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1.
X‐ray fluorescence measurements for O‐containing [polyethylene oxide, polyvinyl alcohol, polyvinyl methyl ether], CO‐containing [polyvinyl methyl ketone, polyethylene terephthalate], N‐containing [poly‐4‐vinylpyridine (P4VP), polyaniline oligomer (PAO)], and S‐containing [polyphenylene sulfide] substances are presented. Carbon Kα X‐ray emission spectra (XES) and X‐ray photoelectron spectra (XPS) are compared with our DFT calculations performed with the Amsterdam density functional (ADF) program. The combined analysis of valence XPS and carbon Kα XES allows us to determine the individual contributions from pσ‐ and pπ‐bonding molecular orbitals of the polymers. The ΔSCF calculations yield the accurate C1s core‐electron binding energies (CEBEs) for all carbon sites of the organic compound. We calculate all CEBEs of the model molecules using the ΔE KS approach. Our simulated C1s photoelectron and C Kα emission spectra are in good agreement with our measurements. We also obtain WD (work function and the other energies) values for the polymers and PAO from the difference between calculated (gas‐phase) and measured (solid) CEBE values. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 162–172, 2007  相似文献   

2.
Thin Ni layers were deposited onto clean polymethyl methacrylate (PMMA) and poly(styrene‐co‐acrylonitrile) (SAN) surfaces by a high vacuum thermal evaporation process. The resulting interfaces were studied by X‐ray photoelectron spectroscopy. The Ni deposition on PMMA changes the relative intensity of the C1s spectra associated with the O CO and C O carbon species, and modifies the shape of the O1s peak, while the Ni evaporation on SAN alters the C1s band intensity assigned to the CN moiety and gives a second N1s band at low binding energies. These observations suggest the formation of new chemical species at the interface between Ni and the PMMA ester group, and between Ni and the SAN nitrile group, which are the most reactive sites on these two polymers. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

3.
Poly(N‐acryloyl‐N′‐methylpiperazine) (PAMP) forms complexes with four strong acidic polymers, namely, poly(styrenesulfonic acid), poly(vinylphosphonic acid), poly(acrylic acid) and poly(methacrylic acid) in ethanol/water (1:1) solution. The nature of interpolymer interactions in various complexes was studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). Both the carbonyl oxygen and the amide nitrogen of PAMP are involved in hydrogen‐bonding interactions. Some of the amine nitrogens of PAMP are protonated and therefore PAMP also interacts with the acidic polymers through ionic interactions. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 501–508, 2000  相似文献   

4.
Various effects on the coupling selectivity of the oxidative polymerization of 4‐phenoxyphenol catalyzed by (1,4,7‐triisopropyl‐1,4,7‐triazacyclononane)copper(II) halogeno complex [Cu(tacn)X2] are described. With respect to the amount of the catalyst and the nature of the halide ion (X) of Cu(tacn)X2, the coupling selectivity hardly changed. The Cu(tacn) catalyst possessed a turnover number greater than 1860. As the temperature of the reaction and the polarity of the reaction solvent were elevated, the C O coupling at the o‐position increased, but the C C coupling was not involved. For the polymerization in toluene at 80 °C, poly(1,4‐phenylene oxide), obtained as a methanol‐insoluble part, showed the highest number‐average molecular weight of 4000 with a melting point (Tm) of 195 °C. Only a slight change in the coupling selectivity was observed in the presence or absence of hindered amines as the base. Surprisingly, however, the C O selectivity decreased from 100 to 24% with less hindered amines, indicating that the selectivity drastically changed from a preference for C O coupling to a preference for C C coupling. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4792–4804, 2000  相似文献   

5.
Water soluble alternating copolymers were prepared by oxidative free radical copolymerization of 4‐vinylbenzyl methoxypoly(oxyethylene) ether (PEGSt) and molecular oxygen at 50 °C. NMR spectroscopy established alternate sequence of PEGSt and peroxy bonds ( O O ) along the polymer main‐chain. The obtained polymers show temperature induced hydrophilic to hydrophobic phase separation, confirmed by UV‐visible spectroscopy and dynamic light scattering. The cloud point temperature (TCP) of the polymers can be tuned by changing the chain length of side‐chain poly(ethylene oxide) and incorporation of hydrophobic methyl methacrylate in the copolyperoxides. Exothermic degradation of these polyperoxides was confirmed by differential scanning calorimetry and the degradation products have been characterized by electron impact mass spectroscopy. Finally, N,N‐dimethylacrylamide was polymerized in the presence of these polyperoxides in toluene, highlighting their potential as polymeric free radical initiator during polymerization of vinyl monomers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2030–2038  相似文献   

6.
The miscibility and hydrogen‐bonding interactions of carbon dioxide and epoxy propane copolymer to poly(propylene carbonate) (PPC)/poly(p‐vinylphenol) (PVPh) blends were investigated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). The single glass‐transition temperature for each composition showed miscibility over the entire composition range. FTIR indicates the presence of strong hydrogen‐bonding interassociation between the hydroxyl groups of PVPh and the oxygen functional groups of PPC as a function of composition and temperature. XPS results testify to intermolecular hydrogen‐bonding interactions between the oxygen atoms of carbon–oxygen single bonds and carbon–oxygen double bonds in carbonate groups of PPC and the hydroxyl groups of PVPh by the shift of C1s peaks and the evolution of three novel O1s peaks in the blends, which supports the suggestion from FTIR analyses. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1957–1964, 2002  相似文献   

7.
Plasticized poly(vinyl chloride) (PVC) used for biomedical disposable devices was studied in the non‐sterilized state after different exposure times to soft x‐ray irradiation in a commercial photoelectron spectrometer (Al Kα, 15 kV/300 W; Mg Kα, 12 kV/240 W) by XPS surface analysis. The detailed spectra of C 1s, Cl 2p and O 1s have been recorded and processed. Irradiation with soft x‐rays induces a clear decrease of the total Cl 2p intensity, an increase of total C 1s intensity and a doubling of the O 1s intensity after 45 min of irradiation with Al Kα (300 W). Irradiation with Mg Kα (240 W) is slightly less damaging. These results can be interpreted with the classical PVC degradation model, e.g. bond cleavage with the formation of HCl gas, although the Cl 2p high‐resolution spectra reveal the formation of an additional side‐product, probably CaCl2. For further studies of plasticized PVC using XPS surface analysis it can be concluded that a complete analysis of a polymer sample should not take >10 min of x‐ray exposure in order to avoid notable polymer degradation. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

8.
Traditionally polymer depth profiling by X‐ray photoelectron spectroscopy (XPS) has been dominated by the damage introduced by the ion beam rather than the X‐rays. With the introduction of polyatomic and especially argon gas cluster ion‐beam (GCIB) sources for XPS instruments, this is no longer the case, and either source of damage may be important (or dominate) under particular conditions. Importantly, while ion‐beam damage is a near‐surface effect, X‐ray damage may extend micrometres into the bulk of the sample, so that the accumulation of X‐ray damage during long depth profiles may be very significant. We have observed craters of similar dimensions to the X‐ray spot well within the perimeter of sputter craters, indicating that X‐rays can assist GCIB sputtering very significantly. We have measured experimentally sputter craters in 13 different polymers. The results show that X‐ray exposure can introduce much more topography than might previously have been expected, through both thermal and direct X‐ray degradation. This can increase the depth of a crater by a remarkable factor, up to three in the case of poly‐L‐lactic acid and polychlorotrifluorothylene under reasonably normal XPS conditions. This may be a major source of the loss of depth resolution in sputter depth profiles of polymers. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

9.
A series of comb‐type polycarbosilanes of the type [Si(CH3)(OR)CH2]n {where R = (CH2)mR′, R′ = ? O‐p‐biphenyl? X [X = H (m = 3, 6, 8, or 11) or CN (m = 11)], and R′ = (CF2)7CF3 (m = 4)} were prepared from poly(chloromethylsilylenemethylene) by reactions with the respective hydroxy‐terminated side chains in the presence of triethylamine. The product side‐chain polymers were typically greater than 90% substituted and, for R′ = ? O‐p‐biphenyl? X derivatives, they exhibited phase transitions between 27 and 150 °C involving both crystalline and liquid‐crystalline phases. The introduction of the polar p‐CN substituent to the biphenyl mesogen resulted in a substantial increase in both the isotropization temperature and the liquid‐crystalline phase range with respect to the corresponding unsubstituted biphenyl derivative. For R = (CH2)11? O‐biphenyl side chains, an analogous side‐chain liquid‐crystalline (SCLC) polysiloxane derivative of the type [Si(CH3)(O(CH2)11? O‐biphenyl)O]n was prepared by means of a catalytic dehydrogenation reaction. In contrast to the polycarbosilane bearing the same side chain, this polymer did not exhibit any liquid‐crystalline phases but melted directly from a crystalline phase to an isotropic liquid at 94 °C. Similar behavior was observed for the polycarbosilane with a fluorocarbon chain, for which a single transition from a crystalline phase to an isotropic liquid was observed at ?0.7 °C. The molecular structures of these polymers were characterized by means of gel permeation chromatography and high‐resolution NMR studies, and the crystalline and liquid‐crystalline phases of the SCLC polymers were identified by differential scanning calorimetry, polarized optical microscopy, and X‐ray diffraction. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 984–997, 2003  相似文献   

10.
The effects of experimental conditions on the fractal structure of electrosynthetic polyparaphenylene films were studied by electrochemical impedance spectroscopy. The results indicate that, at the potential range (0‐0.6 V), the film surface fractal dimension rises while the corresponding charge transfer resistances Rct decrease as charge increases. This is consistent with the oxidized behavior of the conducting polymer. As for the degradation of electrolytes, scanning electron microscopy observations of poly(para‐pheneylene) (PPP) film provide evidence of the close relationship between the degradation of electrolytes and the film morphology, also in good agreement with the electrochemical impedance results interpretation. The X‐ray photoelectron spectroscopic analysis results present that the relative oxygen content ratio (O/C) of the films increases with the times the electrolyte is used, which reveals that the degradation of the electrolyte may result in a compact and passivation PPP film.  相似文献   

11.
The vacuum‐UV (VUV)‐induced conversion of commercially available poly(1,1‐dimethylsilazane‐co‐1‐methylsilazane) into methyl‐Si‐O‐Si networks was studied using UV sources at wavelengths around 172, 185, and 222 nm, respectively. Time‐of‐flight secondary ion mass spectroscopy (TOF‐SIMS), X‐ray photo electron spectroscopy (XPS), and Fourier transform infrared (FTIR) measurements, as well as kinetic investigations, were carried out to elucidate the degradation process. First‐order kinetics were found for the photolytically induced decomposition of the Si? NH‐Si network, the subsequent formation of the methyl‐Si‐O‐Si network and the concomitant degradation of the Si? CH3 bond, which were additionally independent of the photon energy above a threshold of about 5.5 eV (225 nm). The kinetics of these processes were, however, dependent on the dose actually absorbed by the layer and, in the case of Si‐O‐Si formation, additionally on the oxygen concentration. The release of ammonia and methane accompanied the conversion process. Quantum‐chemical calculations on methyl substituted cyclotetrasilazanes as model compounds substantiate the suggested reaction scheme. Layers <100 nm in thickness based on mixtures of poly(1,1‐dimethylsilazane‐co‐1‐methylsilazane) and perhydropolysilazane (PHPS) were coated onto polyethylene terephthalate (PET) foils by a continuous roll to roll process and cured by VUV irradiation by using wavelengths <200 nm and investigated for their O2 and water vapor‐barrier properties. It was found that the resulting layers displayed oxygen and water vapor transmission rates (OTR and WVTR, respectively) of <1 cm3 m?2 d?1 bar?1 and <4 g m?2 d?1, respectively.  相似文献   

12.
Degradation behaviors of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) layers on NiO in the presence of H2O at ambient pressure and dark conditions were studied using X‐ray photoelectron spectroscopy (XPS). Upon H2O exposure at 120 °C, partial oxidation of P3HT together with molecular water incorporation, but with the maintained local ring‐structure, were deduced by XPS. Valence band spectra of XPS evidenced that the partial oxidation of P3HT local structure could alter π‐conjugation systems of P3HT layers, forming additional electronic states close to its original highest occupied molecular orbital. For comparison, P3HT surface was also exposed to O2, and no change in the S 2p and C 1s spectra was found by O2 exposure at 120 °C, implying that H2O plays a major role at the initial stage of P3HT oxidation. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

13.
We covalently immobilized poly(ethylene oxide) (PEO) chains onto a fluorinated ethylene propylene copolymer (FEP) surface. On the FEP surface, aldehyde groups were first deposited by plasma polymerization of acetaldehyde or acrolein. Then, amino‐PEO chains were immobilized through Schiff base formation, which was followed by reduction stabilization with sodium cyanoborohydride. The PEO‐grafted polymer surfaces thus prepared were characterized by X‐ray photoelectron spectroscopy (XPS), atomic force microscopy, contact‐angle measurements, and protein adsorption. The dramatic increase in the C O intensity of the high‐resolution XPS C 1s spectrum, together with an overall increase in oxygen content, indicated the successful attachment of PEO chains onto the acetaldehyde plasma surfaces. The amount of grafted PEO chains depended on the superfacial density of the plasma‐generated aldehyde groups. The grafted monoamino‐PEO chains formed a brushlike structure on the polymer surface, whereas the bisamino‐PEO chains predominately adopted a looplike conformation. The PEO surface had a regular morphology with greater roughness than the aldehyde surface underneath. Surface hydrophilicity increased with the grafting of PEO. Also, the bisamino‐PEO‐grafted surface had slightly higher surface hydrophilicity than its monoamino‐PEO counterpart. These PEO coatings reduced fibrinogen adsorption by 43% compared with the substrate FEP surface. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2323–2332, 2000  相似文献   

14.
A novel anhydrogalactosucrose derivative 2′‐methoxyl‐O‐1′,4′:3′,6′‐dianhydro‐βD‐fructofuranosyl 3,6‐anhydro‐4‐chloro‐4‐deoxy‐αD‐galactopyranoside ( 4 ) was prepared from 3,6:1′,4′:3′,6′‐trianhydro‐4‐chloro‐4‐deoxy‐galactosucrose ( 3 ) via a facile method and characterized by 1H NMR, 13C NMR and 2D NMR spectra. The single crystal X‐ray diffraction analysis shows that the title molecule forms a two thee‐dimensional network structure by two kinds of hydrogen bond interactions [O(2) H(2)···O(7), O(5) H(5)···O(8)]. Its stability was investigated by acid hydrolysis reaction treated with sulfuric acid, together with the formation of 1,6‐Di‐O‐methoxy‐4‐chloro‐4‐deoxy‐βD‐galactopyranose ( 5 ) and 2,2‐Di‐C‐methoxy‐1,4:3,6‐dianhydromannitol ( 6 ). According to the result, the relative stability of the ether bonds in the structure is in the order: C(1) O C(5)≈C(3′) O C(6′)≈C(1′) O C(4′)>C(3) O C(6)≈C(1) O C(2′)>C(2′) O C(5′).  相似文献   

15.
Summary: The laser irradiation at 193 nm of a gaseous mixture of carbon disulfide and ethene induces the copolymerization of both compounds and affords the chemical vapour deposition of a C/S/H polymer, the composition of which indicates the reaction between two to three CS2 molecules and one C2H4 molecule. Polymer structure is interpreted on the basis of X‐ray photoelectron and FT‐IR spectra as consisting of >CS, >CC<,  CH2 CH2 , (CC)SnC4 − n,  C (CS) S ,  S (CS) S , and C S S C configurations. The gas‐phase copolymerization of carbon disulfide and ethene represents the first example of such a reaction between carbon disulfide and a common monomer.

Scheme showing the expected reaction of excited CS2 molecules with other CS2 molecules to form dimers, which then react with another CS2 molecule or add to ethene.  相似文献   


16.
In this work, aluminium (Alclad 2024‐T3) substrates were cleaned by an r.f. (13.56 MHz) plasma, using argon (Ar), oxygen (O2) and a mixture of O2/Ar (50:50) gases. The effectiveness of plasma cleaning was checked in situ using X‐ray photoelectron spectroscopy (XPS) and ex situ using water contact angle measurements. XPS O/Al surface atomic ratios are in excellent agreement with those of the crystalline boehmite and the pseudoboehmite. Oxygen O 1s peak‐fitting was used to quantify the proportion of hydroxyl ions and the functional composition on the aluminium surface: the surface cleaned with O2 plasma contains 50% of aluminium hydroxides, the ones cleaned with Ar plasma and with Ar/O2 plasma contain, respectively, 25 and 37% hydroxyl ions. The binding energy separation between Al 2p and O 1s is characteristic of AlO(OH). Thin SiOx films were subsequently deposited from a mixture of hexamethyldisiloxane (HMDSO) and oxygen. In the absence of oxygen, a hydrophobic (Θ≥ 100° ) film characteristic of polydimethylsiloxane (PDMS) is formed: polysiloxane‐like thinner films (SiOx) are obtained with the introduction of oxygen. XPS and contact angle measurements confirmed both the composition and the structure of these films. More importantly, contact angle measurements using different liquids and interpreted with the van Oss‐Good‐Chaudhury theory allowed determination of the surface free energy of the deposited films: the calculated values of surface tension of the film formed from HMDSO/O2: (50/50) are in excellent agreement with those of reference silica‐based materials such as a silicon wafer and cleaned glass. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

17.
The crystal structures of N‐aryl‐1,2,3,4‐tetrahydro‐3,3‐dimethyl‐2,4‐quinolinediones bearing methoxy‐ ( 1 ), methyl‐ ( 2 ), and chloro‐ ( 3 ) substituents in 2′‐position of the phenyl ring have been determined by X‐ray crystal structure analysis. The heterocyclic ring in 1–3 adopts an envelope conformation, with the smallest ring puckering in the ortho‐chloro derivative 3 . The N‐aryl ring is almost perpendicular with respect to the quinoline‐2,4‐dione ring. The corresponding dihedral angle values are 83.2(1)°, 80.0(9)°, and 83.4(2)° in 1, 2 and 3 , respectively. The hydrogen bond of C H⋅⋅⋅O type joins the molecules of the ortho‐methoxy derivative 1 into dimers. The supramolecular structure also contains two C H⋅⋅⋅π interactions that link the hydrogen‐bonded dimers into sheets. In ortho‐methyl derivative 2 , one C H⋅⋅⋅π interaction generates infinite chains, whereas two C H⋅⋅⋅O hydrogen bonds and three C H⋅⋅⋅π interactions in the ortho‐chloro derivative 3 form three‐dimensional framework. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:325–331, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20436  相似文献   

18.
A PdCl2‐catalyzed direct alkynylation of arylboronic acids to give diarylacetylenes is described. The optimal conditions using PdCl2 as catalyst, MeOH PhMe H2O as solvent and K2CO3 as base effectively suppressed the formation of homo‐coupling product and afforded moderate to good yield of the desired unsymmetrical coupling product. This reaction represents a Suzuki‐type sp2(C B)–sp(C X) cross‐coupling. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

19.
The surface modification of Ag/Ag2CO3 with Fe(III) ions has been achieved through simply photoreduction‐impregnation method. The obtained products were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and UV‐vis absorption spectroscopy. Under visible‐light irradiation (γ>420 nm), the Fe(III)/Ag/Ag2CO3 sample displays a higher photocatalytic activity and stability than pure Ag2CO3 and Ag/Ag2CO3 samples for the degradation of methyl orange (MO). The improved photocatalytic activity and stability of this ternary system could be ascribed to the synergetic effect between Ag nanoparticles and Fe(III) nanocluster. The metallic Ag nanoparticles cause an obviously enhanced visible‐light absorption to produce more photogenerated charges, while the Fe(III) works as an active site for the following oxygen reduction to reduce the recombination rate of photogenerated electrons and holes.  相似文献   

20.
Plasma polymerisation of N ‐isopropyl acrylamide (NIPAAm) presents an exciting route for the production of thermally responsive coatings on a wide variety of substrates for applications in tissue culture and microfluidics. One issue associated with the polymerisation of NIPAAm via plasma polymerisation is the limited volatility of the monomer and the subsequent requirement for monomer and reactor heating to create and maintain the vapour. It is already well established that power is critical in the balance between polymer functionality and coating stability in plasma polymers. However, little is known of how reactor and substrate temperatures may be used to influence the physico‐chemical characteristics of polymers produced from such low‐volatility monomers. In this paper, we examine the effects of a range of plasma deposition parameters on the functionality and stability of plasma‐polymerised NIPAAm surfaces. X‐ray photoelectron spectroscopy (XPS), near‐edge X‐ray absorption fine structure spectroscopy (NEXAFS), ellipsometry and contact angle goniometry have been used to examine coating chemistry, stability in aqueous environments, deposition rates and thermo‐responsive behaviour. Our results indicate that plasma polymerisation at low powers and low temperatures enhances the ability of plasma‐polymerised NIPAAm to display a wettability phase transition, but also contributes to instability of the coating to dissolution or delamination in water. Our spectroscopic measurements confirm that retention of the monomer structure is facilitated by low power and temperature deposition and reveal that conversion of the amide groups to amine and nitrile groups occurs during the polymerisation process, particularly at high discharge powers. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

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