Device for the temporary storage and dispensing of water

Abstract

A device for the temporary storage and release of water, such as humidity or rainwater, is proposed. It comprises, on the one hand, a compressible storage material suitable for the reversible absorption of water, and on the other hand, a support structure in which the storage material is embedded. The invention provides that the support structure is formed from a two-way shape-memory polymer, which is sandwiched between - a first form in which the supporting structure essentially accommodates the storage material without pressure, and - a second form in which the supporting structure compresses the storage material in order to squeeze out water absorbed from the storage material (2), It can be switched back and forth reversibly. The two-way shape memory polymer possesses this capability for this purpose. - a first switching temperature at which it is transformed from its first form into its second form, and - a second switching temperature, lower than the first switching temperature, at which it is transformed from its second form into the first form.

Description

[0001] The invention relates to a device for temporarily storing and dispensing water, in particular in the form of air humidity and / or rainwater, comprising - at least one compressible storage material suitable for the reversible absorption of water and - at least one supporting structure in which the storage material is embedded.

[0002] The adequate supply of water, especially in the form of drinking water, is a growing problem in many regions of the world, not least against the backdrop of a growing global population and climate change. For example, it is to be feared that with globally rising temperatures, the amount of precipitation will continue to decline in many arid or semi-arid regions. Furthermore, even in areas that currently have basically sufficient water supplies, serious water shortages are increasingly occurring due to rising population numbers, advancing industrialization, or the expansion of agricultural land. If the earth warms by around 2°C by the end of the century, this could lead to a large proportion of the world's population no longer being able to have sufficient access to (drinking) water.

[0003] Drinking and industrial water production in regions with insufficient groundwater and surface water reserves is currently primarily achieved through seawater desalination using reverse osmosis. However, the systems required for this require relatively high energy consumption of more than 3 kWh per m, in addition to high investment costs and ongoing maintenance. 3 desalinated water, which limits its use to a few, more highly developed industrial countries.

[0004] In many regions of the world, such as coastal regions, islands with few rainy days, deserts, steppes and (dry) savannas, there is a significant difference in temperature and humidity between day and night, with very high temperatures and very low air humidity occurring during the day, while at night there is a significant cooling of typically between about 15°C and 30°C, which is accompanied by a significant increase in relative humidity.

[0005] In practice, so-called fog collectors are known for capturing air humidity. These enable the direct extraction of water from the atmosphere through condensation of the humidity on textile surfaces. However, the quantities of water obtainable in this way are very limited, with air humidity of almost 100% being required to extract water. Furthermore, the collection of the condensate is complex and inefficient due to the poor drip-off properties of the textiles used. A device for extracting water from an aerosol, such as fog in particular, by means of a textile separation element for separating the liquid contained in the aerosol is known, for example, from DE 10 2008 042 069 A1, wherein the separation element is formed from a three-dimensional textile structure.

[0006] Furthermore, devices for extracting water from atmospheric moisture are known, which involve expelling the separated water stored in a sorbent via the intermediate step of the gas phase from the sorbent (DE 10 2004 026 334 A1, DE 44 30 901 C1, DE 101 07 981 A1). However, this proves to be complex and expensive both from a structural point of view and also requires considerable process engineering effort, which is why such devices have not yet been able to gain practical acceptance.

[0007] JP H06 - 322 798 A describes a closed device for obtaining water by absorbing atmospheric moisture on a sorbent in the form of a polymer hydrogel, wherein the hydrogel has the property of absorbing moisture up to a certain switching temperature and releasing water in condensed form once this switching temperature is reached.

[0008] Finally, DE 10 2010 047 788 B4 discloses a device for obtaining drinking water by absorbing atmospheric moisture from ambient air, which device contains a sorbent immobilized on or in a carrier substrate. While the carrier substrate is a textile fabric or nonwoven, a polymeric hydrogel is provided as the sorbent. The water release from the hydrogel can be switched by changing the ambient temperature, with the water being released from the hydrogel in condensed form after a switching temperature of the hydrogel is reached or exceeded, and the carrier substrate having a darkened, in particular black, surface in order to heat the hydrogel under sunlight. The known device has a simple structure and, particularly due to the switching properties of the hydrogel, enables the extraction of water in relatively large quantities without the need for external energy.

[0009] Based on this, the object of the invention is to develop a device for temporarily storing and dispensing water of the type mentioned at the outset in a simple and cost-effective manner in such a way that it has an increased storage and, in particular, dispensing capacity for water compared to the prior art without the need for an energy supply.

[0010] According to the invention, this object is achieved in a device of the type mentioned at the outset in that the support structure contains at least one two-way shape memory polymer or is formed entirely from it, wherein the at least one two-way shape memory polymer of the support structure is arranged at least between - a first form in which the support structure accommodates the storage material essentially without pressure, and - a second form in which the supporting structure compresses the storage material in order to press out water absorbed thereon from the storage material, reversibly switchable back and forth, wherein the at least one two-way shape memory polymer has at least - a first switching temperature at which it is converted from its first form into the second form, and - a second switching temperature, lower than the first switching temperature, in which it is converted from its second form into the first form, has.

[0011] Shape memory polymers are polymers that typically consist of at least two polymer components or, in particular, of one polymer component with different segments. These include "hard" segments that also function as network points. On the other hand, they include "soft" segments that connect the network points and are also referred to as switching segments. They are amorphous or elastic at elevated temperatures, while rigid at lower temperatures (in this case, they exist in semi-crystalline or vitrified form). Such polymers can be programmed with regard to their shape by heating them to a temperature that corresponds at least to the so-called switching temperature at which the phase transition (glass transition or melting transition) of the soft or switching segments occurs.At such a temperature, the polymer can then be mechanically deformed under the influence of a deformation force. Afterward, it can be cooled to its so-called shape-fixing temperature while maintaining the deformation. This temperature corresponds to the crystallization temperature or glass transition temperature of the soft or switching segments and can be in the range of the switching temperature, but is usually at least somewhat lower. The soft or switching segments then return to a semi-crystalline or vitrified form, so that the shape is retained.This shaping, however, is only temporary insofar as when a shape memory polymer that has been mechanically deformed in this way is heated to a specific temperature, namely its switching temperature, the soft segments (switching segments) are converted back to their amorphous form, so that they can no longer counteract the restoring force induced by the hard component (network points), and the shape memory polymer returns to its original shape, thus "reversing" the mechanical deformation without the need for a new force. Furthermore, programming by cold forming is often also possible, in that the polymers can be deformed at a temperature below their switching temperature, e.g., at ambient temperature, and, if necessary, cooled to their shape-setting temperature if the shape-setting temperature is lower.In this case, too, only temporary deformation takes place, since upon further heating to at least the switching temperature in order to convert the soft segments (switching segments) into the amorphous phase and thereby relax the mechanical stresses induced during cold working, a re-deformation takes place without having to apply a deformation force again.

[0012] In addition to such shape memory, thermoresponsive polymers typically also exhibit temperature memory. This means that when the shape memory effect is triggered, the shape recovery begins at approximately the same temperature at which the mechanical deformation was previously introduced into the material. Polymers with semicrystalline network structures, such as thermoplastic polyurethane elastomers, exhibit this type of material behavior (N. Fritzsche, T. Pretsch in Macromolecules 47, 2014, 5952-5959; N. Mirtschin, T. Pretsch in RSC Advances 5, 2015, 46307-46315).

[0013] In addition, polymers with shape memory properties are known which have two-way shape memory properties and can therefore be switched thermoreversibly, wherein the switching segments of such two-way shape memory polymers undergo a change in shape during the transition between their predominantly crystalline state and their predominantly amorphous state in such a way that they can be reversibly switched back and forth between their permanent shape and their temporary form, on the one hand by cooling the polymer below the crystallization temperature, which is referred to as the “second switching temperature” in the context of the present disclosure, and on the other hand by heating the polymer into the switching temperature range, which is referred to as the “first switching temperature” in the context of the present disclosure, i.e. the correspondingly programmed polymer deforms automatically back and forth when the temperature is controlled accordingly. Such polymers are known, for example, from T.Pretsch, M. Bothe: “Bidirectional actuation of a thermoplastic polyurethane elastomer”, Journal of Materials Chemistry A, 20 (2013), 14.491-14.497.

[0014] The back-and-forth deformation of such two-way shape memory polymers can, on the one hand, be more or less purely temperature-induced, without the need to apply deformation forces. As explained in more detail below, two-way shape memory polymers are also known that exhibit their two-way shape memory properties particularly under the influence of permanent mechanical preload, such as from permanent pressure, so that they are under permanent tension to promote the crystallization of the soft segments during cooling, as is known, for example, from the article by M. Bothe and T. Pretsch: "Two-Way Shape Changes of a Shape Memory Poly(ester urethane)" in Macromol. Chem. Phys. 213 (2012), 213, 2378-2385.

[0015] The invention now provides that the support structure contains at least one such two-way shape memory polymer or is formed substantially entirely from it, wherein the two-way shape memory polymer of the support structure is preferably programmed in such a way that it is at least between - a first form in which the support structure accommodates the storage material essentially without pressure, and - a second form in which the support structure compresses the storage material in order to press out water absorbed therein from the storage material, reversibly and in particular without the application of external forces. The at least one shape memory polymer of the supporting structure has at least - a first switching temperature, in which it is converted from its first form, in which the support structure receives the storage material essentially without pressure, into the second form, and - a second switching temperature which is lower than the first switching temperature and in which it is converted from its second form, in which the support structure compresses the storage material in order to press out water absorbed thereon from the storage material, into the first form.

[0016] In this way, a purely temperature-dependent, reversible change in shape between its first shape and its second shape is programmed into the at least one two-way shape memory polymer of the support structure, which change in shape offers the storage material accommodated in the support structure sufficient space to absorb water, such as precipitation water or in particular atmospheric humidity, at low temperatures (e.g. at night) below the second switching temperature at which the two-way shape memory polymer is in its first form, while at higher temperatures (e.g. during the day) above the first switching temperature at which the two-way shape memory polymer is in its second form, the water absorbed in the storage material is effectively squeezed out and the water yield is consequently increased.

[0017] The water pressed out of the support structure with the at least one two-way shape memory polymer in its second form can then be drained from the support structure in a manner known per se, for example by means of outlets or the like provided in or on the support structure, and collected and transferred, for example, into a suitable (drinking) water reservoir. As soon as the at least one two-way shape memory polymer of the support structure has been converted back into its first form due to the temperature falling below the second switching temperature, in which the support structure absorbs the storage material essentially without pressure, this can again absorb large quantities of rainwater and / or air humidity, etc. The volume ratio of the at least one two-way shape memory polymer of the support structure and the storage material embedded therein can expediently be, for example,between up to about 100:1 and about 1:100, depending on which - first or second - form the two-way shape memory polymer of the supporting structure is in.

[0018] The device according to the invention for temporarily storing and dispensing water can - as already mentioned - be used in particular for energy-independent (drinking) water production, but also for other applications, such as for energy-independent drying of buildings or other facilities, such as industrial plants, technical equipment, land, water, air, and space vehicles, etc., whereby the storage material (see also below) can be adapted to the respective intended use. In any case, it can be designed in the form of a mobile, preferably portable, system or in the form of a stationary system.

[0019] As already indicated, the at least one two-way shape memory polymer of the support structure can be essentially mechanically unstressed, with a purely temperature-dependent, reversible shape change between its first shape and its second shape being programmed into the at least one two-way shape memory polymer of the support structure, taking place without the influence of external forces. Such a configuration is particularly suitable for portable devices with the lowest possible weight.Instead, depending on the type of two-way shape memory polymer used for the supporting structure, it can also be provided that the at least one two-way shape memory polymer of the supporting structure is mechanically under permanent tension, wherein the gravitational force of at least one surface load acting on the supporting structure can in particular serve to generate such permanent tension, so that the permanent mechanical preload to promote the two-way shape memory effect likewise does not require any external energy supply.

[0020] With regard to a structurally simple, yet effective design of the device according to the invention, it can be provided in an advantageous embodiment that the support structure made of the at least one two-way shape memory polymer has at least one chamber in which the storage material is embedded, wherein the hollow space volume of the chamber in the first shape of the at least one two-way shape memory polymer of the support structure, in which the support structure receives the storage material essentially without pressure, is larger than in the second shape of the at least one two-way shape memory polymer of the support structure, in which the latter compresses the storage material in order to press water absorbed thereon out of the storage material.

[0021] In this case, the support structure made of the at least one two-way shape memory polymer can, in particular, have a plurality of chambers, each of which accommodates the storage material. The chambers, in particular, communicate with one another, so that the moisture surrounding the device can, as a result of diffusion, easily and quickly penetrate into the storage material of each chamber or be pressed out and removed. The chamber(s) can, in principle, have virtually any shape, which expediently allows the chambers to be arranged close together and / or one above the other. The at least one chamber can, for example, be substantially cylindrical, cuboid-shaped, or honeycomb-shaped.

[0022] While the support structure - as already mentioned - can be designed with corresponding outlets and, in the case of a structure comprising several chambers, can in particular also have passages arranged between adjacent chambers (the at least one two-way shape memory polymer can in this case, for example, be compact and essentially comprise plate-shaped support elements which form the walls of a respective chamber), it can alternatively or additionally preferably be provided that the support structure is at least partially open-pored, wherein the at least one two-way shape memory polymer of the support structure can in particular be in the form of a predominantly open-cell foam which can be produced, for example, by the use of blowing agents in the two-way shape memory polymer during its shaping. In this way, a very large-area fabric orWater exchange between the environment and the storage material accommodated in the supporting structure and, in the case of a supporting structure with several chambers, also ensures that air humidity can easily and quickly penetrate the storage material of all chambers and be squeezed out of them.

[0023] The support structure made of the at least one two-way shape memory polymer can further preferably have a substantially sandwich-like structure, wherein each layer of such a sandwich-like structure can, for example, comprise a plurality of chambers of the type described above, or each layer has a substantially plate-like extension, wherein the storage material is accommodated between such approximately plate-like support elements of the support structure. The substantially plate-like support elements can, in turn, be formed, for example, from the at least one two-way shape memory polymer in a compact form and be designed with a plurality of passages serving for mass transfer, or the at least one two-way shape memory polymer can, for example, be in the form of a predominantly open-pore foam.

[0024] Furthermore, it is particularly conceivable for the support structure made of the at least one two-way shape memory polymer to comprise essentially lattice- and / or mesh-shaped support elements, which ensure a very high mass transfer through the openings of the lattice or mesh. Such lattice- and / or mesh-shaped support elements of the support structure can in turn be arranged in a sandwich-like manner above and / or next to one another in order to accommodate the storage material between them, or the lattice- and / or mesh-shaped support elements of the support structure can in turn form, for example, a plurality of chambers that accommodate the storage material. The at least one two-way shape memory polymer of the support structure can in this case also be compact or foamed.

[0025] The first and second switching temperatures of the at least one two-way shape memory polymer of the support structure can be adapted to the respective intended use, in particular by appropriate selection and chain length of its switching segments, wherein, in particular in the case of use of the device according to the invention for temporarily storing and dispensing water for (drinking) water production in arid or semi-arid dry areas, it can be provided, for example, that - the first switching temperature, in which the at least one two-way shape memory polymer of the support structure is converted from its first form, in which the support structure receives the storage material substantially without pressure, into the second form, in which the support structure compresses the storage material in order to press out water absorbed thereon from the storage material, between about 10°C and about 70°C, in particular between about 15°C and about 60°C, preferably between about 20°C and about 50°C, e.g. between about 20°C and about 40°C, and / or - the second switching temperature, at which the at least one two-way shape memory polymer of the support structure is converted from its second form into the first form, between about -20°C and about 35°C, in particular between about -10°C and about 30°C, preferably between about 0°C and about 25°C, e.g. between about 10°C and about 20°C, Depending on the melting temperature (“first switching temperature”) and the crystallization temperature (“second switching temperature”) of the switching segments of the at least one two-way shape memory polymer of the support structure, at which the transition between a predominantly amorphous and a predominantly crystalline state of the switching segments takes place, the first and second switching temperatures can be very close to each other, for example by about 1°C or a few °C, or the first and second switching temperatures can also be several °C apart, for example up to about 30°C or up to about 35°C.

[0026] While in principle any known two-way shape memory polymers can be used for the support structure, the switching temperatures of which are in a range suitable for the respective intended use of the device according to the invention for temporarily storing and dispensing water, the at least one two-way shape memory polymer of the support structure can, for example, preferably be a polyurethane elastomer, in particular a thermoplastic one.

[0027] Examples of such two-way shape memory polymers are known, for example, from the article by T. Pretsch, M. Bothe: “Bidirectional actuation of a thermoplastic polyurethane elastomer”, Journal of Materials Chemistry A, 20 (2013), 14.491-14.497, in which a thermoplastic polyurethane elastomer with hard segments or network points based on methylene diphenyl isocyanate (MDI) and 1,4-butanediol (crystalline / amorphous) and with switching or soft segments based on polybutylene-1,4-adipate, which can be obtained by reacting 1,4-butanediol with adipic acid, is mentioned as an example. If this polymer is first heated to a deformation temperature of approximately 60°C, it can be deformed for the purpose of programming, preferably at a slow deformation rate of, for example, approximately 1% / s, e.g. with a total elongation of up to approximately 1000%, after which it is cooled to approximately 0°C in order to achieve a linear expansion of the material.If the polymer is then heated to the switching temperature range ("first switching temperature") of approximately 30°C to 55°C, the switching segments are melted and transformed from their predominantly crystalline state to their predominantly amorphous state, so that the polymer is switched back or contracts without the need for a further deformation force. If it is subsequently cooled back to its crystallization temperature ("second switching temperature") in the range below approximately 20°C, the switching segments crystallize again and the polymer is switched or deformed again, etc.

[0028] Examples of two-way shape memory polymers whose two-way shape memory properties can be promoted in particular by the application of a permanent compressive load, so that the two-way shape memory polymer is under permanent mechanical stress, are known, for example, from the article by M. Bothe, T. Pretsch: “Two-Way Shape Changes of a Shape Memory Poly(ester urethane)” in Macromol. Chem. Phys. 213 (2012), 213, 2378-2385, wherein a polyester urethane with soft segments made of crystallizable poly(1,4-butylene adipate) (PBA) is mentioned as an example, which, in the appropriately programmed state, has two-way shape memory properties in order to expand upon cooling below the crystallization temperature (“second switching temperature”) and to contract upon heating above the switching temperature range (“first switching temperature”).In particular, to promote the transition between an amorphous state of the PBA at high temperatures and a crystalline state of the PBA at low temperatures, and to achieve a very high degree of crystallinity of the PBA—associated with very strong deformation—such a two-way shape memory polymer can be subjected to a mechanical stress, e.g., in the range of approximately 1.5 MPa. Furthermore, it should be noted at this point that by varying such a mechanical stress, the crystallization temperature (“second switching temperature”) of the soft segments of the two-way shape memory polymer, and thus their melting temperature (“first switching temperature”), can be specifically adapted to the respective intended use of the device according to the invention or to the local conditions at its location of use.Furthermore, the at least one two-way shape memory polymer of the supporting structure can, for example, also be subjected to permanent mechanical stress only in certain areas, such as, for example, as a result of the gravitational force of a surface load acting only in certain areas on the supporting structure.

[0029] According to an advantageous development, it can be provided that the at least one two-way shape memory polymer of the support structure is mixed with and / or coated with a medium that absorbs electromagnetic radiation in the infrared and / or ultraviolet spectrum, so that it heats up quickly, particularly when the outside temperature rises and / or under solar radiation, and can be reliably converted from its first shape to its second form upon exceeding the first switching temperature of the at least one two-way shape memory polymer in order to press out the water previously absorbed in the storage material. Largely in accordance with the above-cited DE 10 2010 047 788 B4, the support structure can, in the simplest case, be provided for this purpose, for example, with a coating or paint applied at least externally in a dark, preferably black, color.Alternatively or additionally, it is preferably also conceivable that at least one, in particular powdered or particulate, additive with infrared and / or ultraviolet radiation absorbing properties is added to the at least one two-way shape memory polymer of the support structure, such as, for example, fillers and / or reinforcing materials based on carbon, e.g. in the form of graphite or expanded graphite, carbon black, carbon nanotubes (CNT), graphene flakes or the like, metals and metal compounds including their alloys and oxides, etc., whereby, of course, combinations of several different filler materials can also be used.In addition, for example, particularly dark dyes or pigments or, in principle, other additives largely known from the prior art, particularly biocompatible and physiologically acceptable, such as lubricants, plasticizers, antioxidants, UV stabilizers, reinforcing agents, flame retardants, antistatic agents, hydrolysis stabilizers, impact modifiers, biostatic agents (see also below), etc., can be added to the at least one polymer with two-way shape memory properties.

[0030] While any known storage materials for the reversible absorption of water, particularly hygroscopic ones, are generally suitable for the compressible storage material of the device according to the invention for temporarily storing and dispensing water, the storage material can preferably be a superabsorbent, particularly in the form of a hydrogel or aerogel. The latter are highly porous solids with a pore volume fraction of up to approximately 99.99%, based on the total volume of the aerogel, which can be used, for example, on a silicate basis, but also, for example, on a plastic, carbon basis, or the like.

[0031] In an advantageous embodiment, the storage material can be, for example, a polymeric hydrogel, in particular based on polyacrylic acid including its amides, starch including its copolymers, cellulose including its copolymers and / or cotton.

[0032] In this case, the storage material may in particular have a volume phase transition temperature at which it undergoes a volume change, wherein the volume phase transition temperature is in particular between about 5°C and about 50°C, preferably between about 10°C and about 45°C, for example between about 15°C and about 40°C or between about 15°C and about 35°C.Such superabsorbent hydrogels have swellable, cross-linked structures which, in the presence of water, undergo a volume phase transition of the so-called LCST type ("lower critical solution temperature"). Below the critical temperature ("volume phase transition temperature"), they form gels with water, while above the critical temperature ("volume phase transition temperature") they displace the water from the then more hydrophobic structure. In conjunction with the support structure based on two-way shape memory polymers, the greatest possible water absorption and release capacity of the device according to the invention can be ensured. Examples of suitable polymeric hydrogels can be found in the above-cited DE 10 2010 047 788 B4, which is hereby explicitly incorporated into the present disclosure.

[0033] Furthermore, the support structure and / or the storage material can be provided with an antimicrobial finish, particularly—although not exclusively—in the event that the device according to the invention is intended for the temporary storage and dispensing of drinking water, to prevent undesirable germ or fungal growth. The antimicrobial finish should be harmless to health and may, for example, comprise fillers, fibers, or threads based on silver and its sparingly or insoluble salts. Furthermore, appropriate filters, for example in the form of activated carbon filters, can of course be provided, which are inserted into the outlets of the support structure to filter the water extracted and pressed out of the storage material.

[0034] Further features and advantages of the invention will become apparent from the following description of an embodiment with reference to the drawings. Fig. 1 a highly schematic cross-sectional view of an embodiment of a device according to the invention for temporarily storing and dispensing water, comprising a compressible storage material suitable for the reversible absorption of water and a support structure in which the storage material is embedded, wherein the two-way shape memory polymer of the support structure is in its first form, in which the support structure accommodates the storage material substantially without pressure; and Fig. 2 one of the Fig. 1 corresponding, highly schematic cross-sectional view of the device for temporarily storing and dispensing water according to Fig. 1, wherein the two-way shape memory polymer of the support structure is in its second shape, in which the support structure compresses the storage material to squeeze out water absorbed thereon from the storage material.

[0035] In the Fig. 1 and Fig. 2 shows a schematic cross-sectional view of an embodiment of a device, designated overall by the reference numeral 1, for temporarily storing and dispensing water, in particular in the form of atmospheric moisture and / or rainwater. The device 1 comprises, on the one hand, a compressible storage material 2 suitable for the reversible absorption of water, e.g., in the form of a polymeric hydrogel, and, on the other hand, a support structure 3 in which the storage material 2 is embedded. The support structure 3 is formed from at least one two-way shape memory polymer, such as one of the type described above, and in the present case comprises an approximately sandwich-like structure with a plurality of chambers 4 arranged next to and above one another, in which the storage material 2 is embedded. The chambers 4 are, for example,are essentially cuboid-shaped and are fluidically connected to one another, with adjacent chambers 4 communicating with one another, for example via passages not shown in the drawing (the two-way shape memory polymer of the support structure 2 can in this case be compact, for example), and / or the support structure 3 is open-pored, with the two-way shape memory polymer of the support structure 3 being in the form of a predominantly open-cell foam. Furthermore, the support elements of the support structure 3 delimiting the chambers 4 can, for example, have a grid-like or net-like structure, so that a good exchange of substances—or more precisely: moisture or water exchange—can also take place between adjacent chambers 4.The two-way shape memory polymer of the support structure 3 can further be mixed with and / or coated with a medium that absorbs electromagnetic radiation in the infrared and / or ultraviolet spectrum. It can contain, for example, particularly dark dyes, pigments, or filler particles, e.g., based on carbon or metals. Furthermore, the two-way shape memory polymer of the support structure 3 and / or the storage material 2 can be provided with an antimicrobial finish to prevent the formation of germs or fungi. As described in the . Fig. 2, the device 1 further comprises a collecting device 5 arranged below the support structure 3, which serves to collect the discharged water 6, which in turn can be discharged by means of outlets (not shown) provided at least on the underside of the support structure 3 and / or through the open-pore foam structure of the two-way shape memory polymer of the support structure 3.

[0036] As continues the Fig. 1 and Fig. 2, the two-way shape memory polymer of the support structure 3 is programmed to move between - a first form according to the Fig. 1, in which the support structure 3 accommodates the storage material 2 essentially without pressure (the cavity volume of the chambers 4 is sufficiently large to practically not compress the storage material 2), and - a second form according to the Fig. 2, in which the supporting structure 3 compresses the storage material 2 in order to press out the water 6 absorbed thereon from the storage material 2 (the cavity volume of the chambers 4 is significantly smaller due to the deformation of the chambers 4) can be switched back and forth reversibly and without the influence of external forces, wherein the switching back and forth of the two-way shape memory polymer of the support structure 3 between its first and second shape is exclusively temperature-dependent, because the two-way shape memory polymer - a first switching temperature, in which it changes from its first form according to the Fig. 1 into the second form according to the Fig. 2 is transferred, and - a second switching temperature, lower than the first switching temperature, in which it changes from its second form according to the Fig. 2 into the first form according to the Fig. 1 is transferred, The first or second switching temperature, which - as described above - can be relatively close to each other, depending on the application or -location of the device, for example, between about 15°C and about 50°C or between about 0°C and about 20°C.

[0037] In this way, the device 1, which requires only a very low expenditure on equipment and is of simple construction, can be used in a simple manner and without any external energy requirement, in particular for the production of drinking water from atmospheric humidity in arid or semi-arid regions of the earth, by absorbing the atmospheric humidity in the cold night hours by the storage material 2 when the supporting structure 3 is in its first form (cf. the Fig. 1). If the supporting structure 3 heats up due to increasing daytime temperatures and / or solar radiation, the supporting structure 3 is switched to its second form (see the Fig. 2), in which the storage material 2 is compressed and the water 6 absorbed therein is pressed out in its very high proportion and in a short time. As soon as the ambient temperatures drop again in the evening or night hours, the supporting structure 3 is returned to its first form ( Fig. 1) and the aforementioned absorption process of humidity begins again.

Claims

[1] Device (1) for temporarily storing and dispensing water, in particular in the form of atmospheric humidity and / or rainwater, comprising - at least one compressible storage material (2) suitable for the reversible absorption of water and - at least one supporting structure (3) in which the storage material (2) is embedded, characterized by that the support structure (3) contains at least one two-way shape memory polymer or is formed entirely therefrom, wherein the at least one two-way shape memory polymer of the support structure (3) is arranged at least between - a first form in which the support structure (3) receives the storage material (2) essentially without pressure, and - a second shape, in which the support structure (3) compresses the storage material (2) in order to press out water (6) absorbed thereon from the storage material (2), is reversibly switchable back and forth, wherein the at least one two-way shape memory polymer at least - a first switching temperature at which it is converted from its first form into the second form, and - has a second switching temperature which is lower than the first switching temperature and at which it is converted from its second form into the first form. [2] Device (1) according to claim 1, characterized by that the at least one two-way shape memory polymer of the support structure (3) - is essentially not subject to mechanical pre-stress; or - is mechanically under a permanent tension, wherein the permanent tension is generated in particular by the gravity of at least one surface load acting on the supporting structure (3). [3] Device (1) according to claim 1 or 2, characterized by in that the support structure (3) made of the at least one two-way shape memory polymer has at least one chamber (4) into which the storage material (2) is embedded, wherein the cavity volume of the chamber (4) is larger in the first shape of the at least one two-way shape memory polymer of the support structure (3) than in the second shape of the at least one two-way shape memory polymer of the support structure (3). [4] Device (1) according to claim 3, characterized by that the support structure (3) made of the at least one two-way shape memory polymer has a plurality of chambers (4) which in particular communicate with one another. [5] Device (1) according to claim 3 or 4, characterized by that the at least one chamber (4) is substantially cylindrical, cuboid or honeycomb-shaped. [6] Device (1) according to one of claims 1 to 5, characterized bythat the support structure (3) is open-pored, wherein the at least one two-way shape memory polymer of the support structure (3) is in particular in the form of a predominantly open-cell foam. [7] Device (1) according to one of claims 1 to 6, characterized by that the supporting structure (3) has an essentially sandwich-like structure. [8] Device (1) according to one of claims 1 to 7, characterized by that the support structure (3) essentially comprises grid-shaped and / or net-shaped support elements. [9] Device (1) according to one of claims 1 to 8, characterized by , that - the first switching temperature, at which the at least one two-way shape memory polymer of the support structure (3) is converted from its first form into the second form, is between 10°C and 70°C, in particular between 15°C and 60°C, and / or - the second switching temperature, at which the at least one two-way shape memory polymer of the support structure (3) is converted from its second form into the first form, is between -20°C and 35°C, in particular between -10°C and 30°C. [10] Device (1) according to one of claims 1 to 9, characterized by that the at least one two-way shape memory polymer of the support structure (3) is a polyurethane elastomer, in particular a thermoplastic one. [11] Device (1) according to one of claims 1 to 10, characterized by that the at least one two-way shape memory polymer of the support structure (3) is mixed and / or coated with a medium absorbing electromagnetic radiation in the infrared and / or ultraviolet spectrum. [12] Device (1) according to one of claims 1 to 11, characterized bythat the storage material (2) is a superabsorbent, in particular in the form of a hydrogel or an aerogel. [13] Device (1) according to one of claims 1 to 12, characterized by that the storage material (2) is a polymeric hydrogel, in particular based on polyacrylic acid including its amides, starch including its copolymers, cellulose including its copolymers and / or cotton. [14] Device (1) according to one of claims 1 to 13, characterized by that the storage material (2) has a volume phase transition temperature at which it undergoes a volume change, wherein the volume phase transition temperature is in particular between 5°C and 45°C, preferably between 10°C and 45°C. [15] Device (1) according to one of claims 1 to 14, characterized bythat the supporting structure (3) and / or the storage material (2) is / are provided with an antimicrobial finish.

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