POLYMERIC FILMS.

Abstract

A polymer film includes a substrate at least partially coated with hydrophobic particles, the hydrophobic particles include: a metal oxide core; and a hydrocarbon chain having from 2 to 40 carbon atoms, wherein the hydrocarbon chain is chemically bonded to the metal oxide core.

Description

POLYMERIC FILMS FIELD OF INVENTION This specification relates to polymer films and, in particular, to polymer films having a water contact angle (WCA) of approximately 140° or more. In some embodiments, the polymer films have a WCA in excess of 150°. The polymer films of the present invention are non-toxic, meaning they can be used in a wide range of applications, including food and liquid packaging. BACKGROUND OF THE INVENTION Surfaces that are difficult to wet are known as hydrophobic surfaces. Such surfaces have several commercially important properties. For example, surfaces that are difficult to wet can be non-stick, self-cleaning, and / or stain-resistant. Hydrophobic materials are commonly used to create hydrophobic surfaces. These materials typically include waxes, fluorinated polymers such as polytetrafluoroethylene (PTFE), organosilanes, and others. For example, silicones, siloxanes, and various fluoroacrylate polymers are the predominant materials used in formulations for waterproof textiles. Hydrophobic formulations are generally sprayed onto the surface of a textile and, after curing or air drying, provide effective water repellency against rain and moisture, as well as protection against various dirt and stains. However, known hydrophobic materials do not normally adhere well to all surfaces, particularly thermoplastic films. In addition, known hydrophobic materials often contain fluorine, and these fluorine-containing hydrophobic materials can be toxic. Consequently, there is a need for improvement. In particular, there is a need for non-toxic, hydrophobic materials that adhere well to surfaces such as thermoplastic films, thereby providing polymer films that are difficult to remove. Π LA L Lñ / LZñZ / E / YIAI moisten, self-cleaning and / or pollution resistant. BRIEF DESCRIPTION OF THE INVENTION The embodiments of the present invention aim to provide polymer films having a water absorption coefficient (WAC) of approximately 140° or more, wherein the adhesion between the substrate and the hydrophobic particles is improved compared to the prior art. The embodiments of the present invention also aim to provide polymer films that are less toxic compared to the prior art. According to a first aspect of the invention, a polymeric film is provided comprising a substrate coated at least partially with hydrophobic particles, wherein the hydrophobic particles comprise: a metal oxide core; and a hydrocarbon chain having from 2 to 40 carbon atoms, wherein the hydrocarbon chain is chemically bonded to the metal oxide core. The average diameter of hydrophobic particles can be less than or equal to approximately 200 nm. The average diameter of hydrophobic particles can be less than or equal to approximately 50 nm, for example, less than or equal to approximately 20 nm. The average diameter of hydrophobic particles can be from approximately 8 nm to approximately 20 nm, such as from approximately 8 nm to approximately 15 nm. The metal oxide core may comprise one or a combination of aluminum oxide, iron oxide, zinc oxide, and silicon oxide. The hydrocarbon chain can be aliphatic. The hydrocarbon chain can be linear or branched. The hydrocarbon chain can have from 2 to 32 carbons. The hydrocarbon chain can have from 6 to 32 carbons, for example, from 6 to 24 carbons. The hydrocarbon chain can be covalently bonded to the metal oxide core through a functional group, for example, an anionic functional group. nLRL Ln / Lznz / E / YILI The functional group may comprise any one or a combination of hydroxide, carboxylate, phosphonate, phosphinate, thiolate, and thiocarboxylate. Hydrophobic particles may be fluorine-free. The substrate may comprise a thermoplastic film. For example, the substrate may comprise one or more films of polyolefin, vinyl polymer, polyester, and polyacetal. The substrate may comprise a coextruded bilayer or multilayer film. For example, the coextruded bilayer or multilayer film may comprise layers of any one or a combination of polyethylene (PE), polypropylene (PP), acetal, acrylic, polyamide, polyvinyl chloride (PVC), ethylene vinyl acetate (EVA), polyvinylidene chloride (PVDC), polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polycarbonate (PC). Hydrophobic particles can be deposited (e.g., sprayed) onto the substrate. For example, hydrophobic particles can be mixed with a carrier, such as a volatile solvent, and the resulting mixture can be sprayed onto the substrate. The mixture of hydrophobic particles and the carrier can form a solution or suspension. The mixture can have a concentration of hydrophobic particles of approximately 0.5 wt to approximately 20 wt, such as approximately 0.5 wt to approximately 10 wt, or approximately 0.5 wt to approximately 5 wt, for example, 0.5 wt, 1 wt, 2 wt, 3 wt, 4 wt, or 5 wt. Hydrophobic particles can become at least partially embedded in the substrate. The substrate can be heated to allow hydrophobic particles to at least partially embed themselves in it, forming a three-dimensional hydrophobic surface. Embedding of the hydrophobic particles can be enhanced by physical means, such as rolling the heated substrate between rollers. During processing, the volatile solvent (when used) evaporates naturally, and when the substrate cools, the hydrophobic particles remain bonded to it and are not removed by washing. The temperature to which the substrate is heated will vary depending on the type of substrate used. In general, the substrate is heated to a temperature at which it begins to deform plastically. It should be noted that an expert in the field will be aware of this. The temperature can be determined by basic experimentation. For the five-layer coextruded thermoplastic film of EVA / EVA / PVDC / EVA / EVA used in the following examples, the deformation temperature of the plastic was between approximately 80°C and approximately 90°C. Hydrophobic particles and the substrate can be bonded together using an adhesive, such as an epoxy resin. For example, an adhesive can be deposited onto the substrate followed by the hydrophobic particles. Alternatively, the hydrophobic particles can be deposited onto the substrate followed by the adhesive. The hydrophobic particles can become at least partially embedded in the adhesive, which in turn provides the bond between the substrate and the hydrophobic particles. When the adhesive cures, the result is a polymer film with a three-dimensional hydrophobic surface. The hydrophobic particles and the adhesive can be mixed and the resulting mixture can be deposited onto the substrate. When hydrophobic particles and adhesive are mixed, the mass ratio of hydrophobic particles to adhesive can be from approximately 10:1 to approximately 2.0:1. Mass ratios of hydrophobic particles to adhesive in this range have been found to produce polymer films that have particularly good hydrophobic surfaces. Hydrophobic particles or hydrophobic particle / adhesive mixture can be sprayed onto the substrate using a carrier, for example, a volatile solvent, as described above. In all methods for bonding hydrophobic particles to the substrate, it has been found that water-based adhesives (WCAs) are not adversely affected even after the polymer film has been immersed in or exposed to a solvent. Such treatment may result in some of the hydrophobic particles being removed from the substrate, but this removal has a negligible effect on the WCA. The hydrophobicity of the polymer film can be adjusted in different regions of its surface. This means that a first region of the polymer film can have a first WCA measurement associated with it, and a second region of the polymer film can have a second WCA measurement associated with it that differs from the first WCA measurement. The hydrophobicity of the polymer film can be adjusted in several ways. For example, more layers of hydrophobic particles can be deposited in the first region than in the second. Consequently, the first region will typically have a higher water absorption capacity (WCA) measurement than the second. Alternatively, a more concentrated mixture of hydrophobic particles can be deposited in the first region than in the second. The concentration of hydrophobic particles in the mixture can be adjusted by dilution with the solvent and / or a different species, such as a hydrophilic particle and / or a non-functionalized metal oxide. Additionally, different types of hydrophobic particles can be deposited in the respective first and second regions.Consequently, the first and second regions will typically have different WCA measures. The present invention provides self-cleaning polymer films and processes for producing self-cleaning polymer films, wherein the polymer films have a hydrophobic surface formed by attaching hydrophobic particles to a substrate. The methods for bonding hydrophobic particles to the substrate result in a polymer film with a three-dimensional surface structure capable of achieving a water-cure angle (WCA) of approximately 140° or higher. Consequently, the polymer films of the invention can offer improved self-cleaning properties and / or resistance to contamination. According to a second aspect of the invention, the use of a polymeric film according to the first aspect of the invention is provided as a food packaging film. According to a third aspect of the invention, a container or receptacle for food or liquids is provided comprising a surface at least partially coated with a polymeric film according to the first aspect of the invention. The surface of the food or liquid container or receptacle may comprise metal, alloy, plastic, cardboard and / or glass. According to a fourth aspect of the invention, a sheet of nLRL Ln / Lznz / E / YIAI glass coated at least partially with a polymeric film according to the first aspect of the invention is provided. The glass sheet can be used in a windshield, for example, a windshield for a vehicle. According to a fifth aspect of the invention, a plastic sheet coated at least partially with a polymeric film according to the first aspect of the invention is provided. According to a sixth aspect of the invention, a sheet of fabric coated at least partially with a polymeric film is provided according to the first aspect of the invention. According to a seventh aspect of the invention, a garment or footwear is provided that is at least partially coated with a polymeric film according to the first aspect of the invention. BRIEF DESCRIPTION OF THE FIGURES The embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: Figure 1 is a representation of a hydrophobic particle. Figure 2 shows a polymeric film according to an embodiment of the invention comprising a substrate having hydrophobic particles at least partially embedded therein. Figure 3 shows a polymeric film according to an embodiment of the invention comprising a substrate and hydrophobic particles bonded to it by means of an adhesive. DETAILED DESCRIPTION OF THE INVENTION With reference to Figure 1, a hydrophobic particle, generally represented as 1, is shown. The hydrophobic particle 1 comprises a metal oxide core 10 and six hydrocarbon chains 12. It should be noted that in other embodiments the hydrophobic particle 1 may have more or fewer than six hydrocarbon chains 12. Each hydrocarbon chain 12 has from 2 to 40 carbon atoms. The hydrocarbon chains 12 are branched, although they could be straight. Πίβί ίη / ίΖΠΖ / Ε / ΥΙΛΙ The hydrocarbon chains 12 are chemically bonded to the metal oxide core 10. In some embodiments, the hydrocarbon chains 12 may be covalently bonded to the metal oxide core 10 via a functional group 14. Suitable metal oxide cores 10 include aluminum oxide, iron oxide, zinc oxide, and silicon oxide. The term oxide, as used herein, is intended to include oxides-hydroxides, hydroxides, and also oxides that have multiple oxidation states of metals. For example, iron oxide may include Fe3O4 or Fe2O3 or a combination of both. In some embodiments, the hydrophobic particle 1 comprises a metal oxide core 10 having a hydrocarbon chain 12 covalently linked thereto by a carboxylate functional group 14. In other embodiments, alternative functional groups may be employed provided that a stable covalent interaction is formed between the metal oxide cores 10 and the hydrocarbon chain 12. The alternative functional groups 14 may comprise any one or a combination of hydroxide, phosphonate, phosphinate, thiolate, and thiocarboxylate. In some embodiments, the hydrocarbon chain 12 can be aliphatic. In particular, the hydrocarbon chain 12 can be chosen from any suitable alkyl organic group as defined by the formula CxHy, where x and y are integers and x ranges from 2 to 40. In some embodiments, the hydrocarbon chain 12 can have from 6 to 32 carbons, as well as from 6 to 24 carbons. In some embodiments, the hydrocarbon chain 12 can be straight. For example, the hydrophobic particle 1 can be created by the reaction of octanoic acid (CH3(CH2)oCO2H) with the metal oxide core 10. In some embodiments, the hydrocarbon chain 12 may be branched. For example, the hydrophobic particle 1 can be created by the reaction of either isostearic acid (CH3CfDioCOOH) or 2-hexyldecanoic acid (CH3CfClO2CChH) with the metal oxide core 10. The creation of hydrocarbon chains 12 as described herein can provide the advantage that the resulting hydrophobic particles 1 are fluorine-free. This means that the hydrophobic particles 1 of the invention have environmental benefits because they are less toxic compared to prior art materials. With reference now to Figure 2, a polymeric film is shown, generally denoted by 2. The polymeric film 2 comprises a substrate 3 having the hydrophobic particles 1 at least partially embedded therein. In some embodiments, the polymer film 2 is prepared by depositing, for example, by spraying, hydrophobic particles 1 onto a heated substrate 3. The hydrophobic particles 1 may be dissolved or suspended in a solvent. The exposed surface of the substrate 3 may be heated until softened, followed by the deposition of the solution or suspension onto the softened surface. After allowing the solvent to evaporate and the substrate 3 to cool, the hydrophobic particles 1 become at least partially embedded in the substrate 3. The result is a polymer film 2 that has a stable, textured, and hydrophobic surface. In some embodiments, the substrate 3 may be heated by radiation (for example, using infrared lamps) or by conduction (for example, by placing the substrate 3 on a heated plate or exposing it to hot air).It should be understood that any method that provides sufficient heating to soften substrate 3 without compromising its integrity may be used. The choice of solvent is limited only by the need for the solvent to evaporate from the substrate surface 3. Suitable solvents include, but are not limited to, isopropanol, toluene, and ethanol. With reference now to Figure 3, a polymeric film, generally denoted as 20, is shown. The polymeric film 20 comprises a substrate 30. Hydrophobic particles 1 are attached to the substrate 30 by means of an adhesive 40. In some embodiments, adhesive 40 may be an epoxy resin. Adhesive 40 may be applied to substrate 30, followed by the deposition of the solution or suspension containing the hydrophobic particles 1, or vice versa. The adhesive 40 is allowed to cure, at which point the hydrophobic particles 1 bond to the substrate 30 by virtue of being at least partially embedded in the adhesive 40. In some forms, the hydrophobic particles 1 and the adhesive 40 can Πίβί ίη / ίΖΠΖ / Ε / ΥΙΛΙ mix and the resulting mixture can be deposited, for example, sprayed onto the substrate 30. Spraying can be carried out by dissolving or suspending the mixture in a solvent and using a propellant or compressor, as is well known in the industry. Materials The substrate may comprise a thermoplastic film, for example, a polyethylene copolymer. The substrate used for all subsequent experiments was a five-layer coextrusion of EVA / EVA / PVDC / EVA / EVA with a thickness of 75 microns. Aluminum oxide (Al2O3) particles with an average diameter of 13 nm were acquired from Sigma-Aldrich. Iron oxide (Fe3O4) particles with an average diameter of 15 to 20 nm were acquired from Sigma-Aldrich. Isostearic acid was purchased from Nissan Chemical Industries and used without further purification. VWR Chemicals supplied toluene and isopropanol. SP106 multipurpose epoxy resin system, 1 kg of MB Fiberglass slow hardener was purchased. The Spraycraft universal airbrush propeller was used for spray coating and was purchased from Axminster Tools and Machinery. Water contact angle (WCA) measurements Water absorption capacity (WAC) measurements were used to study the wettability of polymer films. WAC measurements were obtained by depositing 4 pL H₂O drops onto the polymer films. The WAC values ​​reported here are the average of three measurements, recorded at different positions on the surfaces. Standard deviations are used to represent the uncertainties associated with these values. Comparative Example 1 The WCA of the uncoated substrate (i.e., the clean five-layer coextruded EVA / EVA / PVDC / EVA / EVA film) was 883° ± 1.7°. Comparative Example 2 The substrate was coated with non-functionalized Al₂O₃ particles. The deposition of the non-functionalized Al₂O₃ particles onto the substrate was achieved by coating (Ί LA L ίΠ / ί7Π7 / E / YILI) by spraying 2 wt% isopropanol suspensions at room temperature. Three sprays were used to try to achieve maximum coverage of the substrate by the non-functionalized Al₂O₃ particles. Coating the substrate with non-functionalized Al₂O₃ particles at room temperature resulted in the polymer film surface becoming superhydrophilic. Consequently, it was not possible to accurately measure the water content (WCA) of the resulting polymer film. Comparative Example 3 The substrate was coated with non-functionalized Fe3O4 particles. Deposition of the non-functionalized FesCL particles onto the substrate was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to try to achieve maximum coverage of the substrate by the non-functionalized Fe3O4 particles. The WCA of the resulting polymer film was 107.2° ~ 3.4°. Example 1 Functionalized aluminum oxide (Al₂O₃) particles were synthesized as follows. Aluminum oxide (Al₂O₃) particles (d = 13 nm, 10.0 g, 98.0 mmol, 1.0 equiv.) were refluxed with isostearic acid (39.1 g, 137.3 mmol, 1.4 equiv.) in toluene (250 mL) for 24 hours. After the reaction time, the reaction mixture was collected and centrifuged at 5000 rpm for one hour. The solid was then recovered and centrifuged at 5000 rpm in isopropanol for one hour. Following this, the solid was centrifuged in ethanol at 5000 rpm for one hour three more times and then dried at 80°C for six hours. The substrate was coated with functionalized Al₂O₃ particles. The deposition of the functionalized Al₂O₃ particles onto the substrate was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to try to achieve maximum coverage of the substrate by the functionalized Al₂O₃ particles. The WCA of the resulting polymer film was 151.1° + 1.0°. (Ί LA L ίΠ / ί7Π7 / Ε / ΥΙΛΙ Example 2 Functionalized iron oxide (Fe3O4) particles were synthesized as follows. Iron oxide (Fe3O4) particles (d = 15–20 nm, 5.0 g, 21.6 mmol, 1.0 equiv.) were refluxed in toluene (100 mL) with isostearic acid (18.4 g, 64.7 mmol, 3.0 equiv.) for approximately 24 hours under mechanical stirring. After the reaction time, the mixture was centrifuged at 5000 rpm for one hour. The solid was then recovered and dried at 80°C for six hours. The substrate was coated with the functionalized FesCU particles. The deposition of the functionalized Fe3U4 particles onto the substrate was achieved by spray coating with 2 wt% isopropanol suspensions at room temperature. Three sprays were used to attempt to achieve maximum substrate coverage by the functionalized FesCU particles. The WCA of the resulting polymer film was 151.9° + 2.1°. Example 3 The substrate was heated and coated with the functionalized Al₂O₃ particles described in Example 1. The functionalized Al₂O₃ particles were spray-coated onto the substrate after it had softened as a result of heating. The substrate was heated as follows. First, the substrate was physically bonded at its edges to the surface of a glass Petri dish. The purpose of this was to secure the substrate and limit the degree to which it changed shape during the heating process. Heat was then applied to the Petri dish until physical deformation of the substrate was observed. Once physical deformation of the substrate was observed, the functionalized Al₂O₃ particles were deposited onto the substrate by spray coating. The functionalized Al₂O₃ particles were spray-coated from a 2.0 wt% suspension.Five spray coatings were used to achieve maximum substrate coverage by the Al₂O₃ functionalized particles. After each spray coating, the substrate was continuously heated to accelerate isopropanol removal. An additional spray coating was performed on the substrate when no liquid was observed on its surface. The substrate temperature was not measured before the spray coating. However, it was observed that the substrate would begin to deform plastically when heated to between 80 and 90°C. The WCA of the resulting polymer film was 142.0° ± 3.9°. Although this value is slightly lower than when the functionalized Al₂O₃ particles were deposited onto the substrate at room temperature (Example 1), it is noteworthy that water droplets would readily roll off the polymer film. Consequently, this suggests that heating the substrate during the application of the hydrophobic particles does not significantly impair the desired hydrophobic nature of the resulting polymer film. In order to determine how well the functionalized hydrophobic AI2O3 particles bonded to the substrate, the polymer film was sonicated in isopropanol for approximately ten minutes and the WCA was re-analyzed. After sonication, the WCA of the polymer film was 137.7° ± 7.9°. It is evident that the WCA did not change significantly after sonication, indicating strong thermal embedding of the functionalized hydrophobic Al2O3 particles within the substrate. Example 4 The substrate was heated and coated with the FesOr functionalized particles described in Example 2 according to the method described in Example 3. The WCA of the resulting polymer film was 151.9° ± 2.7°. To determine how well the functionalized hydrophobic Fe3O4 particles bonded to the substrate, the polymer film was subjected to isopropanol sonication for approximately ten minutes and the WCA was re-analyzed. After sonication, the water content (WCA) of the polymer film was 90.3° ± 0.5°. This represents a WCA close to that of the uncoated substrate. This indicates that most of the functionalized Fe3O4 hydrophobic particles were removed by sonication. While not tied to any particular theory, it is understood that functionalized FesCU hydrophobic particles form relatively large agglomerates on the substrate that are less strongly embedded than, say, functionalized Al2O3 hydrophobic particles. Consequently, functionalized Fe3O4 hydrophobic particles are removed more easily than functionalized Al2O3 hydrophobic particles. However, this does not mean that modalities incorporating functionalized FegOg hydrophobic particles are not commercially viable.The sonication test simply replicates a highly destructive environment to determine the degree of bonding between the hydrophobic particles and the substrate. Hydrophobic films are unlikely to experience such a destructive environment under normal use. Examples 5 to 9 In examples 5 to 9, the bonding of functionalized Al2O3 particles and the substrate using an epoxy resin was studied. In Example 5, 0.08 g of epoxy resin was added to 0.66 g of the functionalized Al₂O₃ particles described in Example 1 and suspended in 40 mL of isopropanol, so that the mass ratio of functionalized Al₂O₃ particles to epoxy resin was approximately 8.6:1.0. The mixture was deposited onto the substrate by spray coating at room temperature, as previously described. Spray coating of this suspension onto the substrate resulted in a polymer film with a WCA of 144.3° ± 4.3°. In examples 6 to 9, the ratio of functionalized Al2O3 particles and epoxy resin was adjusted. The proportions of functionalized Al2O3 particles and epoxy resin and the corresponding WCAs for the polymer films of Examples 5 to 9 are summarized in Table 1. Table 1 also shows the WCAs for the polymer films after they have been sonicated in isopropanol for approximately ten minutes. Table 1. Water contact angle (°) before and after sonication as a function of the proportion of functionalized Al2O3 particles and epoxy resin. Πίβί ίΠ / ίΖΠΖ / Ε / ΥΙΛΙ Example Functionalized Al2O3 Particles: Epoxy Resin Water Contact Angle (°) Water Contact Angle (°) after Sonication 5 8.6:1.0 144.3 ±4.3° 132.2 ±7.4° 6 2.0:1.0 149.9 ±1.1° 137.1 ±1.0° 7 1.5:1.0 150.7 ±1.2° 135.9 +7.5° 8 1.0:1.0 149.0 ±7.8° 141.1 ±1.6° 9 1.0:1.4 138.1 ±10.4° 142.0 ±0.6° Although all examples 5 to 9 achieved high WCAs, it is clear that polymer films with the best hydrophobicity were created when the ratio of functionalized Al2O3 particles and epoxy resin was approximately 1.0:1.0 (i.e., 149.0 + 7.8°) to approximately 2.0:1.0 (i.e., 149.9 + 1.1°), e.g., 1.5:1.0 (i.e., 150.7 + 1.2°). Furthermore, as in Example 3, it is evident that the WCAs of Examples 5 to 9 did not change significantly after sonication. This appears to indicate strong embedding of the functionalized hydrophobic Al₂O₃ particles within the epoxy resin. Examples 10 to 14 The bonding of functionalized Fe3O4 particles to the substrate using an epoxy resin was studied in Examples 10 to 14. The substrate was coated with a mixture of the epoxy resin and the functionalized FeaCL particles described in Example 2. In these examples, epoxy resin was added to the suspension of functionalized FesOr particles. The deposition of the mixture onto the substrate was carried out by spray coating at room temperature, as previously described. The ratios of functionalized Fe3O4 particles and epoxy resin and the corresponding WCAs for the polymer films of Examples 10 to 14 are summarized in Table 2. Table 2 also shows the WCAs for the polymer films after they have been subjected to sonication in isopropanol for approximately ten minutes. Table 2. Water contact angle (°) before and after sonication as a function of the proportion of functionalized FesCh particles and epoxy resin. Πίβί ίη / ίΖΠΖ / Ε / ΥΙΛΙ Example FC3O4 particles functionalized with isostearate: epoxy resin Water contact angle (°) Water contact angle (°) after sonication 10 11.8:1.0 124.3 ±10.6° 92.7 ±8.3° 11 6.5:1.0 102.1 ±4.3° 85.3 ±14.5° 12 2.0:1.0 89.9 ±4.7° 84.4 +5.9° 13 1.0:1.0 75.4+2.2° 81.4 +3.0° 14 1.0:1.5 80.7+10.8° 81.8 ±2.5° When compared to Examples 5 through 9, the WCAs of Examples 10 through 14 are not as high. However, there is a clear trend for the WCA to increase with increasing ratios of functionalized FesCU particles to epoxy resin. Therefore, it is plausible that the WCA could exceed 140° in configurations where the ratio of functionalized Fe3U4 particles to epoxy resin exceeds 15:1. In summary, the present invention relates to polymer films that have enhanced self-cleaning properties by bonding hydrophobic particles comprising a metal oxide core having hydrocarbon chains with 2 to 40 carbon atoms to a substrate, such as a thermoplastic film. The surface energy of these polymer films has been found to be very low and non-toxic. Consequently, the polymer films can be used in a wide range of applications, including food and liquid packaging. It is also anticipated that the polymer films can be laminated onto a sheet of glass, plastic, or fabric to enhance their hydrophobicity. It can be useful to adjust the water content (WCA) in different regions of the polymer film. In some formulations, polymer films may have a first region with an associated WCA measurement and a second region with an associated WCA measurement, so the WCA measurements in the first and second regions are different. One way to achieve this is by varying the concentration of hydrophobic particles deposited in the first and second regions. For example, a 4 wt% solution of hydrophobic Al₂O₃ particles can be deposited in the first region, and a 2 wt% solution of hydrophobic Al₂O₃ particles can be deposited in the second region. Consequently, the first region will have a higher WCA than the second region due to the higher concentration of hydrophobic Al₂O₃ particles. As used herein, the term hydrocarbon chain is intended to have its usual meaning, that is, a molecule consisting entirely of hydrogen and carbon. Representative characteristics are set out in the following clauses, which are independent or may be combined, in any combination, with one or more characteristics described in the text and / or drawings of the specification. When used in this specification and in the claims, the terms The terms Π LA L ίΠ / ί7Π7 / E / YΙΛΙ and ίΠ / ί7Π7 / Ε / ΥΙΛΙ and variations thereof mean that the specified features, steps, or whole numbers are included. The terms should not be interpreted as excluding the presence of other features, steps, or components. The features disclosed in the preceding description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means of carrying out the disclosed function, or a method or process for achieving the disclosed result, as appropriate, may, separately, or in any combination of such features, be used to carry out the invention in various forms thereof. Although certain exemplary embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims should be interpreted literally, intentionally, and / or to encompass equivalents.

Claims

1. A polymeric film characterized in that it comprises a substrate at least partially coated with hydrophobic particles, the hydrophobic particles comprising: an aluminum oxide core; and a hydrocarbon chain having from 2 to 40 carbon atoms, wherein the hydrocarbon chain is chemically bonded to the aluminum oxide core, the hydrophobic particles and the substrate being fixed together by means of an adhesive, and wherein the mass ratio of the hydrophobic particles to the adhesive is from approximately 1.0:1.0 to approximately 2.0:1.

0.

2. The polymeric film according to claim 1, further characterized in that the average diameter of the hydrophobic particles is less than or equal to approximately 200 nm.

3. The polymeric film according to claim 2, further characterized in that the average diameter of the hydrophobic particles is less than or equal to approximately 50 nm.

4. The polymeric film according to claim 3, further characterized in that the average diameter of the hydrophobic particles is from approximately 8 nm to approximately 20 nm.

5. The polymeric film according to any of the preceding claims, further characterized in that the hydrocarbon chain is aliphatic.

6. The polymeric film according to any of the preceding claims, further characterized in that the hydrocarbon chain is linear or branched.

7. The polymeric film according to any of the preceding claims, further characterized in that the hydrocarbon chain has from 6 to 32 carbons.

8. The polymeric film according to claim 7, further characterized in that the hydrocarbon chain has from 6 to 24 carbons.

9. The polymer film according to any of the preceding claims, further characterized in that the hydrocarbon chain is covalently linked to the aluminum oxide core via a functional group. nLRL Ln / Lznz / E / YIAI 10. The polymeric film according to claim 9, further characterized in that the functional group comprises any one or a combination of hydroxide, carboxylate, phosphonate, phosphinate, thiolate and thiocarboxylate.

11. The polymeric film according to any of the preceding claims, further characterized in that the hydrophobic particles are fluorine-free.

12. The polymeric film according to any of the preceding claims, further characterized in that the substrate comprises a thermoplastic film.

13. The polymeric film according to claim 12, further characterized in that the thermoplastic film comprises a polyolefin, vinyl polymer or polyacetal film.

14. The polymeric film according to any of the preceding claims, further characterized in that the substrate comprises a coextruded bilayer or multilayer film.

15. Use of the polymeric film in accordance with any of the preceding claims as a food packaging film.

16. A container for food or liquids characterized in that it comprises a surface, wherein a polymeric film in accordance with any of claims 1 to 14 is laminated to the surface.

17. The container for food or liquids according to claim 16, further characterized in that the surface comprises metal, alloy, plastic, cardboard and / or glass.

18. A sheet of glass characterized in that it has the polymeric film according to any of claims 1 to 14 laminated thereto.

19. A plastic sheet characterized in that it has the polymeric film according to any of claims 1 to 14 laminated thereto.

20. A sheet of fabric characterized in that it has a polymeric film according to any of claims 1 to 14 laminated thereto.

21. An article of clothing or footwear characterized in that it has the polymeric film conforming to any of claims 1 to 14 laminated thereto.