Advances in glass Microfabrication. Femtosecond laser irradiation followed by chemical etching.

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

Source: Chimica Oggi – Chemistry Today.

Volume: 30 Pages: 10-13. December (2012).

ABSTRACT:

Femtosecond laser irradiation followed by chemical etching (F.L.I.C.E.) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure attested in literature, which has been widely studied in the past years, consists of irradiating a glass slab and subsequently apply a chemical etching step. The results obtained by different research groups vary widely. In this paper we present a review of the most recent advancements of this technique discussing several critical factors that affect the aspect ratio, the length and the etching speed of the microchannel.

http://www.teknoscienze.com/Articles/Chimica-Oggi-Chemistry-Today-Advances-in-glass-Microfabrication-Femtosecond-laser-irradiation.aspx#.UouCWycUlZM

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 RHO(CF2CF2O)n(CF2O)mRH 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