JPS63171671A - Manufacture of large area-two-dimensional arranged article of tightly packaged colloidal particle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing large-area two-dimensional arrangements of closely backed colloidal particles.

[Conventional technology]

Coating solid surfaces with precisely ordered colloidal particles is useful in many fields of science and technology.

Randomly arranged colloidal particle coatings are known as interference and antireflection coatings (Iler, U.S. Pat.
No. 485,658) and as a fusion target (fu
sion targets)'s tampe
r 1ayer) (Bahia 7- (Peiffer)
) and Deck7:/ (Deckman, U.S. Pat. No. 4,404,255) have been shown to be useful. Regular arrangements of colloidal particles coated on a surface are useful as diffraction gratings, optical recording media or interference layers. Monolayer-thick arrangements of random and ordered colloidal particles have been found to be useful as lithographic masks for producing precisely controlled surface structures [Deckma'
J (Decknan) and Dunsmuir (Dunsmu)
ir) U.S. Pat. No. 4,407.695]. Surface structures produced lithographically from monolayers of colloidal particles can include microstructures of uniform size over large areas that are difficult to produce with conventional lithographic techniques. with uniform size,
Applications of large area surface structures include selective solar absorbers (U.S. Pat. No. 4,284,689 to Craighead et al.), optical gratings, and optically enhanced solar cells (Deckman et al.).
No. 4,497,974). The present invention relates to a method for producing defect-free, densely backed colloidal particle coatings.

Techniques for coating a support with a monolayer thickness of randomly arranged colloidal particles of a particular type are well known. Such coatings are called random colloidal coatings, and the method for making them is described in U.S. Patent No. 3.4 of Eyler.
85.658, Eyler, Journal of Colloid and Interface Science
rnal of Co11oid and Interf
ace 5 Science) 21.569-594 (1
966); Eyler, Journal of the American Ceramic Society
he American Ceramic 5ocie
ty) 47 (4), 194-198 (1964)
; marshall and kitchener
Kitchener), Journal of Colloid and Interface Science 22.34
2-351 (1966); and Peifer and Deckman, US Pat. No. 4,315,958. These coating techniques utilize electrostatic attraction to deposit random arrangements of colloidal particles onto a support.

When colloidal particles are electrostatically attracted to a support, they stick where they impact the surface. Electrostatic attraction occurs because a surface charge opposite to that of the support is induced on the colloidal particles. In this type of colloidal monolayer, the particles are randomly arranged and there are spaces between most of the particles. Examples of interparticle spaces in random colloid coatings are shown in FIGS. 1 and 2.

FIG. 1 is an electron micrograph showing the arrangement of monodisperse spherical latex particles in a random colloidal coating. In this micrograph, the spaces between the particles are clearly visible. FIG. 2 is an electron micrograph showing the arrangement of 2 μm polystyrene latex particles in a random colloidal coating. The interparticle spacing in random colloidal coatings arises because of the limited number of particles that can diffuse and electrostatically adhere to the surface being coated to form a monolayer. Randomly arranged particles are placed in a sol with pH conditions such that the surface of the support and the colloidal particles have charges of opposite signs.
It is made by dipping the support. The colloidal particles diffuse through this sol and reach the support, where opposite charges interact to electrostatically bind the particles to the support. Once the surface to be coated has been coated with colloidal particles at a certain density of coverage (this varies depending on the details of the coating method), the remaining uncoated surface is electrostatically charged by the presence of adjacent deposited particles. Other particles that are shielded by the sol and diffuse toward the surface undergo repulsion and are returned to the sol.

A method for forming ordered colloidal particle arrays is disclosed in Deckman and Dunsmoor, US Pat. No. 4,407,695 (1983). In this method, a regular array of colloidal particles is formed by spin coating. This particle regularity allows the sol to flow across the support at high shear rates while eliminating excess coating material to form a tightly packed microcrystalline arrangement. arise. This colloid must moisten the support and the spin speed must be optimized. If the spin rate is too slow, a multilayer coating will form, whereas if the final spin rate is too high, voids will form in the monolayer coating. Sol rheology and other factors such as particle concentration, substrate surface chemistry, and charge differential between support and colloid must be optimized for each particle size. A systematic approach to optimizing these factors requires a detailed understanding of the dynamics of the coating process, which is currently not clear. For spheres beyond the size range of 0.3 to 1.0 μm, it is very difficult to optimize the coating method. Imperfections in grain alignment include point defects, dislocations, and grain boundaries. The maximum number of submicron spheres found in a single crystal is 105, with typical particles containing 50 to 1000 spheres. FIG. 3 is an electron micrograph showing the microcrystalline arrangement of spin-coated monodisperse polystyrene latex particles. Figure 3 shows 0.49
Figure 3 shows a backing defect in a section of 7,62 cm (3 inch) silicon waeno uniformly coated with a microcrystalline array of 7±0, OO 6 μm spheres. The coating was applied to a surfactant-cleaned wafer using polystyrene latex (Dow Diagnostics) containing 15% solids by weight.
LIA27] and then spun at 340 rpm until dry.

The present invention relates to a method for making a third class of colloidal particle arrangements that is distinctly different from either regular or random colloidal coatings. The most notable of these differences is the adjustment and elimination of interparticle spaces found in random coatings and the ability to form either random or ordered coatings using a single coating technique. It is the ability to do.

The present invention includes a method of forming a densely packed coating of colloidal particles on a support. This method forms a monolayer of particles at the liquid-gas (maybe air) interface,
It involves compressing a monomolecular layer of particles on a liquid surface, transferring the compressed layer of particles from the liquid surface to a support, and drying the support.

[Means for solving problems]

The present invention includes a method of making a tightly packed coating of colloidal particles on a support. The method eliminates intervening spaces between colloidal particles.

These intervening spaces are removed by compressing the random colloid layer on the liquid surface to squeeze out these spaces. The squeezing method includes the following steps.

(1) forming a monolayer of colloidal particles on the liquid surface; (2) compressing the random colloidal coating on the liquid surface by physical or chemical means; (3) compressed monolayer coating. transferring the material from the liquid surface to either the dish support or a new support; (4) drying the compressed layer on the support.

In step [1], the support coated with a thick monomolecular layer of colloid is gradually immersed through the liquid interface so that the colloid layer is picked up from the support at the meniscus position and floats on the liquid surface. can be achieved. A representative schematic example of this method is shown in FIG. As the support passes through the liquid interface 9, the colloidal layer is picked up from the support by the water meniscus and becomes trapped at the liquid interface 9. Step (1) can also be accomplished by spreading droplets containing colloidal particles suspended in a second liquid that is immiscible with the first liquid onto the liquid surface. The second liquid must be chosen such that it evaporates leaving a colloidal layer trapped at the liquid interface.

In a preferred embodiment, the liquid α used in step (1)
Q is water. The most efficient confinement of colloidal particles at the water-air interface occurs when the particle surface is made hydrophobic. The contact angle between water and the hydrophobic particle surface provides very stable confinement of colloidal particles. Hydrophobic colloid particle surfaces can be formed by treating the particle surface with a silylating agent, a hydrophobically terminated amine, and a hydrofunctionalizing agent. For example, micron-sized colloidal particles of ZK-5 zeolite can be prepared using hexamethylene disilazane (HMDS) or n-benzyltrimethyl-ammonium hydroxide (40% methanol solution).
It can be prepared by washing with Excess detergent can be removed by physical separation methods such as filtration, centrifugation or decantation. The treatment provides zeolite particles functionalized by a monolayer of chemically bonded molecules.

Confined colloidal particle monolayers are similar in nature to Langmuir-Bl.
7 illum [for example, B, Blodgett and 1. Langminia (L)
angmuir.

Phys, Rev, (Phys, Rev,) 51
(1973) 964;
G. G. Rodgett), U.S. Pat. No. 2,220,860, 1940;

Roberts, P.S., Vincetto (V.
incett), W, A, bar o - (Barlaw)
, Huiz, Chikunor.

(Phys, Technol,) 12 (1981
) 69]. Langmuir-Prodgett films are prepared with at least one layer of amphiphilic molecules. Entrapment of molecules at the air/water interface occurs because the molecules have both hydrophobic and hydrophilic ends. The colloidal particles described in this invention are not amphiphilic as they do not have both hydrophobic and hydrophilic properties either on opposite sides of the particles or in the vicinity. air/
Confinement of colloidal particles at the water interface is caused by forces such as surface tension, CP, and Vinilanski (Pie et al.
ranski), Huiz, Shiv. Letter (Phys,
Rev. Lett) Dan (1980) 569]. This confinement is fundamentally different from that for amphiphilic molecules because it does not depend on having hydrophobic and hydrophilic ends connecting the water interface.

In the second step, the monolayer coating on the liquid support can be spread mechanically, i.e. by a movable barrier above the liquid surface, or chemically, i.e. with piston oil deposited on the liquid surface. area (thearea available)
This is achieved by reducing e to). The molecules of piston oil or the temporary barrier exert a force on the colloidal particles, compressing the monolayer. If piston oil is used, the spreading of the piston oil is hindered due to the surface tension of the piston oil layer 7. Items that can be used as piston oil include surfactants such as sodium lauryl sulfate and oils. The surface tension of the piston oil layer must be sufficient to compress the colloidal particles so that they do not float freely on the liquid surface 9. When the random colloid layer is compressed by the piston oil layer, the random nature of the original film tends to be preserved. The monolayer can be compressed on the liquid surface by adding a layer of piston oil after transferring the particles onto the liquid surface 9 or by spreading out the piston layer 7 before transferring the particles onto the liquid surface. can.

FIG. 4 shows a schematic diagram of the random colloid coating 3,
The random colloidal coating is compressed by the spread piston oil layer 7 before the coating 3 is swept away from the support 1 (5). In this case steps 1 and 2 are accomplished simultaneously.

The monolayer 5 transferred to the liquid surface can also be compressed by a mechanical barrier. 7.8.9 and 10
The figure shows the compression of a colloidal monolayer confined above a liquid surface by a mechanical barrier. As shown in Figure 7,
The colloidal monolayer must be transferred to the liquid surface not covered by piston oil. A support 31 containing a random colloidal coating 33 is immersed between physical barriers 37, leaving a monolayer 35 of colloidal particles freely spread over the liquid surface 39. A support 31 placed along one of the barriers or at the bottom of a liquid reservoir 38, as shown in FIG.
can be removed. The support at the bottom of the liquid reservoir is
Can be easily removed from around the physical barrier. The monolayer 35 can be compressed by moving the barrier as shown in FIG. As shown in FIG. 10, the compressed layer is moved onto a solid support 41, and the support is removed from below the liquid surface. By adjusting the compression rate by the mechanical barrier 37, more time is obtained for the shown marspheres to organize, resulting in a stone with a higher degree of regularity.

Such a compression method is based on the Langmuir-Blodgett Coatin.
Previously used to create a layer of surfactant molecules for g). (For example, K, B, Bron1"/t (Bl
) and 1. Langmuir
r) Physical Rev--(Phys, Rev,) 5
1 (1937); K, B.

Projet, U.S. Pat. No. 2,220,860, 194
Year 0; G, G, O bar 7 (Roberts), P, S
, Vincett, W.A., Barlow, Phys.
, Technol, ). ) Their use of this method to compress large molecular aggregates (e.g., colloidal particles) into stable films was unprecedented.

When piston oil is used to compress a monomolecular Langmuir-Prodgett layer, the piston oil is of the same size as the molecules being compressed.

Also, the molecular species are compressed so that only pores of molecular size exist between the compressed molecules. For colloid compression, the molecules in the piston oil are
It can be made about 1/10,000 times smaller. Furthermore, although the particles can be in contact along their diameter, the base of the particles in contact with the liquid can be spaced apart by as much as 10,000.

The third step is carried out by placing the original support or new support in the liquid phase just below the surface and removing the support such that the compressed layer moves from the interface of the liquid to the surface of the support. A schematic representation of this is shown in FIG. 5 and FIG. 1O. FIG. 5 shows transferring the compressed colloidal monolayer from the liquid surface 9 onto a support 11 taken out of the liquid 10 to form a compressed colloidal monolayer 3 on the support surface. . 101st! 1 shows the compressed monolayer 36 transferred from below the liquid surface 39 to the support 41 . support 41 by lowering it below the surface of the liquid outside of the physical barrier 37 that defines it.
can be introduced.

The fourth step is carried out by evaporating the residual water trapped between the support 17 and the compressed monolayer 13.

The compressed random layer is now in intimate contact 15 with the support. A diagram of this process is shown in FIG. When the layer moves as shown in FIG. 5, FIG. 6 shows a state in which a liquid layer 17 remains trapped between the support 11 and the colloid monomolecules 13. The changes during coating are shown as the liquid 17 evaporates leaving a compressed colloidal coating 15.

Monolayers formed in this way can exhibit locally tightly packed structures.

Figures 11 and 12 are electron micrographs showing the tightly packed random structures obtained with this method. Voids large enough to accommodate a single colloidal particle are generally not present in the coatings shown in FIGS. 11 and 12. The difference in local regularity in Figures 11 and 12 is due to the way the monolayer was compressed. Due to the random structure of the initial colloidal monolayer prior to compression, some voids (usually accompanied by dust or other impurities) are present in the compressed film. However, surface coverage of greater than 98% of the available surface area is typically obtained. In random colloidal coatings, a large number of voids arise due to the limited number of particles that can be dispersed and deposited onto the surface to be coated. After the surface to be coated has achieved a given density of colloidal particle coverage area, which varies depending on the particulars of the colloidal coating process, the remaining uncoated surface will react with other particles diffused on the surface into the sol. As shown, electrostatic shielding is caused by the presence of adjacent adhering particles. These voids are eliminated by a coating formed from a monolayer compressed at the surface of the liquid.

Figures 11 and 12 illustrate some of the close-packed structures that can be obtained using the present invention. These structures exist in a variety of forms, from random tight backings to well-defined, periodic, localized arrays.

There are generally no voids in the coating large enough to accommodate a single colloidal particle.

The present invention has the following additional advantages.

(1) The colloidal particle layer on the liquid surface can be patterned, producing a precisely shaped deposited layer on the final support; (2) Multilayers can be supported by repeating steps 1-4 in sequence. (3) the support does not need to be spun at high speeds to produce tightly packed monolayers; (4) colloidal methods such as non-aqueous wetting materials; Supports that are not easily coated can be coated with tightly packed colloids by this method: (5) The area covered can be very large;
It is also limited only by device size; (6) the requirement that the colloid be monodisperse can be easily relaxed. Tightly packed coatings of colloidal particles of significant polydispersity can be produced by this method.

According to the present invention: 1. A coating consisting of a monolayer of colloidal particles is formed by suspending the colloidal particles on the surface of a liquid. A monolayer of colloidal particles is stably confined to the liquid surface, and when compressed onto the liquid surface, the film acquires an elasticity reminiscent of a thin film of a polymer. Due to the stability of the colloidal particle layer at the liquid surface, the particles generally
) is not introduced. To avoid introducing defects in the final film, the concentration of particles in the bulk liquid is 1% (
(capacity) is preferably smaller. In a more preferred embodiment, the concentration of particles in the bulk liquid is less than or equal to 10-3% (by volume).

Colloidal particles can be patterned on a liquid surface by transferring a predetermined patterned random colloidal coating onto the liquid surface or by dicing a compressible colloid layer on the liquid surface.

To add a predefined pattern to a random colloidal coating,
The pattern gives the colloid an opposite surface charge and is deposited. The support on which the pattern is coated must acquire a surface charge of the same signal as the colloid. The aforementioned surface charge is created by the surface chemistry of the colloid, which, for colloids suspended in water, depends on the hydroxylation-hydrogenation equilibrium (U.S. Pat. No. 3,485,658 and J. Co.
1oidal and Interface 5cien
ce, 21.569-594 (1966)),
Patterning of deposited films to attract particles is discussed in J. L. Vossen and W. Kern (Eds.), Th1.
n Film Proesses” (Acad
emicPress, New York l 97
It can be carried out using lithographic processing techniques such as those described in 8).

The most convenient colloidal particles that are most frequently applied are polymeric spheres such as polystyrene, polydivinyl-benzene, and polyvinyl-toluene. Such spheres are usually manufactured by either suspension or emulsion polymerization and are conveniently fabricated in sizes ranging from 200 to 25 microns. Coatings of these particles are fabricated on supports of any size that are immersed in a liquid. Multilayer coatings of these particles can be created by sequentially repeating the four basic steps involved in the coating method: (1) transfer of a monolayer of colloidal particles onto the liquid surface;
(2) Compression of the monolayer; (3) transfer of the compressed layer onto the support; and (4) drying of the compressed layer on the support.

Embodiments of the present invention will be explained in detail in the following examples.

Example 1 A compressed layer was formed at the water-air interface from a random colloidal coating of groups of spherical polystyrene particles of 0.5 micron size. Random colloidal coatings were formed on flat glass supports using the method disclosed in US Pat. No. 3,485,658 (Ira). In detail, a flat glass support is first immersed in a 1% solids alumina sol (particle size 100) at pH 5, rinsed with distilled deionized water and dried in a stream of N2. The alumina-coated glass was then placed in a polymer colloid containing 10-30% by weight of spherical particles at pH=5.
Soak in water. The support is then rinsed with distilled deionized water and dried in a stream of N2. The method of this example provides a random coating of spherical polymer particles with a low degree of density.

To transfer the random colloid coating from the glass support to the water surface, the support is slowly (1 cm/sec) transferred to the water surface. The angle between the support and the water surface was approximately 30°. In order to transfer this layer efficiently, it is preferable to immerse this colloid layer soon after the formation of the colloid layer.
In this case, the random colloid coating was immersed 30 minutes after the colloid coating was formed. When impurities were present in the random colloid coating, the monolayer transferred onto the water surface often tended to become compressed. This compression is based on the "piston oil" effect of impurities. In order to sufficiently shrink this layer, a drop of surfactant (sodium lauryl sulfate) was added to the water surface after the random colloid coating had lifted off the support. The compacted layer was transferred to the water-insoluble glass surface by removing the water-insoluble glass surface from below the ~water interface as shown schematically in FIG. A water layer remains trapped between the shrunken monolayer and the support surface. This aqueous layer is removed by evaporation of water in air, leaving a compressed monolayer in contact with the support surface.

This coating can be used directly or as a template for further coating or for subjecting to etching methods such as vacuum evaporation or plasma or ion beam coating methods.

A random colloidal coating of 0.5 micron spherical polystyrene particles was formed on a glass support using the method described in Example 1. This coating was transferred onto a water surface pre-coated with a layer of piston oil as shown schematically in FIG. The piston oil layer was selected to act as sodium lauryl sulfate.

Side 2 - The support shown in the electron micrograph of Figure 13 is coated on one half with a random colloidal coating and on the other half with a compressed monolayer by the following steps. Produced: (1) A random colloidal coating of 0.5 micron polystyrene particles is formed over the entire surface of a glass support using the method described in Example 1.

(2) Precoating the water surface with sodium lauryl sulfate, which acts as a piston oil.

(3) Immerse half of the support by passing water through the interface as shown in FIG.

(4) Lift the support out of the water. In this case, a compressed monolayer is applied to the surface of the support.

(5) Drying the compressed monolayer forms a compressed coating on the soaked support half.

FIG. 12 is an electron micrograph showing the interface between the random colloid coating and the compressed coating. The random colloidal coating is shown as a group of individual particles on the left half of the figure, and the compressed coating layer is shown as a solid mat of particles on the right half of the figure. Since the spaces between the particles are compressed, the individual particles within the compressed coating are separated (res.
olνe) is difficult to do.

A monolayer coating having a thickness of 10 layers was produced by sequentially repeating the method of Example 1. Immediately after the first compressed monolayer coating was produced, the support was heat treated to improve adhesion between the polymer particles and the glass support. Heat treatment was carried out at 50°C for 15 minutes, but this temperature of 50°C is below the temperature at which the particle spheres melt and flow. Example 1
Sequential monolayers were built up by repeating the steps.

Example 5 A compressed colloidal coating was made from a monolayer compressed by a physical barrier. This physically compressed layer was created by the following steps.

(1) Spread a monomolecular layer of spherical polystyrene particles of 2 microns on the surface of water from a suspension of polystyrene spheres and hexane. Hexane is insoluble in water and the droplets are air-
When placed at a water interface, they float and spread out on the surface of the water.

A polystyrene sphere placed in a hexane droplet will not substantially dissolve and will be carried across the surface of the water by the hexane. When hexane is evaporated, a monolayer of polystyrene spheres remains on the surface of the water.

A hexane-based sol was prepared by centrifuging the polystyrene aqueous sol, decanting the water, and resuspending the particles in hexane.

The concentration of particles in the hexane sol was approximately 1% solids. Within 5 minutes of making the hexane sol, droplets spread on the surface of the water. After evaporation of hexane, a dispersed monolayer formed on the surface of the water.

(2) The dispersed layer was compressed in the manner shown in FIG. 9 with two Teflon rods acting as physical barriers to force the layers together.

(3) This compressed layer was transferred to a glass substrate using the technique shown in FIG.

(4) The coating on the glass substrate was evaporated leaving a well-adhered coating on the glass.

Example 6 A monolayer of zeolite type ZK-5 was prepared using the following procedure.

(1) Approximately 0.3 g of dry ZK-5 zeolite particles
Mixed with 0 cc of pentane. Approximately 0.5c to this mixture
Hexamethyldisilazane (HMDS) of c was added. This mixture was then stirred ultrasonically for 30 minutes.

(2) A bedding dish was filled with distilled water, and the mixture prepared in step 1 was poured onto the surface. The pentane and HMDS were evaporated leaving a monolayer of ZK-5 zeolite crystals trapped at the air-water interface.

(3) Clean the glass substrate with this monolayer on it, which was to be transferred, using a nonionic cleaning agent (Triton X-100).
) and rinsed with distilled water.

(4) A zeolite monolayer on the water surface was coated with a young aqueous solution of a nonionic surfactant (Triton X-100) (20
0ppn+). A solution of surfactant was applied by placing a drop on the edge of the bird dish. Compression of the monolayer occurred as soon as the droplet contacted the water surface.

(5) The compressed layer was lifted from the air-water interface onto the glass slide made in step 3. Excess water was dried from the slide using a heat lamp, leaving a film of a coherent zeolite monolayer.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph showing an array of monodispersed spherical latex particles in a random colloidal coating. The spacing between particles is evident from the micrograph. FIG. 2 is a micrograph showing the arrangement of 2 μm polystyrene latex particles in a random colloidal coating. FIG. 3 is an electron micrograph showing the microcrystalline arrangement of spin-coated monodisperse polystyrene latex particles. Figure 4 shows the compression of a random colloidal coating as it moves from a support onto a liquid surface coated with a surfactant. This prevents the colloidal particles from spreading out, so that a compressed monolayer is formed. FIG. 5 is a schematic diagram showing the transfer of a compressed colloidal monolayer from the liquid surface onto a support that has been pulled out of the liquid, forming a compressed colloidal monolayer on the support surface. to show that FIG. 6 shows the liquid layer trapped and present between the support and the colloidal monolayer when this layer is transferred as shown in FIG. The changes in the coating as the liquid evaporates leave behind a compacted colloidal coating. Figure 7 shows a random colloid coating transferred from a support to a liquid surface. The colloidal particles are free to spread out between the physical barriers. Figure 8 shows that using the support remaining at the bottom of the liquid layer,
Showing a completely displaced colloid layer. The support can be removed by removing it from the barrier before the next step. FIG. 9 shows a colloidal monolayer on the surface of a liquid. It is compressed by the movement of the physical barrier, thus forming a compressed monolayer. Figure 10 shows the monolayer removed from below the liquid surface, transferred to a support, and compressed. This support is outside the defined physical barrier.
More can be introduced by lowering the support below the surface of the liquid. FIG. 11 is an electron micrograph showing the ordered structure of tightly packed colloidal particles obtained by the method of the invention. FIG. 12 is an electron micrograph showing another structure of tightly packed colloidal particles obtained by the method of the invention. FIG. 13 is an electron micrograph containing the interface of both a random colloidal coating and a compacted monolayer. 17in+ FIG, 1 layer 1τ2 FIG 2 FIG, 3 FiGi3 FIG, 4 FIG, 5 FIG, 6 FIG, 7 FIG, 9 FIG, 10 FiG, t2 ・

Claims (12)

[Claims] (1) (a) forming a monolayer of non-amphiphilic colloid particles at a first liquid-gas interface; (b) forming a monolayer of non-amphiphilic colloid particles on the surface of the first liquid; (c) removing a compressed layer from the first liquid surface onto a support; and (d) drying the support. How to make packed sheathing. (2) The monomolecular layer forming step comprises immersing the voided random colloid coating in the first liquid such that the coating is confined at the first liquid-gas interface. How to make the described coating. (3) The monomolecular layer forming step includes placing a second liquid on the first liquid (provided that the second liquid is immiscible with the first liquid and contains a suspension of particles), and A method of making a coating according to claim 1, comprising spreading a second liquid and a suspension on the surface of the first liquid. 4. A method of making a coating as claimed in claim 1, wherein the compaction step comprises moving a mechanical barrier against the layer of particles so as to eliminate the intervening spaces between the particles. (5) The compression step comprises spreading the piston oil onto the first liquid-gas interface and depositing the piston oil onto the interface so as to compress the intervening spaces between the particles. Method of making the coating described in Section. (6) A method of making a coating according to claim (1), wherein the forming step and the compressing step are a single step. 7. A method of making a coating according to claim 1, wherein the compaction step comprises creating a predetermined pattern of monolayer particles. (8) A method of making a coating according to claim (1), wherein the colloidal particles are a single dispersion. (9) A method of making a coating according to claim (1), wherein the first liquid is water. (10) A method for making a coating according to claim (1), wherein the colloidal particles have a size of 0.1 to 5 μm. (11) A method for producing a coating according to claim (1), wherein the colloidal particles are high molecular weight particles. (12) A method of making a coating according to claim (1), wherein the support is not wetted with water.