摘要:

The interface between a flat solid surface and a cross‐linked elastomer can be considerably strengthened by the addition of chains (chemically identical to the elastomer) that are tethered by one end to the solid surface. At high grafting densities these coupling chains may, however, segregate from the elastomer and the adhesion may drop considerably. This important problem has been recently considered by de Gennesetal. in the case of a monodisperse ‘brush’. In this article we analyse the adhesion between a polydisperse brush and an elastomer, having in mind some very recent experiments by Marcianoetal. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49477

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The adhesive performance of thin aluminum coatings deposited onto polymer substrates is considered. The effects of the evaporation conditions and the metal thickness on the adhesive properties of polyester/aluminum assemblies are examined. A ultrasonic test for adherence measurements of thin metal layers is proposed and its shown that a thermal treatment under stress modifies the adhesive properties of such metallized polymer films. (AIP) ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49489

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The parameters which control the acid‐base properties of oxide surfaces are derived from quantum calculations of the adsorption of protons and hydroxyl groups, for a wide range of oxide ionicities and surface orientations. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49488

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The use of the molecular probe technique in conjunction with X‐ray photoelectron spectroscopy (XPS) for the assessment of acid‐base properties of polymer surfaces is reviewed. The method is based on the determination of the concentration and chemical shifts of Lewis acids (bases) sorbed in polymers of basic (acidic) character. In the case of chloroform (Lewis acid) sorbed in polymers of Lewis basic character,C12pbinding energy is linearly correlated with &Dgr;HAB, the heat of acid‐base complex formation chloroform‐polymer. This relationship has been used to determine the acid‐base properties of poly(phenylene oxide), a homopolymer, and ammonia plasma‐treated polypropylene. This work shows that XPS can now indeed be used to quantitatively assess the acid‐base properties of modified polymer surfaces and perhaps be extended to map acid‐base properties of polymer surfaces at the micron or submicron scale. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49479

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Experimental thermodynamic methods (adsorption isotherms and microcalorimetry) have been applied to the adsorption of &ggr;‐aminopropyl triethoxysilane and of more simple molecules (triethylsilanol., mono di and triethoxyalkylsilanes which have common reactive functions with the aminosilane molecule) on silica. It is shown that the amine function gives to the aminosilane molecule specific superficial properties: it catalyses (like in solution) the superficial hydrolysis of the ethoxy groups (as shown by the appearance of alcohol in the equilibrium solution) which allows subsequent grafting by siloxane bond with the surface. The influence of surface water on the siloxane bond formation is stressed for both the aminosilane and triethylsilanol molecules. Nevertheless, as shown by calorimetry and probe molecules (here phenol and pyridine) most NH2groups are also interacting with the surface. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49486

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The interface between evaporated Ti and PMDA/ODA polyimide is examined using several techniques. The formation of small TiO2particles at this interface (15 to 40 &mgr;m diameter, ca.30 nm thickness, covering about 6% of the interfacial area) is demonstrated. The failure is of cohesive type in the polymer layer. When the residual pressure during Ti evaporation is increased, the number of TiO2particles increases, adhesion of the Ti layer is lowered and the locus of failure is closer to the metal layer. When an oxygen plasma treatment is performed onto PMDA/ODA prior to Ti evaporation, the failure mode remains cohesive in the polymer layer. However the failure occurs at the modified/unmodified polymer limit.Abinitio(SCF) calculations were finally performed on models of the PMDA‐ODA polyimide in interaction with one Ti atom, in order to determine the most favorable interaction sites of this metal with the polymer. The most favorable interaction corresponds to the formation of a complex between Ti and the aromatic ring of the PMDA unit. Other possible sites of interaction are, in decreasing order of stability: the heterocycle of PMDA, the ≳C=O groups of PMDA and the ODA aromatic ring. Calculations of the core MO energies for the various model situations, show that it is not possible to account for the low energy C1s peak observed at ca.282 eV. Introduction in the model of a Ti atom bonded to one of the aromatic carbons permits to account for this peak. Thus, the existence of Ti‐C bonds in the polyimide‐Ti system is clearly confirmed. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49441

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Application of an anodic potential under recycled argon atmosphere to a highly concentrated solution of N‐vinyl‐2‐pyrrolidone (5 mol.dm−3) allows to graft and polymerise the monomer onto a Pt or Au electrode. XPS, UPS and IRRAS spectroscopies reveal the presence of thin PVP films on these surfaces. XPS data point to the formation of C‐metal bonds and support the grafting hypothesis of polymer chains onto the surface of the electrode. XPS and UPS studies performed after annealing indicate that the different structures of the polymer are stable up to 200 °C under ultra high vacuum and confirm the chemisorbed nature of the surface bond. A cationic mechanism is proposed for the grafting and the polymerisation. Preliminary attempts to relax the preparation conditions show that films can be obtained in ambient atmospheric conditions, but their thickness is reduced compared to those obtained under recycled argon conditions. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49451

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The study of 4‐vinylpyridine belongs to an experimental approach developed since the 80sin our laboratory, which consists in studying the ability of vinylic monomers to form under cathodic polarization (in a strictly controlled aprotic medium) high quality films, grafted and polymerized onto a metallic electrode. The electropolymerization of 4‐vinylpyridine was studied as a function of the monomer concentration in the electrolytic medium made of an aprotic polar solvent: acetonitrile, and supporting salts. During the electropolymerization performed under cyclic voltammetry, an adsorption pre‐peak on the I=f(V) curves, corresponding to the polymer formation on the electrode surface, only appears for high monomer concentrations. In fact, the best experimental conditions required to build a poly (4‐vinylpyridine) film were obtained when using an electrochemical medium made of pure monomer and supporting salts. Under cathodic polarization, anionic polymerization of 4‐vinyl pyridine is then able to develop and to lead to the formation, on the electrode surface, of a grafted (and so, insoluble) poly (4‐vinylpyridine) film, which appears chemically pure. Finally, the structure of the polymer on the electrode was characterized by IRRAS (infrared absorption reflexion spectroscopy) and XPS (X ray photoelectron spectroscopy) and was compared with the standard polymer structure. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49452

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The electrosynthesis, structural characterization, morphology, electrochemical and optical properties of poly‐(3‐cyclopromylmethylpyrrole) (PCMPy), a new, hydrophobic, conducting polymer, are reported in this communication. PCMPy films were obtained on Pt electrodes by electrooxidation of 0.1 M 3‐cyclopropylmethylpyrrole (CMPy) acetonitrile solutions in the presence of 0.1 M tetrabutylammonium perchlorate. These films present a strong electroactivity, and their conductivity (about 32 S cm−1), is comparable to that of unsubstituted polypyrrole. Scanning electron microscopy (SEM) data indicate that the structure of PCMPy films is more regular than that of poly(1‐methylpyrrole), and that small aggregates (about 0.4–0.5 &mgr;m diameter) are formed. The existence of acetonitrile‐soluble oligomers, observed using UV absorption spectrometry, is discussed. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49453

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The synthesis of poly(5‐amino 1‐naphthol) doped with heteropolyanions was performed by electropolymerizing 5‐amino 1‐naphthol in presence of PMo12. The doped film presents electrocalytic properties on the reduction of chlorate ions. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49454

出版商:AIP    

年代:1996

数据来源: AIP