Alexandre Beigbeder

Preparation and characterisation of silicone-based coatings filled with carbon nanotubes and natural sepiolite and their application as marine fouling-release coatings

This article reports on the preparation and partial characterisation of silicone-based coatings filled with low levels of either synthetic multiwall carbon nanotubes (MWCNTs) or natural sepiolite (NS). The antifouling and fouling-release properties of these coatings were explored through laboratory assays involving representative soft-fouling (Ulva) and hard-fouling (Balanus) organisms. The bulk mechanical properties of the coatings appeared unchanged by the addition of low amounts of filler, in contrast to the surface properties, which were modified on exposure to water. The release of Ulva sporelings (young plants) was improved by the addition of low amounts of both NS and MWCNTs. The most profound effect recorded was the significant reduction of adhesion strength of adult barnacles growing on a silicone elastomer containing a small amount (0.05%) of MWCNTs. All the data indicate that independent of the bulk properties, the surface properties affect settlement, and more particularly, the fouling-release behaviour, of the filled materials.

Block, random and palm-tree amphiphilic fluorinated copolymers: controlled synthesis, surface activity and use as dispersion polymerization stabilizers

A series of novel fluorinated amphiphilic stabilizers of different architectures (diblock, grafted, or palm tree copolymers) were successfully prepared by reversible addition–fragmentation chain transfer. The surfactant properties of these copolymers were first evidenced by measuring the interfacial tension at the H2O/trifluorotoluene (TFT) interface, and the results were correlated with their stabilizing efficiency in the dispersion polymerization of 2-hydroxyethyl methacrylate (HEMA) in trifluorotoluene. The effects of the architecture and concentration of the stabilizer on the morphology, size and stability of the obtained polyHEMA particles were investigated. Whatever the architecture of the stabilizer, conditions could be adapted to produce submicronic spherical poly(HEMA) particles with diameters around 300 nm and a quite narrow size distribution.

Surface and Fouling-Release Properties of Silicone/Organomodified Montmorillonite Coatings

Poly(dimethylsiloxane) (PDMS)/organomodified montmorillonite (OMMT) nanocomposites have been prepared, characterised and the fouling-release properties of these materials have been studied through laboratory assays involving a representative soft-fouling species, the green alga, Ulva. The bulk mechanical properties of the polymer matrix have been slightly changed by the addition of OMMT, i.e., to a higher Youngs modulus value. The surface properties of the nanocomposites were modified after immersion in water. Indeed, it appears that the surface topography, as observed with AFM, is affected by the presence of OMMT after immersion in water. The data indicate that the modified surface affects the fouling release behaviour of sporelings (young plants) of Ulva; percentage removal by hydrodynamic shear stress increases from 28% for the unfilled PDMS control to 78% for the 2 wt% filled coating.

(Quaternized/betainized) amino-based amphiphilic block copolymers: quantitative composition characterization via FTIR and thermogravimetry

Abstract The objective of the present study is the introduction of well known and readily accessible analytical methods as FTIR, thermogravimetric (TGA) and evolved gas analysis (EGA) for quantitative determination of the degree of polymerization (DP) and degree of quaternization (DQ)/betainization (DB) of amino-based amphiphilic block copolymers. For this purpose a series of amphiphilic poly(dimethylsiloxane)-b-poly[2-{dimethylamino)ethyl methacrylate] (PDMS-b-DMAEMA) diblock copolymers with DP of the PDMAEMA-block ranging from 22 to 162 was synthesized by atom transfer radical polymerization and analyzed by 1H NMR, ATR-FTIR and TGA-co-EGA. The determined composition results have shown linear correlation between the FTIR or TGA and the 1H NMR data and equations allowing the quantitative calculation of PDMAEMA-block DP were found. The errors estimated by ATR-FTIR were less than 1.5%. Further, the PDMAEMA-block was quaternized (or betainized) with DQ (or DB) from 25 % to 100 % and analyzed by TGA-co-EGA. Again, a linear correlation between the quaternized (betainized) PDMAEMA-block mass fraction and the DQ (DB) degrees was obtained by 1H NMR.

Metal-free anti-biofouling coatings: the preparation of silicone-based nanostructured coatings via purely organic catalysis

Abstract The successful formulation of two-part condensation-curing silicone materials via purely organic catalysis is here developed and investigated as fouling-release coating. Several non-toxic organic catalysts and their ‘onium’ salts were studied as potential purely organic catalysts on the silicone condensation reaction but also on the properties of the resulting cured resins. The trifluoroacetic acid was pointed suitable for the production of condensation-curing silicone coatings. To assess favorable fouling-release properties, multi-wall carbon nanotubes (0.05–0.2 wt-%) were added to the resin. Interestingly, the catalytic activity of the trifluoroacetic acid proved not affected by the presence of the nanocharge. The properties of the coatings prepared using 0.1 wt-% acid revealed constant degree of crosslinking independently of the carbon nanotubes loading and pronounced surface nanostructuring suitable for fouling release. This final property was tested against Ulva linza sporelings and revealed that the coatings are highly suitable for fouling-release applications. Graphical abstract