Controlled radical assisted polymerization

Abstract

The present invention is directed to a method of forming a polymer coating on a substrate. The method comprising the steps of providing in an evacuated reaction chamber a substrate having a surface to be coated; and providing a first source of polymer forming material and a second source of radicals. According to the invention the first source and the second source are separated from each other and from the reaction chamber, and the polymer forming material as well as the radicals are, at least temporarily, conducted contemporaneously but spatially separated to the substrate's surface, so that a reaction of the polymer forming material with the radicals is avoided before they reach the substrate's surface. Further, the present invention is directed to a device for carrying out the method according to the invention.

Claims

1. A device for forming a polymer coating on a surface of the substrate, said device comprising: a reaction chamber for accommodating the substrate to be coated; a first source for providing polymer forming material; a second source for providing radicals; a conduit system structured and operable to contemporaneously and spatially separately conduct the polymer forming material and the radicals respectively from the first and second sources to a surface of the substrate to be coated, such that a reaction of the polymer forming material and the radicals is avoided before polymer forming material and the radicals reach the surface of the substrate, wherein the conduit system comprises a first conduit means fluidly separated from a second conduit means, wherein the first conduit means comprises a first comb-shaped member having a plurality of first parallel, hollow teeth, and wherein the second conduit means comprises a second comb-shaped member having a plurality of second parallel, hollow teeth, where the teeth of the first and second comb-shaped members engage one another, and wherein the teeth of the first comb-shaped member comprise a plurality of first outlets and the teeth of the second comb-shaped member comprise a plurality of second outlets.

2. The device according to claim 1, wherein the first conduit means are in fluid communication with the first source and the second conduit means are in fluid communication with the second source, and wherein the first conduit means comprise a plurality of first outlets for spraying the polymer forming material onto the surface of the substrate and the second conduit means comprise a plurality of second outlets for spraying the radicals onto the surface of the substrate.

3. The device according to claim 2, wherein the first outlets and the second outlets are arranged essentially in a plane opposite the surface of the substrate to be coated.

4. The device according to claim 3, wherein the first outlets and the second outlets are arranged essentially parallel to the surface of the substrate to be coated.

5. The device according to claim 3, wherein the first outlets and the second outlets are alternatingly arranged in at least a part of the plane.

6. The device according to claim 5, wherein the conduit system comprises a first inlet in fluid communication with the first source and a second inlet in fluid communication with the second source, and wherein the plurality of first outlets is in fluid communication only with the first inlet and the plurality of second outlets is in fluid communication with only the second inlet.

7. The device according to claim 6, wherein the first and second outlets are arranged such that at least one of the first outlets is adjacent at least two of the second outlets.

8. The device according to claim 6, wherein the first and second outlets are arranged such that at least one of the second outlets is adjacent at least two of the first outlets.

9. The device according to claim 7, wherein a distance from the first and second outlet to the surface of the substrate is less than 20 mm.

10. The device according to claim 7, wherein a distance from the first and second outlet to the surface of the substrate is less than 10 mm.

11. The device according to claim 7, wherein a distance from the first and second outlet to the surface of the substrate is less than 5 mm.

12. The device according to claim 9, wherein the first conduit means and the second conduit means are adapted to supply essentially parallel flows to the respective first and second outlets for spraying essentially parallel streams perpendicularly onto the surface of the substrate to be coated.

13. The device according to claim 12, wherein at least one of: the outlets are alternatingly arranged in one of a honeycomb pattern and a checkerboard pattern; and cross-sections of the first and second outlets are one or more of hexagonal, circular, elliptic, rectangular, triangular, star-shaped and polygonal.

Description

DRAWINGS

(1) In the following, the figures according to the embodiments of the present invention are briefly described. Further details are given in the detailed description of the embodiments. The Figures have the purpose of illustrating the invention and should not be understood in a limiting sense.

(2) FIG. 1 depicts a schematic view of the deposition principle according to an embodiment of the present invention.

(3) FIG. 2 depicts a schematic lateral view of the deposition process and the respective conduit system.

(4) FIG. 3a depicts an arrangement of alternating circular outlets.

(5) FIG. 3b depicts an arrangement of outlets arranged in a checkerboard pattern.

(6) FIG. 3c depicts an arrangement of outlets in a honeycomb pattern.

(7) FIG. 3d depicts a comb-like arrangement of conduit means comprising outlets.

DETAILED DESCRIPTION

(8) FIG. 1 schematically depicts an embodiment of a device 100 according to various embodiments the present invention. A substrate 1 to be coated is placed in a reaction chamber 3 of the device 100. Further, the device 100 comprises a first material source 5 for providing a polymer forming material 6. The first material source 5 can comprise an inert gas, as for example nitrogen or noble gazes, as well as a monomer, oligomer or precursor material 6 depending on the polymer material to be produced. Moreover, the device 100 comprises a second material source 7, i.e. a source of radicals 8.

(9) Such a source 7 can be for instance a plasma radical source 7. However, other possibilities of providing radicals in a separate source 7 are appreciated, as e.g. the formation of radicals 8 via radiation or heating systems. As already described above with respect to the prior art, radicals can assist or trigger the polymerization of polymer forming materials 6.

(10) In various embodiments, both sources 5, 7 can provide material 6, 8 to the substrate's surface 2 with pressures of less than 1 bar. As depicted in FIG. 1 both sources 5 and 7 are separated from each other and from the reaction chamber 3. However, both sources 5 and 7 could also be installed within the reaction chamber as long as no material from each source 5, 7 can get into the reaction chamber 3 in an uncontrolled manner. In other words, the materials 6, 8 from both sources 5, 7 are guided to the sample's surface 2 via conduit means 9, 10 but especially not via an uncontrollable diffusion through the reaction chamber 3.

(11) Depending on the used radicals 8 and/or radical source 7, the amount of radicals 8 can for example be controlled by the time of flight through the conduit means 10. For example, it is possible to avoid the arrival of ions generated in a plasma radical source 7 by choosing the length of the conduit means 10 from the radical source 7 to the outlet 12 such that ions have already recombined to molecules (being not relevant to the polymerization process), since free ions have a shorter lifetime than radicals. Alternatively, or in addition, control can also be possible by adjusting the pressure in the conduit means 10 and/or the flow velocity through the conduit means 10.

(12) Likewise, it is possible to control the amount of polymer forming material 6 arriving at the substrate's surface 2 by controlling the pressure and/or flow velocity through the conduit means 9.

(13) For example, polymer forming materials 6 can comprise one or more of the following substances: EDOT, pyrole, ethyl-glycol, methanol, monoglyme, tetraglyme, nipam and propylamine. These substances can also be used to form radicals 8 in a radical source 7. This is a non-exhaustive list of materials since any kind of organic substances can be polymerized with this method.

(14) Further, radicals 8 can also be one or more of: carbon-tetra-fluoride, di-tert-butylperoxide, hydrogen-peroxide and borontrifluoride or can be formed in source 7 from methane or ammonia. Radicals 8 can also be obtained directly from the polymer forming materials.

(15) Produced polymer coatings or films can be for instance polymers which are obtainable from the above mentioned substances. In particular, poly-EDOT, polypyrole, polyethyl-glycol, polymethanol, polymonoglyme, polytetraglyme, polynipam and polypropylamine. However, it is emphasized that the above listed materials or substances have merely been mentioned for the sake of illustration but must not be understood in a limiting sense. The principle of the invention can be applied to a vast variety of materials and substances falling under the scope of the present disclosure.

(16) In various embodiments, a mode of providing the sample's surface 2 with radicals 8 and polymer forming material 6 is depicted in FIG. 2. The depicted conduit system 4 allows a determined or defined application of polymer forming material 6 and radicals 8 to the substrate's surface 2. The conduit system 4 can comprise the first conduit means 9 for conducting or guiding the polymer forming material 6 from the first source 5 to first outlets 11, and second conduit means 10 for conducting or guiding the radicals 8 from the second source 7 to second outlets 12. Thus, the flows of polymer forming material 6 and radicals 8 are (fluidly) separated from each other in the conduit system 4.

(17) In general, the conduit means 9, 10 can be provided in the form of channels or lines. Such channels can have any cross shape as for example circular, ovoid, or polygonal.

(18) Furthermore, the conduit system 4 and/or conduit means 9, 10 can be heatable, wherein the temperature of the surface 2 to be coated is chosen lower than the temperature of the conduit means 9, 10 and in particular of the outlets 11, 12, so as to promote condensation of polymer forming material 6 on the substrate's surface 2.

(19) Thus, the reaction chamber can have a temperature of between about 0 C. and about 150 C. In various embodiments, the conduit system 4 is heatable. In various implementations, such heating can provide temperatures of up to 200 C., for example in order to avoid condensation of polymers on the surface of the conduit system 4. In various embodiments, the substrate 1 can have a temperature of between about 0 C. and about 80 C., e.g., between about 10 C. and about 60 C. However, neither the conduit system 4 nor the reaction chamber 3 shall be heated over temperatures of 170 C. in order to avoid degradation of polymers or polymer forming material 6.

(20) In particular, a pyrolysis of polymer forming material 6 or polymers within the reaction chamber 3 or the conduit means 9, 10 is to be avoided, since such a reaction results in an uncontrollable degradation of materials, and has thus a negative impact on the formed polymer coating.

(21) In general, the chamber 3 can be evacuated with a pressure of less than 10 mbar, e.g., in the order of between 0.1 mbar and 10 mbar. The substrate or sample 1 can have a flat shape and can have a thickness of less than 1 cm, e.g., of 0.1 m to 3 mm. The lateral size of the sample 1 can be in the order of 1 cm to 100 cm. However, these sizes must not be understood in a limiting sense but have rather an illustrative purpose.

(22) When polymer forming material 6 and radicals 8 are streamed through the outlets 11, 12, of the conduit system 4, they can form parallel jets or streams 13, 14 hitting perpendicularly the substrate's surface 2. The jets 13, 14 can also have a conical shape broadening when approaching the substrate's surface 2. Providing such jets 13, 14 to the surface 2 of the substrate 1 helps to avoid a reaction of polymer forming material 6 with the radicals 8 before both materials reach the substrate's surface 2.

(23) In various embodiments, the width of the outlets 11, 12 can be between about 0.5 mm to about 30 mm and the smallest distance 0 between an outlet 11, 12 and the substrate's surface 2 can be between 3 mm and 50 mm.

(24) The outlets 11, 12 of the conduit system 4 can be arranged essentially in a plane essentially parallel to the substrate's surface 2 to be coated. In other words, the outlets 11, 12 face the surface to be coated.

(25) FIGS. 3a to 3c depict various possible arrangements of outlets or openings 11, 12. In particular, the outlets 11, 12 can be arranged in an alternating manner in order to achieve a homogeneous supply of radicals 8 and polymer forming material 6 over the substrate's surface 2.

(26) For example, the outlets 11, 12 can have one or more of the following cross-sections: circular (11, 12, 11, 12), ovoid, rectangular (11, 12), triangular, hexagonal (11, 12), polygonal, round, cross, star, slit, etc. In various embodiments, an outlet 11 for polymer forming material 6 has at least two neighbors of outlets 12 for radicals 8, or vice versa.

(27) As depicted in FIG. 3a, the outlets 11, 12 can have a circular shape and can be arranged in lines. In general, the outlets 11, 12 can be arranged at equal distances. The arrangement of outlets 11, 12 can have essentially the form of a honeycomb pattern (see FIG. 3c) or a checkerboard pattern (see FIG. 3b), or the like.

(28) As depicted in FIG. 3d the conduit system 4 can comprise two comb-shaped (hollow) members 15, 16. Each comb-shaped member 15, 16 can be in fluid communication with only one of the sources 5, 7. For example, each comb-shaped member 15, 16 can comprise a plurality of (hollow) teeth 17, 18 being in fluid communication with one another. Each tooth 17, 18 can comprise a plurality of outlets or openings. In any case one comb-shaped member 15, 16 is adapted to apply only material of one of the sources 5 or 7 to the substrate's surface 2. In various embodiments, the teeth 17, 18 are arranged in parallel to the substrate's surface 2 and comprise openings 11, 12 facing the substrate's surface 2. In various embodiments, both members 15, 16 mesh or engage each other. In particular, the teeth 17, 18 of both members 15, 16 mesh or engage each other. This arrangement can substantially simplify the production of the conduit system 4. Moreover, this arrangement allows for replacing comb-shaped members 15, 16 with one another so that e.g. the position, form, and/or size of outlets can be changed. In particular, a plurality of comb-shaped members 15, 16 can be provided having each outlets 11, 12 with different cross-sections or different positions of the outlets on the teeth 17, 18.

(29) The invention has been described with reference to best modes of carrying out the invention. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations in so far as they come within the scope of the present disclosure or the equivalents thereof.

(30) In any case the above described embodiments shall not be understood in a limiting sense. In particular, the features of the above embodiments can also be replaced or combined with one another.

LIST OF REFERENCE SIGNS

(31) 1 substrate/sample 2 substrate's surface to be coated 3 reaction chamber 4 conduit system 5 first source/monomer source/polymer forming material source 6 polymer forming material/monomer material 7 second source/source of radicals 8 radicals 9 first conduit means 10 second conduit means 11 outlet supplied by first source 11 alternative outlet supplied by the first source 11 alternative outlet supplied by the first source 11 alternative outlet supplied by the first source 12 outlet supplied by second source 12 alternative outlet supplied by the second source 12 alternative outlet supplied by the second source 12 alternative outlet supplied by the second source 13 spray cone/stream of polymer forming material 14 spray cone/stream of radicals 15 comb-like conduit means supplied by the first source 16 comb-like conduit means supplied by the second source 100 device D distance between outlets and the sample's surface to be coated