SURFACE-STRUCTURED POLYMER BODIES AND METHOD FOR THE FABRICATION THEREOF

Abstract

Surface-structured polymer bodies in which polymer bodies with dimensions of at least 100 cm.sup.2 are present. The surfaces of the bodies are at least partially covered with at least one nano- to micrometer-thick layer, and the layers are physically and/or chemically coupled to the polymer bodies, and the surface of the polymer bodies with the layers is at least partially deformed. The deformation is periodic within a deformation type and the arrangement of multiple different deformation types on a polymer body is anisotropic or isotropic, and the elastic modulus of the material of the polymer body is less than the elastic modulus of the layer materials.

Claims

1. Surface-structured polymer bodies in which polymer bodies with dimensions of at least 100 cm.sup.2 are present, the surfaces of which are at least partially covered with at least one nano- to micrometer-thick layer, and the layers are physically and/or chemically coupled to the polymer bodies, and the surface of the polymer bodies with the layers is at least partially deformed, wherein the deformation is periodic within a deformation type and the arrangement of multiple different deformation types on a polymer body is anisotropic or isotropic, and wherein the elastic modulus of the material of the polymer body is less than the elastic modulus of the layer materials.

2. The surface-structured polymer bodies according to claim 1 in which polymer bodies with dimensions of 100 cm.sup.2 to 100 m.sup.2 are present.

3. The surface-structured polymer bodies according to claim 1 in which a layer with a layer thickness between 10 nm and 100 m is present.

4. The surface-structured polymer bodies according to claim 1 in which the surfaces are coated with a layer composite of two to 10 layers on top of one another, wherein the total thickness of all layers is not more than 100 m.

5. The surface-structured polymer bodies according to claim 1 in which the surface of a polymer body is completely or partially coated with a layer or a layer composite of different layer materials on top of or next to one another.

6. The surface-structured polymer bodies according to claim 1 in which the physical coupling of the polymer bodies and layer or layer composite is achieved by mechanical interlocking or by means of van der Waals forces, and the chemical coupling of the polymer bodies and layer or layer composite is achieved through chemical covalent bonds.

7. The surface-structured polymer bodies according to claim 1 in which the deformation within a deformation type on a polymer body is periodic and anisotropic.

8. The surface-structured polymer bodies according to claim 1 in which, with the arrangement of multiple deformation types on a polymer body, the deformation within one arrangement is aligned in a periodic and isotropic manner and the deformations among the different deformation types are aligned anisotropically to one another.

9. The surface-structured polymer bodies according to claim 1 in which the polymer bodies comprise multiple deformation types which differ in regard to the periodicity, dimensions, and/or shape of the deformations.

10. The surface-structured polymer bodies according to claim 1 in which the materials of the polymer bodies are elastomers, thermoplastic elastomers, thermoplastics, and/or duromers, or these materials are at least present at or contained in the polymer body surface that is to be coated.

11. The surface-structured polymer bodies according to claim 1 in which the layer or the layer composite is composed of metallic, polymeric, polymer-composite, ceramic, or vitreous materials.

12. The surface-structured polymer bodies according to claim 1 in which the elastic modulus of the material of the polymer body is at least 1 order of magnitude less than the elastic modulus of the layer materials.

13. A method for the fabrication of surface-structured polymer bodies in which polymer bodies with dimensions of at least 100 cm.sup.2 are subjected to a stretching strain in at least one direction at least above the critical wrinkling stress and maximally up to below the fracture stress of the material of the polymer bodies, the surfaces of the polymer bodies are coated in the strained state with at least one nano- to micrometer-thick layer or layer composite by means of an atmospheric plasma or by means of printing or by means of knife coating, and the stretching strain of the polymer bodies is then released at least in sections, wherein the elastic modulus of the materials used in the polymer bodies is less than the elastic modulus of the applied layer materials, and wherein the fabrication process is carried out continuously.

14. The method according to claim 13 in which the critical wrinkling stress of the material of the polymer bodies is determined according to: ${}_c=\frac{F_c}{\mathrm{hw}}={\left[\frac{9}{64}.Math.\left(\frac{E_s}{1-v_s^2}\right).Math.{\left(\frac{E_k}{1-v_k^2}\right)}^2\right]}^{1/3}$

15. The method according to claim 13 in which the layer application is carried out by means of atmospheric plasmas, for example, by means of plasma jet, by means of corona discharge, or by means of dielectric barrier discharge.

16. The method according to claim 13 in which precursor materials of the layer materials are used.

17. The method according to claim 13 in which the layer application is carried out by means of a plasma jet, the plasma activation cross-section of which is beam-shaped, in the shape of a rotating circle, and/or linearly flat.

Description

EXAMPLE 1

[0076] A 100200.025 cm film of polydimethylsiloxane (PDMS) with an elastic modulus of 2.5 MPa was stretched in a roll-to-roll stretching device. The stretching strain of the film was thereby set to a constant value of 10%. For the coating of the 7020 cm effectively available area of the polymer film, the film was passed over by a punctiform plasma nozzle (PlasmaTreat GmbH, Steinhagen, Germany) with a diameter of 1 cm. The distance of the nozzle from the sample surface was 10 mm, the rated power of the plasma nozzle was 5.04 kW (280 V at 18 A), the travel speed of the nozzle over the sample was 100 mm/s.

[0077] As precursors for the layer deposition, tetraethyl orthosilicate (TEOS) with an elastic modulus of 450 MPa for the resulting layer was fed to the plasma nozzle. By means of the plasma nozzle, a homogeneous 100 nm-thick layer was deposited, which was composed of oligomeric, minimally cross-linked silicate following the deposition.

[0078] With the unrolling of the coated polymer film from the last roller of the roll-to-roll stretching device, the stretching strain was discontinued during the continuous process, and a surface-structured polymer film was present.

[0079] The surface structuring was composed of anisotropically arranged wrinkles with a periodicity of 1.5 m and a structure height of 450 nm.

EXAMPLE 2

[0080] A 100200.1 cm film of acrylonitrile butadiene rubber (NBR) with an elastic modulus of 2.3 MPa was stretched in a roll-to-roll stretching device. The stretching strain of the film was thereby set to a constant value of 8%. The for the coating of the 7020 cm effectively available area of the polymer film, the film was passed over by a rotating plasma nozzle (PlasmaTreat GmbH, Steinhagen, Germany) with a diameter of 0.5 cm. The distance of the nozzle from the sample surface was 16 mm, the rated power of the plasma nozzle was 4.77 kW (265 V at 18 A), the travel speed of the nozzle over the sample was 100 mm/s.

[0081] As a precursor for the layer deposition, hexamethyldisiloxane (HMDSO) with an elastic modulus of 250 MPa for the resulting layer was fed to the plasma nozzle. The deposition rate of the precursor was varied between 4 and 120 g/h.

[0082] By means of the plasma nozzle, a layer of varying thickness between 5 and 200 nm was deposited, which was composed of oligomeric, minimally cross-linked silicate following the deposition.

[0083] With the unrolling of the coated polymer film from the last roller of the roll-to-roll stretching device, the stretching strain was discontinued during the continuous process, and a surface-structured polymer film was present.

[0084] The surface structuring was composed of anisotropically arranged wrinkles with a periodicity between 350 mm and 3.75 m and a structure height of 100 nm and 1.15 m nm.

EXAMPLE 3

[0085] A 100500.0025 cm film of polydimethylsiloxane (PDMS) with an elastic modulus of 2.5 MPa was set out on a base paper with a longitudinal pre-strain of 15%. The 9550 cm area of the polymer film effectively available for the coating was subjected to a plasma treatment with a dielectric barrier discharge (DBD) (4-part DBDFraunhofer IST, Braunschweig, Germany). The distance of the electrode to the sample surface was set to 0.2 mm, the rated power of the DBD was 600 W, the unrolling and rolling-up speed was 0.5 m/min.

[0086] As a precursor for the layer deposition, tetramethyldisiloxane (TMDSO) with an elastic modulus of 300 MPa for the resulting layer was used. The deposition rate of the precursor was set to 7 L/m by means of a gas transport, which corresponds to a theoretical deposition rate of 3 g/h. After the unrolling of the coated polymer film from the last roller of the roll-to-roll DBD device, the stretching strain was discontinued, and a surface-structured polymer film was present.

[0087] The surface structuring was composed of anisotropically arranged wrinkles with a periodicity between 2.5 m and 7 m and a structure height between 450 nm and 2 m

EXAMPLE 4

[0088] A 20100.0075 cm film of polydimethylsiloxane (PDMS) with an elastic modulus of 2.4 MPa was set out on a base paper with a longitudinal pre-strain of 20%. A UV cross-linkable resin was imprinted on the PDMS using a 3D printing method and cured at 80 C. for 30 min. The layer obtained had an elastic modulus of 1.2 GPa at a thickness of 20 m. After the printing, the stretching strain of the sample was released.

[0089] The surface structuring was composed of anisotropically arranged wrinkles with a periodicity of 475 m and a structure height of 120 m.

[0090] With the imprinting of a second layer having the same elastic modulus, a total layer thickness of 40 m was achieved, which resulted in a periodicity of 850 and a structure height of 200 m. A third layer resulted in a total layer thickness of 60 m and a periodicity of 1.15 mm at a structure height of 300 m.

EXAMPLE 5

[0091] A 40100.2 cm film of ethylene propylene diene monomer rubber (EPDM) with an elastic modulus of 5.7 MPa was stretched in a stretching device. The stretching strain of the film was thereby set to a constant value of 15%. A UV cross-linkable resin was applied to the EPDM using a knife coating method and cured under UV light. The layer obtained had an elastic modulus of 500 MPa at a thickness of 50 m. After the curing, the stretching strain of the sample was released.

[0092] The surface structuring was composed of anisotropically arranged wrinkles with a periodicity of 200 m and a structure height of 20 m.

EXAMPLE 6

[0093] 1) Bisinusoidal and Quadrisinusoidal Wrinkling

[0094] A 100100.050 cm film of polydimethylsiloxane (PDMS) with an elastic modulus of 2.1 MPa was stretched in a roll-to-roll stretching device. The stretching strain of the film was thereby set to a constant value of 85%. For the coating of the polymer film, the film was passed over by a punctiform plasma nozzle (PlasmaTreat GmbH, Steinhagen, Germany) with a diameter of 1 cm. The distance of the nozzle from the sample surface was 10 mm, the rated power of the plasma nozzle was 6.3 kW (350 V at 18 A), the travel speed of the nozzle over the sample was 25 mm/s.

[0095] The PDMS was oxidized in situ in order to thus create the layer. The layer obtained had a thickness of 180 nm at an average elastic modulus of 150 MPa for the resulting layer.

[0096] With the unrolling of the coated polymer film from the last roller of the roll-to-roll stretching device, the stretching strain was discontinued during the continuous process, and a surface-structured polymer film was present.

[0097] The surface structuring was composed of anisotropically arranged bisinusoidal wrinkles with a periodicity of 1.5 m and a structure height of 650 nm for the deep amplitude and 125 nm for the flat amplitude.

[0098] If the film is stretched to 95%, anisotropically arranged quadrisinusoidal wrinkles are obtained with a periodicity of 1.45 m and a structure height of 750 nm for the deep amplitude, 450 nm for the middle amplitude, and 75 nm of the flat amplitude.

[0099] 2) Biaxial Stretching Orthogonal to One Another

[0100] A 100100.125 cm film of polydimethylsiloxane (PDMS) with an elastic modulus of 2.0 MPa was stretched longitudinally in a roll-to-roll stretching device and, transversely thereto, in two sliding film stretchers made of polytetrafluoroethylene (PTFE). The stretching strain of the film was thereby set to a constant value of 5% in both directions orthogonal to one another. For the coating of the polymer film, the film was passed over by a circularly rotating plasma nozzle (PlasmaTreat GmbH, Steinhagen, Germany) with a diameter of 2.5 cm. The distance of the nozzle from the sample surface was 13 mm, the rated power of the plasma nozzle was 6.3 kW (350 V at 18 A), the travel speed of the nozzle over the sample was 50 mm/s.

[0101] The PDMS was oxidized in situ in order to thus create the layer. The layer obtained had a thickness of 110 nm at an average elastic modulus of 85 MPa for the resulting layer.

[0102] With the unrolling of the coated polymer film from the last roller of the roll-to-roll stretching device, the stretching strain was discontinued during the continuous process, and a surface-structured polymer film was present.

[0103] The surface structuring was composed of anisotropically arranged wrinkles that were directed orthogonally to one another in regular patterns, also referred to as a chevron or herringbone structure. A periodicity of 1.4 m and a structure height of 80 nm were present in both spatial directions.