PROCESS FOR MODIFICATION OF A SOLID SURFACE

Abstract

A process for the modification of a surface of a solid material, including the step of contacting the surface with a surface-modifying compound under irradiation with light of a wavelength in the range of 200 to 800 nm optionally in the presence of a photoinitiator, wherein a) the surface has SiOH groups, COH groups or epoxy groups and the surface-modifying compound is a hydrosilane, or b) the surface has OSiH groups and the surface-modifying compound is a silanol or an alcohol.

Claims

1. A process for the modification of a surface of a solid material, comprising the step of: contacting the surface with a surface-modifying compound under irradiation with light of a wavelength in the range of 200 to 800 nm optionally in the presence of a photoinitiator, wherein a) the surface has SiOH groups, COH or epoxy groups and the surface-modifying compound is a hydrosilane, or b) the surface has OSiH groups and the surface-modifying compound is a silanol or an alcohol.

2. The process according to claim 1, wherein the surface has the SiOH groups or the COH groups and the surface-modifying compound is a hydrosilane.

3. The process according to claim 1, wherein a predetermined part of the surface is selectively subjected to the irradiation.

4. The process according to claim 1, wherein the irradiation is performed in the absence of a photoinitiator and the light has a wavelength in the range of 200 nm to 300 nm.

5. The process according to claim 1, wherein the process further comprises the step of treating the surface to have micro- and/or nanoscale surface roughness before the irradiation step.

6. The process according to claim 1, wherein the surface-modifying compound is contacted with the surface in the form of a surface-modifying compound composition comprising the surface-modifying compound and one or more of a photoinitiator, a solvent, a compound that is reactive towards the surface-modifying compound and micro and/or nanoparticles.

7. The process according to claim 1, wherein the surface-modifying compound is contacted with the surface in the form of a surface-modifying compound composition comprising the surface-modifying compound and a compound that is reactive towards the surface-modifying compound, wherein the amount of the compound that is reactive towards the surface-modifying compound in the surface-modifying compound composition is 50-99.9 vol % of the surface-modifying compound composition.

8. The process according to claim 1, wherein the process involves a) and the surface has SiOH groups and the solid material is selected from the group consisting of silica, glass, oxidized silicon, oxidized silicon nitride and oxidized silicon carbide and a polymer provided on the surface with a film of one of the foregoing materials.

9. The process according to claim 1, wherein the process involves a) and the surface has COH groups and the solid material is selected from the group consisting of polysaccharides, paper, poly(vinyl alcohol), etched silicon carbide, oxidized diamond, oxidized graphite, oxidized graphene and oxidized polymers.

10. The process according to claim 1, wherein the process involves a) and the hydrosilane is represented by ##STR00008## wherein at least one of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is H and at least one of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is not H, where each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is, independently, H, linear C.sub.1-30 alkyl, branched C.sub.1-30 alkyl, cyclic C.sub.3-30 alkyl, linear C.sub.2-30 alkenyl, branched C.sub.2-30 alkenyl, linear C.sub.2-30 alkynyl, branched C.sub.2-30 alkynyl, C.sub.6-20 aralkyl, C.sub.6-10 aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000, wherein the polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, polymethacrylates and polysiloxanes, wherein each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is optionally substituted with one or more substituents selected from the group consisting of F, Cl, Br, CN, NO.sub.2, O, NCO, NCS, ##STR00009## N.sub.3, NR.sup.eR.sup.f, SR.sup.g, OR.sup.h, CO.sub.2R.sup.i, PR.sup.jR.sup.kR.sup.l, P(OR.sup.m)(OR.sup.n)(OR.sup.p), P(O)(OR.sup.q) (OR.sup.8), P(O).sub.2OR.sup.t, OP(O).sub.2OR.sup.u, S(O).sub.2R.sup.v, S(O)R.sup.w, S(O).sub.2OR.sup.x, C(O)NR.sup.yR.sup.z, and OSiR.sup.aaR.sup.bbR.sup.cc, wherein each of R.sup.e, R.sup.f, R.sup.g, R.sup.h, R.sup.i, R.sup.j, R.sup.k, R.sup.l, R.sup.m, R.sup.n, R.sup.p, R.sup.q, R.sup.s, R.sup.t, R.sup.u, R.sup.v, R.sup.w, R.sup.x, R.sup.y, and R.sup.z, is, independently, H, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10 alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, or C.sub.6-10 aryl, and is optionally substituted with one or more substituents selected from the group consisting of F, Cl, and Br, wherein each of R.sup.aa, R.sup.bb, and R.sup.cc is, independently, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10, alkynyl, branched C.sub.2-10 alkynyl, C.sub.06-12 aralkyl, C.sub.6-10 aryl, F, Cl, Br, or OR.sup.dd, where R.sup.dd is linear C.sub.1-10 alkyl or branched C.sub.1-10 alkyl.

11. The process according to claim 9, wherein one or two of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is H, preferably two of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is H.

12. The process according to claim 1, wherein the process involves b) and the solid material is hydrogen-terminated glass (H-glass), polymer modified to have a surface having OSiH groups or poly(methylhydrosiloxane).

13. The process according to claim 1, wherein the process involves b) and the surface-modifying compound is represented by
HOSiR.sup.1R.sup.2R.sup.3 wherein at least one of R.sup.1, R.sup.2, R.sup.3 is not H, where each of R.sup.1, R.sup.2 and R.sup.3 is, independently, H, linear C.sub.1-30 alkyl, branched C.sub.1-30 alkyl, cyclic C.sub.3-30 alkyl, linear C.sub.2-30 alkenyl, branched C.sub.2-30 alkenyl, linear C.sub.2-30 alkynyl, branched C.sub.2-30 alkynyl, C.sub.6-20 aralkyl, C.sub.6-10 aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000, wherein the polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, polymethacrylates and polysiloxanes, wherein each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is optionally substituted with one or more substituents selected from the group consisting of F, Cl, Br, CN, NO.sub.2, O, NCO, NCS, ##STR00010## N.sub.3, NR.sup.eR.sup.f, SR.sup.g, OR.sup.h, CO.sub.2R.sup.i, PR.sup.jR.sup.kR.sup.l, P(OR.sup.m)(OR.sup.n)(OR.sup.p), P(O)(OR.sup.q) (OR.sup.8), P(O).sub.2OR.sup.t, OP(O).sub.2OR.sup.u, S(O).sub.2R.sup.v, S(O)R.sup.w, S(O).sub.2OR.sup.x, C(O)NR.sup.yR.sup.z, and OSiR.sup.aaR.sup.bbR.sup.cc, wherein each of R.sup.e, R.sup.f, R.sup.g, R.sup.h, R.sup.i, R.sup.j, R.sup.k, R.sup.l, R.sup.m, R.sup.n, R.sup.p, R.sup.q, R.sup.s, R.sup.t, R.sup.u, R.sup.v, R.sup.w, R.sup.x, R.sup.y, and R.sup.z, is, independently, H, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10 alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, or C.sub.6-10 aryl, and is optionally substituted with one or more substituents selected from the group consisting of F, Cl, and Br, wherein each of R.sup.aa, R.sup.bb, and R.sup.cc is, independently, linear C.sub.1-10alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10, alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, C.sub.6-10 aryl, F, Cl, Br, or OR.sup.dd, where R.sup.dd is linear C.sub.1-10 alkyl or branched C.sub.1-10 alkyl, or HOCR.sup.4R.sup.5R.sup.6, wherein at least one of R.sup.4, R.sup.5, R.sup.6 is not H, where each of R.sup.4, R.sup.5, R.sup.6 is, independently, H, linear C.sub.1-30 alkyl, branched C.sub.1-30 alkyl, cyclic C.sub.3-30 alkyl, linear C.sub.2-30 alkenyl, branched C.sub.2-30 alkenyl, linear C.sub.2-30 alkynyl, branched C.sub.2-30 alkynyl, C.sub.6-20 aralkyl, C.sub.6-10 aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000, wherein the polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, polymethacrylates and polysiloxanes, wherein each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is optionally substituted with one or more substituents selected from the group consisting of F, Cl, Br, CN, NO.sub.2, O, NCO, NCS, ##STR00011## N.sub.3, NR.sup.eR.sup.f, SR.sup.g, OR.sup.h, CO.sub.2R.sup.i, PR.sup.jR.sup.kR.sup.l, P(OR.sup.m)(OR.sup.n)(OR.sup.p), P(O)(OR.sup.q) (OR.sup.8), P(O).sub.2OR.sup.t, OP(O).sub.2OR.sup.u, S(O).sub.2R.sup.v, S(O)R.sup.w, S(O).sub.2OR.sup.x, C(O)NR.sup.yR.sup.z, and OSiR.sup.aaR.sup.bbR.sup.cc, wherein each of R.sup.e, R.sup.f, R.sup.g, R.sup.h, R.sup.i, R.sup.j, R.sup.k, R.sup.l, R.sup.m, R.sup.n, R.sup.p, R.sup.q, R.sup.s, R.sup.t, R.sup.u, R.sup.v, R.sup.w, R.sup.x, R.sup.y, and R.sup.z, is, independently, H, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10 alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, or C.sub.6-10 aryl, and is optionally substituted with one or more substituents selected from the group consisting of F, Cl, and Br, wherein each of R.sup.aa, R.sup.bb, and R.sup.cc is, independently, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10, alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, C.sub.6-10 aryl, F, Cl, Br, or OR.sup.dd, where R.sup.dd is linear C.sub.1-10 alkyl or branched C.sub.1-10 alkyl.

14. The surface-modified solid material obtained by the process according to claim 1.

15. An article comprising the surface-modified solid material according to claim 14, wherein the article has micro- or nanostructures.

16. The article according to claim 15, wherein the article is selected from the group consisting of a substrate for biochip applications such as microarray applications and cell culture applications; a microfluidic device such as a lab-on-a-chip device and an organ-on-a-chip device.

17. The process according to claim 2, wherein a predetermined part of the surface is selectively subjected to the irradiation, wherein the irradiation is performed in the absence of a photoinitiator and the light has a wavelength in the range of 200 nm to 300 nm, and wherein the process further comprises the step of treating the surface to have micro- and/or nanoscale surface roughness before the irradiation step.

18. The process according to claim 17, wherein the surface-modifying compound is contacted with the surface in the form of a surface-modifying compound composition comprising the surface-modifying compound and one or more of a photoinitiator, a solvent, a compound that is reactive towards the surface-modifying compound and micro and/or nanoparticles, and a compound that is reactive towards the surface-modifying compound, wherein the amount of the compound that is reactive towards the surface-modifying compound in the surface-modifying compound composition is 50-99.9 vol % of the surface-modifying compound composition.

19. The process according to claim 18, wherein the process involves a) and the hydrosilane is represented by ##STR00012## wherein at least one of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is H and at least one of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is not H, where each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is, independently, H, linear C.sub.1-30 alkyl, branched C.sub.1-30 alkyl, cyclic C.sub.3-30 alkyl, linear C.sub.2-30 alkenyl, branched C.sub.2-30 alkenyl, linear C.sub.2-30 alkynyl, branched C.sub.2-30 alkynyl, C.sub.6-20 aralkyl, C.sub.6-10 aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000, wherein the polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, polymethacrylates and polysiloxanes, wherein each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is optionally substituted with one or more substituents selected from the group consisting of F, Cl, Br, CN, NO.sub.2, O, NCO, NCS, ##STR00013## N.sub.3, NR.sup.eR.sup.f, SR.sup.g, OR.sup.h, CO.sub.2R.sup.i, PR.sup.jR.sup.kR.sup.l, P(OR.sup.m)(OR.sup.n)(OR.sup.p), P(O)(OR.sup.q) (OR.sup.8), P(O).sub.2OR.sup.t, OP(O).sub.2OR.sup.u, S(O).sub.2R.sup.v, S(O)R.sup.w, S(O).sub.2OR.sup.x, C(O)NR.sup.yR.sup.z, and OSiR.sup.aaR.sup.bbR.sup.cc, wherein each of R.sup.e, R.sup.f, R.sup.g, R.sup.h, R.sup.i, R.sup.j, R.sup.k, R.sup.l, R.sup.m, R.sup.n, R.sup.p, R.sup.q, R.sup.s, R.sup.t, R.sup.u, R.sup.v, R.sup.w, R.sup.x, R.sup.y, and R.sup.z, is, independently, H, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10 alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, or C.sub.6-10 aryl, and is optionally substituted with one or more substituents selected from the group consisting of F, Cl, and Br, wherein each of R.sup.aa, R.sup.bb, and R.sup.cc is, independently, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10, alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, C.sub.6-10 aryl, F, Cl, Br, or OR.sup.dd, where R.sup.dd is linear C.sub.1-10 alkyl or branched C.sub.1-10 alkyl.

20. The process according to claim 18, wherein the process involves b) and the surface-modifying compound is represented by
HOSiR.sup.1R.sup.2R.sup.3 wherein at least one of R.sup.1, R.sup.2, R.sup.3 is not H, where each of R.sup.1, R.sup.2 and R.sup.3 is, independently, H, linear C.sub.1-30 alkyl, branched C.sub.1-30 alkyl, cyclic C.sub.3-30 alkyl, linear C.sub.2-30 alkenyl, branched C.sub.2-30 alkenyl, linear C.sub.2-30 alkynyl, branched C.sub.2-30 alkynyl, C.sub.6-20 aralkyl, C.sub.6-10 aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000, wherein the polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, polymethacrylates and polysiloxanes, wherein each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is optionally substituted with one or more substituents selected from the group consisting of F, Cl, Br, CN, NO.sub.2, O, NCO, NCS, ##STR00014## N.sub.3, NR.sup.eR.sup.f, SR.sup.g, OR.sup.h, CO.sub.2R.sup.i, PR.sup.jR.sup.kR.sup.l, P(OR.sup.m)(OR.sup.n)(OR.sup.p), P(O)(OR.sup.q) (OR.sup.8), P(O).sub.2OR.sup.t, OP(O).sub.2OR.sup.u, S(O).sub.2R.sup.v, S(O)R.sup.w, S(O).sub.2OR.sup.x, C(O)NR.sup.yR.sup.z, and OSiR.sup.aaR.sup.bbR.sup.cc, wherein each of R.sup.e, R.sup.f, R.sup.g, R.sup.h, R.sup.i, R.sup.j, R.sup.k, R.sup.l, R.sup.m, R.sup.n, R.sup.p, R.sup.q, R.sup.s, R.sup.t, R.sup.u, R.sup.v, R.sup.w, R.sup.x, R.sup.y, and R.sup.z, is, independently, H, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10 alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, or C.sub.6-10 aryl, and is optionally substituted with one or more substituents selected from the group consisting of F, Cl, and Br, wherein each of R.sup.aa, R.sup.bb, and R.sup.cc is, independently, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10, alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, C.sub.6-10 aryl, F, Cl, Br, or OR.sup.dd, where R.sup.dd is linear C.sub.1-10 alkyl or branched C.sub.1-10 alkyl, or HOCR.sup.4R.sup.5R.sup.6, wherein at least one of R.sup.4, R.sup.5, R.sup.6 is not H, where each of R.sup.4, R.sup.5, R.sup.6 is, independently, H, linear 1-30 alkyl, branched C.sub.1-30 alkyl, cyclic C.sub.3-30 alkyl, linear C.sub.2-30 alkenyl, branched C.sub.2-30 alkenyl, linear C.sub.2-30 alkynyl, branched C.sub.2-30 alkynyl, C.sub.6-20 aralkyl, C.sub.6-10 aryl, or a polymeric moiety having a molecular weight of about 1000 to about 100,000, wherein the polymeric moiety is selected from the group consisting of hydrocarbon polymers, polyesters, polyamides, polyethers, polyacrylates, polyurethanes, epoxies, polymethacrylates and polysiloxanes, wherein each of R.sup.a, R.sup.b, R.sup.c, and R.sup.d is optionally substituted with one or more substituents selected from the group consisting of F, Cl, Br, CN, NO.sub.2, O, NCO, NCS, ##STR00015## N.sub.3, NR.sup.eR.sup.f, SR.sup.g, OR.sup.h, CO.sub.2R.sup.i, PR.sup.jR.sup.kR.sup.l, P(OR.sup.m)(OR.sup.n)(OR.sup.p), P(O)(OR.sup.q) (OR.sup.8), P(O).sub.2OR.sup.t, OP(O).sub.2OR.sup.u, S(O).sub.2R.sup.v, S(O)R.sup.w, S(O).sub.2OR.sup.x, C(O)NR.sup.yR.sup.z, and OSiR.sup.aaR.sup.bbR.sup.cc, wherein each of R.sup.e, R.sup.f, R.sup.g, R.sup.h, R.sup.i, R.sup.j, R.sup.k, R.sup.l, R.sup.m, R.sup.n, R.sup.p, R.sup.q, R.sup.s, R.sup.t, R.sup.u, R.sup.v, R.sup.w, R.sup.x, R.sup.y, and R.sup.z, is, independently, H, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10 alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, or C.sub.6-10 aryl, and is optionally substituted with one or more substituents selected from the group consisting of F, Cl, and Br, wherein each of R.sup.aa, R.sup.bb, and R.sup.cc is, independently, linear C.sub.1-10 alkyl, branched C.sub.1-10 alkyl, cyclic C.sub.3-8 alkyl, linear C.sub.2-10 alkenyl, branched C.sub.2-10 alkenyl, linear C.sub.2-10, alkynyl, branched C.sub.2-10 alkynyl, C.sub.6-12 aralkyl, C.sub.6-10 aryl, F, Cl, Br, or OR.sup.dd, where R.sup.dd is linear C.sub.1-10 alkyl or branched C.sub.1-10 alkyl.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0081] FIG. 1 shows photochemical surface modification with different concentrations of dihydro-F17, showing the difference in WCA between the irradiated (squares) and non-irradiated (circles) part of the sample.

[0082] FIG. 2 shows photochemical surface modification with different concentrations of trihydro-F17, showing the difference in WCA between the irradiated (squares) and non-irradiated (circles) part of the sample.

[0083] FIG. 3 shows irradiation spectra used for photochemical surface modification without (black line) and with (gray line) the presence of an additional glass filter. The dotted line indicates the transmission spectrum of the glass filter.

DETAILED DESCRIPTION OF THE INVENTION

[0084] The invention is now elucidated by way of the following examples, without however being limited thereto.

Examples

[0085] General

[0086] Materials

[0087] Commercially available hydrosilanes and solvents were obtained from Sigma-Aldrich or Gelest. When needed, compounds were purified using Kugelrohr vacuum distillation. Hydrosilanes that are not commercially available were synthesized by reduction of the corresponding chlorosilanes with LiAlH.sub.4 using a procedure adapted from literature.

[0088] Surface Modification

[0089] The sample was placed on a custom-made sample holder and a volume of hydrosilane (neat or as a surface-modifying compound composition) was deposited on the surface. Then, the sample was covered by a quartz cover, resulting in a uniform liquid film between the sample and the mask.

[0090] Next, the sample was irradiated with UV light at an intensity of 10-15 mW/cm.sup.2, using a collimated light source. After completion of the reaction samples were rinsed with a suitable solvent, followed by rinsing and ultrasonication with dichloromethane. Finally, samples were dried in a stream of Ar.

[0091] Surface Characterization

[0092] Samples were analyzed by static water contact angle (WCA) measurements using a Krss DSA-100 goniometer. Using the automated dispensing unit, 3 L water droplets were deposited on the surface, images were captured using a digital camera and analyzed using a suitable fitting algorithm, depending on the wettability of the surface.

[0093] XPS spectra were recorded on a JPS-9200 apparatus (JEOL). Measurements were done using a monochromatic Al K source operated at 12 kV and 20 mA. All binding energies were calibrated relative to the hydrocarbon (CH.sub.2) peak, which was set to a binding energy of 285.0 eV. Charge compensation was used to prevent electrostatic charging of the substrate during measurement. Spectra were analyzed with Casa XPS software.

[0094] Fluorescence microscopy was used to demonstrate the formation of micro-patterned surfaces. Droplets of a 1 mg/ml solution of a fluorescently labelled protein (BSA labelled with AlexaFluor 488, Thermo Fisher) were deposited on the patterned substrate and incubated for 15 min. at room temperature. Unbound protein was removed from the surface by rinsing with water and washing with PBS (pH 7.4) containing 0.05% (v/v) of Tween 20, PBS (pH 7.4) and once more with water (5 min. immersion on a shaker in each washing solution). Samples were analyzed using a fluorescence microscope.

[0095] 1 Surface Modification of Glass with Fluorinated Hydrosilanes

[0096] Sample Preparation

[0097] Standard glass microscope slides were cleaned by ultrasonication in acetone, followed by exposure to a low-pressure O.sub.2 plasma and immersion in piranha solution. After thorough rinsing with deionized water, samples were dried using a stream of Ar.

[0098] Following fluorinated hydrosilanes were used.

TABLE-US-00001 TABLE 1 Name Abbreviation (heptadecafluoro-1,1,2,2-tetra hydro-decyl)- monohydro-F17 dimethylhydrosilane (heptadecafluoro-1,1,2,2-tetra hydro-decyl)- dihydro-F17 methylhydrosilane (heptadecafluoro-1,1,2,2-tetra hydro-decyl)- trihydro-F17 trimethylhydrosilane (heptadecafluoro-1,1,2,2-tetra hydro-decyl)- isopropyl-F17 di-isopropylhydrosilane

[0099] Surface Modification

[0100] To demonstrate the principle of photochemical surface modification using hydrosilanes, a very simple photomask was used with which half of the substrate is irradiated, and the other half is not. By using hydrosilanes with a hydrophobic fluorinated tail, successful surface modification will result in a large wettability contrast between the modified (irradiated) and unmodified (non-irradiated) parts of the substrate, which can easily be demonstrated by water contact angle (WCA) measurements.

[0101] To investigate the effect of the number of SiH bonds in the hydrosilane, molecules with one, two and three SiH bonds were used. These are abbreviated as monohydro-F17, dihydro-F17 and trihydro-F17, respectively. The names of these hydrosilanes are given in Table 1. Fluorinert FC-70 was used as the solvent, and surface modifications at different hydrosilane concentrations (given as % (v/v)) and irradiation times were compared.

[0102] 1.1 ResultsNumber of SiH Bonds

[0103] After cleaning and activation, glass slides are strongly hydrophilic with a water contact angle (WCA) of less than 20.

[0104] FIG. 1 shows the change in WCA upon reaction with dihydro-F17. In the non-radiated part of the sample, no reaction takes place and the WCA stays very close to its original value. In the irradiated part on the other hand, a strong increase in WCA is observed, finally reaching a value of 1081.

[0105] For the neat hydrosilane and the 60% solution, the maximum WCA is reached within 15 minutes. At a concentration of 30% the reaction takes longer to complete, but the same WCA is reached eventually.

[0106] FIG. 2 shows the change in WCA upon reaction with trihydro-F17. Formation of a trihydro-F17 layer takes much less time, as shown in FIG. 2. For the neat trihydro-F17 and the 60% solution, the layer is complete within 5 minutes. Also, the maximum WCA of 1112 is somewhat higher than for dihydro-F17.

[0107] However, there is also an increase in WCA in the non-radiated part of the sample. Thus, simultaneous to the photochemical surface modification, some unwanted reaction takes place, making it less suitable for the patterning of a solid material when the solid material is glass.

[0108] Surface modifications were also carried out using a 30% solution of monohydro-F17. For this hydrosilane, a maximum WCA of 1013 was reached after 75 minutes of irradiation. In the non-radiated area, a WCA of 283 was measured.

[0109] Hence, the reaction speed was the highest with trihydro-F17, then dihydro-F17 and then monohydro-F17. The contrast was the best with dihydro-F17.

[0110] XPS analysis also confirmed the results of the WCA measurements in that much larger amounts of elements F and C were found in the irradiated areas, as shown in Table 2.

[0111] Table 2: Apparent atomic concentrations (%) measured by XPS on glass samples after reaction with different hydrosilanes.

TABLE-US-00002 TABLE 2 Apparent atomic concentrations (%) measured by XPS on glass samples after reaction with different hydrosilanes. monohydro-F.sub.17 dihydro-F17 element illuminated non-illuminated illuminated non-illuminated O1s 46.2 61.0 49.6 55.9 Si2p 29.6 35.1 32.4 35.9 F1s 12.7 1.6 11.6 3.5 C1s 11.5 2.3 6.4 4.7

[0112] 1.2 ResultsEffect of Organic Substituent

[0113] In the experiments described above the number of SiH bonds and methyl substituents was varied. To investigate the role of the organic group, a surface modification was done using a fluorinated monohydrosilane with two isopropyl substituents (isopropyl-F17, cf. Table 1). For this molecule, the same surface modification procedure as for the methyl-substituted monohydro-F17 was used (30% hydrosilane solution, 75 min. irradiation). The resulting WCAs are 32 and 108 in the non-radiated and irradiated area, respectively. This result shows that the photochemical surface modification reaction is not limited to hydrosilanes with methyl substituents and that other substituents, including more bulky ones, may also be used.

[0114] 1.3 ResultsPreparation of Micropatterned Surfaces

[0115] To investigate the lateral resolution of the photochemical hydrosilane surface modification, a different photomask was used, consisting of a pattern of lines of varying width. After photochemical surface modification with dihydro-F17 (neat, 15 min. irradiation), this should yield fluorinated lines with a width between 1 and 500 m. The spacing between the lines is twice the width of the line.

[0116] These patterns are too small to perform routine WCA measurements. To confirm and visualize pattern formation, samples were incubated with fluorescently labelled BSA, which is known to adsorb differently to hydrophobic (e.g. fluorinated) and hydrophilic (e.g. glass) surfaces. Fluorescence microscopy clearly showed that there is a difference in fluorescence intensity between the fluorinated lines and the non-fluorinated background. Similar experiments were done with monohydro-F17 (30% solution, 75 min. irradiation), this time using a pattern of 5 m circular dots and using both the positive and negative pattern. Also here, there was a clear difference in fluorescence intensity between the fluorinated and non-fluorinated areas on the sample. These results demonstrate that photochemical surface modification by hydrosilane layers can be used for the preparation of micro patterned surfaces with feature sizes down to at least 5 m.

[0117] 1.4 ResultsPreparation of Superhydrophobic/Superhydrophilic Patterns

[0118] In the experiments described above it has been demonstrated that (micro)patterns with a large wettability contrast can be prepared using photochemical surface modification by hydrosilanes. The wettability contrast can be increased further by introducing roughness to the surface. One way to achieve this is the growth of so-called silicone nanofilaments (SiNF).

[0119] Based on a literature procedure, SiNF were prepared from methyltrichlorosilane, using a gas-phase procedure and subsequently oxidized using a low-pressure O.sub.2 plasma to render the surface with hydroxyl groups and leading to a superhydrophilic SiNF layer on the surface (WCA)<10.

[0120] These substrates were used for photochemical surface modification using trihydro-F17 (30% solution, 8 min. irradiation). On the non-irradiated area, the substrate remains superhydrophilic (WCA) <10. On the irradiated area, reaction with the fluorinated hydrosilane renders the surface superhydrophobic (static WCA >150 C., sliding angle <10). Thus, photochemical surface modification by hydrosilanes can be used to prepare patterns of superhydrophobic and superhydrophilic areas.

[0121] 1.5 ResultsPhotoactivation of Hydrosilanes

[0122] The collimated light source used in the experiments uses a Hg/Xe lamp in combination with a 260 mirror set. In the resulting irradiation spectrum (the light that is actually illuminating the sample surface), three groups of peaks can be distinguished: 220-255 nm, 255-290 nm and 290-320 nm, see FIG. 3.

[0123] To investigate which parts of the spectrum are needed for the photochemical surface modification, an additional filter was used to prevent part of the light from reaching the sample. For this purpose a piece of glass was used which completely blocks the light in the 220-255 nm wavelength range and most of the 255-290 nm range. FIG. 3 shows the transmission spectrum of the glass filter and the resulting filtered irradiation spectrum.

[0124] With the glass filter in place, a standard surface modification was done with dihydro-F17 (neat, 15 min. irradiation). The resulting WCA are 29 and 105 for the non-radiated and irradiated area, respectively. These values are almost identical to those obtained without the glass filter. Thus, it can be concluded that the reaction does not necessarily require light in the 220-255 nm range. Considering the large intensity difference between the filtered and unfiltered irradiation spectra in the 255-290 nm range (see FIG. 3), a lower quality layer would have been expected if light in this wavelength range would be essential for the reaction to proceed. Therefore, these results indicate that the photochemical surface modification reaction by hydrosilanes can effectively be initiated by light in the wavelength range 290-320 nm, where the effect of the glass filter is small to marginal.

[0125] The fact that the presence of a glass filter does not significantly affect the surface modification not only provides information about the required wavelength. It also demonstrates that photochemical surface modification using hydrosilanes can also be performed inside a channel with a glass cover. This is highly relevant for applications in microfluidics.

[0126] 1.6 Results Addition of Acrylate

[0127] It was found that both the wettability contrast and the lateral resolution of the patterns can be improved by the addition of 1H,1H,2H,2H-perfluorodecyl acrylate (F17-acrylate) to the hydrosilane. Photochemical surface modification was done using dihydro-F17 containing F17-acrylate in concentrations varying between 0.1 and 99.9% (v/v) and irradiation times between 1 and 30 minutes.

[0128] Good results were obtained using F17-acrylate concentrations below or equal to 1% and an irradiation time of 15 minutes. In this case, WCA of 20 and 1141 are obtained in the non-radiated and irradiated area, respectively. Thus, the wettability contrast is improved compared to the experiment without F17-acrylate, where WCA of 20 and 1081 were obtained in the non-radiated and irradiated area, respectively (as shown in FIG. 1). Moreover, the interface between the hydrophobic (radiated) and hydrophilic (non-radiated) areas of the sample is sharper when F17-acrylate is added. This improvement in the lateral resolution is visualized by allowing water vapor to condense on the samples. The difference in wettability between irradiated and non-radiated areas results in condensation patterns. On samples with F17-acrylate, significantly sharper lines between hydrophobic and hydrophilic areas are observed.

[0129] Even though good results are obtained using a low concentration of F17-acrylate, surface modification can also be done using much higher concentrations. For example, an experiment using 99% F17-acrylate and 1% dihydro-F17 yielded WCA of 312 and 1162 in the non-irradiated and irradiated area, respectively.

[0130] As control experiments, two reactions were done using 1) a solution of 1% F17-acrylate in FC-70 and 2) using the F17-acrylate neat, i.e. both without any hydrosilane. In both cases, hardly any change in wettability is observed (1% F17-acrylate in FC-70 yielding WCA 20 in both irradiated and non-radiated area, and neat F17-acrylate yielding WCA 425 and 292 in irradiated and non-radiated area, respectively), indicating that no significant surface modification takes place. These results demonstrate that the hydrosilane is required for surface modification, and the observed wettability contrast of the patterns is not caused by surface binding of F17-acrylate alone.

[0131] 1.7 Results Surface Modification Using Longer Wavelengths in the Presence of a Photoinitiator

[0132] As shown above, photochemical surface modification using hydrosilanes takes place under irradiation with light in the wavelength range 200-320 nm. To investigate the effect of longer wavelengths, surface modifications were done using a 365 nm UV-A lamp. In an experiment using dihydro-F17 containing 1% F17-acrylate and an irradiation time of 15 minutes, WCA of 351 and 383 were obtained in the non-radiated and irradiated area, respectively. This result shows that no significant surface modification takes place at this wavelength.

[0133] In a next experiment, 1% of a photoinitiator (2,2-dimethoxy-2-phenylacetophenone, DMPA) was added to the dihydro-F17/F17-acrylate mixture. Again an irradiation time of 15 minutes was used. To reduce the effect of ambient light, the experiment was done in a dark room. The reaction with DMPA yielded WCA of 76 and 105 in the non-irradiated and irradiated area, respectively. The wettability contrast between the irradiated and non-irradiated area is smaller than in experiments where wavelengths below 320 nm were used for irradiation (without photoinitiator). However, there is still a clear difference in WCA between the irradiated and non-radiated area, indicating that light with a wavelength above 320 nm can be used for photochemical surface modification using hydrosilanes provided a suitable photoinitiator is present.

[0134] 2 ResultsSurface Modification of COH Surfaces with Hydrosilanes

[0135] 2.1 Cyclic Olefin Copolymer

[0136] Sample Preparation

[0137] Pieces of Cyclic Olefin Copolymer (COC) were activated by exposure to a low-pressure 02 plasma. This results in a strong decrease of WCA from approximately 100 to <20, indicating the presence of a significant amount of hydrophilic COH groups on the surface.

[0138] Surface Modification

[0139] For surface modification of thus activated COC, trihydro-F17 was used. 2 l of hydrosilane (30% solution) was deposited on the surface, which was then covered by the photomask and irradiated for 10 minutes. After rinsing, samples were vacuum dried before being analyzed.

[0140] Results

[0141] After surface modification, the irradiated part of the sample had a WCA of 90, while the non-irradiated part had a WCA of 46. These values suggest that a photochemical surface modification of COC has taken place. The increased WCA in the non-irradiated part indicates that beside photochemical surface modification, some other reaction also takes place. This is confirmed by XPS analysis, which shows the presence of fluorine on both the irradiated and the non-irradiated side of the sample. However, the amount of fluorine on the irradiated area is more than twice as high. Therefore, the results demonstrate that hydrosilanes can be used for photochemical surface modification of COC.

[0142] Table 3: Apparent atomic concentrations (%) measured by XPS after reaction of COC with trihydro-F17.

TABLE-US-00003 TABLE 3 Apparent atomic concentrations (%) measured by XPS after reaction of COC with trihydro-F17. trihydro-F.sub.17 on COC Element radiated non-radiated O1s 20.5 21.7 Si2p 4.3 4.8 F1s 8.7 3.8 C1s 66.5 69.7

[0143] 2.2 Cellulose

[0144] Sample Preparation

[0145] Pieces of cellulose blotting paper were cleaned by sonication in dichloromethane and vacuum dried.

[0146] Surface Modification

[0147] For surface modification of cellulose, trihydro-F17 was used. 50 l of hydrosilane (30% solution) was deposited on the surface, which was then covered by the photomask and irradiated for 30 minutes. After rinsing, samples were dried with Ar before being analyzed.

[0148] Results

[0149] After surface modification, the irradiated side of the sample had a WCA of approximately 120. On the non-irradiated area, WCA could not be measured, since the droplet sinks into the hydrophilic porous paper. This result indicates that hydrosilanes can be used for photochemical surface modification of cellulose.

[0150] 3 ResultsSurface Modification of Epoxide Surfaces with Hydrosilanes

[0151] 3.1 Epoxysilane

[0152] Sample Preparation

[0153] To prepare surfaces with epoxide groups, glass microscope slides were treated with an epoxysilane according to a silanization procedure adapted from literature. Samples were cleaned by ultrasonicating in acetone for 5 minutes. Samples were dried using a stream of nitrogen and subsequently placed in an oven at 140 C. for 5 minutes. Then, samples were exposed to a low pressure 02 plasma for 5 minutes and immediately immersed in a 2% (v/v) solution of (3-glycidyloxypropyl)trimethoxysilane in hexane for 2 hours. After silanization, samples were cleaned by 5 minutes ultrasonication in acetone and drying in a stream of nitrogen. After this silanization procedure, the epoxide-terminated surfaces have a WCA of 55.

[0154] Surface Modification

[0155] In one experiment, surface modification of epoxide-terminated surfaces was done by depositing trihydro-F17 on the surface, covering the sample with the photomask and irradiating it for 30 minutes. In another experiment, a mixture of dihydro-F17 (95% v/v) and F17-acrylate (5% v/v) was used for surface modification, using an irradiation time of 30 minutes. After irradiation, samples were cleaned by rinsing and ultrasonication in trifluorotoluene and dichloromethane, followed by drying in a stream of nitrogen.

[0156] Results

[0157] After surface modification with trihydro-F17, the irradiated area of the sample has a WCA of 110, while the WCA on the non-irradiated side remains unchanged at 55. XPS analysis shows the presence of a large amount of fluorine (17 atom %) on the irradiated area, while on the non-irradiated area no detectable amount of fluorine is present. After surface modification with the dihydro-F17/F17-acrylate mixture, the irradiated area of the sample has a WCA of 114, while the WCA on the non-irradiates side remains unchanged at 55. These results indicate that a photochemical reaction of the hydrosilanes with the epoxide groups on the surface has taken place on the irradiated area, while no reaction has taken place on the non-irradiated area.

[0158] 3.2 SU-8

[0159] Sample Preparation

[0160] SU-8 is a negative photoresist containing many epoxide groups. After curing of SU-8, a number of residual epoxide groups will be present on the surface of the material. Therefore, SU-8 surfaces were used for surface modification with hydrosilanes without any pretreatment.

[0161] Surface Modification

[0162] A mixture of dihydro-F17 (99% v/v) and F17-acrylate (1% v/v) was deposited on the SU-8 surface, covered with a quartz slide and irradiated for 30 minutes. The sample was then rinsed and sonicated in trifluorotoluene and dichloromethane and dried in a stream of nitrogen.

[0163] Results

[0164] Before surface modification, the WCA of the SU-8 surface is 79. After surface modification, the WCA of the sample increased to 95. This result indicates that hydrosilanes can be used for the photochemical surface modification of SU-8.