wilhelm Peter , Nase Michael , Langer Beate , Grellmann Wolfgang , Baumann Hans Joachim 
Published: May 2008

AbstractSummary: The environmental scanning electron microscope (ESEM) enables in situ analyses of non‐conducting samples such as polymers, thus allowing microscopic phenomena to be correlated to macroscopic measurement data. Unfortunately, irradiation of polymers with electrons always causes beam damage1 and it is unclear whether this damage could influence the outcome of the experiments. The amount of beam damage in polymers is mainly determined by the electron dose, which is a function of the probe current, the irradiation time, the irradiated area and the type of imaging gas used. The beam damage during in situ tensile tests of peel films was assessed using Fourier transformed infrared spectroscopy (FTIR). The band at 965 cm−1 turned out to be significant for the estimation of beam damage in this material, which was verified by long‐term measurements. The measurements were performed in an ESEM Quanta 600 FEG at parameters comparable to the prior in situ tensile tests. Additional measurements were performed in a Quanta 200 at parameters typical of in situ investigations. Again, the out‐of‐plane trans CH wag at 965 cm−1 turned out to be significant for beam damage and was used as an indicator for beam damage (dehydrogenation) for this type of material.
Orientation Dependent FT Raman Microspectroscopy on Hemp Fibers
Authors: Kovur S. K. , Schenzel K. , Diepenbrock W. 
Published: May 2008

AbstractSummary: FT Raman microspectroscopy was used for polarization experiments on strained hemp fibre cells. The cellulosic plant fibers were macerated with alkaline and enzymatic solutions. Those cleaned and refined single fiber cells were subjected to micro tensile tests as well as to polarization measurements under the FT Raman microscope. Mechanical parameters of the fiber cells (e.g. E‐modulus) were determined and changes in orientation of the (COC) structure units of the cellulose were considered with respect to fiber stress and molecular fiber structures. Intensity ratios R1 and R2 calculated on the polarized micro FT Raman spectra of the strained fibers describe the order parameter 〈P2〉 and 〈P4〉 allowing the quantitative determination of the orientation of the structure units (COC) of fiber cellulose with respect to the fiber cell axis.
The Structure of Aminopropylsiloxane Polymerized in DC Electric Field
Authors: Bistričić Lahorija , Volovšek Vesna 
Published: May 2008

AbstractSummary: The Raman spectra of aminopropylsiloxane (APS) polymerized on PVC substrate in DC electric field were measured to study the structure of deposited films. The modelling of low wavenumber Raman spectra was achieved using contribution of acoustic phonons, intramolecular vibrations as well as optical phonons related to librational motions of ladders. Results suggest that electric field influences the orientations of ladders increasing thus the degree of order in microdomains.
Indirect Measurement of the Cooperative Hydrogen Bonding of Polymers Using NMR Quadrupole Relaxation and PFG Methods
Authors: Kříž Jaroslav , Dybal Jiří 
Published: May 2008

AbstractSummary: A general method of measurement of polymer hydrogen bond (HB) cooperativity using a low‐molecular weight model ligand named marker and two independent methods of 2H NMR is presented. As marker, a deutero‐compound chemically similar to the functional groups of one of the polymers is used, e.g. pyridine‐d5 in the investigated interaction of poly(4‐vinylpyridine) with poly(4‐vinylphenol) or acetic acid‐d4 in the interaction of polyacrylic acid with poly(4‐vinylphenol) reported here. The method is based on the fact that a substantial fraction of the marker, originally bound to the groups of one of the polymers, is liberated by the cooperative interaction between the two polymers. For the establishment of the fraction of the bound marker before and after mixing the polymers, 2H NMR quadrupolar relaxation or 2H PFG NMR diffusion measurement can be used with comparable precision. In both these methods, the results must be normalized to a standard viscosity using the relaxation or diffusion of an added inert compound such as CDCl3.
Fourier‐Filtering Methods of Interference‐Patterned Spectra in Multivariate Calibration and Prediction for Sample Identification and Thickness Determination
Authors: Jeszenszky Éva , Kocsányi László , Barócsi Attila , Richter Péter 
Published: May 2008

AbstractSummary: Determining the thickness or identification of polymer materials with building a multivariate calibration model is based on the near infrared spectral information of the material. The spectrum of a thin plastic sheet is modulated by the interference of multiply reflected beams from the boundary surfaces and causes a disturbing signal component. On one hand, this yields unidentifiable samples or introduces large errors in the sample prediction set. On the other hand, interference‐patterned spectra have to be excluded from the calibration set. Fourier‐transformation of an interference‐patterned spectrum vs. wave number leads to a Fourier‐spectrum as a function of the optical path length (OPL) containing a well recognizable interference peak. After replacing these interference‐components and performing an inverse Fourier‐transformation, the spectra can be used for calibration or prediction. Two types of replacing were studied: the spline‐interpolation on Fourier‐ spectrum vs. OPL and a novel method based on linear approximation between Fourier‐spectra and thickness values. The effectiveness of each filtering method was tested on low‐density polyethylene and polypropylene sheets.
Interactions and Temperature Transitions of Ethylene Oxide – Propylene Oxide – Ethylene Oxide tri‐block Copolymers in Water Media
Authors: Schmidt Pavel , Dybal Jiří 
Published: May 2008

AbstractSummary: ATR FTIR spectra of two ethylene oxide – propylene oxide – ethylene oxide (EO)n‐(PO)m‐(EO)n tri‐block copolymers (Pluronics) with different lengths of the EO blocks were investigated in water media at various temperatures. The observed wavenumber shifts and intensity changes of the bands of different chemical groups of polymers and of water molecules served as a basis for the estimation of structural changes and interactions of polymers with the surrounding water molecules. Two types of such interactions, i.e. hydrophilic (ether group – water) and a hydrophobic (methyl group – water) are detected. In the copolymer with shorter length of the EO blocks, an interchain H2O bridge in a liquid crystalline phase was discovered and confirmed by ab initio calculations. A model for the structural changes during the temperature transitions is specified.
Absorption Study of Norfloxacin – DNA Interaction
Authors: Vijan L. E. , Conci M. 
Published: May 2008

AbstractSummary: Norfloxacin, a quinolone antibacterial reagent, has been studied with respect to its binding to calf thymus DNA using absorption spectroscopy. We examined the self‐association of the norfloxacin, in order to determine the molar absorption coefficient of the monomer, the molar absorption coefficient of the dimer and the dimerization constant. We also examined the interaction of norfloxacin with DNA by measuring the number of binding sites per DNA segment and the binding constant. Hypochromism, broadening of the envelope and a red‐shift in the drug absorption region are apparent for the norfloxacin that bound to DNA. The results were rationalized taking into account both self‐association of the drug and the cooperatively effects, in terms of several literature models, Benesi‐Hildebrand, Scott, Scatchard, Schwarz and Watanabe‐Schwarz.
Spectroscopic Study of Hedamycin – DNA Interaction
Authors: Vijan L.E. , Raducu A. 
Published: May 2008

AbstractSummary: Binding of hedamycin, a member of the antitumour antibiotics pluramycin class, to calf thymus DNA has been studied using UV‐Vis absorption spectroscopy. The results have been rationalized in terms of several literature models: Wolfe, Benesi‐Hildebrand, Scott and Scatchard.
Investigations on Multilayer Films: Electron Microscopy and Infrared Spectroscopy – Possibilities and Limitations
Authors: Chernev B. , Belegratis M. R. , Ingolič E. 
Published: May 2008

AbstractSummary: The study of multilayer films has become an important issue, since every year improved materials are produced. They have to be optimally designed in order to enable the maintenance of aroma, taste and nutritional value of the goods. This is primarily achieved by the use of special laminated films, additives and oxygen barriers. In addition, ecological and economical factors force the industry forwards to create more environmental‐friendly and cheaper films. In this study, two multilayer packaging films differing in the layer and barrier composition are examined with light microscopy (LM), transmission electron microscopy (TEM) and Fourier transformed infrared (FTIR) microspectroscopy: LM gives the number and the thickness of the layers, but there is no information about the chemical composition and the coatings. FTIR and Raman Spectroscopy enable the chemical characterization of the identified layers, but the lateral resolution is restricted in the µm range. TEM visualizes the important characteristics (coatings, filler particles) and enables the detection of inorganic fillers (EELS, EDX), but the organic components cannot be analyzed. Therefore, the use of complementary techniques is crucial in order to achieve a complete analysis of multilayer foils.Special attention was paid on the preparation procedure, since ultrathin sections are an important prerequisite for TEM observation and there is little known about the “perfect” preparation of multilayer films.