Direct fluorination of carbon monoxide in microreactors.

Author(s): NAVARRINI W., VENTURINI, F., TORTELLI V., BASAK S., PIMPARKAR K. P., ADAMO A., JENSEN K. F. Source: Journal of Fluorine Chemistry. Volume: 142 Pages: 19-23. DOI: 10.1016/j.jfluchem.2012.06.006. Published: Oct (2012). ABSTRACT:

Many attempts to obtain a clean stream of COF2 have been carried out in the past by means of the direct fluorination of carbon monoxide with elemental fluorine or by electrochemical fluorination. The reaction is highly exothermic, therefore difficult to control. It can easily develop into a thermal runaway with a poor selectivity. We have successfully circumvented these critical issues by using a stainless steel parallel channel microreactor (surface/volume ratio approximate to 1 x 104 m(-1), residence time T approximate to 0.1 s) for the direct fluorination of carbon monoxide. Its performance in terms of operability and selectivity is compared to that of a standard reactor assembly, namely a fluorine burner reactor coupled with a water cooled heat exchanger. While the microreactor assembly succeeded to control the exothermic reaction, in the same experimental conditions the standard assembly reactor underwent serious corrosion issues that lead to nozzle meltdown lack of selectivity and consequent plant shutdowns. http://www.sciencedirect.com/science/article/pii/S0022113912001790

Micromanufacturing in Fused Silica via Femtosecond Laser Irradiation Followed by Gas-Phase Chemical Etching.

Author(s): VENTURINI F., SANSOTERA M., VAZQUEZ R. M., OSELLAME R., CERULLO G., NAVARRINI W.

Sources: Micromachines

Volume: 3 (4) Pages: 604-614.

DOI:10.3390/mi3040604.

Published: Sept (2012).

ABSTRACT:

Femtosecond laser irradiation followed by chemical etching (FLICE) with hydrogen fluoride (HF) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure, as described in literature, consists of irradiating a silica slab followed by chemical etching using hydrogen fluoride. With aqueous HF the etching process is diffusion-limited and is self-terminating, leading to maximum microchannel lengths of about 1.5 mm, while the use of low-pressure gaseous HF etchant can quickly produce 3 mm long channels with an aspect ratio (Length/Diameter) higher than 25. By utilizing this methodology the aspect ratio is not constant, but depends on the length of the channel. When the microchannel is short the aspect ratio increases quickly until it reaches a maximum length at around 1400 um hereafter the aspect ratio starts to decrease slowly. In this paper we present a variation of the low-pressure gaseous HF etching method, which is based on the dynamic displacement of the etchant. This method results in a 13% increase in the aspect ratio (L/D = 29) at the expense of a low etching speed (4 um/min).

Direct trifluoro-methoxylation of aromatics with perfluoro-methyl-hypofluorite.

Author(s): VENTURINI F., NAVARRINI W., FAMULARI A., SANSOTERA M., DARDANI P., TORTELLI V.

Source: Journal of Fluorine Chemistry.

Volume: 140 Pages: 43-48.

DOI: 10.1016/j.jfluchem.2012.04.008.

Published: Aug (2012).

ABSTRACT:

The reactivity of CF3OF (FM) has been widely studied especially in halogenated olefinic systems and its use in pharmaceutical synthesis as a mild radical and electrophilic fluorinating agent is well documented. On the other hand, the chemical behavior of the perfluoro-methyl-hypofluorite with aromatic substrates is much less studied. Up to now few and scattered data regarding its use as electrophilic fluorinating agent of variously substituted aromatic compounds are found in the literature. In this work the reactivity of CF3OF with simple electron rich and electron poor aromatics (alpha,alpha,alpha-trifluoro-toluene, toluene. benzene, chloro-benzene, methoxybenzene) has been investigated. The possibility of selectively bind the trifluoro-methoxy group (via radical mechanism) or the fluorine atom (via electrophilic addition) by varying the reaction conditions has been explored. In particular we have observed that the trifluoromethoxy free radical substitution can be the main synthetic pathway if the reaction is promoted by an independent and steady source of CF3O radical. http://www.sciencedirect.com/science/article/pii/S0022113912001145

UV-resistant amorphous fluorinated coating for anodized titanium surfaces

Author(s): Navarrini, Walter; Diamanti, Maria Vittoria; Sansotera, Maurizio; Persico, Federico; Wu Menghua; Magagnin, Luca; Radice, Stefano.

Source: PROGRESS IN ORGANIC COATINGS

Volume: 74 Issue: 4 Special Issue: SI Pages: 794-800

DOI: 10.1016/j.porgcoat.2011.09.023

Published: AUG 2012

ABSTRACT:

In this work, a high molecular weight copolymer of tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole (HYFLON (R) AD60) and two perfluoropolyethers (PFPEs) containing ammonium phosphate or triethoxysilane functionalities, FLUOROLINK (R) F10 and FLUOROLINK (R) S10 respectively, have been evaluated as protective coatings that can be easily applied on anodized titanium surfaces. Water and n-dodecane contact angle measurements have been recorded by using the sessile drop method for bare and coated surfaces in order to determine the hydrophobic and oleophobic properties of the coatings. The UV-stability of coatings have been studied by Fourier transform infrared spectroscopy (FT-IR) analyses and by observing the variation of water contact angles on coated substrates before and after UV irradiation at regular time intervals. The thickness of the fluorinated films has been measured by ellipsometry and by weight evaluation. Preliminary tests of the adhesion between films and substrate have been conducted. http://www.sciencedirect.com/science/article/pii/S0300944011003699

An Environmentally Friendly Class of Fluoropolyether: alpha,omega-Dialkoxyfluoropolyethers.

Author(s): WU M., NAVARRINI W., SPATARO G., VENTURINI F., SANSOTERA M.

Source: Applied Sciences.

Volume: 2 (2) Pages: 351-367.

DOI: 10.3390/app2020351. Published: Apr. (2012).

ABSTRACT:

The alpha,omega-dialkoxyfluoropolyethers (DA-FPEs) characterized by the structure R_HO(CF₂CF₂O)_n(CF₂O)_mR_H have been developed as a new class of environmentally friendly hydrofluoroethers (HFEs) suitable as solvents, long-term refrigerants, cleaning fluids, and heat transfer fluids. Synthetic methodologies for DA-FPEs described here consist of radical-initiated oxypolymerization of olefin, peroxy-elimination reaction in peroxidic perfluoropolyethers (P-PFPEs) and further chemical modification of alpha,omega-diacylfluoride PFPE. The physical properties of selected alpha,omega-dimethoxyfluoropolyethers (DM-FPEs) have been evaluated and compared with analogous hydrofluoropolyethers (HFPEs) having -OCF₂H as end-groups. Atmospheric implications and global warming potentials (GWPs) of selected DA-FPEs are also considered.

http://www.mdpi.com/2076-3417/2/2/351

Conductivity and superhydrophobic effect on PFPE-modified porous carbonaceous materials.

Author(s): SANSOTERA M., NAVARRINI W., GOLA M., DOTELLI G., STAMPINO P. G., BIANCHI C.L.

Source: INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

Volume: 37 Issue:7 Pages: 6277-6284

DOI: 10.1016/j.ijhydene.2011.07.041

ABSTRACT:

The thermal decomposition of a linear perfluoropolyether peroxide produced perfluoropolyether radicals that covalently bonded the unsaturated moieties on the surface of carbon black and carbon cloth. Measurements of contact angles demonstrated that water droplets were enduringly stable on the treated materials and that contact angle values were significantly high, exceeding the superhydrophobicity threshold. On the contrary, the droplets were adsorbed in few seconds by the native materials. Conductivity measurements showed that the covalent linkage of fluorinated chains weakly modified the electrical properties of the conductive carbonaceous materials, even if the surface properties changed so deeply. The relationship between the linkage of fluorinated chains and the variations of physical-chemical properties were studied combining X-ray photoelectron spectroscopy, resistivity measurements, scanning electron microscopy and surface area analysis. The modified carbon cloth was also tested out as gas-diffusion layer in a fuel cell and preliminary results were recorded.

http://www.sciencedirect.com/science/article/pii/S0360319911017010

Electrodeposition of Hierarchical Nanostructured Gold Coatings as Facile Route for Fabrication of Superhydrophobic Surfaces

Author(s): Magagnin, L.; Menghua, W.; Tabatabaei, S. Torabi; Demir, B.; Sansotera, M.; Talaeemashhadi, S.; Navarrini, W.

Source: ELECTRODEPOSITION OF NANOENGINEERED MATERIALS AND DEVICES 4 Book Series: ECS Transactions

Volume: 41 Issue: 44 Pages: 111-119 DOI: 10.1149/1.4718399 Published: 2012

Conference: Symposium on Electrodeposition of Nanoengineered Materials and Devices 4 Held During the 220th Meeting of the Electrochemical-Society (ECS) Location: Boston, MA Date: OCT 09-14, 2011

ABSTRACT:

Herein electrochemical approaches for fabrication of hierarchical nanostructured gold coatings (HNGCs) are presented. Examples of HNGCs obtained by electrodeposition in sulphite based electrolyte on nickel electroplated copper (Ni/Cu) substrates are reported. The morphology and microstructure of the nanostructured surface were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD). The effects of the electrodeposition current density (J) and deposition time on the morphological features of nanostructured gold coating will be discussed. The surface wettability on thiols treated gold surface as a function of the electrodeposition current density is investigated. Thiols treated electrodepsited HNGCs can possess superhydrophobic behavior with water contact angle of 179 degrees.

http://ecst.ecsdl.org/content/41/44/111

Electrodeposition of nanostructured columnar cobalt for self-lubricant coatings

Author(s): Zhao, F.; Franz, S.; Vicenzo, A.; Cavallotti, P. L.; Sansotera, M.; Navarrini, W.

Source: ELECTROCHIMICA ACTA Volume: 56 Issue: 26 Special Issue: SI Pages: 9644-9651

DOI: 10.1016/j.electacta.2011.06.033 Published: NOV 1 2011

ABSTRACT:

The preparation of cobalt-perfluoropolyether (PFPE) composite coating with dry lubrication capability is addressed. An original process scheme is proposed involving the electrodeposition of a nanostructured columnar cobalt layer, a grain boundary etching post-deposition treatment of the layer and its further processing by vacuum impregnation with PFPE. The influence of the operating parameters on deposition kinetics and crystal structure of the cobalt layer was investigated in detail, with the objective of identifying the optimum deposition conditions for the growth of a nanocolumnar cobalt film. In particular, the main operating conditions, namely deposition temperature and current density, were analyzed by studying their effect on deposits microstructure and texture. Control of the growth stability of the nanocolumnar structure was achieved in the presence of a suitable concentration of a surfactant. The subsequent steps of grain boundary etching and impregnation with PFPE were successfully implemented completing the planned process scheme. Friction force measurements provided evidence validating the functionality of the Co-PFPE nanocomposite.

http://www.sciencedirect.com/science/article/pii/S0013468611009194

Modification of carbonaceous materials

US Patent: 2011190544 A1

Date: Aug 4, 2011

Inventors: W. Navarrini, M. Sansotera, P. Metrangolo, P. Cavallotti, G. Resnati

US2011190544A1 – PDF

Peroxidic perfluoropolyether for the covalent binding of perfluoropolyether chains on carbon black surface.

Author(s): SANSOTERA M., NAVARRINI W., GOLA M., BIANCHI C. L., WORMALD P., FAMULARI A., AVATANEO M.

Source: Journal of Fluorine Chemistry.

Volume: 132 (12) Pages: 1254-1261.

DOI: 10.1016/j.jfluchem.2011.07.018. Published: Dec. (2011).

ABSTRACT

Peroxidic perfluoropolyethers (PFPEs) are suitable tools for the covalent linkage of fluorinated groups on substrates containing aromatic moieties. Thus the thermal decomposition process of such fluorinated peroxides allowed the covalent linkage of PFPE radicals to the polycyclic aromatic structure of a graphitic carbon black. Contact angle measurements on molded pellets made with modified carbon black powders revealed a gradual enhancement of the hydrophobicity, which follows the increase of the fluorine content on the surface according to XPS experiments. BET analyses also revealed variations of the surface area of carbonaceous samples. Products and by-products were also evaluated by mass balances of decomposed portions of PFPE residues, respectively, PFPE chains bonded on carbon black and PFPE fluids obtained by homocoupling side-reactions. Modified carbonaceous materials were analyzed by solid state 19F-MAS NMR and the results are in agreement with the proposed radical mechanism.

http://www.sciencedirect.com/science/article/pii/S0022113911002831

alpha,omega-dialkoxyfluoropolyethers: a promising class of hydrofluoroether (HFE).

Author(s): WU M., NAVARRINI W., AVATANEO M., VENTURINI F., SANSOTERA M., GOLA M.

Source: Chimica Oggi – Chemistry Today.

Volume: 29 (3) Pages: 67-71. Published: Jun. (2011).

ABSTRACT:

The alpha,omega-dialkoxyfluoropolyethers (DA-FPEs) characterized by structure RHO(CF2CF2O)n(CF2O)mRH have been recently developed as a new class of environmental friendly hydrofluoropolyethers (HFPEs) suitable as solvents, refrigerants and heat transfer. The synthetic methodologies for the preparation of this new class of fluid have been reviewed and physical properties of selected alpha,omega-dimethoxyfluoropolyethers have been evaluated and compared with analogous hydro- fluoropolyethers (H-FPEs) having -OCF2H as end-groups. Atmospheric implications and global warming potentials (GWP) of selected alpha,omega-dimethoxyfluoropolyethers have been also considered.

http://www.teknoscienze.com/Articles/Chimica-Oggi-Chemistry-Today–alpha-omega-dialkoxyfluoropolyethers-a-promising-class-of.aspx#.UozCCCcUlZM

Henri Moissan 1906 Nobel Prize on Chemistry

Author(s): Navarrini, Walter

Source: CHIMICA OGGI-CHEMISTRY TODAY

Volume: 29 Issue: 3 Pages: 4-5 Published: MAY-JUN 2011

ABSTRACT:

Professor H. Moissan madeoutstanding contributions to thedevelopment of applied chemistry inthe late XIX and early XX century. For thefirst time he obtained fluorine in freestate, studied a number of fluorinecompounds, designed an electricarc furnace and set the foundationof high-temperature chemistry.He synthesized many high-meltingcompounds and isolated boron andother elements by reducing their oxides, finallyhe theorised and attempted the preparation of artificial diamond(1). He was awarded with the Nobel Prize (1906) in recognition to theisolation of fluorine and for his studies on high-temperature chemistry.He died suddenly in Paris in February 1907, shortly after his return fromreceiving the Nobel Prize in Stockholm.

http://www.teknoscienze.com/Articles/Chimica-Oggi-Chemistry-Today-Henri-Moissan-1906-Nobel-Prize-on-Chemistry.aspx

Anti-Fingerprints Fluorinated Coating for Anodized Titanium Avoiding Color Alteration.

Author(s): NAVARRINI W.; BRIVIO T.; CAPOBIANCO D.; DIAMANTI M. V.; PEDEFERRI M.; MAGAGNIN L.; RESNATI G.

Source: JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH.

Volume: 8 Issue: 2 Pages: 153-16.

DOI: 10.1007/s11998-010-9293-y Published: Mar. (2011).

ABSTRACT:

In this study amorphous fluorinated coatings applied to anodized titanium surface have been investigated. A copolymer between tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole (AD60) and two perfluoropolyether containing ammonium phosphate (F10) or triethoxysilane (S10) functionalities have been tested. To estimate the color alteration of the anodized titanium surfaces due to the application of the coatings, spectrophotometric analyses have been made. Water and n-dodecane contact angles as well as apparent surface energy have been evaluated. Ellipsometry and atomic force microscopy data have been used to measure the thickness of the fluorinated coatings. A tailored mechanical preliminary test has also been explored to evaluate the adhesion of the coatings on the anodized titanium surface. The resistance to surface soiling with castor oil was also preliminarily investigated. The fluorinated coating tested on anodized titanium showed a low apparent surface energy and high chromatic aspect conservation, this is particularly evident for the titanium anodized coated with triethoxysilane functionalities fluoropolymers S10. http://link.springer.com/article/10.1007%2Fs11998-010-9293-y

Selective Iterative Etching of Fused Silica with Gaseous Hydrofluoric Acid.

Author(s): Venturini, Francesco; Navarrini, Walter; Resnati, Giuseppe; Metrangolo, Pierangelo; Vazquez, Rebeca Martinez; Osellame, Roberto; Cerullo, Giulio.

Source: JOURNAL OF PHYSICAL CHEMISTRY C

Volume: 114 Issue: 43 Pages: 18712-18716

DOI: 10.1021/jp107055s

Published: NOV 4 2010

ABSTRACT:

Femtosecond laser irradiation followed by chemical etching (FLICE) with hydrofluoric acid (HF) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels. With liquid HF, the etching process is diffusion-limited and is self-terminating, leading to maximum microchannel lengths of approximate to 1.5 mm. A strategy to overcome this limitation would be to perform iterative etching, periodically removing the exhausted products and replenishing the partially etched channel with fresh acid; this procedure is, however, quite cumbersome in the liquid phase. In this paper we present what is to our knowledge the first implementation of the FLICE technique with low-pressure gaseous HF etchant. The use of a gas-phase etchant naturally lends itself to the application of iterative etching techniques, since it is very easy to remove the etchant, by pumping vacuum in the reaction chamber after each etching step. We demonstrate that iterative etching in the gas phase overcomes the limitations of wet etching and allows to achieve nearly constant etching rate for a microchannel length up to approximate to 3 mm.

http://pubs.acs.org/doi/abs/10.1021/jp107055s

Hydrophobic carbonaceous materials obtained by covalent bonding of perfluorocarbon and perfluoropolyether chains.

Author(s): Sansotera, Maurizio; Navarrini, Walter; Magagnin, Luca; Bianchi, Claudia L.; Sanguineti, Aldo; Metrangolo, Pierangelo; Resnati, Giuseppe.

Source: JOURNAL OF MATERIALS CHEMISTRY.

Volume: 20 Issue: 39 Pages: 8607-8616.

DOI: 10.1039/c0jm02077j. Published: 2010

ABSTRACT:

Perfluorocarbon residues, i.e. perfluoroethyl (PFE), CF(3)CF(2)-, perfluoro-n-propyl (PFnP), CF(3)CF(2)CF(2)-, perfluoro-isopropyl (PFiP), (CF(3))(2)CF-, and perfluoropolyether (PFPE) chains, e. g. (CF(2)CF(2)O)(m)(CF(2)O)(n), were covalently bonded on the surface of carbon black (CB) and diamond-like carbon (DLC) using PFPE and perfluorodiacyl (PFDA) peroxides. The thermal decomposition of the peroxidic moieties of these perfluorinated peroxides generated reactive perfluorinated radicals. The perfluorinated free radicals could directly bond to the sp(2) sites avoiding any spacer, which usually decreases both thermal and chemical stabilities of the resulting materials. The effects of chemical treatment on the carbonaceous materials were studied using X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Contact Angle (CA) measurements. The surface areas of CB powders were determined by the BET technique; the morphology of the DLC coatings was evaluated by Atomic Force Microscopy (AFM) and the friction forces were measured by means of Lateral Force Microscopy (LFM).

http://pubs.rsc.org/en/Content/ArticleLanding/2010/JM/c0jm02077j#!divAbstract