EP2516524A1

EP2516524A1 - Method for treating the surface of a device for dispensing a fluid product

Info

Publication number: EP2516524A1
Application number: EP10809159A
Authority: EP
Inventors: Pascal Bruna; Matthieu Laurent; Fabien Nekelson; Sébastien ROUSSEL; Lorraine Tessier
Original assignee: Aptar France SAS
Current assignee: Aptar France SAS
Priority date: 2009-12-23
Filing date: 2010-12-22
Publication date: 2012-10-31
Also published as: FR2954326A1; CN102639616A; JP2013515805A; WO2011077055A1; FR2954326B1; US20130081953A1

Abstract

The invention relates to a method for treating the surface of a device for dispensing a fluid product, said method comprising a chemical grafting step in order to form a thin film on at least one supporting surface of at least one part of said device, which can be moved during the actuation of said device, the thin film having anti-friction properties.

Description

Surface treatment method of a fluid dispensing device

The present invention relates to a surface treatment method for fluid dispensing devices.

Dispensing devices for fluid products are well known. They generally comprise one or more tanks, a dispensing member, such as a pump, a valve or a piston moving in the tank, and a dispensing head provided with a dispensing orifice. In some cases, lateral actuation systems are provided for actuating the dispensing member. Alternatively, the fluid dispensing devices may also be inhalers comprising a plurality of reservoirs each containing an individual dose of powder or liquid, and means for opening and expelling said doses during successive actuations. These different devices may further comprise a counter or dose indicator for counting or indicating the number of doses dispensed or remaining to be dispensed from the dispensing device. Thus, these devices have many parts or moving parts, which move relative to each other during actuation. Friction control, which can cause annoying noises and / or malfunctions, is a major issue. In particular in the pharmaceutical field, the risks of dysfunction of the dispensing device can be critical, for example for crisis treatments, such as asthma. These problems of friction can arise in particular at the pump piston or the valve valve, which must not especially lock. It is the same in inhalers, where the means of displacement or tank opening, as well as the dose distribution means are sensitive to friction, or in the dose counters, which must give an accurate indication to the patient. user not to deceive him about the number of doses remaining at his disposal. Any blocking of friction is therefore potentially harmful. Existing surface treatment methods all have disadvantages. Thus, some processes can only be used on flat surfaces. Other methods require a limited choice of substrate, for example gold. The plasma-induced polymerization of molecules is complex, expensive, and the resulting coating layer is difficult to control and has aging problems. Similarly, ultraviolet-induced polymerization of molecules is also complex and expensive, and only works with photosensitive molecules. The same is true of atom transfer radical polymerization (ATRP), which is also complex and expensive. Finally, electrografting processes are complex and require conductive support surfaces.

The present invention aims to provide a surface treatment method that does not reproduce the aforementioned drawbacks.

In particular, the present invention aims to provide a surface treatment method that is effective, durable, non-polluting and simple to achieve.

The present invention therefore relates to a surface treatment method of a fluid dispenser device, said method comprising the step of forming by chemical grafting a thin film on at least one support surface of at least a part said device which is movable upon actuation of said device, said thin film having anti-friction properties.

In an advantageous embodiment, said grafting step comprises contacting said surface in contact with the fluid product with a solution comprising at least one adhesion primer, said adhesion primer being a cleavable aryl salt and at least one monomer or a polymer selected from the group consisting of vinyl-terminated or acrylic-terminated siloxanes.

Advantageously, said thin film is a polymeric film comprising silicone.

Advantageously, said silicone is a grade DM300 or DM1000 silicone Advantageously, said chemical grafting creates covalent bonds between the molecules of said thin film and said support surface. This creates a strong and lasting connection over time.

Advantageously, said chemical grafting is carried out in an aqueous medium. This allows a non-polluting or green chemistry, which does not present risks for the environment.

In one embodiment, the cleavable aryl salt is selected from the group consisting of aryl diazonium salts, aryl ammonium salts, aryl phosphonium salts, aryl sulfonium salts, and salts thereof. aryl iodonium.

The cleavable aryl salts are chosen from compounds of the general formula ArN ₂ ⁺ , X ^" in which Ar represents the aryl group and X ^" represents an anion. The aryl group in an organic compound is a functional group derived from an aromatic ring.

In one embodiment, the X ^" anions are chosen from inorganic anions such as halides, such as I ^" , Cl ^" and Br ^" , haloborates such as tetrafluoroborate and organic anions such as alcoholates, carboxylates, perchlorates and sulfonates.

In one embodiment, the Ar aryl groups are chosen from aromatic or heteroaromatic compounds, optionally mono- or polysubstituted, consisting of one or more aromatic rings of 3 to 8 carbons. The heteroatoms of the heteroaomatic compounds are chosen from N, O, P and S. The substituents may contain alkyl groups and one or more heteroatoms such as N, O, F, Cl, P, Si, Br or S.

In one embodiment, the aryl groups are chosen from aryl groups substituted with attracting groups such as NO ₂ , COH, CN, CO ₂ H, ketones, esters, amines and halogens.

In one embodiment, the aryl groups are selected from the group consisting of phenyl and nitrophenyl.

In one embodiment, the cleavable aryl salt is selected from the group consisting of phenyldiazonium tetrafluoroborate, 4-nitrophenyldiazonium tetrafluoroborate, tetrafluoroborate 4- bromophenyldiazoniunn, 4-aminophenyldiazonium chloride, 4-aminomethylphenyldiazonium chloride, 2-methyl-4-chlorophenyldiazonium chloride, 4-benzoylbenzenediazonium tetrafluoroborate, 4-cyanophenyldiazonium tetrafluoroborate, 4-carboxyphenyldiazonium tetrafluoroborate, tetrafluoroborate of 4-acetamidophenyl diazonium, 4-phenylacetic diazonium acid tetrafluoroborate, 2-methyl-4 - [(2-methylphenyl) diazenyl] benzenediazonium sulfate, 9,10-dioxo-9,10-dihydro- 1-anthracenediazonium, 4-nitronaphthalenediazonium tetrafluoroborate and naphthalenediazonium tetrafluoroborate.

In one embodiment, the cleavable aryl salt is selected from the group consisting of 4-nitrophenyldiazonium tetrafluoroborate, 4-aminophenyldiazoniunn chloride, 2-methyl-4-chlorophenyldiazonium chloride, 4-carboxyphenyldiazonium tetrafluoroborate .

In one embodiment, the salt concentration of cleavable aryl is between 5.10 ^"3 M and ^{10" 1} M.

In one embodiment, the concentration of cleavable aryl salt is of the order of 5.10 ^-2 M.

In one embodiment, the cleavable aryl salt is prepared in situ.

Advantageously, said chemical grafting step is initiated by chemical activation of a diazonium salt to form an anchoring layer for said thin film.

Advantageously, said chemical grafting step is initiated by chemical activation.

In one embodiment, said chemical activation is initiated by the presence of a reducing agent in the solution.

In one embodiment, the solution comprises a reducing agent.

By reducing agent is meant a compound which in an oxidation-reduction reaction yields electrons. According to one aspect of the present invention, the reducing agent has a redox potential whose potential difference with respect to the oxidation-reduction potential of the cleavable aryl salt is between 0.3 V and 3 V. According to one aspect of the invention, the reducing agent is selected from the group consisting of reducing metals which may be in finely divided form such as iron, zinc, or nickel, a metal salt which may be in the form of metallocene and an organic reducing agent such as hypophosphorous acid, ascorbic acid.

In one embodiment, the concentration of reducing agent is between 0.005 M and 2 M.

In one embodiment, the concentration of reducing agent is of the order of 0.6 M.

In one embodiment, said thin film has a thickness of less than 1 micrometer, between 10 and 2000 angstroms, advantageously between 10 and 800 angstroms, preferably between 400 and 1000 angstroms. No conventional coating technique makes it possible to obtain such thin layers chemically grafted.

The term "vinyl or acrylic terminated siloxane" means a saturated hydride of silicon and oxygen formed of straight or branched chains, of alternating silicon and oxygen atoms comprising vinyl units or terminal acrylic units.

In one embodiment, the vinyl-terminated or acrylic-terminated siloxanes are chosen from the group consisting of polyalkylsiloxanes with acrylic or vinyl terminations, such as vinyl-terminated or acrylic-terminated polymethylsiloxane, and vinyl-terminated or acrylic-terminated polydimethylsiloxane, such as polydimethylsiloxane-acrylate (PDMS). acrylate), vinyl-terminated or acrylic-terminated polyarylsiloxanes such as vinyl-terminated or acrylic-terminated polyphenylsiloxane, such as polyvinylphenylsiloxane, and vinyl-terminated or acrylic-terminated polyarylalkylsiloxanes, such as vinyl-terminated or acrylic-terminated polymethylphenylsiloxane.

In one embodiment a potential difference is applied in said solution. By potential difference is meant the difference in redox potential measured between two electrodes.

In one embodiment, the potential difference is applied by a generator connected to two identical or different electrodes immersed in the solution during the soaking step.

In one embodiment, the electrodes are selected from stainless steel, steel, nickel, platinum, gold, silver, zinc, iron, copper, in pure form or in the form of alloy.

In one embodiment, the electrodes are made of stainless steel.

In one embodiment, the potential difference applied by a generator is between 0.1 V and 2 V.

In one embodiment, it is of the order of 0.7 V.

In one embodiment, the potential difference is generated by a chemical battery.

A chemical cell is a cell composed of two electrodes connected by an ion bridge. According to the present invention, the two electrodes are judiciously chosen so that the potential difference is between 0.1 V and 2.5 V.

In one embodiment, the chemical stack is created between two different electrodes dipping into the solution.

In one embodiment, the electrodes are selected from nickel, zinc, iron, copper, silver in pure form or in alloy form.

In one embodiment, the potential difference generated by the chemical battery is between 0.1 V and 1.5 V.

In one embodiment, the potential difference is of the order of 0.7 V.

In one embodiment, the electrodes are chemically isolated to prevent contact between the substrate immersed in the solution and the electrodes also immersed in the solution. Advantageously, said support surface is made of synthetic material, especially comprising polyethylene and / or polypropylene, elastomer, glass or metal.

Advantageously, the method further comprises the step of forming by chemical grafting at least one additional thin film on said support surface.

Advantageously, the method comprises the step of forming by chemical grafting a first additional thin film on said support surface, said first additional thin film limiting the bonding of the fluid product on said support surface.

Advantageously, the method comprises the step of forming by chemical grafting a second additional thin film on said support surface, said second additional thin film preventing interactions between said support surface and said fluid product.

According to a variant, said at least one additional thin film is deposited on said support surface during at least one successive chemical grafting step, each carried out in a single-component bath.

According to another variant, said at least one additional thin film is deposited on said support surface simultaneously during the same chemical grafting step in a multi-component bath.

Advantageously, said dispensing device comprises a reservoir containing the fluid, a dispensing member, such as a pump or a valve, fixed on said reservoir, and a dispensing head provided with a dispensing orifice, for actuating said organ of distribution.

Alternatively, said dispensing device includes a plurality of individual reservoirs each containing a dose of fluid, reservoir opening means, such as a piercing needle, and dose delivery means for dispensing a dose of product. fluid from an individual reservoir open through a dispensing orifice.

Alternatively, said dispensing device comprises a reservoir containing one or two dose (s) of fluid, and a piston moving in said reservoir at each actuation. Advantageously, said dispensing device comprises a dose counter for counting the number of doses dispensed or remaining to be dispensed from said dispensing device.

Advantageously, said fluid product is a pharmaceutical fluid product intended in particular to be sprayed nasally or orally.

In one embodiment, a method similar to that described in WO 2008/078052, which describes a method for preparing an organic film on the surface of a solid support under non-electrochemical conditions, can be used. Surprisingly, this type of process has been found to be suitable for forming an anti-friction thin film on moving surfaces upon actuation of the aforementioned dispensing devices. Such an application of this grafting method had never been considered.

In a synthetic manner, the process aims to prepare a thin film on the surface of a solid support, in particular polyethylene and / or polypropylene. This method mainly comprises contacting said support surface with a liquid solution. This comprises at least one solvent and at least one adhesion primer allowing the formation of radical entities from the adhesion primer.

The "thin film" can be any polymeric film, in particular of organic nature, for example derived from several units of organic chemical species, and covalently bonded to the surface of the support on which the process is carried out. It is particularly a film covalently bonded to the surface of the support and comprising at least one layer of similar structural units of nature. Depending on the thickness of the film, its cohesion is ensured by the covalent bonds that develop between the different units. Preferably, the thin film contains silicone.

The solvent employed in the process may be protic or aprotic in nature. It is preferable that the primer is soluble in said solvent. By "protic solvent" is meant a solvent which comprises at least one hydrogen atom capable of being released in the form of a proton. The protic solvent may be chosen from the group consisting of water, deionized water, distilled water, acidified or not, acetic acid, hydroxylated solvents such as methanol and ethanol, and low-level liquid glycols. molecular weights such as ethylene glycol, and mixtures thereof. In a first variant, the protic solvent consists only of a protic solvent or a mixture of different protic solvents. In another variant, the protic solvent or the mixture of protic solvents may be used in admixture with at least one aprotic solvent, it being understood that the resulting mixture has the characteristics of a protic solvent. Acidified water is the preferred protic solvent and, more particularly, acidified distilled water or acidified deionized water.

By "aprotic solvent" is meant a solvent which is not considered as protic. Such solvents are not likely to release a proton or accept one under non-extreme conditions. The aprotic solvent is advantageously chosen from dimethylformamide (DMF), acetone and dimethyl sulfoxide (DMSO).

The term "adhesion primer" corresponds to any organic molecule susceptible, under certain conditions, to chemisorber on the support surface by radical reaction such as radical chemical grafting. Such molecules comprise at least one functional group capable of reacting with a radical and also a reactive function with respect to another radical after chemisorption. These molecules are thus capable of forming a film of polymeric nature after grafting of a first molecule on the surface of the support and then reaction with other molecules present in its environment.

The term "radical chemical grafting" refers in particular to the use of molecular entities having an unpaired electron to form covalent link bonds with the support surface, said molecular entities being generated independently of the support surface on which they are intended to be grafted. So the reaction radical leads to the formation of covalent bonds between the support surface concerned and the grafted adhesion primer derivative and then between a grafted derivative and molecules present in its environment.

By "derivative of the adhesion primer" is meant a chemical unit resulting from the adhesion primer, after the latter has reacted by radical chemical grafting in particular with the support surface, or with another radical. It is clear to those skilled in the art that the reactive function with respect to another radical after chemisorption of the adhesion primer derivative is different from the function involved in the covalent bond, especially with the support surface. The adhesion primer is advantageously a cleavable aryl salt selected from the group consisting of aryl diazonium salts, ammonium aryl salts, aryl phosphonium salts, arylsulphonium salts and aryl iodonium salts.

Preferably, the thin film comprises silicone, which may be of different medical grades, for example DM300 or DM1000. As an alternative to the direct covalent bonds of the silicone on the support surface, obtained in an aqueous medium, it is also possible to use a process for impregnating a porous layer previously grafted with silicone.

In an advantageous embodiment of the invention, at least one additional thin film is produced by chemical grafting on the same support surface, to give at least one other property to this support surface. Thus, the fluid product may be likely to stick to a surface with which it is in contact, which may in particular have a detrimental effect on the reproducibility of the dispensed dose. The invention advantageously provides for forming by chemical grafting a first additional thin film which prevents the fluid product from sticking to the support surface. Advantageously, it could also be envisaged to apply a second additional thin film by chemical grafting to give a third property to the support surface. For example, in fluid product dispensing devices, some materials are likely to interact with the fluid product in case of contact, which can be detrimental to the fluid product. The invention advantageously provides for forming by chemical grafting a second additional thin film that prevents interactions between the fluid product and the support surface. These additional thin films can be applied during successive chemical grafting steps. In this case, each chemical grafting step is carried out in a single-component bath. It should be noted that the order of these successive chemical grafting steps can be arbitrary. As a variant, the additional thin films can also be applied during a single chemical grafting step, which is then carried out in a multi-component bath. A combination of the two variants is also conceivable.

The present invention is applicable to multidose devices, such as pump or valve devices mounted on a reservoir and operated for the successive delivery of doses. It also applies to multi-dose devices comprising a plurality of individual reservoirs each containing a dose of fluid, such as pre-dosed powder inhalers. It also applies to single-dose or bidose devices, in which a piston moves directly into a reservoir each time it is actuated. The invention is particularly applicable to nasal or oral spray devices, ophthalmic dispensing devices and syringe-type needle devices.

The invention also relates to the use of a grafting method according to the invention for forming a thin film on at least one support surface of at least a part of a fluid dispensing device which is movable from the actuation of said device, said thin film having anti-friction properties.

The following examples were carried out in a glass vessel. Unless otherwise specified, they were made under normal conditions of temperature and pressure (about 22 ° C under about 1 atm) in ambient air. Unless otherwise stated, the reagents employed were directly obtained commercially without further purification. The samples are subjected to ultrasonic cleaning with soapy water at 40 ° C. EXAMPLE 1 Grafting of a Poly (Dimethylsiloxane) Film on Parts of a Pump for Lubrication By "pump" is meant a manually operated fluid dispensing device comprising a pump body in which one or more pistons slides.

The vinyl-terminated poly (dimethylsiloxane) (1.0 g, 5 g / L) was poured into a solution of Brij® 35 (0.874 g to 4.37 g / L) in 70 mL of milliQ water and then the suspension. was magnetically stirred to form an emulsion.

4-Aminobenzoic acid (1. 370 g, 10 ^-2 mol) was solubilized in a solution of hydrochloric acid (4.0 mL in 120 mL of MQ water) and hypophosphorous acid (6.3 mL 6.0 × 10 ^-2 mol). This solution was added to the PDMS emulsion.

To this emulsion was added 8 ml of an aqueous solution of NaNO ₂ (0.667 g, 9.7 10 ^-3 mol) and the samples of the pump.

After 30 minutes of reaction, the samples: a body made of PP, low piston top piston and PE tube were removed and then rinsed in successive baths of soapy water (Renoclean) at 1% under ultrasonics at 40 ° C and baths of water.

After drying the parts with compressed air, the presence of PDMS on the samples was confirmed by IR analyzes by PDMS specific bands at 1260, 11 and 1045 cm ^-1 .

Example 2 - grafting of a poly (dimethylsiloxane) film of parts of a valve to lubricate it

By valve is meant a fluid dispensing device containing propellant gas, comprising a valve body in which slides a valve. Sodium dodecyl benzene sulfonate (1.307 g, 0.015 M) was solubilized in 175 mL of milliQ water. Vinyl-terminated poly (dimethylsiloxane) (2.5 g, 10 g / L) was added and then the mixture was magnetically stirred to form an emulsion.

4-Aminobenzoic acid (3.462 g, 2.5 × 10 ^-2 mol) was solubilized in a solution of hydrochloric acid (9.6 mL in 20 mL of MQ water) and hypophosphorous acid (33 mL, 3.1 10 ^-1 mol). This solution was added to the PDMS emulsion.

To this emulsion was added 10 ml of a solution of NaNO ₂ (1.664 g, 2.37 10 ^-2 mol) in MQ water and the samples: EPDM or Nitrile gaskets and POM valve top as well as only a gold blade witness.

After 15 minutes of reaction, the samples were removed and then rinsed successively with MilliQ water, ethanol and hexane.

The presence of PDMS on the gold slide and the other samples was confirmed by IR analyzes with PDMS-specific bands at 1260, 11 and 1045 cm- ¹ .

Example 3 Electrocatalyzed Chemical Grafting of a PDMS Acrylic Polymer Film on a Polyethylene Substrate

The following example illustrates how to graft a lubricant coating (PDMS-acrylic) on a thermoplastic such as polyethylene (PE).

Cleaning of the PE samples with ethanol, ultrasound (power of 50%, temperature of 40 ° C) for 5 minutes is carried out.

The preparation of the biphasic solution takes place in two stages. In the beaker (1) are added in order and with magnetic stirring (300 rpm), the PDMS-acrylate (1 g / L); Brij® 35 in solution in water at 8.5% wt (4.37 g / L) and 33 mL of water Dl. The emulsification is then sonicated at 40 ° C under a power of 200 W (100%) for 15 minutes.

In the beaker (2) are added, with magnetic stirring (300 rpm), nitrobenzene diazonium tetrafluoroborate (0.05 mol / L); 130 mL of Dl water and hydrochloric acid (0.23 mol / L). The contents of the beaker (2) are poured into the emulsion of the beaker (1). PE samples (x 2), a galvanized steel wire (wound on 10 turns, approximately 25 to 30 cm long) and a Ni wire (wound on 10 turns, a length of about 25 30 cm) are placed in the beaker (1). The two wires are connected to each other and an ammeter is connected in series.

Finally, once the assembly is ready, the hypophosphorous acid (0.7 mol / L) is added last which marks the beginning of the reaction. After 30 minutes of reaction at ambient temperature, the PE samples are removed and rinsed successively with water, with ethanol and finally with isopropanol in a soxhlet extractor for 16 hours.

The soxhlet consists of a glass body in which the sample is placed, a siphon tube and an adduction tube. The soxhlet is placed on a flask (here 500 ml heated and stirred via a balloon heater) containing the solvent (in this case 300 ml of isopropanol) and surmounted by a coolant.

When the flask is heated, the solvent vapors pass through the adductor tube, condense in the refrigerant and fall back into the glass body, thus macerating the sample in a pure solvent (heated by the vapors below). The condensed solvent accumulates in the extractor until it reaches the top of the siphon tube, which then causes the liquid to return to the flask, accompanied by the substances extracted, and the solvent contained in the flask thus becomes progressively enriched. soluble compounds.

The solvent then continues to evaporate, while the extracted substances remain in the flask (their boiling temperature must be significantly higher than that of the extracting solvent).

The use of a soxhlet extractor makes it possible to confirm the chemical grafting of PDMS-acrylic on the surface of the PE substrate.

An analysis by IR spectroscopy is performed. The infrared spectrum makes it possible to confirm the grafting of PDMS-acrylic by the presence of the characteristic band at 1260 cm ^-1 corresponding to the vibration of the Si-CH ₃ bond. EXAMPLE 4 Electrocatalyzed Chemical Grafting of a PDMS Acrylic Polymer Film on a Polyethylene Substrate in the Presence of a Potentiostat

The following example illustrates how to graft a lubricant coating (PDMS-acrylic) on a thermoplastic such as polyethylene (PE) in the presence of a potentiostat.

A cleaning of the PE samples with ethanol, ultrasound (power of 100 W, temperature of 40 ° C) for 5 minutes is carried out.

In the beaker (2) are added, with magnetic stirring (300 rpm), nitrobenzene diazonium tetrafluoroborate (0.05 mol / L); 130 mL of Dl water and hydrochloric acid (0.23 mol / L).

The contents of the beaker (2) are poured into the emulsion of the beaker (1). PE samples (x 2), a galvanized steel wire (wound on 10 turns, approximately 25 to 30 cm long) and a Ni wire (wound on 10 turns, a length of about 25 30 cm) are placed in the beaker (1). Both wires are connected to a potentiostat and an ammeter is connected in series. The potentiostat imposes a constant potential difference of 0.5 V and the intensity of the current is measured over time via the ammeter.

Finally, once the assembly is ready, the hypophosphorous acid (0.7 mol / L) is added last which marks the beginning of the reaction. After 30 minutes of reaction at ambient temperature, the PE samples are removed and rinsed successively with water (cascade) and then with ethanol (cascade) and finally with isopropanol in a soxhlet extractor for 16 hours.

The use of a soxhlet extractor makes it possible to confirm the chemical grafting of PDMS-acrylic on the surface of the PE substrate. An analysis by IR spectroscopy is performed. The IR spectrum makes it possible to confirm the grafting of PDMS-acrylic by the presence of the characteristic band at 1260 cm ^-1 corresponding to the vibration of the Si-CH ₃ bond.

Various modifications are also possible for a person skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

claims

1. - A method of surface treatment of a fluid dispenser device, characterized in that said method comprises a step of forming by chemical grafting a thin film on at least one support surface of at least a portion of said device which is displaceable upon actuation of said device, said thin film having anti-friction properties.

2. - Method according to claim 1, wherein said step of grafting comprises contacting said surface in contact with the fluid product with a solution comprising at least one adhesion primer, said adhesion primer being a sodium salt. cleavable aryl and at least one monomer or a polymer selected from the group consisting of vinyl-terminated or acrylic-terminated siloxanes.

3. A process according to claim 1, wherein the vinyl-terminated or acrylic-terminated siloxanes are selected from the group consisting of acrylic or vinyl-terminated polyalkylsiloxanes such as vinyl-terminated or acrylic-terminated polymethylsiloxane, vinyl-terminated or acrylic-terminated polydimethylsiloxane as polydimethylsiloxane-acrylate (PDMS-acrylate), vinyl-terminated or acrylic-terminated polyarylsiloxanes such as vinyl-terminated or acrylic-terminated polyphenylsiloxane, such as polyvinylphenylsiloxane, vinyl-terminated or acrylic-terminated polyarylalkylsiloxanes such as vinyl-terminated or acrylic-terminated polymethylphenylsiloxane.

4. A process according to any one of the preceding claims wherein the cleavable aryl salt is selected from the group consisting of aryl diazonium salts, aryl ammonium salts, aryl phosphonium salts, aryl sulfonium salts and aryl iodonium salts.

5. A process according to any one of the preceding claims, wherein said chemical grafting step is initiated by chemical activation.

6. The process of claim 5, wherein said chemical activation is initiated by the presence of a reductant in the solution.

7. - The method of claim 6, wherein the reducing agent is selected from the group consisting of reducing metals may be in finely divided form such as iron, zinc, or nickel, a metal salt may be under metallocene form and an organic reducing agent such as hypophosphorous acid, ascorbic acid.

8. - Method according to any one of the preceding claims, wherein a potential difference is applied in said solution.

9. - Method according to claim 8, wherein the potential difference is applied by a generator connected to two electrodes, identical or different, plunging into the solution.

10. - Method according to claim 8, wherein the potential difference is generated by a chemical battery.

1 1. - Method according to any one of the preceding claims, wherein said support surface is of synthetic material, including polyethylene and / or polypropylene, elastomer, glass or metal.

12. - Method according to any one of the preceding claims, wherein said thin film has a thickness of less than 1 micrometer, preferably between 10 and 2000 angstroms.

13. - Method according to any one of the preceding claims, wherein the method further comprises the step of forming by chemical grafting at least one additional thin film on said support surface.

14. - The method of claim 13, wherein the method comprises the step of forming by chemical grafting a first additional thin film on said support surface, said first additional thin film limiting the bonding of the fluid product on said support surface.

The method of claim 13 or 14, wherein the method comprises the step of chemically grafting a second additional thin film onto said support surface, said second additional thin film preventing interactions between said support surface and said fluid product.

16. - Method according to any one of claims 13 to 15, wherein said at least one additional thin film is deposited on said support surface during at least one successive chemical grafting step each carried out in a single component bath.

17. - Method according to any one of claims 13 to 15, wherein said at least one additional thin film is deposited on said support surface simultaneously during a single step of chemical grafting in a multi-component bath.

18. - Method according to any one of the preceding claims, wherein said dispensing device comprises a reservoir containing the fluid, a dispensing member, such as a pump or a valve, fixed on said reservoir, and a head of distribution provided with a dispensing orifice for actuating said dispensing member.

19. - Method according to any one of claims 1 to 17, wherein said dispensing device comprises a plurality of individual tanks each containing a dose of fluid, reservoir opening means, such as a piercing needle and dose distribution means for dispensing a dose of fluid from an individual reservoir open through a dispensing orifice.

20. - Method according to any one of claims 1 to 17, wherein said dispensing device comprises a reservoir containing one or two dose (s) of fluid, and a piston moving in said reservoir at each actuation.

21. A method according to any one of the preceding claims, wherein said dispensing device includes a dose counter for counting the number of dispensed or dispensable doses of said dispensing device.

22. - Method according to any one of the preceding claims, wherein said fluid product is a liquid or powdered pharmaceutical product intended in particular to be sprayed nasally or orally.

23. - Use of a grafting method according to any one of the preceding claims for forming a thin film on at least one support surface of at least a portion of a fluid dispensing device which is movable from the actuation of said device, said thin film having anti-friction properties.