Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
  • A01N59/20—Copper
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/34—Shaped forms, e.g. sheets, not provided for in any other sub-group of this main group
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01P—BIOCIDAL, PEST REPELLANT, PEST ATTRACTANT OR PLANT GROWTH REGULATORY ACTIVITY OF CHEMICAL COMPOUNDS OR PREPARATIONS
  • A01P1/00—Disinfectants; Antimicrobial compounds or mixtures thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/14—Paints containing biocides, e.g. fungicides, insecticides or pesticides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/08—Oxides
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
  • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3464—Sputtering using more than one target

Definitions

• Object of the present invention is a transparent composite material having antimicrobial properties in particular antibacterial, antiviral, anti-fungal and antiprotozoal activities, a method for its preparation and use in articles, surfaces and coatings for outdoor, indoor environments, human and animal devices.
• the commonly used surfaces represent a passive element where microorganisms that may lead to the spread of infections proliferate. Therefore, the use of antibacterial/antiviral coatings may enable a pattern change, in which surfaces of various materials (metals, plastics, ceramics, etc.) may become an active first element in reducing the risk of infection.
• an antibacterial composition that comprises an antibacterial agent constituted by silver nanoparticles (Ag NP) that show a nearly spherical structure and are bound to the surface of a dispersing agent that prevents their agglomeration, is known.
• the silver nanoparticles Ag NP do not form agglomerates, that is, these are dispersed and homogeneously distributed on the surface of the dispersing agent.
• the aforementioned composite materials of the known art despite aiming to provide an antibacterial action and/or antimicrobial composition as well as an antibacterial and/or antimicrobial surface and/or material, still fail to disclose an adequate size and concentration of the active material nanoparticles in a composite material, which is crucial, in combination with the size and arrangement of said active material in the composite material, in light of an exchange between antibacterial activity - transparency - adequate mechanical properties.
• composite materials with antimicrobial, preferably antibacterial and/or antiviral properties that are capable of showing one or more, preferably two or more, of the following properties: i) keeping high mechanical and antibacterial/antimicrobial properties for a long period of time; ii) ensuring that the aesthetic appearance of the component/surface to which the composite material is to be applied is not altered by the composite material itself; iii) minimizing the amount of heavy metals or non-biocompatible substances of active materials used while retaining excellent antibacterial, antiviral, anti-fungal and anti -protozoal activity, preferably antibacterial and/or antiviral; iv) enabling the composite material itself to be electrically conductive, if required by the specific application.
• an object of the present invention is to provide a composite and antimicrobial material that overcomes the drawbacks of the prior art.
• Another object of the invention is to provide a transparent composite and antimicrobial material.
• Another object of the invention is to provide a process for the preparation of said composite material.
• a further object of the invention is to provide the use of said composite material for making articles, surfaces, coatings and devices with antimicrobial properties and a method for making such articles, surfaces, coatings and devices.
• Object of the present invention is to provide a preferably transparent antimicrobial composite material comprising a preferably transparent matrix, an antimicrobial active material, characterized in that said active material is present at least inside said composite material in the form of a plurality of clusters arranged in at least one portion of layer inside said composite material, wherein each cluster is separated from the adjacent cluster by a specific distance.
• said matrix material allows the contact of the active material inside the composite material with the external environment. It should be emphasized that by "active material present inside the composite material” is meant that the active material is completely included in the matrix. An embodiment in which the active material is only inside the composite material is within the scope of protection of the present invention.
• said plurality of clusters has at least one dimension of less than 10 nm, preferably less than 5 nm, wherein each cluster is separated from the adjacent cluster by a distance ranging from 3 nm to 1 pm, preferably less than 100 nm, even more preferably less than 50 nm.
• the clusters of active material of the invention have a size that enables the quantum confinement effect in at least one direction.
• the active material is present in the composite material at the concentration (C) of 0.01% ⁇ C ⁇ 10%.
• the combination of antimicrobial activity and hardness and, depending on need, transparency ensures that this composite material is potentially applied both on transparent surfaces per se, such as electronic device screens, eye wear, goggles, masks and face masks, breathing and filtration systems with integral face protection, gowns, panes and plexiglass for separation or protection, transparent components for biomedical field, etc., but also on all those metal and non-metal non-transparent objects for which the antimicrobial function is required and whose aesthetics are not to be altered, such as handles, buttons, banknotes and surfaces in general subject to being touched by more than one person. Further applications may be found in all of those fields in which the combination of antimicrobial activity and hardness is required, such as surfaces of biomedical instruments and equipment: scalpels, operating room tables and various tools, prosthetics, etc.
• FIGS 1 to 4 show schematic representations of the composite material of the invention according to different embodiments
• Figure 5 shows the band gap calculated by the Tauc plot method of AgO nanoparticles deposited on glass
• Figure 6 shows an atomic-force microscope image of a composite material containing pure AZO (on the left) and a composite material containing AgO x :AZO (on the right);
• Figure 7 shows the antibacterial activity of different M and M:AM coating formulations on the pathogen E. coll ATTC 8739 (on the left) and the pathogen S. aureus 6538P (on the right) according to the ISO method 22196, as a function of time by calculation of the percent reduction of the colony forming unit (CFU/mL);
• Figure 8 shows a summary of the biocidal properties of a composite material comprising a) AZO and b) AgO-AZO against A. coll, S. aureus and SARS-CoV-19, in which it may be seen that the AgO clusters significantly increase the antibacterial activity and confer antiviral activity;
• Figure 9 shows a sample of transparent composite material of the invention
• Figures 10 and 11 show two SEM images of the composite material of the invention.
• object of the present invention is an antimicrobial composite material comprising a matrix material and an antimicrobial active material, characterized in that said active material is present at least inside the composite material in the form of a plurality of clusters having at least one dimension of less than 10 nm, preferably less than 5 nm, which are arranged in at least one portion of layer inside said composite material, each cluster being separated from the adjacent cluster by a distance (d) ranging from 3 nm to 1 pm, preferably less than 100 nm, even more preferably less than 50 nm, said matrix material allowing contact of the active material present inside the composite material with the external environment.
• d distance
• said active material is present only inside said composite material.
• said active material is also present on the surface of said composite material.
• the matrix material allows the contact of the active material inside the composite material with the external environment by one or more of the following options: a. the matrix material is porous; and/or b. the matrix material may be deteriorated, for example, it is water- soluble.
• Option a. allows the active material to contact the external environment and thus exert its antimicrobial, preferably antibacterial and/or antiviral action through the pores of the said matrix material, as for example schematically shown in Figure 4 and Figures 10 and 11, which show two SEM images of a composite material representative of the invention from which it may be seen that said composite material has an open structure to the outside.
• option b. allows contact between the active material and the external environment through the deterioration, as for example the dissolution of the matrix material itself.
• the matrix material which is at least partially water-soluble dissolves, thus allowing contact between the active material and said droplets of moisture.
• option a. is to be preferred when is intended to maximize the antimicrobial activity
• option b. is to be preferred when is intended to maximize the mechanical stability of the composite material.
• the matrix is porous according to option a. Even more preferably, the matrix comprises a plurality of communicating mesopores and/or nanopores.
• the matrix is entirely occluded but configured to provide at least partial dissolution over time, that is, it provides at least partial deterioration of its structure over time, for example by dissolution in water.
• the active material that is included in the matrix results or ends up being partially exposed to the external environment and, when the composite of the invention is in an operational condition, may provide an antimicrobial action toward any pathogenic agents/organisms present in the external environment with which the composite of the invention is in contact.
• the matrix may also provide at least minimal antimicrobial activity.
• antimicrobial denotes antibacterial, antiviral, anti-fungal and anti-protozoal activity, preferably antibacterial and/or antiviral.
• the term “cluster” denotes at least a single particle of active material, preferably a pool including two or more particles of active material, said cluster having at least one size of less than 10 nm.
• the term "particle” denotes an atomic and/or molecular aggregate having an equivalent diameter greater than 0.5 nm, preferably between 0.5 nm and 10 nm, even more preferably between 0.5 nm and 5 nm.
• layer it will be meant a region constituting the composite material having its own thickness and extending along a prevailing direction. In particular, one layer occupies the entire length of such composite material.
• a portion of layer is a region of composite material having its own thickness that extends along a prevailing direction but not capable of extending along the entire length of the composite material, but only along part of its length.
• said cluster has a substantially spherical structure and an equivalent diameter of less than 10 nm, preferably less than 5 nm, said equivalent diameter being at least greater than 0.5 nm.
• said cluster has a "disk" structure, that is, it has a two-dimensional structure with a first dimension of less than 10 nm, preferably in the range of 0.5 nm to 5 nm, and a second dimension of less than 100 nm, preferably in the range of 10 nm to 100 nm.
• the clusters of active material of the invention have a size that is configured to provide the quantum confinement effect in at least one direction. Particularly, the quantum confinement effect takes place along the smallest dimension of the cluster.
• transparent denotes the physical property of the composite material to enable the visible light to pass through without appreciable dispersion or absorption.
• transparent herein is defined as any material with an average total transmittance T greater than 50% and a diffuse transmittance of less than 10% over the visible range of the light spectrum, i.e., 380- 700 nm.
• said composite material and said matrix material are transparent.
• said composite material and said matrix material may be less transparent than as stated above or not transparent at all.
• said composite material is transparent when a transparent matrix material is used but, as it is evident to the skilled in the art, the passage of light is a function of the thickness of said material and the related absorption coefficient a.
• the matrix material and the active material of the composite material may be selected such that the absorption coefficient a of the composite material, as a function of the thickness to be made and the number and type of clusters present per unit volume, should be such that the absorptivity A is always less than 50%.
• the absorption coefficient a is an intrinsic characteristic of a material and expresses the ability of that material to absorb the energy associated with the electromagnetic radiation propagating inside a given body.
• the absorptivity A is, on the other hand, the intensity of the electromagnetic radiation that is absorbed by a body. In spectroscopy it is also defined as the opposite of the logarithm of the transmittance.
• absorptivity A of a material may be expressed as follows:
• A l- e' a * x
• a is precisely the absorption coefficient
• x is the thickness of the body subjected to electromagnetic radiation.
• the composite material may be selected with an absorption coefficient a having a value between 100 cm' 1 and 700000 cm' 1 .
• the maximum thickness that may be achieved to obtain an absorptivity A that is, at most, 50% is 10 nm. With values close to 100 cm' 1 , the thickness for which there is still less than 50% absorptivity, assuming a value of about 70 pm, increases significantly.
• the maximum absorption coefficient of the material may be 70,000 cm' 1
• the maximum absorption coefficient of the material selected to make a composite material may be at most 7000 cm' 1 .
• an absorptivity A that is at most 50% will be ensured.
• the minimum value of the absorption coefficient may be maintained at 100 cm' 1 .
• absorptivity A may be directly correlated with transmittance T and reflectance R, therefore if the absorptivity is less than 50%, the transmittance will be greater than 50%, thus falling within the above definition of transparency.
• the active material may have one or more crystalline domains, alternatively it may be entirely amorphous, still alternatively it may include a mixture of amorphous and crystalline fraction.
• the active material is in the matrix in amorphous phase.
• the composite material must be transparent and must have mechanical properties which ensure its use in real-world environments, such as high adhesion, resistance to rubbing and hardness comparable to or greater than that of the coated surface.
• the matrix comprises a preferably transparent, suitable material preferably selected from SiCh, AI2O3, TiCh, ZnO, SnO, CeCh, ZrCh, I112O3, Fe x Oy, WO3, SiN, Y2O3, MgO, rare earth oxides, Li2O, ZrCh, AIN, SiC and mixtures thereof; transparent conducting oxides (TCOs) preferably selected from Al:ZnO (otherwise defined “AZO”, "Aluminum doped Zinc Oxide”), F:SnO, Ta:TiO2 e Sn:In2O3. It has to be understood that any mixture of non-conductive oxides and TCO is within the scope of the present patent.
• TCOs transparent conducting oxides
• the matrix comprises or alternatively consists of AZO.
• said active material is a compound of a cation and an anion and has the electronic characteristics of a semiconductor (and not a metal), capable of producing bioactive ions (Ag, Cu, Zn, others) and/or oxidizing radical species such as ROS, oxysulfides and oxynitrides in contact with water, said compound being in particle form as defined.
• said active material is selected from oxides, chalcogenides, sulfates, sulfites, chlorides, chlorates, bromides, bromates, iodides and iodates of metals and mixtures thereof, said metals being preferably selected from Ag, Cu, Zn, Sn, Fe, Ni, Al and mixtures thereof.
• said active material may be described by the average stoichiometry AgOx/2 with 0 ⁇ x ⁇ 3 and CuOx/2 with 0 ⁇ x ⁇ 2.
• said composite material comprises only one layer of active material.
• said composite material comprises two or more layers of active material or portions of two or more layers.
• said two or more layers, or portions of two or more layers are each separated by a layer of matrix material having thickness (s), said thickness being preferably between 3 nm and 1 pm, more preferably between 5 nm and 100 nm, even more preferably between 10 and 50 nm.
• distance d may refer to two distances: dl and d2.
• the two or more layers are arranged along different planes and/or axes inside the composite material.
• distance d refers to a first distance dl between two adjacent clusters along the same axis and/or plane in the composite material.
• distance d refers to a second distance d2 between adjacent clusters arranged in layers along different axes and/or planes in the composite material.
• said distance (d) comprises a first distance (dl) measured between at least two clusters adjacent to each other in the same layer inside the material of the composite material and a second distance (d2) measured between at least two adjacent clusters placed in different layers inside the composite material.
• said first distance (dl) and said second distance (d2) are equal or different.
• said distance (d) is selected so that the total concentration (C) of the active material in the composite material is greater than 0.01% by weight with respect to the total weight of the composite material, preferably so that said concentration is 0.01% ⁇ C ⁇ 50%, and even more preferably such concentration (C) is 0.1% ⁇ C ⁇ 20%.
• said concentration (C) of the active material is less than 10%.
• the active material is present inside the matrix in the form of a plurality of clusters, each cluster having at least one size of less than 10 nm.
• said at least one dimension is less than 5 nm.
• said dimension is designed to provide the quantum confinement effect for the plurality of clusters of active material in at least one direction, depending on the type of active material employed.
• Such at least one optimized cluster size of active material does not affect the transparency of the matrix and composite material.
• Each cluster of active material is separated from the adjacent cluster by a distance d.
• Such distance d separates two adjacent clusters and is between 3 nm and 1 pm, preferably between 5 nm and 100 nm, even more preferably between 10 nm and 50 nm.
• said distance d provides a total concentration C of the active material in the composite material greater than 0.01%, such concentration being preferably in the range of 0.01% ⁇ C ⁇ 50%.
• this concentration C may vary in the range of 0.1% ⁇ C ⁇ 20%.
• such concentration C of the active material may be set to be less than 10%.
• the active material provides strong antimicrobial activity, for example, antibacterial/antiviral activity while providing transparency thanks to the small cluster size that enables the quantum confinement effect to be achieved.
• the space that lies between two adjacent clusters, the length of which is d, is occupied by the matrix. Consequently, each cluster is surrounded, in at least one direction, by the matrix for a distance d.
• each cluster is surrounded, in at least one direction, by the matrix for a distance d.
• it is possible to identify at least one layer of active material in the composite material as will be better shown in the attached figures.
• Said figures represent the embodiment in which the clusters are substantially spherical in shape, and the size refers to the equivalent diameter.
• Figure 1 shows a schematic representation of an embodiment of the composite material proposed herein.
• Figure 1 shows a composite material 1 comprising a matrix 2 and active material in the form of a plurality of clusters 3, wherein each cluster 3 has an equivalent diameter of less than 10 nm and is separated from an adjacent cluster by a distance d.
• the composite material 1 provides a linear multilayer architecture, as the clusters 3 are arranged along two different axes and/or planes in the composite material in a linear fashion, as further depicted in Figure 2.
• Such distance d may be the same both in the case of two adjacent clusters along the same axis and/or plane in the composite material and between two adjacent clusters arranged along different axes and/or planes in the composite material.
• said first distance dl is equal to said second distance d2.
• the clusters 3 may be arranged along the composite material in a more random way, as best depicted in Figure 3. As previously described, according to the axis and/or plane along which the clusters of active materials are present in the composite material, it is possible to identify at least one active material layer in the composite material, as shown in Figure 2.
• such layers may be separated by at least one distance s.
• the active material is present in said at least one layer in the form of a plurality of clusters, in which each cluster is separated from the adjacent cluster by a space of length d and such space is occupied by the matrix.
• active material layer is meant a plurality of clusters arranged along the same axis and/or plane in the composite material, wherein each cluster is separated from the adjacent one by matrix material.
• Two or more layers of active materials may be separated by a distance s.
• Such distance s may be equal to, less than, or greater than the distance d between two adjacent clusters of active material.
• Such space separating two or more layers by a distance s will correspond to a layer of matrix material, as best depicted in Figure 2 and Figure 3.
• Such at least one layer of (homogeneous) matrix material correspondingly shows a thickness equal to the distance between said two layers of active material; such at least one layer of matrix material in fact has a thickness s.
• Figure 2 depicts a composite material 1 comprising a matrix 2 and an active material in the form of a plurality of clusters 3, in which each cluster 3 has a diameter of less than 10 nm and is separated from an adjacent cluster by a distance d.
• Figure 2 is shown a schematic representation of an embodiment of the composite material according to the invention with a view of the layers 30, 31 of active material.
• the composite material 1 provides a linear multilayer architecture as the clusters 3 are arranged in two layers 30, 31 of active materials along two different axes and/or planes in the composite material in a linear fashion.
• Said distance d may be the same both in the case of two adjacent clusters along the same axis and/or plane in the composite material and between two adjacent clusters arranged along different axes and/or planes in the composite material.
• the first distance dl is equal to the second distance d2.
• the layers 30, 31 of active material are separated from each other by a layer 20 of matrix material.
• Such layer 20 of matrix has a thickness s.
• Such thickness s may be set so as to provide a total concentration C of the active material in the composite material greater than 0.01%, such concentration being preferably of 0.01% ⁇ C ⁇ 50%.
• this concentration C is 0.1% ⁇ C ⁇ 20%. According to a still preferred embodiment, such concentration C of the active material may be set to be less than 10%.
• said thickness s may preferably be in the range of 3 nm to 1 pm, more preferably 5 nm to 100 nm, even more preferably 10 nm to 50 nm.
• the compound 1 in Figure 2 provides a distance d between the clusters 3 that is equal in the case of adjacent clusters belonging to the same layer 30 or 31 of active material, as well as in the case of adjacent clusters belonging to different layers 30, 31.
• Figure 3 depicts another embodiment of the composite material 1, in which the clusters 3 are arranged in two layers 30, 31 of active materials but not in a linear fashion. Each cluster 3 in the two layers 30, 31 of active material is separated from the adjacent cluster along the same layer by a first distance dl.
• each cluster 3 of the layer 30 is separated from the adjacent cluster 3 of the layer 31 by a second distance d2, such distance d2 being variable but greater than dl.
• the two layers 30, 31 of active material are separated from each other by a layer 20 of matrix.
• Such a layer 20 of matrix has a thickness s, s being greater than the distance dl but less than d2.
• Such thickness s may be set so to provide a total concentration C of the active material in the composite material greater than 0.01%, such concentration being preferably of 0.01% ⁇ C ⁇ 50%.
• this concentration C is 0.1% ⁇ C ⁇ 20%.
• concentration C of the active material may be set to be less than 10%.
• said thickness s may preferably be in the range of 3 nm to 1 pm, more preferably 5 nm to 100 nm, even more preferably 10 nm to 50 nm.
• Figure 3 shows a schematic representation of an embodiment of a composite material with a view related to the layers 30, 31 of active material.
• the composite material 1 may comprise a matrix 2 and a plurality of clusters 3 of active material, in which the clusters 3 of active material are arranged, inside the composite material 1, according to different portions 10, 11 of layer.
• Figure 4 shows a schematic representation of an embodiment of the composite material according to the invention, comprising a plurality of pores connected through the body of the composite material.
• the portions 10 and 11 of layer relate to multilayer architectures in which the clusters 3 of active material are arranged in a plurality of layers 30, 31 of active material along different axes and/or planes in the composite material 1, in which each layer 30 is separated from the adjacent layer 31 by a layer 20 of matrix.
• the portions 10, 11 of layer are substantially surrounded by the matrix 2 and each occupies only part of the length of the composite material.
• each cluster 3 is separated from the adjacent clusters and each cluster 3 is surrounded, in at least one direction, by the matrix 2.
• the portions 10, 11 of layer extend along the composite material 1 from the basal face of the composite material 1 in contact with a substrate z toward the opposite face of the composite material directly exposed to the ambient air.
• the composite material 1 may comprise a plurality of pores.
• Each pore 4 is preferably in communication with an adjacent pore 4, thus constituting at least one channel that, starting from the top face of the composite material 1 exposed to the ambient air, branches inside the composite material 1.
• the channel which is constituted by a plurality of connected holes 4 may branch into the space between the portions 10, 11 of layer, and the channel may branch at least partially through the portions 10, 11 of layer as shown in Figure 4.
• the composite material of the invention may have varying thickness. According to an embodiment, such thickness may range from 100 nm to 100 pm.
• the lower limit mentioned above is related to the durability of the composite material over time; in case the composite material proposed herein is to be used as a disposable product, such lower limit may also be less than 100 nm, since for disposables even thinner thicknesses may provide the desired properties.
• the upper limit mentioned above is closely related to a trade-off in terms of feasibility by a sputtering production process (actual production technique employed) and a final cost of the resulting product.
• the composite material as described has a thickness of about 200 nm.
• the composite material of the invention may comprise a single layer of active material inside the matrix or two or more layers of active material, or two or more portions of layer: such layers or portions of layer of active material are separated from each other by a layer of matrix material.
• said composite material may also have clusters in addition to the internal clusters on at least one matrix surface directly exposed to the external environment.
• the composite material of the invention may comprise clusters of active material only inside it, or clusters of active material inside it and also on at least one surface of the matrix.
• the composite material proposed herein may also include further nanoparticles and/or layers of other materials, with the aim of providing additional properties.
• the composite material proposed herein when selecting the matrix from TCO, may also include clusters and/or homogeneous layers of iron oxide and/or tungsten oxide; said oxides may impart a specific color to the composite material, without altering the transparency of the composite material as defined.
• Such additional nanoparticles may also be added to the composite material with the aim of maximizing the efficiency against specific types of bacteria or viruses.
• the composite material described herein may be used alone or, alternatively, in combination with a substrate, such as for example a transparent substrate. Suitable substrates may include glass, silicone, polypropylene non-woven fabric, steel, aluminum, plastics and metals in general, and others.
• object of the invention is a method for the preparation of the composite material as described herein, preferably by a deposition process.
• Said deposition process may comprise at least one source of matrix material, one source of active material and one substrate.
• said deposition process on a substrate may be carried out through the cathodic sputtering technique.
• the deposition process according to the aforementioned examples may involve the steps of: a) setting a first distance between the source of the matrix material and the substrate; b) setting a second distance between the source of active material and the substrate; c) setting a first power density for the source of matrix material; d) setting a second power density for the source of active material; e) activating the two sources; and f) exposing the substrate to the source of matrix material and the source of active material.
• the substrate is exposed to the source of matrix material and the source of active material in such a way that said active material is present inside the composite material in the form of a plurality of clusters having a diameter of less than 10 nanometers, preferably less than 5 nanometers, which are arranged in at least one layer inside said composite material, and in which each cluster is separated from the adjacent cluster by a distance d) which is at least greater than 5 nanometers.
• said matrix material allows the contact of the active material inside the composite material with the external environment.
• said first distance between the source of matrix material and the substrate is set shorter than said second distance between the source of active material and the substrate.
• said first power density for the source of matrix material is set greater than said second power density for the source of active material.
• said first lower distance as well as said first higher power density will provide a densification effect that will be responsible for the desired mechanical and optical properties of the composite material.
• said second greater distance and said second density with lower power will provide nanoparticles having less energy to reorganize and form clusters having large size on the substrate, thus, remaining finely dispersed in the form of clusters having a diameter of less than 10 nm, preferably less than 5 nm, such nanoparticles do not interact with each other.
• the activation of the source of matrix material and the source of active material may be performed simultaneously and alternately; when the two sources are activated simultaneously, the deposition may additionally comprise at least one separator screen so that the substrate is exposed to only one source at a time.
• the exposure of the substrate to the sources may be achieved, according to a first embodiment, by moving the substrate under the two sources while keeping them in a single, fixed position. Otherwise, according to an alternative embodiment, the exposure of the substrate to the sources may take place by moving the two sources and taking the substrate fixed in one position.
• the deposition process preferably takes place in an oxidizing atmosphere; thereby, the nanoparticles of active material are completely oxidized once they reach the substrate.
• the atmosphere may comprise an inert gas mixture.
• such an atmosphere may comprise argon and oxygen.
• argon and oxygen are present in a volume ratio of 60:40.
• the deposition process proposed herein may last for a variable time interval; preferably, said deposition process may last 4 minutes. In such time frame, the deposition process proposed herein may provide an antimicrobial/antiviral composite material having a thickness of 150 nm, with optical transparency averaging more than 50% over the entire visible range (380-700 nm).
• transparent and antimicrobial composite material comprised of a transparent matrix and an antimicrobial active material
• each cluster is separated from the adjacent cluster by a distance d greater than 3 nm and less than 1 pm, preferably less than 100 nm, even more preferably less than 50 nm;
• d refers to the distance between two adjacent clusters along the same axis and/or plane in the composite material and between two adjacent clusters arranged along different axes and/or planes in the composite material;
• each layer, or portion of layer, of active material is separated from another by a matrix layer having thickness s;
• • s may be equal to, less than or greater than the distance d, and is preferably 3 nm to 1 pm, more preferably 5 nm to 100 nm, even more preferably 10 nm to 50 nm.
• object of the invention is a transparent, mechanically robust, antimicrobial coating, for example, antibacterial and/or antiviral coating, which allows overcoming the inherent limitations of the existing solutions.
• the invention has several distinctive characteristics enabling it to be used in applications ranging from the household to the portable electronics and the health care sector.
• This product allows imparting antibacterial/antiviral properties to the surfaces and objects without altering their aesthetic appearance, thanks to its high optical transparency (>50% on average in the visible range).
• the superior adhesion and mechanical properties also ensure that the efficiency of the coating is preserved if exposed to high wear conditions or environmental agents.
• the composite coatings already exist, they fail to ensure transparency, good mechanical properties and sufficient antibacterial/antiviral activity at the same time. The reason is that high transparency requires a small amount of active material, which is often not enough to preserve the antimicrobial effect.
• the proposed invention overcomes this problem by exploiting the quantum confinement effects. It is known from the literature that the nano-scale behavior of materials is markedly different from its counterpart in bulk form. This is especially true when referring to the optical properties. There are several examples of band gap adjustment, which show a shift towards blue of the absorption edge for the semiconductors whose size is reduced from 3D to 0D (in the range of 10 to 2 nm). This shift is due to the quantum confinement effect.
• the Bohr radius of the charge carriers exceeds the size of the nanoparticles, thus leading to the formation of discrete (quantized) energy levels responsible for the electronic transitions of the material.
• the active material comprises oxides, chalcogenides, chlorides, bromides and iodides of metals such as Ag, Cu, Zn, Sn, Fe, Ni, Al with at least one size of less than 10 nm, preferably less than 5 nm.
• the smaller the crystal size of a semiconductor the wider its band gap becomes, possibly shifting its absorption limit into the UV.
• the extreme case is that of an amorphous semiconductor or cluster of molecular size.
• the advantage of the composite semiconductors over their base metals is their higher activity due to a combination of ionic availability, redox reactions and the formation of reactive oxygen species or other active anionic species. Thus, it is possible to reduce the amount of metal.
• the composite material of the invention has antimicrobial, preferably antibacterial and antiviral properties.
• the antibacterial activity was evaluated by the standardized ISO 22196 method.
• minimal antibacterial activity is meant at least a 90% reduction in the maximum number of viable bacteria present on the transparent material after 24 hours.
• the Applicant has made a first generation of coatings having transmittance above 90% in the visible range and with antibacterial and antiviral activity above 90% within the 24-hour test period.
• the invention solved the problem posed by providing a transparent coating with antimicrobial activity and high mechanical strength, i.e., providing a useful technical solution to solve the disadvantages and fill the gaps in the prior art.
• QCANs quantum-confined active nanoparticles
• a multilayer architecture is the easiest to implement for the control. From the studies performed, an AgO concentration of 1% in Al:ZnO is sufficient to achieve antibacterial activity (ISO 22196) and antiviral activity against SARS-CoV2 and other viruses with less than 10% absorption in the range of 400 to 700 nm.
• the manufacturing of the composite material may be carried out by pulsed DC Magnetron Sputtering. Two sources are employed so that the deposition parameters of the matrix (M) and active material (AM) may be adjusted independently.
• the matrix material employed belongs to the family of the transparent conductive oxides (TCOs). Their good electrical conductivity allows pDC-MS to be used instead of rf-MS, thus achieving a high deposition rate.
• the material of choice is Aluminum-doped Zinc Oxide (AZO). However, the selection of this material is mainly made on the basis of its high optical transparency in the visible range (Eg ⁇ 3.4 eV).
• the active material must induce a significant increase in the antimicrobial, for example, antibacterial and/or antiviral efficacy compared to the bare matrix; ii) the species of active material must exhibit quantum confinement effects; iii) the active material must not induce significant changes to the aesthetic appearance of the coating; iv) the loading of active material must be sufficient to ensure adequate coating durability without significant loss of performance.
• quantum-confined semiconductor nanoparticles particle diameter ⁇ 10 nm
• metal oxides such as Ag x O and CuxO
• the calculated band gap (by using the Tauc graph method) of AgO nanoparticles deposited directly on glass with nominal sizes between 10 and 5 nm.
• the band gap (forbidden band) increases from 2.85 eV to 3.27 eV (corresponding to a wavelength of 379 nm, outside the visible spectrum) as the particle size decreases.
• the deposition equipment may employ two pDC-MS sources and a supporting structure of the mobile substrate. Screens may be used in such a way as to ensure that the substrates are exposed to only one source at a time.
• the source-substrate distance plays a key role in obtaining the desired M:AM structure.
• a short M-StS distance in the range of 30 mm to 200 mm is preferred, so that the densification effect is achieved during the deposition of the matrix material to provide the desired mechanical and optical properties.
• the AM-StS distance in the range of 50 mm to 300 mm, is selected to be > than the M-StS distance, so that the nanoparticles have less energy to reorganize and form large clusters on the substrate, thus remaining finely dispersed but not interacting with each other.
• Such process may be carried out in an oxidizing atmosphere; so that the metallized nanoparticles of AM are completely oxidized once they reach the substrate.
• An indicative process atmosphere might comprise a mixture of an inert gas (e.g., Argon) and oxygen in a volume ratio of 60:40, with a pressure in the range of 0.5 Pa to 5 Pa.
• a single AZO target containing 1% molar Ag is sputtered by pDC-MS in an Ar:O2 atmosphere as in the previous case, at a targetsubstrate distance of 50 mm.
• the parameters of the pDC source are those that, in this example, ensure that the desired result is achieved.
• an appropriate power density indication could be 1 - 10 W/cm 2 , preferably 3 - 8 W/cm 2 for M and 0.1 - 1 W/cm 2 , preferably 0.1 - 0.6 W/cm 2 for AM, respectively.
• the typical power density used may be in the range of 1 to 10 W/cm 2 , preferably 3 to 8 W/cm 2 .
• the interaction between all of these parameters ensures that the AM nanoparticles are: i) approx. 5 nm in diameter; ii) finely dispersed in the matrix.
• the processing time for such a configuration is about 4' for an M:AM thickness of 150 nm with average transparency optics of 95% over the entire visible range.
• the processing time depends on the number of coated substrates and the power.
• the bulk structure of the coating is expected to comprise a fine dispersion of AM nanoclusters and nanoparticles (d ⁇ 10 nm) embedded in a compact matrix material.
• the AM clusters and nanoparticles must be separated by s > 5 nm in all directions inside the matrix.
• the maximum separation between the clusters is sprang from the need to maintain a total concentration C of AM > 0.1%, with an optimum at 0.5% ⁇ C ⁇ 10%.
• Figure 6 shows an atomic-force microscope image of a pure AZO matrix and AgO x :AZO compound.
• the antibacterial activity of the M and M: AM coating was evaluated by using non-pathogenic E. coli ATTC 8739 and the pathogenic S. aureus 6538P according to ISO 22196 method. Both bacterial strains were grown in Luria Bertani (LB) medium at 37°C overnight and diluted to obtain a bacterial concentration between 10 5 cells/mL and 10 6 cells/mL. The M and M:AM coatings were incubated with bacterial suspensions at 35°C for different periods. At the end of each incubation time, the bacterial culture was recovered to quantify viable bacteria and to determine the percentage of biocidal activity.
• Figure 8 describes the antibacterial effect of different coatings on the growth of both microorganisms, confirming the ability to kill the bacteria within 24 h.
• Figure 7 shows the antibacterial activity of various M and M:AM coating formulations on the pathogen E. coli ATTC 8739 (on the left) and the pathogen S. aureus 6538P (on the right) according to the ISO method 22196, as a function of time by calculation of percent reduction of the colony forming unit (CFU/mL).
• Figure 8 shows a summary of the biocidal properties of a) AZO and b) AgO- AZO composite material against E. coh. S. aureus and SARS-CoVv-19.
• the AgO clusters significantly increase antibacterial activity and confer antiviral activity.
• the transparent composite material proposed herein is shown below in Figure 10.
• Figure 9 shows an image of the new composite material of the invention.
• object of the invention is the use of the composite material of the invention in surfaces and coatings for outdoor environments, indoor environments, human and animal devices.
• object of the invention is the use of the composite material of the invention for making articles, surfaces, coatings and devices with antimicrobial properties.
• object of the invention is a method for providing antimicrobial activity to articles, surfaces, coatings and devices that comprises including in such articles, surfaces, coatings and devices the composite material of the invention.
• object of the invention is a mixed target of matrix (M) and active material (AM), wherein said matrix is selected from SiCh, AI2O3, TiCh, ZnO, SnO, CeCh, ZrCh, ImCh, Fe x O y , WO3, SiN, Y2O3, MgO, rare earth oxides, Li2O, ZrCb, AIN, SiC and mixtures thereof, and transparent conducting oxides (TCOs) preferably selected from Al:ZnO (also known as AZO), F:SnO, Ta:TiO2 and SmlmCh, and said active material is selected from oxides, chalcogenides, chlorides, bromides, iodides of metals and mixtures thereof, said metals being preferably selected from Ag, Cu, Zn, Sn, Fe, Ni, Al and mixtures thereof.
• M matrix
• AM active material
• object of the invention is a method for the preparation of the composite material of the invention that comprises the step of depositing a mixed target of matrix (M) and active material (AM) as defined above on a substrate.
• M matrix
• AM active material
• the targets can also be distinct from each other.
• a mixed target when referred to, it means a material obtained by preliminarily mixing the matrix material and the active material in the concentration ranges mentioned above. This allows for a very fine dispersion of the clusters of the active material.

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