Fabien Nekelson

ABS Polymer Electroless Plating through a One-Step Poly(acrylic acid) Covalent Grafting

A new, efficient, palladium- and chromium-free process for the electroless plating of acrylonitrile-butadiene-styrene (ABS) polymers has been developed. The process is based on the ion-exchange properties of poly(acrylic acid) (PAA) chemically grafted onto ABS via a simple and one-step method that prevents using classical surface conditioning. Hence, ABS electroless plating can be obtained in three steps, namely: (i) the grafting of PAA onto ABS, (ii) the copper Cu(0) seeding of the ABS surface, and (iii) the nickel or copper metallization using commercial-like electroless plating bath. IR, XPS, and SEM were used to characterize each step of the process, and the Cu loading was quantified by atomic absorption spectroscopy. This process successfully compares with the commercial one based on chromic acid etching and palladium-based seed layer, because the final metallic layer showed excellent adhesion with the ABS substrate.

Nonlinear absorption properties of some 1,4,8,11,15,18,22,25-octaalkylphthalocyanines and their metallated derivatives

The third-order nonlinear optical properties of a series of 15 unmetallated and metallated 1,4,8,11,15,18,22,25-octaalkylphthalocyanines have been investigated. The palladium-metallated compound is the strongest nonlinear absorber of the series, but, due to its comparatively high linear absorption coefficient, it exhibits a relatively low ratio of excited- to ground-state absorption cross-sections (κ) when compared to the other compounds. The highest values for κ were found for derivatives metallated with indium and lead. The nickel-metallated compounds are the weakest nonlinear absorbers, indicating that they are unsuitable as potential materials for practical passive optical limiters. Phenomenologically, the data for κ and the saturation energy density (Fsat) were found to follow trends dependent upon the linear absorption coefficient. This may have some implications for the design of phthalocyanines for nonlinear optical applications.

Tunable grafting of functional polymers onto carbon nanotubes using diazonium chemistry in aqueous media

In this work, we present an efficient grafting of functional polymers onto multi-walled carbon nanotubes using a simple and versatile chemical process carried out in open air and in aqueous media. The method involves in situreduction of substituted (–COOH, –NH2, –F…) aryl diazonium salts which yields poly(phenylene)-like coatings covalently grafted on the nanotube surface. Tuning the concentration of in situ generated diazonium was found to be an efficient way to control the total amount of grafted polymer. Functionalized nanotube samples were studied by complementary techniques such as electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy.

Stepwise syntheses of complex μ-oxo-linked heterochromophore arrays containing phthalocyanine, porphyrin and subphthalocyanine ligands

The article reviews the exploitation of the serendipitous discovery that dihydroxysilicon 1,4,8,11,15,18,22,25-octakis(hexyl)phthalocyanine 1 reacts at one face only to form a μ-oxo linked bond to dichlorosilicon phthalocyanine. Reaction of 1 with dihydroxysilicon octaethylporphyrin led to an unstable μ-oxo linked Pc-O-Pn heteroligand dyad that could not be isolated. However, reaction with dihydroxygermanium octaethylporphyrin gave a stable dyad that showed substantial broad band absorption attributable to exciton effects. A small amount of the μ-oxo linked homo dyad formed by self-condensation of dihydroxygermanium octaethylporphyrin was detected by MALDI-TOF mass spectrometry but was not isolated. Reaction of 1 with chloroboron subphthalocyanine afforded the stable Pc-O-SubPc heterodyad as the main product and the SubPc-O-Pc-O-SubPc triad as a minor side product. Both gave absorption spectra that showed the main features of the ligands present, implying limited exciton coupling. A further reaction of 1 with axial-hydroxy, axial-methyl silicon phthalocyanine provided a key Pc-O-Pc′ dyad that proved to be an ideal intermediate for developing a synthetic strategy to access a series of hetero-metalloid/hetero-ligand Pc-O-Pc′-O-Pn triads. X-ray structural data for examples of these arrays are discussed. A feature of the triad compounds is their very broad band absorption spectra that extends from the UV through the visible region to near IR wavelengths.

A remarkable side-product from the synthesis of an octaalkylphthalocyanine: formation of a tetrabenzotriazaporphyrin.

1,4,8,11,15,18,22,25-Octahexyl-29H,31H-tetrabenzo[b,g,l,q][5,10,15]triazaporphyrin has been isolated as the main side product in the preparation of 1,4,8,11,15,18,22,25-octahexylphthalocyanine via a lithium pentyloxide induced cyclotetramerisation of 3,6-dihexylphthalonitrile.