Durable low surface-energy surfaces

• US 5,266,222 A
• Filed: 03/06/1992
• Issued: 11/30/1993
• Est. Priority Date: 05/23/1990
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Willis, Paul B., McElroy, Paul M., Hickey, Gregory H.
• Primary Examiner(s): Howard, Jacqueline V.
• Application Number:
  US07/847,384
• Time in Patent Office: 634 Days
• Field of Search: 252/49.6, 106/287.11, 106/287.13, 106/2, 106/38.22, 523/169
• US Class Current: 508/206
• CPC Class Codes: B05D 1/185 applying monomolecular layers B05D1/204 takes precedence
• CPC Class Codes: B28B 7/384 Treating agents for plastic moulding materials in general B29C33/60; lubricants in general C10M
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C03C 17/30 with silicon-containing compounds
• CPC Class Codes: C04B 35/00 Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/463 Organic solvents
• CPC Class Codes: C04B 41/4922 applied to the substrate as monomers, i.e. as organosilanes RnSiX4-n, e.g. alkyltrialkoxysilane, dialkyldialkoxysilane
• CPC Class Codes: C04B 41/4944 containing atoms other than carbon, hydrogen, oxygen, silicon, alkali metals or halogens, e.g. N-silyldisilazane: Image
• CPC Class Codes: C04B 41/84 Compounds having one or more carbon-to-metal of carbon-to-silicon linkages
• CPC Class Codes: C07F 7/1804 Compounds having Si-O-C linkages Si-O-acyl linkages C07F7/1896
• CPC Class Codes: C08G 77/22 containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/24 halogen-containing groups
• CPC Class Codes: C09D 4/00 Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16

Abstract

A formulation for forming a low surface-energy surface on a substrate having (i) a fluoroalkyl silane having a low surface energy part, (ii) a liquid crystal silane operable for enhancing the orientation of the molecules of the fluoroalkyl silane and for crosslinking with the fluoroalkyl silane, and, (iii) a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate. In one embodiment the formulation can includes a crosslinking agent for crosslinking the fluoroalkyl silane. In another embodiment the formulation has a condensation catalyst for enhancing chemical bonding of the fluoroalkyl silane to the substrate. The transport medium can be an alcohol such as methanol or ethanol.

Claims

1. A formulation for forming a low surface-energy surface on a substrate comprising:

a. a fluoroalkyl silane;

b. an effective amount of a liquid crystal silane for enhancing the low surface energy property of the fluoroalkyl silane; and

,

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.

2. The formulation of claim 1, wherein the fluoroalkyl silane has the general formula ##STR3## wherein "n" is at least 2, wherein at least one R is selected from the group consisting of methyl groups, ethyl groups, and mixtures thereof,

wherein at least one R is selected from the group consisting of Cl, Br, OCH₃, and OC₂ H₅ radicals, and mixtures thereof, which are hydrolyzable to form a silanol, and,

wherein X is selected from the group consisting of fluorinated aliphatic groups, fluorinated alicyclic groups, and mixtures thereof, having a low surface energy part.

3. The formulation of claim 1, wherein the fluoroalkyl silane is tridecafluoro-1,1,2,2-tetrahydrooctyl-1-triethoxysilane.

4. The formulation of claim 1, wherein the liquid crystal silane is n-octadecyldimethyl[3-(trimethoxysily)-propyl] ammonium chloride.

5. The formulation of claim 1, further comprising a crosslinking agent for crosslinking the fluoroalkyl silane.

6. The formulation of claim 5, wherein the crosslinking agent is selected from the group consisting of multifunctional silyl ethers, multifunctional silicates, and mixtures thereof, which are capable of hydrolysis and reaction with the fluoroalkyl silane and the liquid crystal silane.

7. The formulation of claim 1, further comprising a condensation catalyst for enhancing chemical bonding of the fluoroalkyl silane to the substrate.

8. The formulation of claim 1, wherein the transport medium is an alcohol.

9. The formulation of claim 8, wherein the alcohol is selected from the group consisting of methanol, ethanol, and mixtures thereof.

10. The formulation of claim 1, wherein the formulation is operable for producing an autophobic surface having a thickness as determined by Auger Electron Spectroscopy of between about 100 and about 200 Å

.

11. A formulation for forming a low surface-energy surface on a substrate comprising:

a. a fluoroalkyl silane having the general formula ##STR4## wherein "n" is at least 2, wherein at least one R is selected from the group consisting of alkyl groups,

wherein at least one R is selected from the group consisting of halogens, alkyl ethers, and mixtures thereof, which are hydrolyzable to form a silanol, and,

wherein X is selected from the group consisting of fluorinated aliphatic groups, fluorinated alicyclic groups, and mixtures thereof, having a low surface energy part;

b. an effective amount of a liquid crystal silane for enhancing the low surface energy property of the fluoroalkyl silane; and

,

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.

12. The formulation of claim 11, wherein X is completely fluorinated.

13. The formulation of claim 11, wherein X is partially fluorinated.

14. The formulation of claim 11, wherein the formulation is operable for producing a surface having a thickness of between about 100 and about 200 Å

.

15. A formulation for forming a low surface-energy surface on a substrate comprising:

a. A fluoroalkyl silane having the general formula ##STR5## wherein "n" is at least 2, wherein one of the R'"'"'s is selected from the group consisting of alkyl groups,

wherein two of the R'"'"'s are selected from the group consisting of halogens, alkyl ethers, and mixtures thereof, which are hydrolyzable to form a silanol, and,

wherein X is selected from the group consisting of fluorinated aliphatic groups, fluorinated alicyclic groups, and mixtures thereof, having a low surface energy part;

b. an effective amount of a liquid crystal silane for enhancing the low surface energy property of the fluoroalkyl silane; and

,

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.

16. The formulation of claim 15, wherein the formulation is operable for producing a surface having a thickness of between about 100 and about 200 Å

.

17. A formulation for forming a low surface-energy surface on a substrate comprising:

a. a fluoroalkyl silane;

b. an effective amount of a liquid crystal silane having the general formula ##STR6## wherein n is at least 2, wherein Q is selected from the group consisting of halogens, alkyl ethers, and mixtures thereof, which are hydrolyzable to form a silanol, and,

wherein Z is selected from the group consisting of organic groups having liquid crystal properties, for enhancing the low surface energy property of the fluoroalkyl silane; and

,

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.

18. The formulation of claim 17, wherein the Z is selected from the group consisting of alkyl quaternary ammonium salts, substituted biphenyl compounds, terphenyl compounds, azoxybenezenes, cinnamates, pyrimidines, benzoates, and mixtures thereof.

19. The formulation of claim 17, wherein the formulation is operable for producing a surface having a thickness, of between about 100 and about 200 Å

.

20. A formulation for forming a low surface-energy surface on a substrate comprising:

a. a fluoroalkyl silane;

b. an effective amount of a liquid crystal silane having the general formula ##STR7## wherein n is at least 2, wherein Q is selected from the group consisting of Cl, Br, OCH₃, OC₂ H₅ radicals, and mixtures thereof, which are hydrolyzable to form a silanol, and, wherein Z is selected from the group consisting of organic groups having liquid crystal properties, for enhancing the low surface energy property of the fluoroalkyl silane; and

,

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.

21. The formulation of claim 20, wherein the formulation is operable for producing a surface having a thickness of between about 100 and about 200 Å

.

22. A formulation for forming a low surface-energy surface on a substrate comprising:

a. a fluoroalkyl silane;

b. a liquid crystal silane for enhancing the orientation of the molecules of the fluoroalkyl silane;

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate; and

,

d. a crosslinking agent for crosslinking the fluoroalkyl silane, wherein the crosslinking agent is selected from the group consisting of tetramethyl orthosilicates, tetraethyl orthosilicates, and mixtures thereof.

23. The formulation of claim 22, wherein the crosslinking agent is bis-1,2-(trimethoxysilyl)ethane.

24. A formulation for forming a low surface-energy surface on a substrate comprising:

a. a fluoroalkyl silane;

b. a liquid crystal silane for enhancing the orientation of the molecules of the fluoroalkyl silane;

c. a transport medium for applying the fluoroalkyl silane and the liquid crystal silane to the surface of a substrate; and

,

d. a condensation catalyst for enhancing chemical bonding of the fluoroalkyl silane to the substrate, wherein the condensation catalyst is selected from the group consisting of tertiary amines, hindered secondary amines, and mixtures thereof, which are capable of catalyzing the hydrolysis and condensation of the fluoroalkyl silane and the liquid crystal silane.

25. The formulation of claim 24, wherein the condensation catalyst is N,N-dimethyl benzylamine.

26. A formulation for forming an improved low surface-energy surface on a substrate comprising:

a. an alcohol;

b. a fluoroalkyl silane having a low surface energy part;

c. an effective amount of a liquid crystal silane operable

for enhancing the low surface energy property of the fluoroalkyl silane, and

for crosslinking with the fluoroalkyl silane;

d. a crosslinking agent for crosslinking the fluoroalkyl silane; and

,

e. a condensation catalyst for chemically bonding of the fluoroalkyl silane to the substrate;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.

27. The formulation of claim 26, wherein the fluoroalkyl silane, the liquid crystal silane, the crosslinking agent and the condensation catalyst are dissolved in the alcohol.

28. The formulation of claim 26, wherein the amount of fluoroalkyl silane is from about 0.4 to about 10% by weight of the formulation,

wherein the amount of liquid crystal silane is from about 0.1 to about 5% by weight of the formulation,

wherein the amount of crosslinking agent is from about 0.1 to about 5% of the formulation, and,

wherein the amount of condensation catalyst is from about 0.05 to about 1% by weight of the formulation.

29. The formulation of claim 26, wherein the weight ratio of the liquid crystal silane to the fluoroalkyl silane is from about 0.05 to about 0.5,

wherein the weight ratio of the crosslinking agent to the fluoroalkyl silane is from about 0.05 to about 0.5, and,

wherein the weight ratio of the condensation catalyst to the fluoroalkyl silane is from about 0.05 to about 0.25.

30. A formulation for treating a substrate surface to transform it into a low surface-energy surface, the formulation comprising:

a. an alcohol;

b. an effective amount of a fluoroalkyl silane operable for forming a low surface-energy substrate surface, the molecules of the fluoroalkyl silane having a low energy part and a substrate-chemically reactive part;

c. an effective amount of a liquid crystal silane operable

for enhancing the low surface energy property of the fluoroalkyl silane so that the low energy part thereof forms a surface on the substrate having a lower surface energy than such surface would have in the absence of the liquid crystal silane, and

for crosslinking with the fluoroalkyl silane;

d. an effective amount of a crosslinking agent for crosslinking and orienting molecules of the fluoroalkyl silane so that the low energy part thereof forms a surface on the substrate having a lower surface energy than such surface would have in the absence of the crosslinking agent; and

,

e. an effective amount of a condensation catalyst for enhancing the reaction of the substrate-chemically reactive part of the fluoroalkyl silane to the substrate surface so that the durability of the low surface-energy surface on the substrate is greater than the durability of such low surface-energy surface formed in the absence of the condensation catalyst;

wherein the effective amount of liquid crystal silane in combination with the fluoroalkyl silane is operable for producing a surface energy on such low surface-energy surface that is lower than the surface energy formed from a formulation comprising the fluoroalkyl silane and the transport medium without the liquid crystal silane.