Agent for the surface epilamization of an article

Abstract

The present invention relates to an agent in particular for the surface epilamization of an article comprising one or more molecules having the general formula (1)
A-F(1)
wherein: A is an anchor group comprising a moiety selected from the group consisting of silane groups, hydroxyl groups, catechol groups, phosphate groups, phosphonate groups, carboxylic acid groups, amine groups, thiol groups and any combination of two or more of the aforementioned groups and F is a functionalizing group, wherein the functionalizing group com-prises a branched polymer having a backbone and at least two side groups, wherein at least one of the side groups is a C1-20 hydrocarbon group or a perhalogenated C1-20 hydrocarbon group. The invention pertains to the technical field of epilame for timepiece mechanical parts.

Claims

1. An article comprising a substrate having at least one surface, wherein at least part of said at least one surface is coated with an agent for the surface epilamization of an article comprising one or more molecules having the general formula (1):
A-F (1) wherein: A is an anchor group comprising a moiety selected from the group consisting of silane groups, hydroxyl groups, catechol groups, phosphate groups, phosphonate groups, carboxylic acid groups, amine groups, thiol groups and any combination of two or more of the aforementioned groups and F is a functionalizing group, wherein the functionalizing group com-prises a branched polymer having a backbone and at least two side groups, wherein at least one of the side groups is a C4-20 hydrocarbon group or a perhalogenated C4-20 hydrocarbon group; and in that the agent includes, as epilame function, at least one side group that is a partially fluorinated hydrocarbon group.

2. The article according to claim 1, wherein at least one, preferably at least 50%, more preferably at least 80%, even more preferably at least 90% and most preferably all of the side groups are a C4-18 hydrocarbon group, more preferably a C6-16 hydrocarbon group and most preferably a C8-14 hydrocarbon group.

3. The article according to claim 1, wherein the at least one side group is a partially fluorinated hydrocarbon group and preferably a perfluorinated hydrocarbon group.

4. The article according to claim 1, wherein the hydrocarbon group is an alkyl ester group and preferably a linear alkylester group.

5. The article according to claim 4, wherein the hydrocarbon group is selected from the group consisting of acrylate esters, methacrylate esters, styrene derivatives having at least one alkyl group attached to the aromatic ring and any combination of two or more of the aforementioned groups.

6. The article according to claim 1, wherein the branched polymer comprises 2 to 50, preferably 3 to 30, more preferably 4 to 20, even more preferably 5 to 15 and most preferably 7 to 13 side groups.

7. The article according to claim 6, wherein all of the side groups are, the same or different, C.sub.4-10 hydrocarbon groups, preferably C.sub.3-9 hydrocarbon groups and most preferably C.sub.4-.sub.8 hydrocarbon groups.

8. Article according to claim 1, wherein all of the side groups are partially fluorinated hydrocarbon groups and preferably perfluorinated hydrocarbon groups.

9. The article according to claim 1, wherein at least one of the side groups has at least one functional group which is capable of cross-linking with another molecule of the agent having the general formula (1), wherein the branched polymer comprises at least one block comprising at least 5 and preferably at least 10 side groups, wherein at least 2 of these side groups comprise each at least one functional group which is capable of cross-linking with another molecule of the agent having the general formula (1).

10. The article according to claim 9, wherein the branched polymer contains at least one further block comprising at least 5 and preferably at least 10 side groups, wherein all side groups of this at least one further block do not contain functional groups being capable of cross-linking with another molecule of the branched polymer, wherein the branched polymer more preferably contains two of the further blocks each of which comprising at least 5 and preferably at least 10 side groups, wherein all side groups of these further blocks do not contain functional groups being capable of cross-linking with another molecule of the branched polymer, wherein the block comprising at least 5 and preferably at least 10 side groups, wherein at least 2 of these side groups comprise each at least one functional group which is capable of cross-linking with another molecule of the agent having the general formula (1), is arranged between the two further blocks.

11. The article according to claim 1, wherein the at least one surface being coated with the agent is composed of a material selected from the group consisting of silicon, diamond-like carbon, silicon carbide, sapphire, steel, metal-coated steel, nickel-plated steel, ruby, aluminium oxide, iron oxide, a magnesium alloy, silicon oxide, niobium oxide, titanium oxide, a polymer and any combination of two or more of the aforementioned materials.

12. A method for producing an article according to claim 1 comprising the steps of: a) providing a substrate having at least one surface, b) bonding at least one anchor group selected from the group consisting of silane groups, hydroxyl groups, catechol groups, phosphate groups, phosphonate groups, carboxylic acid groups, amine groups, thiol groups and any combination of two or more of the aforementioned groups onto at least one of the at least one surface of the substrate, c) providing at least one kind of monomer and d) graft polymerizing the at least one kind of monomer onto the at least one anchor group to form at least a branched polymer which is covalently bonded to the at least one anchor group.

13. A method for producing an article according to claim 1 comprising the steps of: c) providing at least one kind of monomer, d) graft polymerizing the at least one kind of monomer onto the at least one anchor group selected from the group consisting of silane groups, hydroxyl groups, catechol groups, phosphate groups, phosphonate groups, carboxylic acid groups, amine groups, thiol groups and any combination of two or more of the aforementioned groups to form at least one branched polymer which is covalently bonded to the at least one anchor group, a) providing a substrate having at least one surface and b) bonding said at least one anchor group onto at least one of the at least one surface of the substrate.

14. A method for producing an article according to claim 1 comprising the steps of: d) graft polymerizing the at least one kind of monomer in order to form at least one branched polymer, a) providing a substrate having at least one surface, b) bonding at least one anchor group selected from the group consisting of silane groups, hydroxyl groups, catechol groups, phosphate groups, phosphonate groups, carboxylic acid groups, amine groups, thiol groups and any combination of two or more of the aforementioned groups onto at least one of the at least one surface of the substrate and e) bonding said at least one branched polymer onto said at least one anchor group.

15. A timepiece comprising an article according to claim 1.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) Dimethylchlorosilane (Aldrich-Fine Chemicals, 98%), 10-undecen-1-ol (Aldrich-Fine Chemicals, 98%), 2-bromo-2-methylpropionyl bromide (Acros Organics, 98%) and chloroplatinic acid hexahydrate (ABCR Deutschland 99.9%) used for the initiator synthesis were used as received from the suppliers.

(2) 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate was freed from the inhibitor by passing through a column filled with alumina using acetone as eluent and removal of the eluent in vacuum.

(3) Copper (II) bromide (Sigma-Aldrich, 99%) was used as received. Copper (I) bromide (Aldrich-Fine Chemicals, 5N) was purified by washing in glacial acetic acid. Therefore, 4 g of CuBr were suspended in 400 ml of acetic acid and the resulting mixture was stirred at room temperature overnight. Afterwards CuBr was separated by filtration using filter paper, subsequently washed with methanol and diethyl ether and dried under vacuum. The so obtained CuBr was stored at room temperature under inert gas.

(4) The synthesis of 11-(2-bromo-2-methyl-propionyl)-dimethylchlorosilane initiator (BPCS) having a dimethylchlorosilane anchor group was performed following a two-step protocol described by Sanjuan (Lang-muir 2007, 23, 5769-5778 Sanjuan et al.).

(5) ##STR00001##

(6) To 10.7 ml of 10-undecen-1-ol in 50 ml of dry tetrahydrofuran (Sigma Aldrich, 98%), 9 ml (60 mmol) of triethylamine (Sigma Aldrich, 99.5%) were added, followed by a dropwise addition of a solution of 7 ml of 2-bromo-2-methylpropionyl bromide in 20 ml of dry tetrahydrofuran. The mixture was stirred under inert gas for 24 hours and diluted with 100 ml of hexane, washed twice with 100 ml of 2 M HCl (prepared by adding 42 ml of 37% HCl to 208 ml of H2O) and washed 4 times with 100 ml of ultra-pure water. The organic phase was separated and dried over magnesium sulfate for 60 minutes before being filtered using a filter paper and concentrated at 130 mbar at 40 C. The obtained crude product was purified by passing through a silica column (silica gel 60, diameter 80 mm, height ca. 27 cm, eluent: 1.5 l of dichloromethane, gravity). After removal of the eluent in vacuum 10-undecen-1-yl-2-bromo-2-methylpropionate was obtained as a colourless oily product which was stored under inert gas at 4 C. until the second step described in the following.

(7) In the second reaction step 2.54 g of the 10-undecen-1-yl-2-bromo-2-methylpropionate obtained in the preceding step were added to 10 mg of chloroplatinic acid hexahydrate and 7.93 ml of dimethylchlorosilane. The so obtained mixture was stirred overnight in the dark under inert gas and filtered through a silica plug without using additional solvent. The excess of unreacted silane was removed by drying under vacuum for 24 hours.

(8) The obtained 11-(2-bromo-2-methyl-propionyl)-dimethylchlorosilane initiator (BPCS) was stored at 20 C. in a container filled with inert gas and sealed with parafilm at 20 C.

EXAMPLE

(9) (i) Bonding of the Initiator to a Silicon Surface

(10) Silicon article (P/B<100>, Si-Mat Silicon Wafers, Germany) were washed 3 times with isopropanol in the sonication bath, treated for 30 minutes in a UV ozone cleaner (UV/Ozone ProCleaner and ProCleaner Plus, IA, USA). The so obtained cleaned articles were immediately immersed in a 10 mM solution of the BPCS initiator in freshly distilled toluene and incubated under an inert atmosphere for 24 hours. This was followed by five times washing in toluene performed by immersing into five different baths of toluene for a few minutes and, while being immersed in the last of the five baths, a brief sonication for 20 seconds in order to remove the weakly bound molecules, and final rinsing with isopropanol. The so prepared samples were dried with a stream of nitrogen and stored under an inert atmosphere in the dark in a parafilm-sealed box before being used within seven days.

(11) The BPCS-initiator-functionalized silicon surface obtained according to the preceding protocol was characterized by a static-contact-angle (CA) measurement. This measurement performed on a BPCS layer adsorbed on a UV/ozone-cleaned ultra-hydrophilic silicon surface, which before being immersed into the solution of the BPCS initiator had an initial contact angle of below 3, resulted in a contact angle of 772.

(12) The thickness of the BPCS layer was determined to be 1.80.1 nm by using a variable-angle spectroscopic ellipsometer (VASE) (M-2000F, LOT Oriel GmbH, Darmstadt, Germany). The ellipsometric measurement data were collected at three different angles of incidence 65, 70 and 75, and the incident wavelength was varied between 995 and 370 nm. The obtained thickness values is a result of a fit to a three-layer model, Si jell/SiO2/Cauchy, defined in the WVASE32 software (LOT Oriel GmbH, Darmstadt, Germany).

(13) (ii) Graft Atom Transfer Radical Polymerization of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptadecafluorodecyl Acrylate

(14) At ambient conditions 2.9 ml (4.75 g) of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate, 11.3 ml of cyclohexanone and 167 l (138 mg) of N,N,N,N,N-pentamethyldiethylenetriamine (PMDETA) were added to a flask which was sealed with a rubber septum. The resulting solution was subjected to four freeze-pump-thaw cycles before being transferred to a second flask containing 57.4 mg of copper (I) bromide and 10.0 mg of copper (II) bro-mide under an inert atmosphere. The obtained solution was stirred for 5 minutes under heating with a hot oil bath having a temperature of 110 C. to achieve a dark brown homogeneous mixture. 4 ml of this mixture were transferred to the BPCS-modified silicon article sample prepared in step (i) being placed in a 20 ml Schlenk tube under an inert atmosphere using an oxygen-free syringe. The reaction was kept at 110 C. under an inert atmosphere for three hours. The reaction was quenched by exposure to air atmosphere and addition of toluene, and the obtained article, i.e. a silicon substrate having attached to its surface via a silane moiety the polymer resulting from the aforementioned reaction, was separated from the mixture.

(15) (iii) Purification

(16) The article obtained in the preceding step (ii) was subjected to purification in order to remove the non-bonded material. The purification can be performed by immersing the obtained article in dichloromethane under sonication for 15 minutes which was performed all in all three times before the article was dried. Other kind of purification can be alternatively performed.

(17) The thickness of the surface-bound polymer coating was determined to be between 5 to 30 nm using a variable-angle spectroscopic ellipsometer (VASE) (M-2000F, LOT Oriel GmbH, Darmstadt, Germany).

(18) Furthermore, the contact angles for water, benzyl alcohol ethyleneglycol, Moebius oil 9010 and Moebius testl 3 were determined, the results being presented in the following table:

(19) TABLE-US-00001 Contact angle Contact angle Liquid after fabrication after several cleanings Water 125 N/A Benzyl alcohol 108 N/A Ethyleneglycol 96 N/A Moebius oil 9010 84 86 Moebius testl 3 72 73

(20) It appears that, even after several cleanings, the contact angles remain globally unchanged.

(21) Of course, the present invention is not limited to the illustrated example but may be subject to various variants and alterations, which will be apparent to those skilled in the art. In particular, reaction conditions can be adapted regarding mono- and polymers and/or anchor group and/or cross-linker and/or substrates used.