US Patent: 2011190544 A1
Date: Aug 4, 2011
Inventors: W. Navarrini, M. Sansotera, P. Metrangolo, P. Cavallotti, G. Resnati
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
US Patent: 7704639 B2
Date: Apr. 27, 2010
Inventors: W. Navarrini, S. Panero, B. Scrosati, A. Sanguineti
Author(s): NAVARRINI W., SANSOTERA M., VENTURINI F., BIANCHI C. L., GUARDA P. A., RESNATI G.
Source: Chimica Oggi – Chemistry Today.
Volume: 28 Pages: 24-27. Published: Apr (2010).
ABSTRACT:
The progresses in the magnetic media technology brought to the application of liquid lubricant films on diamond-like carbon (DLC) coatings. Hard surfaces are typically lubricated with fluorinated or perfluorinated organic compounds, such as perfluoropolyethers (PFPE). Many attempts have been done to obtain a stable layer of PFPE lubricant on the DLC surface by dip-coating or by vapour deposition so as to minimize any friction and wear . Diamond-like carbons are formed by an amorphous mixture of sp3 and sp2 hybridized carbon atoms with hydrogen atoms incorporated in the structure (a-C:H DLC). We have established a specific methodology for the straight-forward introduction of perfluorinated groups with carbon-carbon bond formation on a variety of unsaturated materials . Indeed, by using this methodology, perfluorinated radicals can directly bond to the sp2 sites of the DLC structure avoiding any spacer, that usually decreases both thermal and chemical stabilities of the resulting fluorinated layers .
M. Sansotera a, W. Navarrini a, P. Metrangolo a, G. Resnati a, C. Bianchi b, A. Guarda c
a Dip-CMIC ”Giulio Natta”, Politecnico di Milano, via Mancinelli 7, 20131 Milan, Italy;
b Department of Physical Chemistry and Electrochemistry, University of Milan, via Golgi 19, 20133, Milan, Italy
c R&D Centre, Solvay Solexis, viale Lombardia 20, 20021 Bollate (MI), Italy
E-mail: maurizio.sansotera@polimi.it
Perfluorodiacyl peroxides and perfluoropolyether peroxides (FOMBLIN peroxides) are suitable organic peroxides for direct linkage of perfluoroalkyl and perfluoropolyether chains on unsaturated substrates through a radical pathway. Highly graphitic carbon black and a-C:H diamond-like carbon are carbonaceous materials characterized by sp2 hybridized carbon atoms in the structure. Consequently a chemical treatment with high fluorine content organic peroxides allows the introduction of fluorinated groups onto carbonaceous substrates with carbon-carbon bond formation [1]. Depending on the peroxide involved during the treatment, several fluorinated chains, i.e. perfluoroethyl, CF3CF2-, perfluoro-n-propyl, CF3CF2CF2-, perfluoro-iso-propyl, (CF3)2CF-, and perfluoropolyether residual, has been covalently linked on the surface of such carbonaceous materials. Functionalization of carbon black transfers the typical hydrophobic properties of perfluorinated chains to the carbon black surface even preserving its conductive properties. This chemical treatment on diamond-like carbon films produces a covalently linked protective layers with the typical lubricant properties of perfluorinated compounds.
[1] Navarrini W., Sansotera M., Metrangolo P., Cavallotti P., Resnati G. WO 2009/019243 A1.
US Patent: 7534845 B2
Date: May 19, 2009
Inventor: W. Navarrini
Navarrini Walter a*, Venturini Francesco a, Sansotera Maurizio a, Metrangolo Pierangelo a, Resnati Giuseppe a, Galimberti Marco b, Barchiesi Emma b, Dardani Patrizia b .
a Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, 7, via Mancinelli, I-20131, Milano, Italy.
b Solvay-Solexis, R &D Centre, 20, viale Lombardia, I-20021 Bollate (MI), Italy.
In the reaction between perfluoroolefins and perfluoroalkylhypofluorites [1] the existence of two different free radical reaction mechanisms is demonstrated by the presence of characteristic by-products.
In particular in the reaction between trifluoromethyl hypofluorite and highly reactive perfluoroolefins like CF2=CFOCF3 and CF2=CF2, the free radical oligomerization and dimerization products can be suppressed by utilizing the opportune experimental conditions.
These experimental conditions are characterized by the presence of hypofluorite during the addition reaction and can be performed by adding the olefin to the hypofluorite, these conditions herein referred as ”Reverse hypofluorite addition” are different from the standard methodologies described in the literature where generally the hypofluorite is added to the olefin.
The main products of the addition of CF3OF to CF2=CFOCF3 are perfluoro-2,2-bis-(methoxy)-ethane and perfluoro-1,3-bis-(methoxy)-ethane [2] in the molar ratio of 20% and 80% respectively.
We found experimental evidence for the termination products peroxide CF3OOCF3 and perfluoroethersC8F18O4respectively. The first termination product CF3OOCF3 was present at high amount in the reaction where the CF3OF concentration was maintained always above zero and substantially constant, on the contrary the termination products C8F18O4 were completely absent. In this conditions the oligomerization and polymerization of the perfluoroolefins were also suppressed, as well as in the case of the very reactive TFE.
[1] W. Navarrini, V. Tortelli, A. Russo, S. Corti, J. Fluorine Chem. 95(2),(1999)27-39.
[2] W. Navarrini, G. Resnati, P. Metrangolo, M. Cantini, F. Venturini, IT Patent app. MI2007A001384 (2007).