X-ray photoelectron spectroscopic study of poly[4,4′-isopropylidenebis(1,4-phenyleneoxyethylene) diacrylate] photocured in the presence of a fluorine containing monomer

A preliminary X-ray photoelectron spectroscopic (XPS) investigation on poly[4,4′-isopropylidenebis(1,4-phenyleneoxyethylene) diacrylate] samples obtained by photocuring on several substrates in the presence of a fluorine containing acrylic monomer is reported. Quantitative calculations based on F_1s/C_1s area ratios and C_1s peak fitting show a noticeable fluorine surface enrichment that ranges, depending on the substrate, from 17 wt.-% to 59 wt.-% of fluorine containing moiety. The calculations also reveal the presence of a concentration gradient at the surface.     

An ESCA investigation of the inductively coupled RF plasma polymerization of fluoronaphthalene and fluoronaphthalene/hydrogen mixtures

1-Fluoronaphthalene was plasma polymerized and its composition and structure, as a function of position, power, and temperature, were examined by ESCA. The F:C ratio of the deposited film was lower than that of the starting monomer both at room temperature and at 150°C. An asymmetry of the main C_1s photoionization peak was noted. Plasmas were also excited in fluoronaphthalene/hydrogen mixtures where extensive fluorine elimination and hydrogen incorporation occurred. This gave direct evidence that the height of step function or asymmetry of the main C_1s peak is related to the degree of saturation in the compound.     

Carbon-Fluorine Bondings of Fluorinated Fullerene and Graphite

Carbon-fluorine bondings of fluorinated fullerenes and fluorine-graphite intercalation compound C_xF were investigated in detail on the basis of XPS data and the potential model using the charge distribution calculated by semiempirical method. It has been confirmed by the present study that two peaks in the C_1s spectra observed for fluorinated fullerenes are assigned to carbon atoms bonded to fluorine atoms and those unbound to fluorine atoms, and the small difference in charges and Madelung potentials of fluorine atoms in different circumstances well explains the single peak in F_1s spectra of fluorinated fullerenes. In the calculated structures of 1,3-C₆₀F₂ and 1,2-C₆₀F_x (x = 2?6) used as the models of C_xF, three kinds of carbon-fluorine bondings were observed corresponding to nearly ionic, semicovalent and covalent C? F bondings. The calculated result supports that the bi-intercalation structure of stage 1 C_xF consists of nearly ionic and semi-covalent fluorines.     

ESCA applied to polymers. XXVI. Investigation of a series of aliphatic,aromatic, and fluorine-containing polycarbonates

The absolute and relative binding energies for the C_1s, O_1s, and F_1s core levels have been determined using x-ray photoelectron spectroscopy (ESCA) for a series of aliphatic, aromatic, and fluorine-containing polycarbonates. Comparisons of these experimentally determined, core-level binding energies with theoretical calculations using the ground-state potential model in the CNDO/2 SCF MO formalism as well as model compounds have been made on the C_1s and O_1s core levels. The degree of polymerization for low-molecular-weight fluorine-containing polycarbonates, as determined from ESCA measurements, is compared to measurements by vapor-phase osmometry and ¹⁹F-NMR.     

XPS STUDIES ON SURFACE MODIFIED POLY [1-(TRIMETHYLSILYL)-1-PROPYNE] MEMBRANES Ⅱ SURFACE MODIFICATION BY BROMINE VAPOR*

Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm~(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.     

Transfer reaction of the polystyrene radical with electron-acceptor molecules of tetrachlorophthalanhydride

The transfer constants (C_s) of the polystyrene radical with some derivatives of phthalic acid have been determined. Among the agents used, tetrachlorophthalanhydride (TCPA) differs distinctly from other compounds by its value of C_s 3·1 × 10^?3 for thermal and 3·4 × 10^?3 for initiated polymerization of styrene. The values of C_s for phthalanhydride, dimethyl phthalate, and tetrachlorodimethyl phthalate are lower by two decimal orders. The considerable decrease in the degree of polymerization of styrene prepared in the presence of TCPA is mainly attributed to the increased reactivity of chlorine atoms in TCPA induced by the acceptor effect of anhydride ring. Participation of a TCPA-styrene complex in transfer reaction has been assumed but not proved.     

Surface characterization of immunosensor conjugated with gold nanoparticles based on cyclic voltammetry and X-ray photoelectron spectroscopy

This investigation describes the surface characterization of rabbit immunoglobulin G (IgG) conjugated with gold nanoparticles. Goat anti-rabbit immunoglobulin G tagged with 5 nm gold nanoparticles was applied to detect the IgG. Then, the autocatalyzed deposition of Au³⁺ onto the surface of anti-IgGAu increased the surface area per gold nanoparticle. The immobilization chemistries and the atomic concentrations of Au_4f, P_2p, S_2p, C_1s, N_1s and O_1s of the resulting antibody-modified Au electrodes were determined by X-ray photoelectron spectroscopy (XPS). The sulfur that is involved in the cysteamine binding and the enlargement of the gold nanoparticles are identified using cyclic voltammetry. The results reveal that the surface area per gold particle, following the autocatalyzed deposition Au³⁺ on the surface of anti-IgGAu, was approximately seven times higher than that before deposition.     

Theoretical and experimental X-ray photoelectron spectroscopy investigation of ion-implanted nafion

The membrane properties of a Nafion surface can be modified by ion implantation with N⁺ or F⁺. The results are presented of an X-ray photoelectron spectroscopy (XPS) study of implanted surfaces. For the interpretation of the XPS spectra, calculations using a semiempirical quantum chemical formalism (AM1) have been applied, in conjunction with a charge-potential model, to predict the C_1s core electron binding energies. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 551–556, 2004     

Dynamic viscosity of dilute aqueous solutions of poly(acrylic acid) at frequencies of 2–500 kHz

The dynamic viscosity of aqueous solutions of poly(acrylic acid) at a polymer concentration of ca. 0.15 g/100 ml has been measured at frequencies from 2 to 500 kHz as a function of degree of polymerization P, degree of neutralization α, and salt (NaCl) concentration C_s. Relaxation spectra have been obtained from the dynamic viscosity. The spectra in the short relaxation time region can be approximated by the Zimm theory for the conformational relaxation of nonionic polymers. The maximum relaxation time τ₁ of the Zimm spectra is proportional to P² and depends rather moderately on α and C_s. Increased deviation is found, however, in the long relaxation time region, in particular for high values of P and α and low values of C_s. The major part of the deviation is interpreted in terms of rotational relaxation of a molecule as a whole. The rotational relaxation time τ_R is proportional to P³ and increases with increasing α and decreasing C_s. The remaining part of the excess spectra located between τ₁ and τ_R is ascribed to the deviation of the conformational relaxation from the Zimm theory arising from ionization of the polymer.     

Cellulose surface grafting with polycaprolactone by heterogeneous click-chemistry

This work deals with a new approach of grafting cellulose surface fibres by polycaprolactone macromolecular chains in heterogeneous conditions via click-chemistry. Thus, cellulose esters were prepared by reacting Avicel with undecynoic acid, in order to prepare cellulose substrate bearing multiple CC-terminated hairs. The prepared modified Avicel substrates were characterised by FTIR, XPS spectroscopy, elemental analyses and showed that the grafting have indeed occurred. The degree of substitution of the prepared cellulose esters was around 0.1. In parallel, polycaprolactone-diol (PCL) was converted to azido-derivative and the ensuing products characterised by FTIR and ¹³C-NMR spectroscopy. Both methods confirmed the success of such modification. Finally, cellulose esters were reacted with azido-PCL grafts in heterogeneous conditions through “click chemistry”. The thus prepared modified cellulose substrates were characterized by FTIR and XPS spectroscopy as well as elemental analyses. The three techniques confirmed the occurrence of the grafting. A weight gain of 20% was achieved.     

单分散水溶性金纳米团簇的制备及表征

采用改进的Brust方法,用硼氢化钠还原氯金酸,并以巯基丁二酸(MSA)、氮乙酰基半光胺酸(NAC)作为包裹剂,成功制备了单分散的水溶性金纳米团簇。高分辨透射电镜(HRTEM)结果表明,增大硫醇与氯金酸的比例并增加氯金酸的初始浓度,有利于得到尺寸更小的金纳米粒子。当氯金酸的浓度(C_Au)为9.3 mmol·L^-1,C_Au:C_S为1:30时,得到了直径约为1 nm、标准偏差为0.2 nm的Au@MSA纳米团簇。结合紫外(UV)、热重(TG)和X射线光电子能谱(XPS)分析结果,可以推测出单分散金纳米簇的化学式为[Au₃₈(MSANa)₂₆]或[Au₃₉(MSANa)₂₇]。     

Electrochemical Oxidation of Methionine Mediated by a Fullerene‐C60 Modified Gold Electrode

The usefulness of a C₆₀‐fullerene modified gold (Au) electrode in mediating the oxidation of methionine in the presence of potassium ions electrolyte has been demonstrated. During cyclic voltammetry, an oxidation peak of methionine appearing at +1.0 V vs. Ag/AgCl was observed. The oxidation current of methionine is enhanced by about 2 times using a C₆₀ modified gold electrode. The current enhancement is significantly dependent on pH, temperature and C₆₀ dosage. Calibration plot reveals linearity of up to 0.1 mM with a current sensitivity of close to 50 mA L mol^?1 and detection limit of 8.2×10^?6 M. The variation of scan rate study shows that the system undergoes diffusion‐controlled process. Diffusion coefficient and rate constant of methionine were determined using hydrodynamic method (rotating disk electrode) with values of 1.11×10^?5 cm² s^?1 and 0.0026 cm s^?1 respectively for unmodified electrode while the values of diffusion coefficient and rate constant of methionine using C₆₀ modified Au electrode are 5.7×10^?6 cm² s^?1 and 0.0021 cm s^?1 respectively.     

Enhanced radical scavenging activity of polyhydroxylated C<Subscript>60</Subscript> functionalized cellulose nanocrystals

A first demonstration of conjugated polyhydroxylated fullerene (C₆₀(OH)₃₀) on the surface of cellulose nanocrystals (CNC)s is reported. These nanohybrids display favourable antioxidant performance and are an attractive alternative to derivatized fullerene nanocages reported previously. UV–Vis measurements indicated that the C₆₀(OH)₃₀-CNC system scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals to a greater degree than C₆₀(OH)₃₀ alone, due to the nucleation of C₆₀(OH)₃₀ on the surface of CNC and high colloidal stability of the engineered nanohybrid. A mechanism for the 2-stage process of the radical reaction with C₆₀(OH)₃₀-CNC is proposed, and modelled by pseudo-first order kinetics. Successful grafting of C₆₀(OH)₃₀ on CNC was confirmed by FTIR, while TEM revealed the morphology of the system with a grafting degree of 20.8 % C₆₀(OH)₃₀. Zeta potential measurements of C₆₀(OH)₃₀-CNC in aqueous solution showed a high stability in the pH range 4.0-8.0, indicating functionality of the CNC based antioxidant system as a biocompatible and sustainable protocol with potential for use in personal care applications.     

Repair of defects created by Ar+ sputtering on graphite surface by annealing as confirmed using ToF‐SIMS and XPS

Defects were created on the surface of highly oriented pyrolytic graphite (HOPG) by sputtering with an Ar⁺ ion beam, then characterized using X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) at 500°C. In the XPS C1s spectrum of the sputtered HOPG, a sp³ carbon peak appeared at 285.3 eV, representing surface defects. In addition, 2 sets of peaks, the C_x⁻ and C_xH⁻ ion series (where x = 1, 2, 3...), were identified in the ToF‐SIMS negative ion spectrum. In the positive ion spectrum, a series of C_xH₂^+• ions indicating defects was observed. Annealing of the sputtered samples under Ar was conducted at different temperatures. The XPS and ToF‐SIMS spectra of the sputtered HOPG after 800°C annealing were observed to be similar to the spectra of the fresh HOPG. The sp³ carbon peak had disappeared from the C1s spectrum, and the normalized intensities of the C_xH⁻ and C_xH₂^+• ions had decreased. These results indicate that defects created by sputtering on the surface of HOPG can be repaired by high‐temperature annealing.     

Synthesis and characterization of cellulose-g-polyoxyethylene (2) hexadecyl ether solid–solid phase change materials

A series of novel solid–solid phase change materials, namely, cellulose-g-polyoxyethylene (2) hexadecyl ether (Cellulose-g-E₂C₁₆) copolymers, were synthesized using toluene 2,4-diisocyanate (TDI) as a coupling reagent in the ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). The optimum prepolymerization conditions were determined to be 25 °C and 75 min without catalyst, and the optimum reaction conditions of the grafting step were 90 °C, 6 h and 0.1 wt% dibutyltin dilaurate (DBTDL, weight percent of TDI). The successful grafting was confirmed by FTIR and ¹H-NMR. The properties of the Cellulose-g-E₂C₁₆ copolymers were investigated by DSC, TG and XRD. It is shown that the heat storage ability and phase change temperature of Cellulose-g-E₂C₁₆ copolymers depended on the degree of substitution. The crystalline type of the grafted E₂C₁₆ was not affected by the cellulosic backbone. Compared with E₂C₁₆, Cellulose-g-E₂C₁₆ copolymers showed better thermal stability. They are expected to be widely applied in the area of thermal energy storage.     

Types of Inorganic Fluorocarbon Polymer Materials and Structure–Property Correlation Problems

The paper reviews published data on the structure and composition of two large classes of inorganic polymer fluorocarbon materials (IP FCMs), including hightemperature (HT) and lowtemperature (LT) modifications of graphite fluorides and fluorographitelike compounds CF _x (x = 0.5 – 1.12$) and CF_1+y (y = 0.08 – 1.33$) and intercalated fluorographite compounds (IFGCs) based on C _x F (x < 2) matrices. According to Xray diffraction data, C1s and F1s Xray photoelectron spectroscopy (XPS), ¹³C and ¹⁹F NMR, CK and FK Xray spectroscopy, and IR and Raman spectroscopy, as well as MNDO calculations, the structure of monolayers and the properties of IP FCMs of C₂F – CF_1+y composition depend on the combination of C(sp ³) – F fragments bonded to the sp ² fragments of the starting carbon matrices. The structure of hightemperature CF_1+y is specified by the presence of structurally isolated external and internal C(sp ³)F₂ groups located on the boundaries of C(sp ³) – F skeleton monolayers and in the holes of their nanostructures, respectively. The enthalpy of formation of HT FCMs does not depend on the type of starting carbon material and is linearly proportional to the F/C atomic ratio; C(sp ³)F and C(sp ³)F₂ groups are chemically indistinguishable in HT FCMs. Six models for the structure of C₂F and C₄F monolayers in LT FCMs are considered. The best agreement with spectroscopy and MNDO data is obtained using modified Yudanov–Gornostaev's model for C₂F, in which alternating rows of graphitelike sp ² carbon fragments coexist with rows of bonded perfluorocyclohexane sp ³ cells. For lowtemperature C₂₄F–C₂F, electric conductivity and C1s and F1s XPS data are generalized and composition–property diagrams are constructed. In this case, the conductivity, C1s and F1s XPS, and the interplanar distances in monolayers are explained using the concept of planarity of C _x F monolayers and the ensuing ideas of semiionic and semicovalent C=F bonds. For C₄F · yA–C₂F · zA compositions, ¹³C and ¹⁹F NMR data, C1s and F1s XPS, and IR data are accounted for by the predominant sp ³ nature of the structureforming C=F bonds.     

用XPS表征聚苯乙烯-丙烯酸辐射接枝共聚物

应用ESCA研究辐射接枝共聚物的文章已有报道。然而,有关聚苯乙烯-丙烯酸辐射接枝共聚物的表征工作报导甚少。本文用X-光电子能谱(XPS)研究了聚苯乙烯-丙烯酸辐射接枝共聚物,并通过不同环境碳不同位置的峰面积之比表征接枝率。     

Density functional calculation of core‐electron binding energies of isomers of C3H6O2 and C3H5NO

The core‐electron binding energies of six isomers of C₃H₆O₂ and four isomers of C₃H₅NO were calculated by a DFT/uGTS/scaled‐pVTZ approach. An average absolute deviation from experiment of 0.15 eV was found for 14 C, N, and O 1s energies. The results confirm the distinctive nature of the X‐ray photoelectron spectra (XPS) of isomers and support the use of electron spectroscopy complemented by accurate theoretical predictions as a tool for chemical analysis. © 1999 John Wiley & Sons, Inc. Int J Quant Chem 76: 44–50, 2000     

Molecular adsorption and the chemistry of plasma-deposited thin organic films: Deposition of oligomers of ethylene glycol

Weakly ionized, radio-frequency, glow-discharge plasmas formed from methyl ether or the vapors of a series of dimethyl oligo(ethylene glycol) precursors (general formula: H-(CH₂OCH₂)_n-H;n=1 to 4) were used to deposit organic thin films on polytetrafluoroethylene. X-ray photoelecton spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS) of the thin films were used to infer the importance of adsorption of molecular species from the plasma onto the surface of the growing, organic film during deposition. Films were prepared by plasma deposition of each precursor at similar deposition conditions (i.e., equal plasma power (W), precursor flow rate (F), and deposition duration), and at conditions such that the specific energy (energy/mass) of the discharge (assumed to be constrained byW/FM, whereM=molecular weight of the precursor) was constant. At constantW/FM conditions, two levels of plasma power (and, hence, twoFM levels) and three substrate temperatures were examined. By controlling the energy of the discharge (W/FM) and the substrate temperature, these experiments enabled the study of effects of the size and the vapor pressure of the precursor on the film chemistry. The atomic % of oxygen in the film surface, estimated by XPS, and the intensity of theC-O peak in the XPS C_ls spectra of the films, were used as indicators of the degree of incorporation of precursor moieties into the plasma-deposited films. Analysis of films by SIMS suggested that these two measures obtained from XPS were good indicators of the degree of retention in the deposited films of functional groups from the precursors. The XPS and SIMS data suggest that adsorption of intact precursor molecules or fragments of precursor molecules during deposition can have a significant effect on film chemistry. Plasma deposition of low vapor pressure precursors provides a convenient way of producing thin films with predictable chemistry and a high level of retention of functional groups from the precursor.     

Miscibility and hydrogen‐bonding interactions in blends of carbon dioxide/epoxy propane copolymer with poly(p‐vinylphenol)

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 C_1s peaks and the evolution of three novel O_1s 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