Fourier transform infrared spectroscopy study of the effect of pH on anion and cation adsorption onto poly(acrylo‐amidino diethylenediamine)

The role of hydrogen bonding in the chemistry of transition‐metal complexes remains a topic of intense scientific and technological interest. Poly(acrylo‐amidino diethylenediamine) was synthesized to study the effects of hydrogen bonding on complexes at different pHs. The polymer was synthesized through the coupling of diethylene triamine with polyacrylonitrile fiber in the presence of AlCl₃ · 6H₂O addition. The adsorption capacity of this polymer was 11.4 mequiv/g. The ions used for the adsorption test were CrO, PO, Cu²⁺, Ni²⁺, Fe²⁺, and Ag⁺. All experiments were confirmed with Fourier transform infrared. In the study of anion adsorption, at low pHs, only ionic bonds existed, whereas at high pHs, no bonds existed. However, in the middle pH region, both ionic bonds and hydrogen bonds formed between poly(acrylo‐amidino diethylenediamine) and the chromate ion or phosphate ion. When poly(acrylo‐amidino diethylenediamine) and metal ions (Cu²⁺, Ni²⁺, Fe²⁺, and Ag⁺) formed complexes, a hydrogen‐bonding effect was not observed with Fourier transform infrared. The quantity of metal ions adsorbed onto poly(acrylo‐amidino diethylenediamine) followed the order Ag⁺ > Cu²⁺ > Fe²⁺ > Ni²⁺. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2010–2018, 2004     

An Attenuated Total Reflection FT‐IR Spectroscopic Study of Polyamide 6/Clay Nanocomposite Fibers

Summary: An attenuated total reflection FT‐IR spectroscopic study of the hydrogen bonding, molecular orientation, and crystalline phase transitions in polyamide 6 (PA6)/clay nanocomposite (PA6CN) fibers is proposed. The nanoscale dispersed clay layers lowered the degree of order of hydrogen bonding, affected little the hydrogen bonding strength, and increased the degree of orientation of both γ crystalline and overall domains. A partial γ to α phase transition appeared with time.

Schematic representation of the attenuated total reflection FT‐IR dichroism measurements.     

Cu Crystal Growth on a Chelating Fiber with Different Amine Chain Lengths

Summary: Poly(acryloamidino ethyleneamine) (PAEA) and poly(acryloamidino diethylene diamine) (PADD) have been synthesized for the observation of Cu^II complex and Cu(OH)₂ crystal‐growth on the surface of different numbers of amino groups immobilized on polyacrylonitrile (PAN) fibers. The shape of Cu^II crystal growth depends on the amine chain length of the chelating fiber; Cu(OH)₂ crystals grow on the surface of the chelating fiber after Cu^II adsorption.

     

Micro‐FT‐IR study of stretching a single filament: Polymorphic transition in nylon 6

The polymorphic transition (γ → α conversion) in a single nylon 6 filament under stretching has been explored for the first time by using micro‐FT‐IR spectroscopy. The content of γ‐form deceases with straining while the amount of α‐form gradually increases, suggesting γ → α conversion. A two‐step mechanism, that is, melting and recrystallization, seems pertinent for the γ → α conversion considering that the γ‐form shows somewhat reversible and the α‐form keeps nearly intact upon unloading. Moreover, stress‐induced γ → α conversion at large strain can be well correlated with the molecular orientation in the amorphous phase and thus a serial arrangement between the γ crystals and amorphous phase along the stretching direction is proposed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 898–902, 2009     

Quantitative analysis of an organic thin film by XPS,AFM and FT‐IR

We report the characterization of Firpic (iridium(III)bis[4,6‐di‐fluorophenyl]‐pyridinato‐N,C²,]picolinate) organic thin film prepared by vacuum deposition to provide a systematic route to organic film quantification. To analyze the characteristics of thin Firpic films on a Si substrate, various techniques such as XPS, Fourier transform infra‐red (FT‐IR) spectrometer, and atomic force microscopy (AFM) are utilized. The Firpic films remain stable without surface morphological or compositional change during deposition and after exposure to X‐ray irradiation or atmospheric environment, for which qualities these films are believed to be an ideal platform as a pure organic thin film. The monotonic increases in FT‐IR and XPS intensities with film thickness are matching well with each other. In particular, from the XPS intensity analysis, the relative atomic sensitivity factors of the present system, electron attenuation length, and molecular density in the organic thin film can be evaluated. Copyright © 2011 John Wiley & Sons, Ltd.     

螯合吸附分离功能纤维的研究进展

螯合纤堆是一类能与金属离子形成多配位络合物的纤堆状吸附功能材料,是近年来发展起来的一种新型离子交换纤堆,具有吸附选择性高、易洗脱、容易再生等优点。综述了近年来螯合纤堆的制备方法及种类,对其螯合机理进行了探讨,概括了该纤堆的应用范围并指出了其应用前景。     

Main chain thermotropic liquid crystalline polyurethanes containing biphenyl mesogens based on novel AB‐type self‐polycondensation route: FT‐IR and XRD studies

The detailed mesophasic characterization of main chain liquid crystalline polyurethanes containing biphenyl mesogen, which were synthesized by the novel AB‐type self‐polycondensation approach, was carried out by using Differential Scanning Calorimetry (DSC), Polarized Optical Microscopy (POM), variable temperature X‐ray Diffraction (XRD), and Fourier Transform Infrared (FT‐IR) spectroscopic studies. The type of mesophase present in these polymers was identified to be the smectic A phase by POM and XRD studies. The smectic layer thickness was found to increase as the length of the spacer increased. The effect of temperature on the hydrogen bonding was analyzed by FT‐IR studies. The curve‐fitting analysis of the NH stretching and C?O stretching modes of vibrations indicated a gradual decrease in hydrogen bonding during the transition from the crystalline state to the mesophase. The mesophase to isotropic liquid transition was then accompanied by the complete disappearance of the hydrogen bonding. The biphenyl bands also showed changes during phase transitions due to the coupling of biphenyl vibration modes with the urethane linkage attached to it. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1903–1912, 2005     

Investigation of the Variation of Unit Cell Dimensions of Crystalline Polymers with High‐Resolution FT‐IR Spectroscopy

Summary: High‐resolution FT‐IR spectroscopy has been used for the first time to characterize the variation of the unit cell dimensions of high‐density polyethylene (HDPE). In combination with the unit cell parameters of HDPE measured at different temperatures by Swan using wide‐angle X‐ray diffraction, the relationship between the rocking band shift (730 cm⁻¹) and the change of the unit cell volume of HDPE has been established.

High‐resolution variable‐temperature FT‐IR spectra of HDPE rocking bands with decreasing temperature.     

FT‐IR Investigation into the miscible interactions in new materials for optical devices

In this article we determine the miscibility of azobenzene derivative (poly(4‐(N‐(2‐methacryloyloxyethyl)‐N‐ethylamino)‐4′‐nitroazobenzene)₉₀‐co‐(methyl methacrylate)₁₀)/poly(vinyl acetate) (PVAc) and azobenzene derivative/poly(vinyl chloride) (PVC) blends using Fourier Transform infrared (FT‐IR) spectroscopy. With this method we can clearly identify the exact interactions responsible for miscibility. In the azobenzene derivative 50:50PVAc blend new peaks were evident at 2960, 2890, 1237 and 959 cm^?1, these peaks depict miscible interactions. These wavenumbers indicate that the miscible interactions occurring are from the C? H stretching band, the vinyl acetate C?O, conjugated to the ester carbonyl, the cis‐transformation N?N stretch frequency and the acetate ester weak doublet. The azobenzene derivative 80:20PVC blend display peaks identical in profile to the blend homopolymers, indicating no miscible interactions. However, this could be due to overlapping of peaks within the same wavenumber region, making resolution difficult. This research demonstrates FT‐IR can deduce favorable interactions for miscibility and therefore numerous miscible blends can successfully be calculated if possessing the same groups responsible for miscibility. This paves the way for a new generation of designer optical materials with the desired properties. Copyright © 2003 John Wiley & Sons, Ltd.     

Pinecone‐like Cu(II) crystal growth on the surface of amine‐group‐immobilized polymers

Field‐emission scanning electron microscopy (FESEM) was used to monitor pinecone‐like Cu(II) crystal growth on polymeric fibers for various growth times. In FESEM images, Cu(II) complexes and Cu(OH)₂ crystal growth on poly(acryloamidino ethylene amine) and poly(acryloamidino diethylenediamine) were observed. Up to an elapsed time of 16 min, crystal growth was observed in only one direction. However, after an elapsed time of 20 h, pinecone‐like crystals covered the entire surfaces of the synthesized polymers. Fourier transform infrared spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy were used for analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1238–1247, 2005     

Surface characterization of medieval silver coins minted by the early Piasts: FT‐IR mapping and SEM/EDX studies

An investigation of a numismatic collection of silver denarii from the early Piast dynasty was conducted using Fourier‐transform infrared spectroscopy. The studied coins, minted between 995 and 1020 ad under the rules of Boleslaus the Brave and Mieszko II Lambert, belong to the collection of the National Museum in Kraków. Fourier‐transform infrared spectroscopy imaging and mapping have been used for recording a visual image of the surface chemistry based on vibrational spectra and accurately representing the distribution of chemical compounds, respectively. Additionally, scanning electron microscopy coupled to energy‐dispersive X‐ray analysis was used to study the surface topography of the coins and characterize their elemental composition. Differences in the distribution of the identified chemical compounds were detected in heterogeneous areas of the denarii. Corrosion effects, associated to many factors including the alloy composition, the metallographic structure, the manufacturing processes, and the environment were also observed and identified.     

FT‐IR characterization and hydrolysis of PLA‐PEG‐PLA based copolyester hydrogels with short PLA segments and a cytocompatibility study

A series of the biodegradable copolyester hydrogels was prepared using a redox‐initiated polymerization with a constant 1:9 mole ratio of the Boltorn‐based acrylate and diacrylate triblock comacromonomers. The Boltorn® macromonomer was derived from the hyperbranched polyester Boltorn H20, which was functionalized at each terminus with poly(ethylene glycol) acrylate, and the diacrylate triblock macromonomer was poly (lactide‐b‐ethylene glycol‐b‐lactide) diacrylate. The hydrolysis of the copolyesters at pH 7.4 in a phosphate buffered saline solution at 37 °C was studied using ATR‐FTIR spectroscopy. It was found that the presence of the Boltorn, the PEG, and lactide block lengths both play vital roles in determining the structure‐property relationships in these materials. The ATR‐FTIR studies showed that with increasing lactide segment length, the rate of ester hydrolysis increased due to the increased concentration of the hydrolytically sensitive poly(lactic acid) (PLA) ester groups in the network. However, incorporation of Boltorn into the PLA‐PEG‐PLA copolymer did not significantly change the kinetic rate constant for hydrolysis of the PLA segments. The cytocompatibility of a typical one of these materials in the presence of its degradation by‐products was assessed using cultured osteoblasts from the rat. The hydrogel was degraded for 28 days and found to be cytocompatible with osteoblasts over days 23 to 28 of the hydrolysis period. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5163–5176     

Analyses of the surfaces of concrete by Raman and FT‐IR spectroscopies: comparative study of hardened samples after demoulding and after organic post‐treatment

Concrete surfaces were studied by two spectroscopic techniques, FT‐IR (in ATR mode) and Raman, to establish a nondestructive method to analyze the distribution of hydrated and organic phases. The surface composition of ordinary clinker, polished concrete, concrete after demoulding, and coated concrete as used in building construction was studied. The clinker's mineral phases and the polished concrete were first analyzed by Raman spectroscopy to determine a spectrum database of the specific phases located on the surface of the concrete. Then, both spectroscopic techniques were used to analyze, directly, the surface of hardened concrete after demoulding. No impact of roughness or porosity was highlighted using Raman spectroscopy; many cementitious, or hydrated phases (alite, belite, tricalcium aluminate, ferrite, portlandite and ettringite) were clearly identified. FT‐IR in ATR mode only identified some hydrated phases: portlandite and CaO? SiO₂? H₂O (C? S? H), but organic residues from the demoulding oil were characterized by this technique. Furthermore, the convenience of using these techniques together was tested by analyzing the composition of concrete surfaces coated by different organic post‐treatments. FT‐IR spectroscopy was useful to identify the main organic groups at the concrete surface, whereas Raman spectroscopy was especially able to characterize the mineral/hydrated phases under a thick post‐treatment layer (constituted of polyester varnish). Due to their own specificities, these complementary techniques should be used together to easily identify all the mineral phases and organic residues/coatings on concrete surfaces. Copyright © 2010 John Wiley & Sons, Ltd.     

Quantitative determination and evaluation of Paris polyphylla var. yunnanensis with different harvesting times using UPLC‐UV‐MS and FT‐IR spectroscopy in combination with partial least squares discriminant analysis

A rapid method was developed and validated by ultra‐performance liquid chromatography–triple quadrupole mass spectroscopy with ultraviolet detection (UPLC‐UV‐MS) for simultaneous determination of paris saponin I, paris saponin II, paris saponin VI and paris saponin VII. Partial least squares discriminant analysis (PLS‐DA) based on UPLC and Fourier transform infrared (FT‐IR) spectroscopy was employed to evaluate Paris polyphylla var. yunnanensis (PPY) at different harvesting times. Quantitative determination implied that the various contents of bioactive compounds with different harvesting times may lead to different pharmacological effects; the average content of total saponins for PPY harvested at 8 years was higher than that from other samples. The PLS‐DA of FT‐IR spectra had a better performance than that of UPLC for discrimination of PPY from different harvesting times.     

Synthesis,crystal structures,spectral FT‐IR,NMR and UV–Vis investigations and Hirshfeld surface analysis of two new 2‐hydroxyethyl‐substituted N‐heterocyclic carbene precursors

This study discusses the synthesis of two new 2‐hydroxyethyl substituted N‐heterocyclic carbene (NHC) precursors. The NHC precursors were prepared from 1‐(alkyl/aryl)benzimidazole and alkyl halides. They were characterized using ¹H NMR, ¹³C NMR, FT‐IR, UV–Vis spectroscopy, and elemental analysis techniques. Molecular and crystal structures of 1 and 2 were determined using the single‐crystal X‐ray diffraction method. Crystal structure of the compounds features NHC precursors and chloride anions. Additionally in 2 , the asymmetric unit has a water molecule, which forms a tetrameric chloride‐hydrate assembly with the chloride anion. The chloride anions play an important role in the stabilization of crystal structures to form a two‐dimensional supramolecular architecture. The 3D Hirshfeld surface and the associated 2D fingerprint plots were also drawn to gain insights into the behavior of the interactions in the compounds.     

Highly Selective Molecularly Imprinted Polymer Sensor for Indium Detection Based on Recognition of In‐Alizarin Complexes

A highly selective molecularly imprinted polymer electrochemical sensor for In³⁺ detection was proposed. In³⁺ ion was chelated with alizarin red S to form a complex In‐ARS. The complex was used as the template molecule to prepare a molecularly imprinted polymer (MIP) based sensor. The selectivity of the sensor was improved significantly due to the three‐dimensional specific structure of the complex, and the selective complexation of ligands for metal ions. Moreover, the sensitivity of the proposed sensor was improved by recording the reductive current of ligand in complex. This technique was highly sensitive for quantitative analysis of In³⁺ in the concentrations ranged from 1×10^?8 mol/L to 2.5×10^?7 mol/L with a detection limit of 4.7×10^?9 mol/L. The proposed sensor has been successfully used in detecting In³⁺ in real samples.     

Miscibility and surface properties of fluorinated copolymer blends involving hydrogen‐bonding interactions

The miscibility and underlying hydrogen‐bonding interactions of blends of a fluorinated copolymer containing pyridine and a nonfluorinated copolymer containing methacrylic acid were studied with differential scanning calorimetry (DSC), transmission Fourier transform infrared (TX‐FTIR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS), whereas the surface properties of the blends were investigated with contact‐angle measurements, time‐of‐flight secondary‐ion mass spectroscopy, XPS, and attenuated total reflectance Fourier transform infrared spectroscopy. DSC studies showed that the presence of a sufficient amount of 4‐vinylpyridine units in the fluorinated copolymer produced miscible blends with the nonfluorinated copolymer containing methacrylic acid. TX‐FTIR and XPS showed the existence of pyridine–acid interpolymer hydrogen‐bonding interactions. Even though the anchoring effect of hydrogen bonding hindered the migration of the fluorinated component to the blend surface, it could not completely eliminate the surface enrichment of the fluorinated component and the surface rearrangement of the fluorinated pendant chain. The air–blend interface was mainly occupied by the fluorinated pendant chain, and the surface energies of the blends were extremely low, even with only 1.5 wt % of the fluorinated component in the blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1145–1154, 2004     

Synthesis,Characterization and Catalysis of Ce‐MCM‐41

The cerium‐containing MCM‐41 (Ce‐MCM‐41) has been synthesized by direct hydrothermal method. The low‐angle XRD patterns revealed the typical five major peaks of MCM‐41 type hexagonal structures. The interplanar spacing d₁₀₀ = 38.4 Å was obtained that can be indexed on a hexagonal unit cell parameter with a_o = 44.3 Å which was larger than that of pure siliceous MCM‐41 (Si‐MCM‐41). Transmission electron micrograph shows the regular hexagonal array of uniform channel characteristics of MCM‐41. The BET surface area of Ce‐MCM‐41 was 840 m²/g, which is much reduced as compared to that of Si‐MCM‐41, with the pore size of 26.9 Å and mesopore volume of 0.78 cm³/g were measured by nitrogen adsorption‐desorption isotherm at 77 K. Along with the results, the synthesized Ce‐MCM‐41 exhibited a well‐ordered MCM‐41‐type mesoporous structure with the incorporation of cerium. Using Ce‐MCM‐41 as a support, the Rh (0.5 wt%) catalyst exhibited very high activity for the NO/CO reactions.     

Novel biodegradable poly(butylene succinate)/poly(ethylene oxide) blend film with compositional and spherulite‐size gradients

Biodegradable poly(butylene succinate) (PBS)/poly(ethylene oxide) (PEO) polymer blend film with compositional gradient in the film thickness direction was prepared using a method of interdiffusion across the interface between the PBS and PEO layers at a temperature above the melting points of both the component polymers. The miscibility between PBS and PEO was confirmed by observation of the glass transition temperature by differential scanning calorimetry. The compositional gradient structure of PBS/PEO was characterized by microscopic mapping measurement of Fourier transform infrared spectra and dynamic mechanical thermal analysis. Furthermore, a new method for confirming the crystalline/crystalline compositional gradient structure through observing the crystallization behavior by POM (polarized optical microscopy) was put forward. A continuous gradient of the spherulite size along the film thickness direction was succeessfully generated in the PBS/PEO blend film. The compositional gradient blend was found to have significantly improved physical properties that cannot be realized for pure PBS, pure PEO, and even their homogeneous miscible blend system. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 368–377, 2005     

A Novel pH/Light‐Triggered Surface for DNA Adsorption and Release

A simple strategy for the immobilization of Cy3‐labeled single strand DNA (Cy3‐ssDNA) on a Si(001) surface and its release under control of both light and pH stimuli is presented. In order to prepare a dual pH/light‐triggered surface, positively chargeable azobenzene molecules are self‐assembled on the Si(001) surface. The surface wettability of this substrate can be changed under influence of both light and pH conditions. The substrates can be positively charged under mildly acidic conditions. The pH‐sensitive behavior of the film allows binding of Cy3‐ssDNA on the functionalized Si(001) surface through e?ective electrostatic interactions with the negatively charged polynucleotide backbone. Moreover, irradiation of the film with UVA light induces trans–cis isomerization of the azobenzene units on the surface. As a result, the binding a?nity for DNA decreases due to the changing surface hydrophilicity. In order to understand and control the reversible photoswitchable mechanism of this surface, water contact angles are measured after UVA and visible light irradiation. The release of DNA from a dual pH/light‐sensitive sample is performed using fluorescence microscopy. The results show that irradiation of the film with UVA light induces trans–cis isomerization of the photoresponsive azobenzene units; this leads to significant changes in the surface hydrophilicity and reduces the binding affinity for DNA.