EP2102319B1 - Ultra-thin water and oil repellent layer, manufacturing method and use in mechanics as a barrier film - Google Patents

Description

The present invention relates to a new ultra-thin hydrophobic and oleophobic layer formed by self-assembly on a solid substrate surface of catechol foot compounds, a process for preparing this ultra-thin layer and the use thereof as a barrier film. , antimigration film or antimouillage film, which will be called "epilame" in the rest of the exposition by analogy with the watchmaking world.

The proper functioning of a mechanical movement depends inter alia on its lubrication. The durability of the lubricant depends in particular on its maintenance in the operating zone: however, a drop of lubricant spreads rapidly over a clean part. The deposition of an epilame layer, generally in the form of a hydrophobic and oleophobic invisible molecular layer, avoids the spreading of the lubricant and its components.

The spreading of a liquid depends on the interaction forces between the liquid, the surface and the surrounding air (cf. JC Berg, "Wettability", Marcel Dekker, New York, 1993 and AW Adamson, "Physical Chemistry of Surfaces", Wiley ). The parameter that characterizes the interaction forces between a liquid and the air is the surface tension, γ _LV . A surface energy γ _SV between a solid and the surrounding air and a parameter γ _LS between the solid and the liquid is similarly defined. For a drop of equilibrium liquid on a surface, the Young equation states that γ _SV - γ _LS = γ _LV COSθ, where θ is the contact angle of the drop of liquid with respect to the surface. Young's equation also shows that if the surface tension of the liquid is lower than the surface energy, the contact angle is zero and the liquid wets the surface. This is what happens with a lubricant deposited on a clean metal surface: in fact, a lubricant has a surface tension of 35-40 mN / m, whereas a current metal surface has a higher surface energy.

• la composition chimique et la structure cristallographique du solide, et en particulier de sa surface,
• les caractéristiques géométriques de la surface et sa rugosité (et donc les défauts et/ou l'état de polissage),
• la présence de molécules adsorbées physiquement ou liées chimiquement à la surface, qui peuvent aisément masquer le solide et modifier considérablement son énergie de surface.

Surface energy depends on several factors ( JP Renaud and P. Dinichert, 1956, "Surface States and Spreading of Clockworks," Bulletin SSC III page 681 ):

• the chemical composition and the crystallographic structure of the solid, and in particular of its surface,
• the geometric characteristics of the surface and its roughness (and therefore the defects and / or the polishing state),
• the presence of molecules physically adsorbed or chemically bonded to the surface, which can easily hide the solid and significantly alter its surface energy.

Surface energy is often determined by the last atomic or molecular layer. The chemical nature of the solid is of little importance in relation to the state of its surface and the contamination that covers it. On a clean metal surface free of organic contamination, the contact angle in advance with a drop of water is less than 10 °. With a self-assembled monomolecular layer (SAM) molecule showing a -OH functional group (eg, HOC ₁₁ H ₂₂ SH), this contact angle is about 30 °, whereas it is about 110 ° for a -CH ₃ functional group (eg C ₁₂ H ₂₅ SH) and about 118 ° for a -CF ₃ functional group (eg C ₁₀ F ₁₇ H ₄ SH ).

The manufacturing techniques used in mechanics left until the 1930s a surface condition minimizing the spreading of lubricants by the presence of a film lowering the surface energy ( M. Osowiecki, 1957, "A new epilame resistant to washes", Bulletin SSC III, page 735 ). This film disappeared with the improvements made to the washing techniques, causing a more or less rapid spreading of the lubricants. In 1930, P. Woog of the Compagnie Française de Raffinage developed an anti-migration product based on stearic acid which he named "epilame". It was used in various branches of the industry until the end of the 60s. The name remained and designates in watchmaking any product used to guarantee the resistance of lubricants on a surface.

Deposition of a compound on a functional surface to lower surface energy and control wettability and adhesion is a fairly common process. However, its application as barrier film or antimigration is limited to watchmaking ( M. Massin, "Epilames and associated lubricants with high stability: properties, application technology and results in watchmaking", Proceedings of the Franco-German Chronometry Congress, page 85, 1970 , and " Design of lubrication in micromechanics: new achievements by preparing surfaces associated with silicone fluids ", Proceedings of the Congress of the German and French Chronometry Societies, page 95, 1971 ), to the space industry ( M. Marchetti "Global and Local Aspects of the Implementation of Fluid Lubrication in the Space Environment," INSA PhD Thesis, Lyon, 2000 ) and electronics. The first two areas have in common the difficulty of replacing a used or exhausted lubricant.

Products based on stearic acid diluted in toluene were used in watchmaking until the 1970s ( M.Osowiecki, reference above and P. Ducommun, 1956, "Synthetic clockwork oils," J. Switzerland Horl. Bij. 9-10, 117 ). Research undertaken in the late 1960s led to two important developments. On the one hand, a product based on silicone was developed (P. Massin, references above) but knew only limited success. On the other hand, products based on fluoropolymers were introduced in the course of the 1970s and are still used today. Requirement DD 238 812 A1 discloses ultra-thin layers involving the use of silanes and perluoroalkanes.

Currently, the vast majority of epilams available on the market, such as Moebius' Fixodrop FK-BS, or the 3M Fluorad (FC-722 and others) line, consist of a fluorinated polymer dissolved in a perfluorinated solvent.

The coating of the components on the substrate is carried out by soaking it in a solution of perfluorinated solvent loaded with polymer. The solvent used is generally tetradecafluorohexane (C ₆ F ₁₄ ) which, once volatilized, is a greenhouse gas since it remains stable for 3200 years in the air and has a greenhouse potential of 7'400 equiv. . CO ₂ .

The object of the invention is to propose compounds which can be used as epilame and which can be attached to a solid substrate surface without the use of environmentally toxic fluorinated solvents.

These objects are achieved by the invention as defined in the attached set of claims.

The invention indeed proposes a new ultra-thin hydrophobic and oleophobic layer formed by self-assembly on a solid substrate surface of catechol foot compounds, and a method for preparing this ultra-thin layer which uses a respectful non-fluorinated solvent. from the environment, for example a mixture of water and 2-propanol. Thanks to the catechol foot of the compounds used, this ultra-thin layer is firmly attached to the solid substrate surface. This ultra-thin layer has satisfactory properties for use as an epilame, in particular a contact angle in advance with water and a spreading of a drop, quite comparable to that of the layer obtained from the product. Fixodrop FK-BS reference product.

The invention thus makes an important contribution to the ecological preparation of epilames.

• A représente un groupe de formule
  
  dans laquelle
  • Z représente C ou N⁺,
  • X représente C-H ou C-L, L étant un groupe électroattracteur choisi parmi F, Cl, Br, I, CF₃, NO₂ et N(CH₃)₃ ⁺,
  • Y représente H ou CH₃, ou Y forme avec X un hétérocycle de 5 ou 6 atomes,
  • T représente NH, NH-CO, NH-CO-NH ou NH2⁺U^-, U^- étant choisi parmi F^-, Cl^-, Br^-, I, OH^-, NO₃ ^-, HSO₄ ^-, SO₄ ^2-, CO₃ ^2-, HCO₃ ^- ou SCN^-, et
• B représente un groupe alkyl linéaire aliphatique C₁-C₂₀ substitué partiellement ou complètement par F.

The catechol foot compounds have the general formula

AB

in which

• A represents a group of formula
  
  in which
  • Z represents C or N ⁺ ,
  • X represents CH or CL, L being an electron-withdrawing group chosen from F, Cl, Br, I, CF ₃ , NO ₂ and N (CH ₃ ) ₃ ⁺ ,
  • Y represents H or CH ₃ , or Y forms with X a heterocycle of 5 or 6 atoms,
  • T represents NH, NH-CO, NH-CO-NH or NH 2 ⁺ U ^- , U ^- being chosen from F ^- , Cl ^- , Br ^- , I, OH ^- , NO ₃ ^- , HSO ₄ ^- , SO ₄ ^2- , CO ₃ ^2- , HCO ₃ ^- or SCN ^- , and
• B represents a C ₁ -C ₂₀ aliphatic linear alkyl group partially or completely substituted with F.

The group A serves in particular to allow the attachment of the compounds to the solid substrate surface thanks to the group catechol and the solubilization of the amphiphilic molecule AB in the dipping solution.

Group B gives the ultra-thin layer its hydrophobic and oleophobic properties.

Preferably group B is a linear aliphatic group perfluorinated in its terminal part, for example of formula

(CH ₂ ) _n - (CF ₂ ) _m CF ₃

wherein n is 1 to 5, especially 1 to 3, and m is 4 to 11, especially 5 to 9.

Interesting groups A are those selected from one of the following groups:

A particularly preferred compound is N- (3,4-dihydroxyphenethyl) -4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11- heptadécafluoroundécanamide

The compounds of formulas AB can be obtained from known compounds using techniques and reactions well known to the organic chemist.

For example, N- (3,4-dihydroxyphenethyl) -4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamide may be obtained by reacting 2H, 2H, 3H, 3H-perfluoro-undecanoic acid-N-succinimidyl ester and 3-hydroxy-tyrosine hydrochloric acid dissolved in DMF in the presence of N-methylmorpholine.

peut être préparé à partir de ANACAT et de 2H,2H,3H,3H-perfluoro-undécanoïque-acide-N-succinimidyl selon des procédés analogues à ceux décrits par Y.Bethuel. K. Gademann, J. Org. Chem 2005, 70, 6258 .; Zürcher, S.; Wäckerlin, D.; Bethuel, Y.; Malisova, B.; Textor, M.; Tosatti, S.; Gademann, K. Journal of the American Chemical Society 2006, 128, 1064-1065 .3- (4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamido) -6,7-dihydroxy-1,1 dimethyl-1,2,3,4-tétrahydroquinolinium

can be prepared from ANACAT and 2H, 2H, 3H, 3H-perfluoro-undecanoic acid-N-succinimidyl by methods analogous to those described by Y.Bethuel. K. Gademann, J. Org. Chem 2005, 70, 6258 . Zürcher, S .; Wäckerlin, D .; Bethuel, Y .; Malisova, B .; Textor, M .; Tosatti, S .; Gademann, K. Journal of the American Chemical Society 2006, 128, 1064-1065 .

peut également être préparé par des procédés analogues à ceux mentionnés ci-dessus, à partir de 1-(2-aminoéthyl)-3,4-dihydroxypyridinium et de 2H,2H,3H,3H-perfluoro-undécanoïque-acide-N-succinimidyl.1- (2- (4,4,5,5,6,6,7,7,8,8,9,9,10,10,10,11,11,11-heptadecafluoroundecanamido) ethyl) -3,4- dihydroxypyridinium

may also be prepared by methods analogous to those mentioned above, from 1- (2-aminoethyl) -3,4-dihydroxypyridinium and 2H, 2H, 3H, 3H-perfluoro-undecanoic acid-N-succinimidyl .

(SuSoS5) peut également être préparé par des procédés analogues à ceux mentionnés ci-dessus, à partir de 3-hydroxy-tyrosine acide chlorhydrique et 1,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8-heptadécafluoro-10-iododécane.N- (3,4-dihydroxyphenethyl) -3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10,10-heptadecafluorodecan-1-aminium

(SuSoS5) can also be prepared by methods analogous to those mentioned above, from 3-hydroxy-tyrosine hydrochloric acid and 1,1,1,2,2,3,3,4,4,5,5 , 6,6,7,7,8,8-heptadecafluoro-10-iododecane.

(SuSoS6) peut également être préparé par des procédés analogues à ceux mentionnés ci-dessus, à partir de 4-(2-aminoéthyl)-5-nitrobenzène-1,2-diol et 2H,2H,3H,3H-perfluoro-undécanoïque-acide-N-succinimidyl.N- (4,5-dihydroxy-2-nitrophenethyl) -4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamide

(SuSoS6) can also be prepared by methods analogous to those mentioned above, from 4- (2-aminoethyl) -5-nitrobenzene-1,2-diol and 2H, 2H, 3H, 3H-perfluoro-undecanoic -acid-N-succinimidyl.

The solid substrate on the surface of which the self-assembly is made can be any solid substrate involved in the operation of a mechanical movement, in particular consisting of a material selected from among gold, silver, silver steel, aluminum, brass, bronze, cuproberyllium, titanium dioxide, ruby, sapphire, as well as other metallic surfaces, such as iron, chromium, tantalum, yttrium, silicon, germanium, copper, platinum, nickel, and nickel-phosphorus, and metal or ceramic oxides, such as zirconia, or niobia (niobium oxide), this list not being limiting. As a substrate, it is also possible to use polymers such as polyethylenes, polystyrols, polyamides, polydimethylsiloxanes, polyvinyl chlorides and epoxy resins, this list not being so limiting. The substrate may also be a substrate in one of these materials or another whose surface has been coated or coated, for example by a galvanic deposition of gold, gold-copper-cadmium and gold, nickel, rhodium, tin-nickel, or treated by anodizing, as in the case of coins aluminum alloy or titanium, or modified by a surface treatment such as oxidation, carburization or nitriding.

The thickness of the ultra-thin layer measured in ellipsometry is 0.5 to 10 nm, which value is higher for the definition of ultra-thin, preferably 1 to 4 nm.

To be effective as an epilame, that is to say to prevent satisfactory oil spreading, the contact angle in advance with the water must generally be at least 100 °.

Preferably the ultra-thin layer of formula A-B remains functional as epilame after two washes.

The invention also relates to a mechanical part characterized in that it comprises an ultra-thin layer as defined above.

The invention also relates to a process for preparing the ultra-thin layer defined above, characterized in that it comprises immersing the substrate in a solution of the compound of formula AB, for example in water, or a mixture of water and protic solvent such as, for example, 2-propanol. This process does not use a fluorinated solvent and is therefore respectful of the environment.

The invention will be better understood with the aid of the following examples which have an illustrative and nonlimiting character.

Example 1 Synthesis of N- (3,4-dihydroxyphenethyl) -4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamide ( SuSoS2) Synthesis of 2H, 2H, 3H, 3H-perfluoro-undecanoic acid-N-succinimidyl ester

2H, 2H, 3H, 3H-perfluoro-undecanoic acid (1.354 g, 2.75 mmol), N-hydroxysuccimide (348 mg, 3.02 mmol), dicyclohexylcarbodiimide (622 mg, 3.02 mmol) were dissolved in ethyl acetate (120 ml) and mixed for 18 hours at room temperature. The white precipitate formed (dicyclohexylurea DCU) was filtered and the remaining solution evaporated to dryness. The residue was recrystallized twice from ethyl acetate. Yield 1.00 g (62%) containing traces of DCU.
¹ H NMR (CDCl ₃ , 300 MHz, ppm): 3.0 (m, 2H CH ₂ ), 2.88 (s, 4H CH ₂ NHS), 2.6 (m, 2H CH ₂ ).

Synthesis of N- (3,4-dihydroxyphenethyl) -4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamide

• Poids moléculaire : 627,29
• % pondéral : C 36,38 ; H 2,25 ; F 51,49 ; N 2,23 ; O 7,65 sans H : C 47,5 ; F 42,5 ; N 2,5 ; O 7,5
• ¹H RMN (CDCl₃, 300 MHz, ppm) : 8,7 (s large, 2H OH), 8,08 (t, 1H NH), 6.7-6.4 (m, 3H dopamine), 3,2 (q, 2H CH₂), 2,7-2,3 (m, 6H CH₂).

correspondant au N-(3,4-dihydroxyphénéthyl)-4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadécafluoroundécanamide

Hydrochloric acid 3-hydroxy-tyrosine (257.5 mg, 1.35 mmol) and N-methylmorpholine (241 μl) were dissolved in DMF (8 ml). Perfluoro-NHS-ester (800 mg) was added and the mixture was stirred under a nitrogen atmosphere overnight. Water (40 ml) was added, the precipitate formed filtered off and washed with water. The solid was dissolved in ethyl acetate and the organic phase was dried with magnesium sulfate. The solvent was evaporated and the residue was recrystallized from chloroform (30ml, 4 ° C). Yield 752 mg (88%).

• Molecular weight: 627.29
• % by weight: C 36.38; H, 2.25; F 51.49; N, 2.23; O 7.65 without H: C 47.5; F 42.5; N 2.5; O 7.5
• ¹ H NMR (CDCl ₃ , 300 MHz, ppm): 8.7 (bs, 2H OH), 8.08 (t, 1H NH), 6.7-6.4 (m, 3H dopamine), 3.2 (q, 2H CH ₂ ), 2.7-2.3 (m, 6H CH ₂ ).

corresponding to N- (3,4-dihydroxyphenethyl) -4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamide

Example 2 Preparation of dipping solutions and immersion of different substrates therein Preparation of SuSoS2 soaking solution

SuSoS2 (0.052 mmol) 33 mg was dissolved in 35 ml of 2-propanol in a graduated 100 ml flask and shaken until completely dissolved. Ultrapure water was added to the mark and shaken vigorously, which increased the temperature of the solution. After returning the solution to room temperature, a few drops of water were added to adjust the volume to 100 ml. The solution was sonicated for 10 seconds to degas it and allow complete mixing of water and 2-propanol.

Immersion of gold, polished steel, titanium oxide and ruby substrates in soaking solutions

Samples of gold, polished steel, aluminum, titanium oxide and rubies were cleaned in a UV / ozone chamber for 30 minutes and immersed overnight in the SuSoS2 solution. The samples were then immersed in 2-propanol for 10 seconds, rinsed with additional 2-propanol and dried with a stream of nitrogen. In the case of steel, the surfaces were lightly polished with a wipe soaked in 2-propanol, rinsed with additional 2-propanol and dried with nitrogen flow.

Example 3 Analysis of ultra-thin layers formed by self-assembly on different substrates

• ellipsométrie spectroscopique à angle variable (VASE : Variable Angle Spectroscopique Ellipsometry ; cf. Feller et al. (2005). "Influence of poly(propylene sulfide-block-ethylene glycol) di-and triblock copolymer architecture on the formation of molecular adlayers on gold surfaces and their effect on protein résistance: A candidate for surface modification in biosensor research.", Macromolecules 38(25): 10503-10510 ),
• mesure d'angle de contact dynamique (dCA : Contact Angle dynamique ; cf. Tosatti et al. (2002) "Self-Assembled Monolayers of Dodecyl and Hydroxy-dodecyl Phosphates on Both Smooth and Rough Titanium and Titanium Oxide Surfaces,"Langmuir 18(9): 3537-3548 .), comme suit : la mouillabilité de surface a été déterminée en mesurant les angles de contact d'avance et le recul sur une goutte (d'eau) sessile (Contact Angle Measuring System, G2/G40 2.05-D, Krüss GmbH, Hamburg, Germany) ; l'expérience a été conduite en automatique en augmentant et diminuant la taille de la goutte à une vitesse de 15 ml par minute ; 480 valeurs ont été mesurées pour l'angle de contact d'avance et 240 pour l'angle de contact de recul, sur 3 emplacements différents pour chaque échantillon) ; les données recueillies ont été analysées par la méthode des tangentes 2 (routine d'ajustement du programme de Drop-Shape Analysis en Version DSA 1.80.0.2 for Windows 9x/NT4/2000, (c) 1997 - 2002 KRUESS"), et
• spectrométrie spectroscopique à rayons X (XPS ; Tosatti et al. ci-dessus).

Monolayers formed by self-assembly on the different substrates were analyzed by

• variable angle spectroscopic ellipsometry (VASE: Variable Angle Spectroscopique Ellipsometry; Feller et al. (2005). "Influence of poly (propylene sulfide-block-ethylene glycol) di-and triblock copolymer architecture on the formation of molecular adlayers on their surfaces and their effect on protein resistance: A candidate for surface modification in biosensor research.", Macromolecules 38 (25 ): 10503-10510 )
• dynamic contact angle measurement (dCA: Dynamic angle contact; Tosatti et al. (2002) "Self-Assembled Monolayers of Dodecyl and Hydroxy-dodecyl Phosphates on Both Smooth and Rough Titanium" Titanium Oxide Surfaces, "Langmuir 18 (9): 3537-3548 .), as follows: The surface wettability was determined by measuring the contact angles in advance and recoil on a sessile (water) drop (Contact Angle Measuring System, G2 / G40 2.05-D, Krüss GmbH, Hamburg, Germany); the experiment was conducted automatically by increasing and decreasing the size of the drop at a rate of 15 ml per minute; 480 values were measured for the advance contact angle and 240 for the recoil contact angle, at 3 different locations for each sample); the data collected were analyzed by the method of tangents 2 (Drop-Shape Analysis program adjustment routine in DSA Version 1.80.0.2 for Windows 9x / NT4 / 2000, (c) 1997 - 2002 KRUESS "), and
• X-ray spectroscopic spectrometry (XPS, Tosatti et al., supra).

• des plaques de silicium recouverts d'un fine couche d'or
• des disques d'acier poli
• des disques de rubis poli
• des plaques d'aluminium
• des plaques de silicium recouverts d'une fine couche de dioxyde de titane

The different substrates used are

• silicon wafers covered with a thin layer of gold
• polished steel discs
• polished ruby discs
• aluminum plates
• silicon wafers coated with a thin layer of titanium dioxide

The main parameters measured by VASE and CA are summarized in Table 1 below. <u> Table 1: Thickness measured by ellipsometry and advance contact angles with water </ u> substratum change Thickness measured by ellipsometry (nm) Angle of contact in advance with water Gold Clean - about 50 SuSoS2 0.7 115.6 ± 0.8 Polished steel Clean - <10 SuSoS2 3.3 116.8 ± 2.5 Aluminum Clean not measured <10 SuSoS2 not measured 126.2 ± 1.9 Titanium dioxide Clean - <10 SuSoS2 1.4 116.5 ± 0.6 Ruby Clean not measured <10 SuSoS2 not measured 109.9 ± 2.1

X-ray photoelectron spectroscopy (XPS) analysis shows that SuSoS2 molecules are present on all surfaces by the detection of N and F elements.

These results show that we obtain on all substrates tested an ultra-thin layer of SuSoS2 whose thickness measured by ellipsometry does not exactly correspond to the expected thickness of a well-ordered monolayer.

Nevertheless, the contact angle values in advance with water are satisfactory for use as epilam (greater than 100 °).

EXAMPLE 4 Comparison of the ultra-thin layers formed by self-assembly of SuSoS2 and Fixodrop FK-BS on surfaces of gold, polished steel and ruby. 1) Preparation of the ultra-thin layers of SuSoS2 and Fixodrop on the surfaces of the different substrates

An ultra-thin layer of SuSoS2 is coated with substrates of gold, polished steel and ruby as described in Example 2. The surface appearance is excellent for gold and ruby: the layer is invisible and no mark is visible due to the deposit.

An ultra-thin layer of Fixodrop FK-BS is coated with gold, polished steel and ruby substrates as specified by the manufacturer by dipping the substrates in a solution of tetradecafluorohexane.

The thickness of this layer measured by ellipsometry on gold is 0.7 nm for SuSoS2 and 1.7 nm for Fixodrop.

2) Measurement of contact angles with different solvents and determination of surface energies

Advance contact angles with water, hexadecane, diodomethane and ethylene glycol were measured by dynamic contact angle measurement according to a goniometric technique similar to that used in Example 3 .

The dispersive and polar components of surface energy were deduced from these measurements with the Owens-Wendt model ( Owens DK and Wendt RC, 1969, Journal of Applied Polymer Science, 13, 8, p. 1741 ).

The main results obtained are summarized in Table 2 below. <u> Table 2: Contact angles and surface energies with different solvents </ u> Liquid SuSoS2 steel Ruby SuSoS2 Gold SuSoS2 Fixodrop Gold Contact angle [°] hexadecane 64.1 56.8 47.3 56.8 diiodomethane 90.4 84.4 77.8 78.0 Ethylene glycol 93.2 87.2 84.9 88.4 Water 103.0 113.8 104.8 104.2 Surface energy [mJ / m ² ] dispersive 12.5 16.3 18.6 16.8 Polar 2.2 0.2 0.8 0.4 total 14.6 16.6 19.4 17.3

For gold, steel and ruby, these contact angles with water, hexadecane, diodomethane and ethylene glycol are acceptable for use as epilam, comparable to those measured for Fixodrop.

For gold, steel and ruby, the layer formed with SuSoS2 shows a dispersive character only, as expected for a molecule of this type. The surface energy seems to vary with the material, but is in any case below 20 mJ / m ² . The weakest energy (and therefore has a priori the best hold) is obtained for steel, followed by ruby and gold.

3) Measurement of spreading lubricants

The spreading of the lubricants on a surface is characterized by measuring the average diameter of a drop of typically 0.5 mm in diameter immediately after the drop has been deposited and after 20 minutes. The spread corresponds to the relative variation of the average diameter after 20 minutes. A good performance of a lubricant corresponds to a spread of 2% or less. Spreading greater than 10% is noticeable in the eye and is not acceptable. The oils used for the tests are a watch oil "941" (Moebius and Fils house, mixture of alkyl-aryl-monooleate and two C ₁₀ -C ₁₃ di-esters, viscosity of 110 cSt at 20 ° C, surface tension 32.8 mN / m) and a test oil CESNIII ( Swiss Laboratory of Horological Research, silicone oil, surface tension of 23.1 mN / m, "The Swiss watchmaker" No 43, 7.11.1974 ).

The spread obtained on steel, ruby and gold surfaces coated with the SuSoS2 molecule, as well as a gold surface coated with the commercial product Fixodrop FK-BS of the Moebius et Fils house, is compared according to the manufacturer's instructions. For the SuSoS2 molecule, the spread is in all cases less than 1%, and is comparable to that measured for the Fixodrop, as shown by the table below. <u> Table 3: Lubricant spreading </ u> Area Ultra thin layer Moebius 941 Oil CESNIII oil Steel SuSoS2 0.11% 0.92% Ruby SuSoS2 0.37% 0.46% Gold SuSoS2 0.30% 0.14% Gold Fixodrop FK-BS -0.90% 0.86%

4) Conclusion

For all the surfaces studied, the contact angle obtained on the ultra-thin layers made with the SuSoS2 molecule is greater than 100 °, the surface energy is less than 20 mJ m ^-2 , and the spread is less than 1%.

The layers are resistant to ruby washes, but less well on gold and steel.

The properties of the ultra-thin layer SuSoS2 are equivalent to those obtained with the commercial product Fixodrop.

Claims (11)

1. An ultra-thin hydrophobic and oleophobic layer, of which the thickness measured in ellipsometry is 0.5 to 10 nm, formed by self-assembly on a solid substrate surface, of compounds of the general formula
   
           A-B
   
   in which

   A represents a group of the formula

   

   in which

   Z represents C or N⁺,

   X represents C-H or C-L, L being an electron-attracting group selected from F, Cl, Br, I, CF₃, NO₂ and N(CH₃)₃ ⁺,

   Y represents H or CH₃, or Y forms a 5- or 6-atom heterocycle with X,

   T represents NH, CO, NH-CO, NH-CO-NH or NH₂ ⁺U^-, U^- being selected from F^-, Cl^-, Br^-, I^-, OH^-, NO₃ ^-, HSO₄ ^-, SO₄ ^2-, CO₃ ^2-, HCO₃ ^- or SCN^-, and

   B represents a C₁-C₂₀ linear aliphatic alkyl group partially or completely substituted with F.
2. An ultra-thin layer as claimed in claim 1, wherein B is a linear aliphatic alkyl group perfluorinated in its terminal section, having the formula
   
           (CH₂)_n-(CF₂)_mCF₃
   
   in which n is from 1 to 5 and m is from 4 to 11.
3. An ultra-thin layer as claimed in claim 2, wherein n is from 1 to 3 and m from 5 to 9.
4. An ultra-thin layer as claimed in one of the preceding claims, wherein A is selected from one of the following groups:

   

   

   
5. An ultra-thin layer as claimed in one of the preceding claims, wherein it is obtained from N-(3,4-dihydroxyphenethyl)-4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanamide.
6. An ultra-thin layer as claimed in one of the preceding claims, wherein the solid substrate is composed of a material selected from gold, silver, steel, aluminium, brass, bronze, copper-beryllium, titanium dioxide, ruby, sapphire, silicon, nickel and nickel phosphorus, as well as other metallic surfaces such as iron, chromium, tantalum, yttrium, germanium, copper, platinum, and metal oxides or ceramics, such as zirconia or niobia (niobium oxide), or polymers such as polyethylenes, polystyrenes, polyamides, polydimethylsiloxanes, polyvinyl chlorides, epoxy resins, or a substrate made of one of these materials or another, the surface of which has been covered or coated, for example by an electroplating of gold, of gold-copper-cadmium and of gold, of nickel, of rhodium, of tin-nickel, or treated by anodising, as in the case of parts made of aluminium alloy or titanium alloy, or modified by a surface treatment such as oxidation, carburisation or nitriding.
7. An ultra-thin layer as claimed in one of the preceding claims, wherein its advancing contact angle with water is at least 100°.
8. A mechanical part, wherein it comprises an ultra-thin layer as claimed in one of the preceding claims.
9. A method of preparing an ultra-thin layer as claimed in one of claims 1 to 7, wherein it comprises the immersion of the substrate in a solution of the compound of formula A-B in water or a mixture of water and protic solvent.
10. A method as claimed in claim 9, wherein the protic solvent is 2-propanol.
11. Use of an ultra-thin layer as claimed in one of claims 1 to 7 as a barrier film.