WO2004055260A1

WO2004055260A1 - Use of multimolecular layers to reduce evaporation of water

Info

Publication number: WO2004055260A1
Application number: PCT/US2003/039614
Authority: WO
Inventors: Rahul Prabhakar Bagwe; Dinesh O. Shah
Original assignee: University of Florida
Current assignee: University of Florida
Priority date: 2002-12-13
Filing date: 2003-12-12
Publication date: 2004-07-01
Anticipated expiration: 2005-06-13
Also published as: AU2003296990A1

Abstract

Methods and compositions for the retardation of evaporation of water from a water/ air interface. The methods comprise applying a multimolecular oil/ surfactant layer to the surface. Preferably the surfactant is BRIJ-93.

Description

USE OF MULTIMOLECULAR LAYERS TO REDUCE EVAPORATION OF WATER

BACKGROUND

The loss of water from open storage by evaporation is a serious problem as a result of the increased use of water for industrial, personal and agricultural purposes. The evaporation loss is particularly high in arid regions having low rainfall and high temperatures. In many such regions, most of the usable fresh water is retained in lakes and reservoirs. Unfortunately, this type of water storage results in a high rate of loss of water by evaporation. Water evaporation is also a problem in many other medical, industrial and agricultural areas.

Many physical and chemical methods have been developed in an attempt to reduce water evaporation. One such technique is the application of a chemical film on the surface of the water to retard evaporation. It is known that a monomolecular layer of surface active material such as fatty acids, fatty alcohols, phospholipids or cholesterol may be formed at a liquid/ air interface. Langmuir, I. and Schaefer, V., J. Franklin Inst. (1943), 235, 119-62 describe the use of monolayers to reduce the rate of evaporation of water. However, the application monomolecular layers has resulted in only a limited reduction in the rate of evaporation from the underlying water sur ace.

E. Heymann and A. Yoffe, Trans. Faraday Soc. (1942) 38, 408-17 discuss the use of multimolecular films of hydrocarbon oils containing spreaders to reduce evaporation from water surfaces. Such multimolecular films can be formed using compositions comprising a surfactant and an oil, and are claimed to be more effective than monomolecular layers in reducing the rate of evaporation.

However, mixtures of oil and certain surfactants, such as stearic acid, become compressed at a water/ air surface to form a monolayer wherein the terminal methyl groups of stearic acid stick out into the air resulting in a low energy surface. This can result in the formation of areas of oil in equilibrium with a monolayer of stearic acid and can significantly reduce the effectiveness of evaporation control obtained using such compositions.

Therefore, it is desirable to provide a composition comprising a surfactant with an appropriate molecular structure to form a uniform multimolecular layer composed of oil and surfactant molecules.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention, there is a method for retarding the evaporation of water from a surface, comprising contacting the surface with a composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether. The composition forms a multilayer film on the surface.

The method may further comprise contacting the surface with a composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether, wherein the multimolecular layer is from 1 micron to 32 microns thick, from 4 microns to 32 microns thick, between from 8 microns to 32 microns thick, from 12 microns to 32 microns thick, and from 10 microns to 16 microns thick.

The method may further comprise contacting the surface with a composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is from 0.2 to 1.4 percentage weight, from 0.4 to 1.4 percentage weight, from 0.6 to 1.4 percentage weight, from 0.4 to 1.0 percentage weight, from 0.4 to 0.8 percentage weight, and wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is about 0.7 percentage weight.

The method may further comprise contacting the surface with a composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether, wherein the surface is the surface of a reservoir or lake, wherein the surface is the surface of an eye or a mouth, wherein the surface is the surface of a pool of tritiated or deuterated water, and wherein a gas is contained within the water and the release of a gas from within the water is reduced.

In another aspect of the invention, there is a method for reducing the evaporation of water from a surface, comprising contacting the surface with a first composition comprising polyvinylalcohol, and contacting the surface with a second composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether. The second composition forms a multimolecular layer on the surface.

The method may further comprise contacting the surface with a first composition comprising polyvinylalcohol, wherein the percentage of polyvinylalcohol in the first composition is from 0.1 to 3.0 weight percentage, from 0.8 to 1.5 weight percentage, from 0.2 to 1.4 percentage weight, and from 0.4 to 1.0 percentage weight.

The method may further comprise contacting the surface with a second composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether, wherein the percentage of polyvinylalcohol in the first composition is from 0.1 to 3.0 weight percentage, the percentage of polyoxyethylene(2.5) oleyl ether in the second composition is from 0.2 to 1.4 percentage weight, and the ratio of the first composition to the second composition is from 1 :3 to 3:1 (v/v).

In yet another aspect of the invention, there is a method for reducing the evaporation of water from a surface comprising contacting the surface of the water with a composition comprising polyvinylalcohol, hexadecane and polyoxyethylene(2.5) oleyl ether. The composition forms a multilayer film on the surface.

In yet another aspect of the invention, there is a composition for reducing the evaporation of water from a surface comprising polyvinylalcohol, hexadecane and polyoxyethylene(2.5) oleyl ether. BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a graph showing the retardation of the evaporation of water by different surfactants.

FIGURE 2 is a graph showing the retardation of the evaporation of water by multimolecular layers of various thicknesses.

FIGURE 3 (a) - (d) are photographs showing Brewster Angle Microscopy studies.

FIGURE 4 is a graph showing the retardation of the evaporation of water at different concentrations of BRIJ-93. FIGURE 5 (a) - (c) are photographs showing Brewster Angle

Microscopy studies.

FIGURE 6 is a graph showing the effect of various additives on the retardation of the evaporation of water.

FIGURE 7 is a graph showing the retardation of the evaporation of water at different temperatures.

DETAILED DESCRIPTION

The present invention provides compositions and methods for reducing the evaporation of water from a water/ air surface by contacting the surface of the water with a composition containing a hydrocarbon oil and a surfactant.

By choosing a surfactant with an appropriate molecular structure, such a composition forms a uniform multimolecular layer composed of oil and surfactant molecules. By "multimolecular layer" applicants mean a uniform film of oil and surfactant containing more than one layer of molecules. In one embodiment of the invention the composition contains a surfactant which is polyoxyethylene (2.5) oleyl ether (BRIJ^®-93, UNIQEMA, New Castle, DE). The composition of the present invention further comprises 0.1 % (w/w) to 2% (w/w) BRIJ-93 in the hydrocarbon oil, hexadecane.

The inventors have found that a surfactant/oii composition containing BRIJ-93 in combination with oil forms a multimolecular layer of uniform thickness at a water/ air interface and is especially effective in reducing the rate of evaporation of water. Such a surfactant/oil composition allows the thickness of the layer to be controlled depending upon the amount of material deposited and reduces the rate of evaporation of water by as much as 98%. At low amounts of the oil/ surfactant composition, the rate of evaporation of water decreases with increasing amounts of oil/ surfactant.

Only limited additional retardation in evaporation is observed after sufficient oil/ surfactant mixture is added, for example, above a 16 micron thick layer on the multimolecular layer.

Optimal retardation of evaporation is obtained at a concentration of approximately 0.7% BRIJ-93 in oil. At higher concentrations, any further increase in the BRIJ-93 concentration results in a decreased retardation of evaporation. Such a decrease in retardation of evaporation at higher BRIJ-93 concentrations is often accompanied by the formation of an oil-in-water emulsion comprising circular emulsion droplets. Preferably the oil/ surfactant composition contains hexadecane and polyoxyethylene(2.5) oleyl ether, with a concentration of polyoxyethylene(2.5) oleyl ether from 0.2 to 1.4 percentage weight (wt%). More preferably, the concentration of polyoxyethylene(2.5) oleyl ether is from 0.4 to 1.4 wt%, more preferably from 0.6 to 1.4 wt%, more preferably from 0.4 to 1.0 wt%, more preferably from 0.4 to 0.8 wt%, and more preferably about 0.7 wt%.

The present invention also provides a composition and method for retarding the evaporation of water from a water/ air surface by contacting the surface of the water with a first composition containing polyvinylalcohol (molecular weight 96,000) (PVA) and a second composition containing a hydrocarbon oil and a surfactant. The addition of a multimolecular layer formed by the second composition on top of PVA retards evaporation to a greater extent than does the presence of the multimolecular layer alone. In one embodiment of the invention, the second composition is the combination of oil and BRIJ-93 described above. In another embodiment of the invention the first composition and the second composition are combined to form a third composition. The third composition is then applied to the surface to retard evaporation of water from the water/ air interface. Preferably, the concentration of polyvinylalcohol in the first composition applied to the water surface is from 0.1 to 3.0 weight percentage. More preferably the concentration of polyvinylalcohol in the first composition is from 0.8 to 1.5 wt%, more preferably from 0.2 to 1.4 wt%, and more preferably from 0.4 to 1.0 wt%. Preferably, the concentration of polyvinylalcohol in the first composition applied to the water surface is from 0.1 to 3.0 weight percentage; the second composition contains hexadecane and polyoxyethylene(2.5) oleyl ether, with a concentration of polyoxyethylene(2.5) oleyl ether from 0.2 to 1.4 percentage weight; and a ratio of the first composition to the second composition of from 1 :3 to 3:1 (v/v).

The multimolecular layers of the invention provide an effective means of evaporation control in many applications where a retardation of evaporation is required. For example, the invention provides a cost effective method of water conservation by retarding the evaporation of water from the surface of a reservoir or lake. In another application, evaporation of water from the surface of a pool of tritiated or deuterated water from a nuclear reactor may be controlled.

The compositions of the invention form a stable multimolecular layer at an air/water interface even at elevated temperatures and under conditions, such as high wind velocity, that normally disrupt monolayer films. Hence, compositions of the invention remain effective in retarding evaporation at an elevated temperature and under conditions causing disruption of the water surface. The compositions of the invention also reduce disruption of the water surface and decrease the time required for the surface to return to an undisturbed condition.

The present invention also has pharmaceutical applications. For example, in the retardation of evaporation from a corneal surface of patients suffering from dry eye and for the treatment of skin burn victims. Personal care applications include the use of the composition to reduce the severity of conditions such as dry skin or dry mouth. In the food industry, the shelf life of fruits, vegetables and other foods can be enhanced by coating such foods with a composition of the present invention to reduce evaporation of water.

The present invention also provides an economical method of reducing the leakage of toxic vapors from a water surface. For example, the leakage of toxic gases such as ammonia or hydrogen sulphide may be reduced.

Method of Application

When used to retard evaporation from the surface of a body of water such as a lake or reservoir, the compositions of the invention can be applied by pouring the compositions or composition onto the surface of the water and allowing the compositions to spread. Alternatively, the compositions or composition can be sprayed onto the water surface.

Preferably, the multimolecular layer formed on the water surface has a thickness of from 1 micron to 32 microns. More preferably, the multimolecular layer formed on the water surface has a thickness of from 4 microns to 32 microns, more preferably from 8 microns to 32 microns, more preferably from 12 microns to 32 microns, and more preferably from 10 microns to 16 microns thick. When used for pharmaceutical or personal care applications, the compositions or composition of the invention can be incorporated into pharmaceutical compositions and applied as discussed below.

Pharmaceutical Compositions Pharmaceutical compositions typically comprise the compositions of the present invention and a pharmaceutically acceptable carrier. A "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration (Gennaro, A.R. 2000. Remington: The science and practice of pharmacy.

Lippincott, Williams & Wilkins, Philadelphia, PA). Preferred examples of such carriers or diluents include, but are not limited to, water, saline, Finger's solutions, dextrose solution, and 5% human serum albumin.

A pharmaceutical composition comprising the compositions of the invention is formulated to be compatible with its intended route of administration, including intradermal, oral (e.g., inhalation), transdermal (i.e., topical), transmucosal, and rectal administration. Solutions or suspensions used for intradermal, or subcutaneous application can include: a sterile diluent such as water, saline solution, antibacterial agents such as benzyl alcohol or methyl parabens, antioxidants such as ascorbic acid or sodium bisulfite, chelating agents such as ethylenediaminetetraacetic acid (EDTA); buffers such as acetates, citrates or phosphates, and agents for the adjustment of tonicity such as sodium chloride or dextrose. The pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. The preparation can be enclosed in ampules, disposable syringes or multiple dose vials made of glass or plastic.

Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the compositions can be incorporated with excipients and used in the form of tablets, troches, or capsules. Oral compositions can also be prepared using a fluid carrier for use as a mouthwash, wherein the compound in the fluid carrier is applied orally. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included. Tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, PRIMOGEL, or corn starch; a lubricant such as magnesium stearate or STEROTES; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, or orange flavoring. For administration by inhalation, the compounds are delivered as an aerosol spray from a nebulizer or a pressurized container that contains a suitable propellant, e.g., a gas such as carbon dioxide.

Systemic administration can also be transmucosal or transdermal. Nasal sprays or suppositories can be used for transmucosal administration.

For transdermal administration, the compositions are formulated into ointments, salves, gels, or creams.

Kits Kits comprising the compositions of the present invention are also provided. Such kits can be of particular applicability for pharmaceutical or personal care applications. Hence, the invention provides kits containing one or more of the following in a package or container: (1) a PVA composition; an oil/ surfactant composition, or combinations thereof; (2) a pharmaceutically acceptable adjuvant or excipient; (3) a vehicle for administration, such as an applicator, syringe or spray; (4) instructions for administration. Embodiments in which two or more of components (1) - (4) are found in the same container are also contemplated.

When a kit is supplied, the different components of the composition may be packaged in separate containers and admixed immediately before use. Such packaging of the components separately may permit long-term storage without losing the active components' functions.

The reagents included in the kits can be supplied in containers of any sort such that the life of the different components are preserved and are not adsorbed or altered by the materials of the container. Ampules may consist of any suitable material, such as glass, organic polymers, such as polycarbonate, polystyrene, etc.; ceramic, metal or any other material typically employed to hold similar reagents. Other examples of suitable containers include simple bottles that may be fabricated from similar substances as ampules, and envelopes, that may comprise foil-lined interiors, such as aluminum or an alloy. Other containers include test tubes, vials, flasks, bottles, syringes, or the like. Containers may have a sterile access port, such as a bottle having a stopper that can be pierced by a hypodermic injection needle. Other containers may have two compartments that are separated by a readily removable membrane that upon removal permits the components to be mixed. Removable membranes may be glass, plastic, rubber, etc. Kits may also be supplied with instructional materials. Instructions may be printed on paper or other substrate, and/or may be supplied as an electronic-readable medium, such as a floppy disc, CD-ROM, DVD-ROM, Zip disc, videotape, audiotape, etc. Detailed instructions may not be physically associated with the kit; instead, a user may be directed to an internet web site specified by the manufacturer or distributor of the kit, or supplied as electronic mail.

A more complete understanding of the present invention can be obtained by reference to the following specific Examples. The Examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitations. Modifications and variations of the invention as hereinbefore set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.

EXAMPLES

Example 1 - Effect of Surfactant on Mulimolecular Layer Properties Oil/ surfactant compositions were prepared by mixing a surfactant with hexadecane at a surfactant concentration of 0.2 percent by weight (wt%). The surfactants examined were:

(a) oleic acid,

(b) stearic acid, (c) palmitic acid,

(d) polyoxyethylene (2.5) oleyl ether (BRIJ-93 (HLB 4.9)), (e) polyoxyethylene (2) stearyl ether (BRIJ-72 (HLB 5.3)), and

(f) polyoxyethylene (2) cetyl ether (BRIJ-52 (HLB 4.9)). The surfactants were obtained from ICI SPECIALITY CHEMICALS (Wilmington, DE), and the hexadecane was obtained from FISHER SCIENTIFIC (Fair Lawn, NJ).

A Langmuir trough having dimensions of 25cm x 11cm x 1cm was filled with 400 mL of de-ionized water and allowed to equilibrate to a temperature of 23 ± 1 °C. For a given set of measurements, one oil/ surfactant composition was deposited via microsyringe onto various areas of the water trough. The average thicknesses of the films were approximately 4 microns (μm). A trough of water without any oil/ surfactant composition was used as a control. A known amount of anhydrous calcium chloride (FISHER SCIENTIFIC) was measured and placed in a Petri dish. The Petri dish was then covered with vinyl cloth, inverted, and placed 3 mm above the surface of the water trough. The rate of evaporation was measured by the increase in weight of the calcium chloride. The percent change in desiccant weight was measured every 10 min over a period of 1 hour.

Referring to the graph of Figure 1 , the oleic acid composition, 1 (a), did not show any reduction in evaporation compared to the control. The stearic acid composition, 1 (b), reduced the evaporation of water by 50%, as did the palmitic acid composition (1(c), not shown in Fig. 1). The stearic acid and palmitic acid compositions formed monolayers of the surfactant on the surface of the water, rather than forming multimolecular layers with the hexadecane as observed for the other compositions. No reduction in evaporation was observed for the BRIJ-72 and BRIJ-52 compositions (1(e) and 1(f), not shown in Fig. 1). When the BRIJ-72 composition was applied, the surfactant precipitated from the hexadecane composition.

The BRIJ-93 composition, 1 (d), reduced the evaporation of water by more than 50%, and increasing the thickness of this layer from 4 μm to 16 μm reduced the evaporation by 98%. The effects of multimolecular layer thickness are further discussed in Example 2. The rest of the results are not shown in Figure 1. Example 2 - Effect of Multimolecular Layer Thickness An oil/ surfactant composition of hexadecane with 0.2 wt% BRIJ-93 was deposited onto 400 mL de-ionized water in a Langmuir trough, as described in Example 1. For a given set of measurements, a different volume of the composition was deposited. The amounts used were 50 microliters

(μL), 100 μL, 150 μL, 400 μL, 500 μL, 700 μL and 800 μL.

The rates of evaporation were measured using the calcium chloride method described in Example 1 , with pure water as a control. Referring to the graph of Figure 2, a greater reduction in evaporation was observed upon increasing the amount of composition deposited from 100 μL to 400 μL. The thickness of the 400 μL layer was approximately 16 μm. No further reduction in evaporation was observed by increasing the amount of oil/ surfactant composition to 800 μL. Both the 400 μL and 800 μL layers showed a 98% reduction in evaporation compared to pure water. Images of the layers were recorded using a BAMI Brewster angle microscope (NANOFILM TECHNOLOGIE GmbH, Gottingen, Germany), using a He-Ne laser (p-polarized) as the light source. The angle of incidence was initially set to 53° and then adjusted to minimize the reflected intensity of the clean water surface prior to depositing each composition. Photos were taken with a rotatable analyzer set at 90° placed between the reflected signal and the CCD camera. A frame-grabbing program (VIDEOPIX, Sun Microsystems) was used to generate photos from videotape and convert them to a computer- readable format. Figures 3A, 3B, 3C and 3D are images of the multimolecular layer formed from the 50 μL composition, the 150 μL composition, the 500 μL composition and the 700 μL composition, respectively. Organized structures of parallel lines were observed for all the multimolecular layers.

Example 3 - Effect of Surfactant Concentration Oil/ surfactant compositions of hexadecane with BRIJ-93 were prepared with different concentrations of BRIJ-93. The concentrations examined were 0 wt%, 0.2 wt%, 0.5 wt%, 0.7 wt%, 1 wt% and 1.4 wt%. For a given set of measurements, a particular composition was deposited onto 400 mL de-ionized water in a Langmuir trough, as described in Example 1 , to form a layer having a thickness of 4 μm. The rates of evaporation were measured using the calcium chloride method described in Example 1 , with pure water as a control. Referring to the graph of Figure 4, the reduction in evaporation increased with increasing concentration of BRIJ-93 up to

0.7 wt%. Higher concentrations of BRIJ-93 allowed more evaporation. Without wishing to be bound by any theory of interpretation, it is believed that the oil/ surfactant composition does not completely cover the water at low concentrations. At higher concentrations, the increased amount of surfactant may form oil-in-water emulsions rather than remaining as a separate layer on the surface. This is consistent with images of the layers recorded as described in Example 2. For the purpose of imaging, the layers were formed using only 30 μL of each composition, providing a layer thickness of approximately 1 μm. Referring to the images of Figure 5, at low surfactant composition of 0.2 wt%, no organized structure is observed (Fig.

5A). The organized structure of parallel lines is observed at an intermediate concentration of 0.5 wt% (Fig. 5B). At a higher concentration of 0.8 wt%, the parallel lines are not observed, but are replaced by circles, which may indicate emulsion droplets (Fig. 5C). The layer containing 0.8 wt% BRIJ-93 also exhibited some turbidity, which is further evidence of the presence of an emulsion.

Example 4 - Effect of Polymer Additive

Polymeric solutions of different polymers were prepared by dissolving poly(vinyl alcohol) (PVA; molecular weight of 96,000), egg albumin (BSA), or hydroxyethyl cellulose (HEC) in water at a concentration of 1 wt%. For a given set of measurements, 100 μL of a polymer solution was first deposited onto 400 mL de-ionized water in a Langmuir trough, as described in Example 1. A 100 μL portion of a 0.2 wt% mixture of BRIJ-93 in hexadecane was then deposited onto the polymer solution film. The total layer thickness was 4 μm.

The rates of evaporation were measured using the calcium chloride method described in Example 1 , with pure water as a control. Referring to the graph of Figure 6, the greatest reduction in evaporation was observed for the PVA layer in combination with the oil/ surfactant composition. The 95% reduction in evaporation was an increase over the 50% reduction observed for 100 μL of the 0.2 wt% BRIJ-93 / hexadecane composition alone (see Figure 2). The BSA and HEC layers did not provide any further reduction in evaporation compared to the 0.2 wt% BRIJ-93 / hexadecane composition alone.

Example 5 - Effect of Temperature An oil/ surfactant composition of hexadecane with 0.2 wt% BRIJ-93 was deposited onto 400 mL de-ionized water in a Langmuir trough, as described in Example 1. The thickness of the layer was 6 μm. The effect of temperature on the rate of evaporation was examined by the calcium chloride method described in Example 1 , except using a Petri dish of 10 cm diameter and 1 cm height. The temperature was raised from 35°C to 75°C. Referring to the graph of Figure 7, the oil/ surfactant layer reduced the evaporation by 75% at 75°C relative to pure water.

Claims

1. A method for retarding the evaporation of water from a surface, comprising: contacting the surface with a composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether; wherein the composition forms a multimolecular layer film on the surface.

2. The method of claim 1 , wherein the multimolecular layer is from 1 micron to 32 microns thick.

3. The method of claim 1 , wherein the multimolecular layer is from

4 microns to 32 microns thick.

4. The method of claim 3, wherein the multimolecular layer is form 8 microns to 32 microns thick.

5. The method of claim 4, wherein the multimolecular layer is from 12 microns to 32 microns thick.

6. The method of claim 3, wherein the multimolecular layer is from 10 microns to 16 microns thick.

7. The method of claim 1 , wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is from 0.2 to 1.4 percentage weight.

8. The method of claim 7, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is from 0.4 to 1.4 percentage weight.

9. The method of claim 8, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is from 0.6 to 1.4 percentage weight.

10. The method of claim 7, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is from 0.4 to 1.0 percentage weight.

11. The method of claim 10, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is from 0.4 to 0.8 percentage weight.

12. The method of claim 7, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the composition is about 0.7 percentage weight.

13. A method for reducing the evaporation of water from a surface, comprising: contacting the surface with a first composition comprising polyvinylalcohol; and contacting the surface with a second composition consisting essentially of hexadecane and polyoxyethylene(2.5) oleyl ether; wherein the second composition forms a multimolecular layer on the surface.

14. The method of claim 13, wherein the percentage of polyvinylalcohol in the first composition is from 0.1 to 3.0 weight percentage.

15. The method of claim 14, wherein the percentage of polyvinylalcohol in the first composition is from 0.8 to 1.5 weight percentage.

16. The method of claim 13, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the second composition is from 0.2 to 1.4 percentage weight.

17. The method of claim 16, wherein the percentage of polyoxyethylene(2.5) oleyl ether in the second composition is from 0.4 to 1.0 percentage weight.

18. The method of claim 13, wherein the percentage of polyvinylalcohol in the first composition is from 0.1 to 3.0 weight percentage; the percentage of polyoxyethylene(2.5) oleyl ether in the second 5 composition is from 0.2 to 1.4 percentage weight; and the ratio of the first composition to the second composition is from 1 :3 to 3:1 (v/v).

19. The method of claim 1 , wherein the surface is the surface of a reservoir or lake.

10 20. The method of claim 1 , wherein the surface is the surface of an eye or a mouth.

21. The method of claim 1 , wherein the surface is the surface of a pool of tritiated or deuterated water.

22. The method of claim 1 , wherein a gas is contained within the 15 water and the release of a gas from within the water is reduced.

23. A method for reducing the evaporation of water from a surface, comprising: contacting the surface of the water with a composition comprising polyvinylalcohol, hexadecane and polyoxyethylene(2.5) oleyl ^"20 ether; wherein the composition forms a multilayer film on the surface.

24. A composition for reducing the evaporation of water from a surface, comprising: polyvinylalcohol; 25 hexadecane; and polyoxyethylene(2.5) oleyl ether.