INERTIZATION OF MATERIAL SURFACES BY FUNCTIONALIZED PERFLUORINATED MOLECULES

Abstract

A method for rendering material surfaces inert is provided. Exemplary surfaces include ceramic, metal or plastic surfaces. The method is accomplished with functionalized perfluorinated compounds for the formation of hyperhydrophobic structures on the surfaces to create inert surfaces. The inert surfaces produced or can be produced in this way have an extremely low surface energy, are resistant to deposits of substances or cells and have a very low coefficient of friction. Practical uses of the inert surfaces are also provided.

Claims

1. A method for rendering material surfaces inert, comprising: a) provision of a material surface; b) providing a functionalized perfluorinated compound; c) reaction of the functionalized perfluorinated compound with the surface to form a covalent bond, an ionic relationship or a metal bond between the perfluorinated compound and the material surface, wherein d) the material surface is a ceramic surface and the functionalized perfluorinated compound comprises a perfluorinated compound and a functional group, the perfluorinated compound comprising at most 20 completely fluorinated atoms.

2. The method according to claim 1, characterized in that the surface is activated prior to step c).

3. The method according to claim 1, characterized in that different activation takes place for partial areas of the material surface.

4. The method according to claim 1, characterized in that the functionalized perfluorinated compounds is a perfluorinated compound with at least one functional group.

5. The method according to claim 1, characterized in that the functionalized perfluorinated compounds is a perfluorinated compound with at least one functional group that comprises at least one double bond and can be attached by UV cross-linking, is a perfluorinated compound with at least one functional group that can be attached to radicals or protons.

6. The method according to claim 5, characterized in that the perfluorinated compounds are perfluorocarbons (PFC).

7. The method according to claim 1, characterized in that the functionalized perfluorinated compounds are one of: F(CF.sub.2)nX, where n=1-50, and X═Br, I, Cl, H or X═groups that contain Si, N, O, S, P; F(CF.sub.2)n-(CH.sub.2)mX, where n=1-50, m=1-26, and X═Si, N, O, S, P, Br, I, H; F(CF.sub.2)n-O.sub.b—CH═CH.sub.2 with n=1-50, and b=0 or 1.

8. The method according to claim 1 characterized in that the perfluorinated compounds are perfluorosilicon compounds.

9. The method according to claim 1, characterized in that the functionalized perfluorosilicon compounds are: siloxanes of the general formula —[—SiR.sub.2—O—].sub.n— with n≥1 and R═perfluorinated carbon or F, siloxanols of the general formula HO-A-[-SiR.sub.3R.sub.4—O—]—Si R.sub.3R.sub.4R.sub.5 with R.sub.3,4,5=F or —F(CF.sub.2)n, with n=1-10 and A=alkyl chain, perfluorinated silicates, silicic acids, sodium silicates, polysilazanes, silicides, silicon tetrahalides, silicones, silicone oils, zeolites, zirconium silicates, silanes of the general formula X—CH.sub.2—Si(OR).sub.3, where X is a leaving group suitable for nucleophilic substitution with X═Cl, Br, I, H, OH or a group comprising amino, vinyl, carbamato, glycidoxy methylalkoxy, phenyl or acetoxy groups and R═F or —F(CF.sub.2).sub.n with n=1-10, or silanes of the general formula X—Si(CF.sub.3).sub.3 or X—Si(R).sub.3, where X is a leaving group suitable for nucleophilic substitution with X═Cl, Br, I, H, OH or functional groups such as amino, vinyl-, carbamato, glycidoxy, methylalkoxy, phenyl or acetoxy groups and R═F or R═F(CF.sub.2).sub.n with n=1-10.

10. The method according to claim 1, characterized in that the material surface is one of: a ceramic surface which is formed by a ceramic selected from a group consisting of: aluminum oxide, zirconium oxide, aluminum titanate, silicon carbide, silicon nitride, aluminum nitride or other non-metallic or metallic substances or dispersion ceramics and piezoceramics, porcelain, stoneware, stealite, glass ceramic, cordlerite, titanium oxide, yttrium oxide, beryllium oxide, magnesium oxide, uranium oxide, titanates. Lead titanium zirconate, ferrites, carbon, nitrides, carbides, borides, silicides (silicon, boron, titanium, molybdenum), a metal surface which is formed by a metal selected from a group consisting of: titanium, aluminum, cadmium, chromium, iron, gold, iridium, cobalt, copper, nickel, palladium, platinum, silver, zinc and tin and alloys which contain these, or a plastic surface which is formed by a plastic selected from a group consisting of: polyacetals, polyacrylates, polyamides, polyaryls, celluloses, polyesters, polyoleofins, polystyrenes, polyvinyacates, polyvinylchlorides, polyetherketones, polyaryletherketones, polylactides, amino resins, epoxy resins, polyether alcohols, butadiene elastomers, fluorocarbon elastomers, ester elastomers, isoprene elastomers, olefin elastomers, silicone elastomers, pentenes elastomers, sulfide elastomers, urethane elastomers and vinyl chloride elastomers.

11. An inerted material surface produced by a method according to claim 1, characterized in that the perfluorinated compounds are covalently bound, bound by ionic relationship or by metal bond to the material surface.

12. The inerted material surface according to claim 1, characterized in that the covalent bond takes place through a linker or spacer molecule.

13. Use of an inertized material surface according to claim 11, in a medical product, in a product of electrical engineering, or in window glass, furnishings, sanitary facilities or buildings.

14. The method according to claim 2, characterized in that the activation takes place by acid, laser, corona, ozone, or plasma treatment.

15. The method according to claim 4, characterized in that the at least one functional group is a nucleophilic leaving group.

16. The method according to claim 15, characterized in that the nucleophilic leaving group is selected from the group consisting of: Br, I, Cl, H, N, O, S, P, hydroxyl, amino, carboxyl groups, carboxylic acids, thiocarboxylic acids, sulfonic acids, sulfinic acids, carboxylic acid halides, sulfonic acid halides, acid amides, carboxylic acid amides, sulfonic acid amides, alcohols, phenols, hydrazines, thiols, amines, imines, hydrazines, isocyanates, thiocyanates, and isothiocyanates.

17. The method according to claim 6, characterized in that the perfluorocarbons (PFC) are C.sub.1-C.sub.100.

18. The method according to claim 17, characterized in that the perfluorocarbons (PFC) are alkanes, alkenes or alkynes which are linear, branched, cyclic, polycyclic or heterocyclic.

19. The method according to claim 9 characterized in that the perfluorosilicon compounds are Si.sub.1-Si.sub.100.

20. The inerted material surface according to claim 12, characterized in that the linker or spacer molecule is one of: hydroxyl or amino groups, carboxyl groups, esters, ethers, thioethers, thioesters, carboxamides, compounds with multiple bonds, carbamates, disulfide bridges and hydrazides, haloalkanes, sulfhydryl, aldehyde, keto, carboxyl, ester and acid amide groups, thiols, amines, imines, hydrazines, or disulfide groups, glycerol, succinylglycerol, orthoesters, phosphoric diesters and vinyl ethers.

Description

EXAMPLES OF WAYS OF INERTING CERAMIC AND METAL SURFACES WITH FUNCTIONALIZED PERFLUORINATED COMPOUNDS

[0143] Modifications of ceramic and metal surfaces with functionalized perfluorinated compounds can be implemented in various ways: [0144] 1) Pre-activation of the surfaces by acids (e.g., with sulfuric acid or hydrofluoric acid), by other agents, by laser treatment, by corona, ozone or plasma treatment or other processes and subsequent reaction with functionalized perfluorinated compounds [0145] 2) direct reaction with functionalized perfluorinated compounds [0146] 3) Coating with a layer on which functionalized perfluorinated compounds can react

[0147] By means of a selective surface treatment (e.g., laser treatment) or a selectively generated print image and the associated accessibility or non-accessibility for the reactions with the functionalized perfluorinated compounds, a defined pattern between areas of different properties (e.g., high and very low surface energy) can be created.

Regarding 1) and 2) (Pre) Activation of the Surfaces with Sulfuric Acid or Hydrofluoric Acid and Subsequent Reaction with a Functionalized Perfluorinated Compound or Direct Reaction:

[0148] Based on the depicted unit cell of the crystalline structure of zirconium (IV) oxide, various modification processes are possible, with several reactions for changing the surface structure being available as options.

##STR00008##

[0149] Since high-performance ceramics made from zirconium (IV) oxide and others have a high chemical and thermal stability, it may be preferable to carry out surface activation using hydrofluoric acid (hydrofluoric acid) and/or concentrated sulfuric acid. In some cases, however, it can be dispensed with (direct reaction).

[0150] As a result of the activation, the oxygen atoms aligned with the surface are first protonated. If another protonation takes place, the oxygen atoms can be split off as water (see reaction equation 1).

##STR00009##

[0151] By splitting off the oxygen, the zirconium atom can exist as a tetravalent ion (Zr.sup.4+) and form an ionic compound with the fluoride ions (salt). This detaches the zirconium ion from the surface structure of the ceramic and is “rinsed out”.

[0152] In this way, different activated states of the ZrO.sub.2 surface structure can be generated in one pretreatment. These are the starting point for the modification with functionalized perfluorinated compounds.

##STR00010##

[0153] As reaction equation 2 shows, the activated first protonated state of the ceramic can nucleophilically attack the positively charged perfluorinated methyl iodide carbon, so that a perfluorinated methyl group is added. The perfluorinated “ether” formed is more difficult for body cells to split than a non-perfluorinated methyl group, since the fluorine atoms contained in it represent poor leaving groups due to their low relative atomic mass, high electronegativity and their small radius (ionic radius) and are therefore not split off.

[0154] In addition, methyl groups with their hydrogen atoms can form both van der Waals interactions and hydrogen bonds, which is clearly more difficult with the perfluorinated radicals.

[0155] This makes it possible to use other perfluorinated groups for modification, which bind to the activated ceramic surface by means of basic reaction mechanisms.

##STR00011##

[0156] As reaction equation 3 shows, the ionic activated intermediate can also be used as an electrophilic reactant. The zirconium ion is attacked nucleophilically by the perfluorinated alcohol. The perfluorinated “diether” is formed by splitting off hydrofluoric acid (which can re-enter the reaction process for further surface activation).

##STR00012##

[0157] Analogously to reaction equation 3, reaction equation 4 also shows a possible reaction in which the activated ceramic surface is used as an electrophilic reactant. A primary amine is used as the nucleophilic reaction partner. Perfluorinated secondary amines can also fulfill this type of reaction. The amine attacks the positively charged zirconium by means of the lone pair of electrons in nitrogen and binds to it. A proton (H+) is split off and forms HF with the fluoride ion, which is available again for surface activation.

##STR00013##

[0158] Based on “silicones”, perfluorinated silanes can be used. This type of reaction corresponds to a condensation in which water is split off as a by-product (see reaction equations 5 & 6). The silane oxygen nucleophilically attacks the positively polarized zirconium. One H.sup.+ and one OH.sup.− group are split off as water.

##STR00014##

[0159] As in reaction equation 5, the silane oxygen nucleophilically attacks the zirconium and an and an OH group are split off as OH.sup.−, which form the by-product water.

[0160] The introduction of silanes or other semimetals or metals (doping) is used to increase the electrical conductivity. Zirconium (IV) oxide can electrolytically transport oxygen ions at high temperatures. This creates an electrical voltage. The doping improves the conductivity at lower temperatures.

[0161] In contrast, the application of perfluorinated organyls to the zirconium (IV) oxide surface reduces or prevents the conduction of electrical current. In electrical engineering (microelectronics), this isolator effect enables precise production of control systems for conducting electrical current.

##STR00015##

[0162] By means of the double bond of the tetrafluoroethene, an addition takes place on the electrophilic zirconium. Subsequent hydrogenation (addition of H2) reduces the former ethene group.

[0163] Reaction equation 7 shows an analogue to the first step of the Ziegler direct method. The tetrafluoroethene is additively attached to the activated zirconium oxide surface and hydrogenated.

##STR00016##

[0164] Reaction equation 8 shows the reaction of a perfluorinated metal organyl (lithium organyl, a copper-lithium organyl would also be possible, for example). The perfluorinated organyl is a strong nucleophile that nucleophilically attacks the positive zirconium ion on the activated ceramic surface. This reaction is also promoted by the formation of the salt LiF (lithium fluoride), which has a strongly negative lattice energy.

##STR00017##

[0165] The reaction already described in reaction equation 8 can also be carried out with the non-ionic intermediate state of the activated zirconium oxide surface. A further activation is achieved by the metalation of the surface oxygen, whereby two perfluorinated organyl residues are already attached to the zirconium center. This lithiated surface is able to enter into further nucleophilic reactions.

[0166] The reactions outlined above also apply in the same way to other ceramics and high-performance ceramics made from metal oxides.

[0167] The aluminum oxide used in a corundum structure is also suitable for these reactions.

##STR00018##

[0168] The oxygen in the surface structure of the ceramic is protonated by the hydrofluoric acid, so that Al(OH).sub.3 and AlF.sub.3 are formed as intermediate stages. Through further protonation of the OH groups, water is split off and the more reactive AlF.sub.3 is formed.

##STR00019##

[0169] The oxygen in Al(OH).sub.3 nucleophilically attacks the positively polarized carbon atom of trifluoroiodomethane. Iodine is eliminated as iodide and forms the by-product hydrogen iodide (HI) with the proton of the OH group.

##STR00020##

[0170] The alcohol oxygen in the perfluorinated alcohol nucleophilically attacks the aluminum. An OH group is split off as OH.sup.− and the alcohol proton (H.sup.+), which form water as a by-product.

##STR00021##

[0171] The silane oxygen attacks the aluminum in a nucleophilic manner and the OH and the proton of the silane OH group are split off, so that water is formed as a by-product.

##STR00022##

[0172] In reaction equation 14, the mechanism proceeds as in equation 13. The silane oxygen attacks the aluminum nucleophilically and OH and the proton of the silane OH group are split off, so that water is formed as a by-product.

##STR00023##

[0173] The lithium organyl shown in reaction equation 15 is strongly polarized. The negatively polarized organyl C atom nucleophilically attacks the aluminum. OH— is split off, which forms a by-product with Li+LiOH.

[0174] Titanium (IV) oxide (TiO.sub.2) is another high-performance ceramic that can be modified by the reactions mentioned above.

##STR00024##

[0175] The oxygen atoms on the TiO.sub.2 surface are protonated by HF until the more reactive TiF.sub.4 is formed.

##STR00025##

[0176] The trifluoroiodomethane shown in reaction equation 17 is polarized, so that an oxygen of the activated ceramic surface attacks the positively polarized carbon atom of the trifluoroiodomethane in a nucleophile manner and iodide is split off. This accumulates with the split off proton to form hydrogen iodide (HI) as a by-product.

##STR00026##

[0177] The activated ceramic surface shown in reaction equation 18 reacts as an electrophile and as such is attacked nucleophilically by the oxygen of the perfluorinated alcohol. The proton (H.sup.+) of the alcohol group is split off, which combines with a fluoride ion to form HF as a by-product, which is available for further surface activation.

##STR00027##

[0178] In reaction equation 19, the perfluorinated primary amine acts as a nucleophile. The amine nitrogen attacks the positive titanium in a nucleophilic manner. An H.sup.+ of the amino group is split off, which forms the by-product HF with an F.sup.−.

##STR00028##

[0179] In reaction equation 20, the silane oxygen attacks the titanium on the ceramic surface in a nucleophilic manner OH.sup.− is split off, which with H.sup.+ forms water as a by-product.

##STR00029##

[0180] In reaction equation 21, the silane oxygen attacks the titanium of the ceramic surface in a nucleophilic manner OH.sup.− is split off, which with H.sup.+ forms water as a by-product.

##STR00030##

[0181] By means of the double bond of the tetrafluoroethene, an addition takes place on the electrophilic titanium. Subsequent hydrogenation (addition of H.sub.2) reduces the previous ethene group to a tetrafluoroethane group.

##STR00031##

[0182] The lithium organyl shown in equation 23 is strongly polarized. The negatively polarized organyl C atom nucleophilically attacks the titanium. OH.sup.− is split off, which forms a by-product with Li.sup.+ LiOH.

##STR00032##

[0183] Reaction equation 24 shows, like equation 23, a nucleophilic addition of the negatively polarized organyl to the titanium. In addition, Li′ binds to the oxygen atoms on the ceramic surface, so that a still reactive species is created.

Regarding 3) Coating with a Layer on which Functionalized Perfluorinated Compounds can React

[0184] Instead of activating the ceramic or metal surface for a reaction with the functionalized perfluorinated compounds, a coating with accessible functional groups can alternatively be applied (cf. Examples 1 and 3 of the exemplary inerting routes for plastic surfaces using functionalized perfluorinated compounds)

[0185] It can thus be preferred that the ceramic is coated with a polyurethane compound which contains OH groups and bonds well to the surface of the ceramic. A reaction with functionalized perfluorinated compounds can then be brought about via the OH groups, in which case a perfluorinated compound with an isocyanate group is used.

[0186] In another example, the ceramic is coated with a polymer compound that contains NH.sub.2 groups and bonds well to the surface of the ceramic. A reaction with functionalized perfluorinated compounds is then brought about via the NH.sub.2 groups, in which case a perfluorinated compound with an aldehyde group is used.

[0187] In a further example, the ceramic is coated with a polymer compound that enables an azide-alkyne cycloaddition. This polymer compound contains azide groups via which the functionalized perfluorinated compounds are bound by means of an alkyne group. Other variants of the click chemistry can also be used.

Exemplary Ways of Inerting Plastic Surfaces Using Functionalized Perfluorinated Compounds:

[0188] The inertization of plastic surfaces can be implemented in different ways: [0189] 1) Direct chemical connection of the functionalized perfluorinated compounds via functional groups of the plastic [0190] 2) Activation of the plastic surface (by plasma, corona or laser treatment, by X-rays or UV radiation, by HF treatment or chemical substances or other processes by which the plastic surface can be activated) and subsequent chemical bonding of the functionalized perfluorinated compounds [0191] 3) Coating of the plastic with a layer that is accessible to the chemical attachment of the functionalized perfluorinated compounds with subsequent attachment of these molecules to this layer

[0192] Through a selective surface treatment (e.g., laser treatment, other) or through a selectively generated print image and the associated accessibility or non-accessibility for the reactions with the functionalized perfluorinated compounds, a defined pattern between areas of different properties (e.g., high and low surface energy or other spatial differentiated properties). [0193] 1) Examples for a direct chemical connection of the functionalized perfluorinated compounds to functional groups of plastic surfaces as well as examples for connection to layers that are accessible to the chemical connection of the functionalized perfluorinated compounds:

##STR00033## ##STR00034##

[0194] Examples of possible applications in principle of functionalized perfluorinated compounds on functional groups of a plastic surface or a coating include:

TABLE-US-00002 TFAA TFBA, TFMBA TFE Reagent Group Anhydride Aldehyde Hydroxyl Primary amine X X Secondary amine X (X) Carboxyl (X) X Hydroxyl X Epoxy X

##STR00035##

[0195] Another possibility is the cross-linking of functionalized perfluorinated compounds with double bonds (e.g., perfluorinated sulfonic acids or perfluorinated carboxylic acids or perfluorinated monomers of plastics such as acrylates) with plastics that also contain double bonds (e.g., polyester) under UVA radiation.

##STR00036##

[0196] Or

[0197] or other plastics with a double bond [0198] 2) Examples for the activation of the plastic surface (by plasma, corona or laser treatment, by X-rays or UV radiation, by chemical substances or other processes by which the plastic surface can be activated) and subsequent chemical bonding of the functionalized perfluorinated compounds:

[0199] In the case of high-energy O.sub.2 plasma UV radiation, for example, hydrogen atoms are knocked out of the plastic surface. These are either replaced by oxygen atoms, which are usually present as radicals, or ions are formed. These activated plastic surfaces can then react very well with functionalized perfluorinated compounds.

[0200] In principle, perfluorinated compounds, whose functional group can be subjected to nucleophilic attack, or positively charged perfluorinated ions are particularly suitable. But other chemical compounds are also possible.

[0201] Examples of preferred functionalized perfluorinated compounds:

##STR00037##

[0202] Without a perfluorinated part of the molecule, the shown molecules would be biodegradable. After attachment to the plastic, the protruding perfluorinated chains shield the attachment from degrading enzymes. [0203] 3) Examples of coating the plastic with a layer that is accessible to the chemical attachment of the functionalized perfluorinated compounds with subsequent attachment of these molecules to this layer: [0204] For example, the plastic is coated with a polyurethane compound that contains OH groups. A reaction with functionalized perfluorinated compounds is then brought about via the OH groups, as exemplified above under 1)/3).

[0205] In another example, the plastic is coated with a polyacrylamide compound that contains NH.sub.2 groups. A reaction with functionalized perfluorinated compounds is then brought about via the NH.sub.2 groups, as exemplified above under 1)/3).

[0206] In another example, the plastic is coated with a layer that enables an azide-alkyne cycloaddition. This polymer compound contains azide groups via which the functionalized perfluorinated compounds are bound by means of an alkyne group. Other variants of the click chemistry can also be used.

Example Connection of Nonafluoro-1-Butanesulfonyl Chloride to Polyurethane

[0207] Polyurethane platelets were wetted with nonafluoro-1-butanesulfonyl chloride (Sigma Aldrich, Art. No. 51974-1G-F) and incubated in a closed container for 30 min at room temperature. The platelets were then washed in isopropanol and with distilled water and dried.

[0208] An XPS measurement was carried out to demonstrate the covalent bond (see BAM measurements)

Example Connection of Perfluorobutyryl Chloride to Glass

[0209] An uncoated glass slide was surface-activated in an HF bath for 30 s and then washed in isopropanol and in distilled water and dried.

[0210] The glass surface was then wetted with perfluorobutyryl chloride (Sigma Aldrich, Art. No. 257923-5G) and incubated in a closed container for 30 min at room temperature. The glass slide was then washed in isopropanol and dried.

[0211] An XPS measurement was carried out to demonstrate the covalent bond (see BAM measurements)

Example Binding of Perfluorobutyryl Chloride to Titanium

[0212] An uncoated titanium support was surface-activated in an HF bath for 30 s and then washed in isopropanol and in distilled water and dried.

[0213] The titanium surface was then wetted with perfluorobutyryl chloride (Sigma Aldrich, Art. No. 257923-5G) and incubated in a closed container for 30 min at room temperature. The titanium support was then washed in isopropanol and with distilled water and dried.

[0214] An XPS measurement was carried out to demonstrate the covalent bond (see BAM measurements)

Example Binding of Perfluorobutyryl Chloride to Steel

[0215] An uncoated steel support was surface-activated in an HF bath for 30 s and then washed in isopropanol and in distilled water and dried.

[0216] The steel surface was then wetted with perfluorobutyryl chloride (Sigma Aldrich, Art. No. 257923-5G) and incubated in a closed container for 30 min at room temperature. The titanium support was then washed in isopropanol and with distilled water and dried. Eserfolgte eine XPS-Messung zum Nachweis der kovalenten Anbindung (siehe BAM-Messungen)

Example Binding of Perfluorobutyryl Chloride to Ceramic

[0217] A ceramic plate was surface-activated in an HF bath for 30 s and then washed in isopropanol and in distilled water and dried.

[0218] The ceramic surface was then wetted with perfluorobutyryl chloride (Sigma Aldrich, Art. No. 257923-5G) and incubated in a closed container for 30 min at room temperature. The ceramic plate was then washed in isopropanol and with distilled water and dried.

[0219] An XPS measurement was carried out to demonstrate the covalent bond (see BAM measurements)