Hygroscopic polymer composites and related preparation methods

Abstract

This disclosure relates to materials with highly stable and reversible water adsorption and retention properties, as well as formulations, methods for manufacturing them, and uses. The composite materials of this disclosure can prevent leakage or seepage of liquid water over a wide range of ambient relative humidity, making them suitable for a variety of applications including thermal management, thermal energy storage, atmospheric water generation, and dehumidification systems. The composite materials disclosed herein may comprise ionomer materials and, in some embodiments, hygroscopic or deliquescent salts. Furthermore, the composite materials disclosed herein may also comprise water vapor permeable or supportive polymer materials that, through porous and / or elastic properties, provide support for reversible expansion or volume changes during water vapor adsorption / desorption cycles, thereby avoiding mechanical limitations that could lead to liquid water leakage or seepage.

Description

[0001] Citations of relevant applications

[0002] This application claims priority to U.S. Provisional Application Serial No. 63 / 535,339, filed August 30, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to materials with highly stable and reversible water adsorption and retention properties, as well as formulations, methods for manufacturing such materials, and uses. The composite materials disclosed herein are suitable for a wide range of applications, including thermal management, thermal energy storage, atmospheric water generation, and dehumidification systems. Background Technology

[0004] Various types of adsorbent materials exist capable of adsorbing water vapor, including hygroscopic or deliquescent salts, fibrous materials (like cellulose), zeolites, silica, hydrogels, and metal-organic frameworks (MOFs). Adsorbent materials can be used in a wide range of devices and applications, such as thermal management, thermal energy storage, atmospheric water generation, and dehumidification systems. These systems have stringent requirements regarding adsorbent material performance related to hygroscopic capacity (e.g., high water vapor absorption without weeping or leakage of liquid water), highly stable and reversible cycling (e.g., rapid adsorption kinetics, low desorption enthalpy), and scalability and low cost.

[0005] need

[0006] For both established and novel applications requiring highly reversible and stable water adsorption behavior, effective thermal properties, robust mechanical strength, and / or other properties based on specific applications, there is a need for adsorbent materials with improved stability. Summary of the Invention

[0007] According to one or more embodiments of this disclosure, the hygroscopic polymer composite material comprises: an ionomer material having an ionized polymer matrix to maintain an equilibrium moisture content; and a water vapor permeable polymer material to support the volume change of the ionomer material between a contracted state having a first equilibrium moisture content and a swollen state having a second equilibrium moisture content greater than the first equilibrium moisture content. In some embodiments, the composite material may further comprise hygroscopic or deliquescent salts incorporated into the ionized polymer matrix of the ionomer material. Furthermore, various embodiments include reinforcing materials to support the volume change of both the ionomer material or ionized material and the water vapor permeable polymer material between the contracted and swollen states.

[0008] In various implementations of this disclosure, a method for manufacturing a hygroscopic polymer composite material may include preparing an ionomer material and a water vapor permeable polymer material to support the ionomer material and hygroscopic or deliquescent salts (if present).

[0009] The materials and methods disclosed herein are applicable to a variety of applications, including thermal management, thermal energy storage, atmospheric water generation, and dehumidification systems. In one or more implementations, the hygroscopic polymer composite material is formed as a layer to receive heat from a surface, such as heat generated by a solar panel during daytime operation, such that water evaporates from the hygroscopic polymer composite material into the surrounding environment as it transitions from a swollen state to a contracted state. Attached Figure Description

[0010] The following figures are illustrated by way of example and not limitation. For the sake of brevity and clarity, each feature of a given structure is not always labeled in every drawing in which the structure appears. The same reference numerals do not necessarily indicate the same structure. Rather, the same reference numerals can be used to indicate similar features or features with similar functions, and so can different reference numerals. The views in the figures are drawn to scale (unless otherwise stated), meaning that, at least for the embodiments shown in the views, the dimensions of the depicted elements are accurate relative to each other.

[0011] Figure 1A A schematic diagram of a hygroscopic polymer composite material is depicted, which comprises an ionomer material and a water vapor permeable supporting polymer material having a porous matrix that facilitates water vapor permeation while providing a semi-rigid or rigid framework to support the volume change of the ionomer material between a shrinkage state and a swelling state. Figure 1B A schematic diagram of a hygroscopic polymer composite material is shown, which comprises an ionomer material and a water vapor permeable polymer material that exhibits elastic volume change between a contracted state and a swollen state. Figure 2A A schematic diagram depicts a hygroscopic polymer composite material containing hygroscopic salts in a polymer matrix incorporating ionomer materials. Figure 2B A schematic diagram of a hygroscopic polymer composite material is shown, which comprises an ionomer material dispersed or supported in a reinforcing fiber material that is permeable to water vapor within the polymer material. Figure 3A The chemical structure of polydiallyl dimethylammonium chloride (poly-DADMAC) ionomer materials was described; Figure 3B The chemical structure of hydroxyl-functionalized poly-DADMAC ionomer material, specifically dihydroxymethyl-functionalized poly-DADMAC, was described. Figure 3C The chemical structure of aminium-functionalized poly-DADMAC ionomer material, specifically 2-hydroxyethyl-N,N-dimethylaminoonium methyl-functionalized poly-DADMAC, was described. Figure 4 The synthesis of poly-DADMAC (diallyl dimethyl ammonium chloride (DADMAC) monomer and piperazineonium crosslinking agent was described. Figure 3A As shown); Figure 5 The synthesis of poly-DADMAC ionomer materials via polymerization of diallyl dimethyl ammonium chloride (DADMAC) monomer and tetraallyl ammonium crosslinking agent is described; Figure 6A The synthesis of long-chain tetraallyl-substituted dihydroxydiamineon crosslinking agents from diallylamine and N,N′-bis(epoxyethylenemethyl)-N,N,N′,N′-tetramethyl-1,6-hexamethylenediamineon dichloride is described. Figure 6B The chemical structures of hydroxylamine-onium-functionalized poly-DADMAC ionomers containing hydroxylamineonium long-chain crosslinking agents, particularly 2-hydroxyethyl-N,N-dimethylamineonium methyl-functionalized poly-DADAMAC, are described. Figure 7A This is an example of a typical NMR spectrum of hydroxymethyl DADMAC monomer, specifically diallyl diethanolammonium chloride; Figure 7B This is an example of a typical NMR spectrum of a piperazineon crosslinking agent, specifically 1,1,4,4-tetraallypropylpiperazineon dichloride; Figure 8A Aminonium-functionalized chitosan ionomer materials were described; Figure 8B A diamineonium diepoxide crosslinker is described, specifically an N,N′-bis(epoxyethylenemethyl)-N,N,N′,N′-tetramethyl-1,6-hexamethyleneonium dichloride crosslinker; Figure 8C The chemical structure of cross-linked hydroxylamine-functionalized chitosan ionomer materials was described; Figure 9A A photograph of a hygroscopic polymer composite body is shown, comprising a functionalized chitosan-based ionomer and a polyisocyanurate-based water vapor permeable supporting polymer. Figure 9B A photograph of a hygroscopic polymer composite body is shown, comprising a poly-DADMAC ionomer, a polyisocyanurate water vapor permeable supporting polymer, and a hygroscopic salt. Figure 9C A photograph of a hygroscopic polymer composite body is shown, comprising a poly-DADMAC ionomer, a polyisocyanurate water vapor permeable supporting polymer, and a hygroscopic salt. Figure 9D A photograph of a hygroscopic polymer composite body is shown, comprising a poly-DADMAC ionomer, a polyisocyanurate water vapor permeable supporting polymer, and a hygroscopic salt. Figure 10 An enlarged photograph of a hygroscopic polymer composite body is shown, comprising a functionalized chitosan-based ionomer and a polyisocyanurate-based water vapor permeable supporting polymer. Figure 11 The following are water adsorption isotherms: A) poly-DADMAC ionomer material and B) poly-DADMAC ionomer material doped with 80 wt.% calcium chloride. Figure 12 The reversible water vapor adsorption cycle for (A) hygroscopic polymer composites, (B) ionomer materials and (C) water vapor permeable supported polymers at 60% RH and 25°C is shown; Figure 13A The water vapor adsorption or water absorption of a hygroscopic polymer composite containing (A) 20 wt% (wt%) of a water vapor permeable support polymer and (B) 30 wt% (wt.%) of a water vapor permeable support polymer are shown at 60% RH and 25°C.

[0012] Figure 13B The water vapor adsorption or water absorption of hygroscopic polymer composites (A) having hygroscopic salts and (B) not having hygroscopic salts are shown at 60% RH and 25°C. Figure 13C The water vapor adsorption or water absorption of (A) a hygroscopic polymer composite having 20 wt.% water vapor permeable support polymer and 60 wt.% hygroscopic salt and (B) a hygroscopic polymer composite having 40 wt.% water vapor permeable support polymer and 40 wt.% hygroscopic salt are shown at 60% RH and 25°C. Figure 14A A cross-sectional view of a solar panel containing a layer or coating of a hygroscopic polymer composite material is shown. Figure 14B A cross-sectional view of a solar panel comprising a multilayer hygroscopic polymer composite material is shown. Figure 15A A photograph shows a hygroscopic polymer composite material formed as a layer for application to the rear surface of a solar cell or panel; Figure 15B Enlarged photographs depicting hygroscopic polymer composites containing poly-DADMAC ionomers and PEBA water vapor permeable polymers; Figure 16 The power output of a solar cell (A) containing a hygroscopic polymer composite material adhered to its rear surface is shown compared to that of a similar solar cell (B) without any rear polymer composite layer. Figure 17 A perspective cross-sectional view of a water generation system comprising a hygroscopic polymer composite material is shown. Figure 18 A method for preparing hygroscopic polymer composites is described.

[0013] For the sake of simplicity and clarity, the accompanying drawings illustrate a general construction method, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Furthermore, the elements in the drawings are not necessarily drawn to scale. For example, the dimensions of some elements in the figures may be enlarged relative to other elements to aid in understanding embodiments of the invention. The same reference numerals in different drawings denote the same elements. Detailed Implementation

[0014] The detailed description of various embodiments herein is illustrated with reference to the accompanying drawings, which show various embodiments in an illustrative manner. While these various embodiments have been described in sufficient detail to enable those skilled in the art to practice this disclosure, it should be understood that other embodiments may be implemented and logical, chemical, and mechanical changes may be made without departing from the spirit and scope of this disclosure.

[0015] Therefore, the detailed descriptions herein are presented for illustrative purposes only and not for limitation. For example, the steps described in any method or process description may be performed in any order and are not required to be in the order presented. Furthermore, any reference to the singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Additionally, any reference to attachment, fixing, connection, etc., may include permanent, removable, temporary, partial, complete, and / or any other possible attachment options. Throughout the figures, surface shading may be used to denote different parts, but does not necessarily indicate the same or different materials.

[0016] This disclosure includes various embodiments of materials, systems, and methods. The term “coupled” is defined as a connection, although not necessarily a direct connection or a mechanical connection. Unless expressly required otherwise by this disclosure, the terms “a” and “an” are defined as one or more. The term “substantially” is defined as largely (but not necessarily entirely) what is specified (and includes what is specified; for example, substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by one of ordinary skill in the art. In any disclosed embodiment, the terms “substantially,” “about,” and “approximately” may be replaced by “within [percentage] of…”, where the percentage includes 0.1%, 1%, 5%, and 10%. Furthermore, an apparatus or system configured in a certain way is configured at least in this manner, but it may also be configured in other ways than those specifically described.

[0017] The terms “comprise” (and any form of inclusion, such as “comprises” and “comprising”), “have” (and any form of having, such as “has” and “having”), “include” (and any form of including, such as “includes” and “including”), and “contain” (and any form of containing, such as “contains” and “containing”) are open-ended connecting verbs. Therefore, an apparatus that “comprises,” “has,” “includes,” or “contains” one or more elements possesses, but is not limited to, those elements. Similarly, a method that “includes,” “has,” “includes,” or “contains” one or more operations or steps possesses, but is not limited to, those operations or steps.

[0018] Any embodiment of any material, composition, device, system, and method may consist of, or substantially consist of, any described step, element, and / or feature, rather than comprising / including / containing / having any described step, element, and / or feature. Therefore, in any claim, the terms “consisting of” or “substantially consisting of” may replace any open-ended connecting verbs used above to change the scope of the given claim from the content otherwise used with open-ended connecting verbs. One or more features of one embodiment may be applied to other embodiments or implementations, even if not described or shown, unless expressly prohibited by the nature of this disclosure or the embodiment.

[0019] This disclosure relates to a novel class of hygroscopic polymer composites possessing unique water vapor adsorption / desorption properties that promote stable performance without leakage (i.e., loss of liquid water from the material) under certain environmental conditions. These composites can be used in a range of devices and applications, including thermal management systems, thermal energy storage systems, passive cooling applications, humidity control systems, air conditioning systems, waste heat recovery systems, atmospheric water generation systems, and dehumidification systems. The materials and compositions of this technology can be deployed in both established and novel applications that can benefit from high hygroscopic capacity, reversible water adsorption cycle characteristics, effective thermal performance via latent heat of vaporization, and / or high mechanical stability at high moisture content. Therefore, this new class of hygroscopic polymer composites can meet the needs of a variety of systems and methods that address challenges such as water scarcity and poor energy efficiency.

[0020] As used herein, the term "hygroscopicity" refers to the characteristic property of attracting and retaining water molecules from and / or adsorbing from the surrounding environment, and of reversibly releasing the captured water as water vapor (e.g., via temperature changes, humidity changes, pressure changes, etc.). The composite materials or materials of this technology can contain a wide range of components or ingredients within a compositional range for deployment in various configurations and systems (e.g., enabling the material to continuously and reversibly adsorb and desorb water vapor from and into the surrounding environment).

[0021] The following description of hygroscopic polymer composite materials is provided by way of example and is detailed enough to enable those skilled in the art to practice this disclosure. It should be understood that other embodiments may be implemented, and logical, chemical, compositional, and other changes may be made without departing from the spirit and scope of this disclosure. In some implementations, the hygroscopic polymer composite material is capable of adsorbing at a first temperature, relative humidity, and / or pressure and desorbing at a second temperature, relative humidity, and / or pressure. The components of the hygroscopic polymer composite material may be provided as a liquid, a solid, or a combination thereof.

[0022] As will be described in detail below, this disclosure describes various hygroscopic polymer composites and materials, their uses, and related preparation methods. The hygroscopic polymer composites of this technology can comprise ionomers having a three-dimensional cross-linked polymer network capable of retaining large amounts of water in a highly reversible manner, such that the composite layer or volume retains all water vapor it attracts into its polymer matrix through hygroscopic affinity without leakage or seepage of liquid water. The composites disclosed herein are unique in their ability to maintain high equilibrium moisture content and cycle through a wide range of equilibrium moisture contents or relative humidity without leakage (e.g., leakage, liquid water loss, surface water formation, beading, etc.). A leakage state can be considered a failure of the material in its ability to absorb and retain all the water it can absorb, for example, through a deliquescence process or swelling beyond the state in which the material can maintain its mechanical integrity. Therefore, the hygroscopic polymer composites of this technology can be considered insoluble at high equilibrium moisture contents, allowing them to cycle through a wide range of ambient relative humidity.

[0023] The hygroscopic polymer composites disclosed herein may comprise an ionomer matrix and a water vapor permeable polymer material, which may act as a supporting polymer material. This supporting polymer material provides flexible or rigid support to the volume changes (e.g., swelling) of the ionomer material (which may have incorporated hygroscopic salts) between a lower moisture content, drier or shrinkage state and a higher moisture content or swelling state. In some cases, the water vapor permeable supporting polymer material may be referred to as the supporting polymer material. The water vapor permeable polymer material may have a porous matrix that facilitates water vapor permeation and provides a rigid framework to support the volume changes of the ionomer material between shrinkage and swelling states. Alternatively or additionally, water vapor permeable polymeric materials can exhibit elasticity due to a flexible cross-linked molecular structure that allows its polymer chains to stretch in a swollen state and return to their initial configuration in a contracted state (e.g., exhibiting the viscoelastic behavior of an elastomer), so as to both promote water vapor permeation and provide a framework to support the volume changes of the ionomer material (and hygroscopic salts, if incorporated therein) between high and low moisture contents in the composite material.

[0024] In various implementations, the ionomer material can be supported or incorporated (e.g., trapped, retained, contained, and / or anchored) into a water vapor permeable polymer matrix or supporting polymer matrix. The chemistry, polymer structure, and / or pore structure of the composite material can be designed such that the materials disclosed herein are uniquely capable of adsorbing water vapor from the air and storing moisture without leakage.

[0025] In some implementations, the hygroscopic polymer composites of this technology may further comprise hygroscopic materials, such as hygroscopic or deliquescent salts. Hygroscopic or deliquescent salts may be incorporated (e.g., trapped, retained, contained, and / or anchored) into the polymer matrix of the ionomer material and / or the water vapor permeable polymer material, or may be incorporated by the polymer matrix of the ionomer material and / or the water vapor permeable polymer material, which typically includes multiple pores or voids. The components of the hygroscopic polymer composites of this technology may include readily available and low-cost materials with minimal environmental impact.

[0026] The term "ionomer material" is used herein to describe polymeric materials having repeating units that are both electrically neutral and ionized. Ionized units containing fixed positive or negative charges can be located in the polymer backbone as side groups, as crosslinking units, or a combination thereof. The degree of ionization or substitution of the ionized units can be selected or adjusted based on desired properties and / or applications and is typically in the range of 10-100 mol%. Furthermore, the degree of crosslinking of the ionomer material can be selected or adjusted based on desired properties and / or applications and is typically in the range of 1-10 mol% and / or 1-5 mol%.

[0027] In some implementations, the ionomer material itself can possess hygroscopic properties. Ionomer materials can also be referred to as "absorbent polymers," "absorbent materials," "water-absorbing polymer materials," etc., because they can absorb water vapor from the air and retain the absorbed water vapor within their charged polymer network, for example, through swelling or volume increase. Furthermore, ionomer materials can also be referred to as hydrogels, which comprise polymer networks with hygroscopic properties to attract and absorb moisture from the air.

[0028] Conventional hydrogels are limited in their ability to maintain high water content in their swollen state without leakage or loss of mechanical stability. While conventional hydrogels with higher crosslinking densities can have more rigid and compact structures, their water adsorption or absorption capacity is limited. Furthermore, conventional hydrogels with high porosity can exhibit greater water adsorption or absorption capacity, but they tend to leak more and / or lose mechanical stability. The ionomer materials and their composites disclosed herein (typically incorporating hygroscopic or deliquescent salts) offer the ability to maintain high water content in the swollen state without leakage or loss of mechanical stability.

[0029] The composite materials of this technology exhibit a unique ability to prevent leakage over a wide range of ambient relative humidity levels (e.g., at relative humidity levels up to 60%, 80%, and / or 90% RH). In various instances, the ability to prevent leakage may result from the absorbency of the polymer gel material, which includes an ionomer. The ionomer can be selected or designed to have a crosslinking degree between 1-10 mol% and / or 1-5 mol%, such that there are enough crosslinking points to form a gel, and enough that there are no mechanical limitations on the absorption of the gel (i.e., absorption of moisture from the air). Furthermore, the composite materials of this technology may contain a water vapor permeable or “supporting” polymer material, which is selected or designed to have mechanical properties to allow reversible expansion during water vapor adsorption / desorption cycles. In one instance, the water vapor permeable polymer material may have rigid or semi-rigid pores or voids that are sized to accommodate the expansion of the hygroscopic component (i.e., the ionomer material and deliquescent salts, if present) to prevent leakage. In another example, the water vapor permeable polymer material is an elastomer that is flexible enough to allow reversible expansion upon absorbing water, thereby avoiding mechanical limitations that could cause leakage.

[0030] Ionomers in their polymeric form, and / or monomers of ionomers, may contain hydrophilic functional groups. For example, hydrophilic moieties such as hydroxyl or alcohol groups, carbonyl groups (e.g., aldehydes, ketones), carboxyl groups (e.g., carboxylic acids), amino groups, amide groups, mercapto groups, thiol groups, phosphate ester groups, and / or combinations thereof may be used. Furthermore, ionomers may contain hydrophilic bonds such as ether bonds, ester bonds, phosphodiester bonds, glycosidic bonds (e.g., disaccharides, polysaccharides), peptide bonds, etc.

[0031] The terms “water vapor permeable polymer,” “water vapor permeable polymer material,” or “water vapor permeable material” are used herein to describe materials having a chemical composition, structure, and / or pore distribution that allows water vapor to permeate through its structure with minimal to no liquid water permeation. Permeability can be enhanced by the chemical structure of the polymer material, such as hydrophilic functional groups like hydroxyl (-OH), carboxyl (-COOH), and amino (-NH2), which can attract and retain water molecules, facilitating their passage through the polymer matrix. In various examples, the permeability of a water vapor permeable polymer can be greater than 10,000 Barrer, greater than 50,000 Barrer, greater than 100,000 Barrer, between 100,000 and 250,000 Barrer, and / or between 100,000 and 250,000 Barrer. Non-limiting examples of water vapor permeable polymers include polydimethylsiloxane (PDMS), sulfonated polyether ether ketone (SPEEK), sulfonated polyether sulfone (SPES), polyether block amide (PEBA) (such as PEBAX®), and polybutylene terephthalate poly(ethylene oxide) (PBT-PEO) block copolymers (such as 1000). PEO 40 PBT 60), polysaccharides (such as ethyl cellulose (EC)), etc.

[0032] Water vapor permeability can be provided through its porous structure, which can be inherent or induced. Inherent porosity can be caused by the natural presence of micropores and channels within the polymer structure, while induced porosity can be achieved through various techniques such as phase separation, leaching, or incorporation of subsequently removed porogens. The size and distribution of pores can be designed to tune the water vapor permeability of the polymer, and consequently, the water vapor permeability of the composite material. For example, the porosity of the water vapor permeable polymer and / or composite material can range from 50 micrometers (µm) to 3 millimeters (mm), depending on the desired composition and pore structure. In various embodiments, hierarchical pore structures can be provided, depending on the desired composition and / or mechanical strength for the specific application.

[0033] In various implementations, besides its water vapor permeability, water vapor permeable polymers provide a framework (e.g., rigid, semi-rigid, elastic, semi-elastic) to support the volume changes of the ionomer material (and any hygroscopic salts incorporated therein, if present) between a contracted state (i.e., low water content, lower relative humidity) and a swollen state (i.e., higher water content, higher relative humidity). As another example, water vapor permeability can be provided by incorporating hydrophilic segments and / or creating amorphous regions within the polymer matrix. For instance, polyether block amides (PEBAs) with alternating polyamide and polyether blocks (such as PEBAX®) can effectively utilize the hydrophilic properties of the polyether segments and microphase separation to facilitate water vapor transport. Similarly, polyethylene glycol (PEG) polymers can utilize the hydrophilic and flexible properties of the PEG chains to enhance water vapor permeability.

[0034] The terms “supporting polymer,” “water vapor permeable supporting polymer,” “water vapor permeable supporting polymer material,” or “supporting polymer material” are used herein to describe polymer materials having a chemical composition, structure, and / or pore distribution to support ionomer materials, and in some embodiments, to support hygroscopic materials such as hygroscopic salts, such that when the ionomer material and / or hygroscopic material acquires water, the forces generated by the expansion or swelling caused by the absorbed water are substantially contained within the supporting polymer matrix, which provides structural support and / or mechanical strength to provide self-supporting or self-supporting composite materials under a range of moisture contents and / or ambient relative humidity.

[0035] In compositions containing hygroscopic salts, ionomers can incorporate, retain, and / or encapsulate the hygroscopic salts within their charged polymer networks, and water vapor permeable polymers or supporting polymers can incorporate, retain, and / or encapsulate the salt-encapsulated ionomers within their porous structures to promote stable adsorption and desorption of water vapor, thereby reducing or avoiding leakage, spillage, swelling, or unstable states, in which moisture accumulates as droplets on the surface of the hygroscopic polymer composite and / or there is a loss of mechanical stability. In various systems and applications related to this technology, moisture beading on material surfaces can degrade performance, leading to instability and / or failure of the adsorbent material (and consequently, the application or device in which the adsorbent material is deployed). In one failure mode, the hygroscopic material (e.g., hygroscopic salts) can migrate or detach from its supporting material, resulting in irreversible loss. In the composite material of this technology, the ionomer material can absorb hygroscopic materials (e.g., deliquescent salts) and retain them in its ionomer matrix, thereby making the loss of hygroscopic materials recoverable.

[0036] In some embodiments, the composite material may include filler materials to provide additional water absorption capacity and / or mechanical strength, such as fibrous materials, clay materials, molecular sieves, silicates, polysaccharides, or combinations thereof. Other examples include cellulose, activated carbon, perlite, vermiculite, attapulgite clay, bentonite, montmorillonite clay, chitosan materials, or combinations thereof.

[0037] Ionomers and / or water vapor-permeable polymers can be selected for high mass transfer rates and high adsorption kinetics rates of water vapor within the composite material. Furthermore, ionomers and / or water vapor-permeable polymers can be selected to minimize the weight and / or density of the hygroscopic polymer composite while maintaining a reversible adsorption rate throughout the service life of the hygroscopic polymer composite. In one example, the water vapor-permeable polymer is a polymer foam configured to form around an ionomer incorporating a hygroscopic salt in a first state (e.g., a swollen or hyperswelled state), such that pores are formed or present when the ionomer incorporating the hygroscopic salt is in a second state (e.g., a shrinkage state or a swollen state with a lower moisture content than the first state).

[0038] In some hygroscopic polymer composites containing deliquescent or hygroscopic salts (e.g., calcium chloride, lithium chloride, etc.), the ionomer material can incorporate or confine the salt within the crosslinked network of its ionized units in the presence of water. A water vapor-permeable polymer material can act as a supporting polymer material, providing a porous matrix for structural support and / or mechanical strength to support the ionomer material incorporating the hygroscopic salt. The polymer network of the composite material can be tuned such that the techniques disclosed herein provide a support platform to retain water in the composite material without leakage or seepage within a range of environmental conditions (e.g., relative humidity fluctuations of 0-99% RH, 0-90% RH, 0-80% RH, and / or 0-60% RH). As a non-limiting illustrative example, the composition can be tuned for a desired humidity range, such as by adjusting the composition to contain 10-25 wt% (balance of deliquescent salts) of polymer (e.g., ionomer material) on a solids basis to avoid leakage at relative humidity below 80-90% RH. As another example, a composite composition based on a solid polymer (e.g., ionomer material) of 5-10% wt.% (balance: deliquescent salts) can be used to avoid leakage at relative humidity below 50-60% RH.

[0039] Previous methods of incorporating deliquescent or hygroscopic salts into polymer materials have been limited by poor containment, leakage, or loss of salt solutions, and therefore have limited feasibility and / or performance for various applications, such as water production systems and apparatus. The hygroscopic polymer composites of this technology exhibit no or low leakage, leakage, or loss of water or salt solutions even under high humidity conditions, such as after exposure to up to 60%, 80%, and / or 90% RH (depending on the conditioned composition) for at least 24, 48, and / or 72 hours, while maintaining mechanical integrity or self-supporting capacity (e.g., the composites exhibit no or minimal swelling). Furthermore, the hygroscopic polymer composites of this technology are resistant to solvation or “salting out” by hygroscopic or deliquescent salt solutions.

[0040] The composite material of this technology can comprise a miscible gel formed from a mixture of an ionomer material and a deliquescent salt. The deliquescent salt can be supplied as an aqueous solution to the ionomer material, and the miscibility of the ionomer material with the deliquescent salt solution can spontaneously generate a homogeneous gel mixture in response to changes in ambient relative humidity. This mixture can remain homogeneous (particularly to avoid leakage) as long as the volume of the desiccant liquid does not exceed the maximum absorbency of the polymer or the ionomer gel. Composite materials in the range of 10-20 wt.% polymer can be stable over a wide range of 0-90% RH. Furthermore, composite materials in the range of 5-10 wt.% polymer (i.e., ionomer material and / or water vapor permeable polymer, on a solids basis, with the balance being deliquescent salt) can be stable over a relative humidity range of 0-60% RH.

[0041] Hygroscopic or deliquescent salts can form stable aqueous solutions that are balanced to atmospheric relative humidity. Polymers, including polymers with ionic moieties (i.e., ionomers), can be removed from aqueous solutions by adding more water-soluble compounds, a process known as "salting out," in which an insoluble solid precipitate or a second liquid solution of higher concentration is formed, which is immiscible with the resulting salt solution. In the composites of this technique, the gel is preferably formed by uniformly dispersing the polymer material in a compatible solvent. To form a gel in a deliquescent salt solution, the gelling polymer needs to be soluble in the deliquescent salt solution. Furthermore, to maintain the hygroscopic properties of both the salt and the soluble polymer gelling agent (i.e., the ionomer), neither component should be consumed during mixing (e.g., via metathesis, such as that occurring in a mixture of calcium chloride and sodium alginate, forming sodium chloride and losing the original ion pairs). Therefore, the ionomer material, the hygroscopic salt, and the water vapor-permeable or supporting polymer material should be selected based on their chemical stability. For example, the mixing of these three components should not produce metathesis reactions that could consume these components.

[0042] The terms "hygroscopic medium" or "hygroscopic material" are used herein to describe functional materials involving the adsorption and desorption of water vapor. As used herein, the term "adsorption" means absorption, adsorption, or a combination thereof. In various implementations, ionomer materials may be referred to as hygroscopic materials because they are capable of adsorbing and desorbing water vapor due to the chemistry and / or structure of their polymer network. Furthermore, the term "hygroscopic material" may refer to a hygroscopic or deliquescent salt that may be present in some compositions of the art, as this salt is capable of absorbing moisture from the air and then dissolving in the absorbed water to form a solution. Additionally, the term "hygroscopic material" may refer to a hygroscopic salt incorporated into the polymer matrix of the ionomer material.

[0043] Various hygroscopic materials (including deliquescent salts) can be included in the hygroscopic polymer composites of this technology. Examples include lithium salts, calcium salts, potassium salts, sodium salts, magnesium salts, phosphates, organic salts, metal salts, ionic liquids, glycerols, glycols, or combinations thereof. Non-limiting examples of deliquescent or hygroscopic salts include calcium chloride, calcium bromide, magnesium chloride, magnesium sulfate, ammonium chloride, lithium bromide, lithium chloride, zinc bromide, sodium bromide, sodium chloride, sodium carbonate, lithium iodide, sodium iodide, sodium sulfate, potassium iodide, potassium carbonate, potassium iodide, potassium sulfate, potassium acetate, potassium bromide, zinc sulfate, combinations thereof, and / or derivatives thereof.

[0044] In some implementations, the hygroscopic polymer composite material may comprise a first hygroscopic or hydrophilic component, such as a deliquescent salt, incorporated into or within a second hygroscopic or hydrophilic component, which is an ionomer material, such as a cationic or anionic polymer. The ionomer material may have repeating units of both electrically neutral units and ionized units, wherein the ionized units may be covalently bonded to the polymer backbone as side-group portions and / or as ionized portions within the polymer backbone itself. The chemical composition of the ionomer material (e.g., the ionized units) may trap, entrain, or retain the hygroscopic salt in the ionomer matrix. In such implementations, the hygroscopic salt may be present in amounts of 1 to 80 wt.% of the ionomer material, 5 to 60 wt.% of the ionomer material, and / or greater than 20 wt.% of the ionomer material.

[0045] Figure 1AA schematic diagram of a hygroscopic polymer composite material 100 is depicted, comprising an ionomer material 120 contained within a plurality of pores or voids of a water vapor permeable polymer material 130. In some implementations, the ionomer material 120 and hygroscopic salts may be provided within the water vapor permeable polymer material 130. In a drier or shrinkage state 104, the ionomer material 120 has a low or reduced water content and its volume increases or swells to a swollen state 106 with a higher water content, for example due to an increase in relative humidity and / or a decrease in temperature. Similarly, the ionomer material 120 may decrease in volume from the swollen state 106 or shrink to the shrinkage state 104, for example due to a decrease in relative humidity and / or an increase in temperature. When the ionomer material expands and contracts during water vapor adsorption / desorption (i.e., water absorption and release), the water vapor permeable polymer 130 acts as a support polymer 130 by promoting a reversible water adsorption cycle, so as to maintain the mechanical stability of the composite material (e.g., no swelling of the composite material itself) and prevent leakage, seepage, or formation of liquid water under a range of environmental conditions (e.g., relative humidity fluctuations of 0-99% RH and 0-90% RH). Therefore, the composite material 100 itself remains mechanically stable as the ionomer material swells or expands with increasing water content.

[0046] In the super-swellable state 108, the ionomer material 120 can swell or expand to fill the pores or voids of the water vapor permeable supporting polymer material 130. The super-swellable state can be described as having such a high water content that water saturates the ionomer polymer beyond its maximum equilibrium water absorption under atmospheric conditions. In the super-swellable state 108, the composite material may lose the open pore volume that allows airflow through the hygroscopic polymer composite material and / or lose its mechanical integrity. Therefore, the composite material 100 can be chemically, compositionally, and structurally designed such that the operation of the device or system incorporating the composite material 100 can reversibly operate between the swollen state 106 and the contracted state 104, such that the volume change of the ionomer material 120 is supported by the mechanical integrity of the water vapor permeable supporting polymer network 130, allowing airflow for reversible water adsorption / desorption without leakage, seepage, or loss of liquid water under a range of environmental conditions (e.g., relative humidity fluctuations of 0-99% RH, 0-90% RH). Therefore, during normal operation of the system or device incorporating composite material 100, composite material 100 transitions between a shrinkage state 104 and a swelling state 106. If the composite material enters a super-swelling state 108 during operation of the system or device incorporating composite material 100, degradation or failure modes may occur.

[0047] However, it may sometimes be desirable to push the ionomer material to a super-swollen state (e.g., state 108). For example, the manufacturing process may include driving the ionomer material into a super-swollen state to form pores or voids within a water vapor-permeable supporting polymer matrix or foam. When used in a system or apparatus, these pores or voids become accessible pores or voids for airflow through the composite material. As the ionomer material 120 dries from the super-swollen state 108 to an equilibrium swollen state 106 or a drier (and also equilibrium) shrinkage state 104, permeable pores are established within the water vapor-permeable supporting polymer for the operational life of the composite material.

[0048] Figure 1B Another schematic diagram depicts a hygroscopic polymer composite material 100 comprising an ionomer material 120 within a water vapor permeable polymer material 130. In some implementations, the ionomer material 120 and hygroscopic salts may be provided within the water vapor permeable polymer material 130. In a drier or shrinkage state 104, the ionomer material 120 has a low or reduced water content and its volume increases or swells to a swollen state 106 with a higher water content, for example due to an increase in relative humidity and / or a decrease in temperature. Similarly, the ionomer material 120 may decrease in volume from the swollen state 106 or shrink to the shrinkage state 104, for example due to a decrease in relative humidity and / or an increase in temperature. As the ionomer material expands and contracts during water vapor adsorption / desorption (i.e., water absorption and release), the water vapor permeable polymer 130 also expands and contracts, providing elastic support and thus promoting reversible water adsorption cycles without leakage, seepage, or formation of liquid water under certain environmental conditions (e.g., relative humidity fluctuations of 0-99% RH and 0-90% RH). Therefore, the composite material 100 itself maintains mechanical stability as the ionomer material swells or expands with increasing water content.

[0049] Figure 2A Another schematic diagram depicts a hygroscopic polymer composite material 100 comprising a hygroscopic salt 110, the hygroscopic salt including mobile cations (e.g., Li) incorporated into the polymer matrix of the ionomer material 120. + Ca 2+ ) and mobile anions (e.g., Cl-) - ,Br -As an illustrative example, ionomer material 120 is depicted as a cationic polymer comprising fixed cationic units 122 of polymer chains (including crosslinks). Alternatively, anionic polymers may be employed without departing from the spirit and scope of this disclosure. Figure 2 depicts the reversible transformation or expansion to a second state (e.g., swollen state 106) of ionomer material 102, which has a low water molecule 112 content, when the ionomer material 102 incorporated with a hygroscopic salt is in a first state (e.g., shrinkage state 104), which has a higher water molecule 112 content.

[0050] Figure 2B Another schematic diagram depicts a hygroscopic polymer composite material 100 comprising an ionomer material 120 dispersed within or supported in a water vapor permeable polymer material 130 of a reinforcing fiber material 140 (e.g., carbon fiber, glass fiber). In some implementations, both the ionomer material 120 and a hygroscopic salt may be provided within the water vapor permeable polymer material 130. The water vapor permeable polymer 130 may also expand as the ionomer material expands and contracts between a first state (e.g., a contracted state 104) and a second state (e.g., a swollen state 106), potentially providing at least some elastic support, while the reinforcing fiber material 140 may provide mechanical stability during adsorption cycles. Furthermore, the reinforcing fiber material 140 may promote dimensional stability of the composite material at macroscopic scales (e.g., as an absorbent, tile, or other shaped component).

[0051] Ionomeric materials and / or hygroscopic salts (if present) can provide in the composite material a threshold determined by the leakage, swelling, or other stability characteristics of that particular material. Leakage, swelling, or instability conditions or states can occur when the hygroscopic material absorbs a sufficiently high amount of water to begin forming an aqueous solution that can irreversibly migrate from the hygroscopic polymer composite. The swelling and leakage instability of the ionomeric material at high water content can be mediated or eliminated by the ionomeric polymer, water vapor permeable polymer, and / or supporting polymer framework, thereby maintaining the mechanical stability and accessibility of the pores or voids of the composite material in the absence of leakage. For example, the solubility of the ionomeric polymer and / or water vapor permeable polymer in the deliquescent salts of the composition can prevent leakage even at high relative humidity. Therefore, pressure drop across the composite material can be minimized and / or degradation or failure of the system in which the composite material is deployed can be avoided.

[0052] A higher content of ionomers and / or hygroscopic salts (if present) in the composite material can support a greater amount of water adsorption; however, at lower total water content in the composite, it can also drive leakage, swelling, or instability conditions. In one instance, at a lower ratio of absorbed water to hygroscopic material, the hygroscopic polymer composite can bind water more strongly, and therefore, more energy may be required to desorb the 'lower grade' or more strongly bound water. In other words, the water vapor pressure of the hygroscopic polymer composite at higher water content (e.g., at high relative humidity and / or low ambient temperature) may require less energy to desorb (i.e., with lower binding energy), while the water vapor pressure of the hygroscopic polymer composite at lower water content (e.g., at low relative humidity and / or high ambient temperature) may require more energy to desorb (i.e., with higher binding energy).

[0053] This document provides various illustrative examples of ionomer materials that can be used in hygroscopic polymer composites. In a preferred embodiment, the ionomer material is provided as a cationic polymer having a monovalent anion such as a halide anion (e.g., chloride ion, bromide ion) to drive the hygroscopic properties. However, anionic polymer materials can be used as ionomer materials in hygroscopic polymer composites, such as calcium alginate or sodium alginate ionically crosslinked by multivalent cations, but other monovalent cations (including ionic liquid cations) can reduce hygroscopic properties relative to monovalent anions (e.g., chloride anions in cationic polymer materials).

[0054] This document provides two exemplary cationic polymer materials based on polydiallyl dimethylammonium chloride (poly-DADMAC) and modified chitosan to illustrate the opportunities presented by incorporating them into composites, as well as their tunability or possible variations, analogues, and derivatives (e.g., through hydrophilic functionalization, cross-linking structures, etc.). However, a variety of other cationic or anionic polymer materials can be used as ionomer materials in hygroscopic polymer composites and can be logically, chemically, compositionally, and otherwise modified without departing from the spirit and scope of this disclosure. For example, ionomer materials based on polyamides, polyacrylamides, polysaccharides, polycarbonates, polyisocyanates, polyepoxides, polyurethanes, peptides, alginates, and / or derivatives and combinations thereof can be used as ionomer materials in hygroscopic polymer composites. Furthermore, various cationic or anionic polymers can be functionalized to increase hygroscopicity, for example via quaternization and / or hydroxyl groups.

[0055] An exemplary polydiallyldimethylammonium chloride (poly-DADMAC) ionomer material comprises repeating units of diallyldimethylammonium chloride (DADMAC) monomers linked together via carbon bonds to form polymer chains. The structure of poly-DADMAC can vary depending on the degree of polymerization, degree of crosslinking, polymerization process, and the crosslinking and functionalizing agents used, and provides a platform to illustrate the functionality of ionomer materials in hygroscopic polymer composites used in this technology.

[0056] In one example, the hygroscopic properties of an ionomer material can be tuned by altering the degree of crosslinking (i.e., the extent of chemical bonds formed between polymer chains that form a three-dimensional polymer network, quantified as a percentage of crosslinks relative to the total number of available binding sites). Ionomer materials (e.g., poly-DADMAC) can be crosslinked at less than 3 mol%, less than 5 mol%, and / or less than 10 mol% to set a sufficiently high water sorption capacity for use as ionomer materials in composites of this technology. Increased crosslinking (e.g., greater than 10%, greater than or equal to 20%) can reduce swelling but also decrease the water sorption capacity. Because water vapor can permeate the porous matrix supporting the polymer material, supporting the volume change of the ionomer material during adsorption cycles, it is preferable to maintain a crosslinking degree of the ionomer material equal to or less than 10% to maintain hygroscopicity. However, there are implementations where the ionomer material and the supporting material are chemically similar but modified or altered to give the ionomer material high hygroscopicity and the supporting material high mechanical strength. As an illustrative example, the composite material may contain an ionomer material (including poly-DADMAC with 5% crosslinking) and a poly-DACMAC support material with 20% crosslinking.

[0057] Figure 3A An exemplary chemical structure of poly-DADMAC, comprising a piperazine-onium crosslinking agent, is depicted for use as an ionomer material in hygroscopic polymer composites. Various modifications or functionalizations of poly-DADMAC are possible, for example, to increase the hydrophilic properties of the ionomer material. As an illustrative example, Figure 3B Hydroxyl-functionalized poly-DADMAC ionomer materials are described, specifically dihydroxymethyl-functionalized poly-DADMAC containing a piperazine-onium crosslinking agent. The hydroxyl-functionalized poly-DADMAC can increase its hydrophilicity. However, other functional groups, including amines and quaternary ammonium compounds, can be used to increase its hygroscopic properties.

[0058] Hydroxymethyl-functionalized poly-DADMAC can be synthesized via the polymerization of hydroxymethyl DADMAC monomers. Figure 7AThese are typical NMR spectra of hydroxymethyl DADMAC monomers, particularly diallyl diethanolamine chloride. Diallyl diethanolamine chloride can be synthesized by extending the reaction time (e.g., greater than 65 hours) of diethanolamine with allyl chloride in warm ethanol in the presence of sodium bicarbonate, resulting in a near-quantitative yield of 100%.

[0059] As another illustrative example, Figure 3C The chemical structures of poly-DADMAC ionomers, including those with additional quaternary ammonium functionalization and hydroxyl functionalization, specifically 2-hydroxyethyl-N,N-dimethylamine-onium methyl chloride-functionalized polydiallyl dimethylammonium chloride (poly-DADMAC), are described. In addition to hydroxyl groups, additional quaternary ammonium groups are introduced to increase the cationic charge density and thus enhance hydrophilicity. Other types of functionalization can also tune the hygroscopicity of the ionomer material depending on the desired properties and applications. For example, poly-DADMAC can be copolymerized with other monomers or polymers to drive hydrophilic properties and / or other desired properties. Furthermore, depending on the specific application, poly-DADMAC can be grafted onto other polymers or surfaces.

[0060] Figure 3C An example of a poly-DADMAC ionomer material, including quaternary ammonium-functionalized and hydroxyl-functionalized materials, is shown; however, many other structures are possible. For example, the poly-DADMAC ionomer material may have larger or more complex polymer branches, such as polyhydroxy or polycationic branches, at the diallyl ammonium position.

[0061] Figure 3A Hydroxymethyl-functionalized poly-DADMAC ionomers can be synthesized from diallyl dimethylammonium chloride (DADMAC) monomers via different polymerization pathways. Figure 4 In the examples, Figure 3A The poly-DADMAC ionomer material shown is synthesized via polymerization of DADMAC monomers and piperazine-onium crosslinking agents such as 1,1,4,4-tetraallypropylpiperazine-onium dichloride crosslinking agent. The use of tetraallypropylpiperazine-onium crosslinking agent increases the interchain distance in the polymer and thus improves the hygroscopicity of the ionomer material.

[0062] Figure 7BThis is an example of a typical NMR spectrum of a 1,1,4,4-tetraallylpiperazine dichloride crosslinking agent that can be synthesized in two steps. In the first step, the monoquaternized intermediate 1,1,3-triallylpiperazine dichloride can be prepared by extending the reaction time (e.g., greater than 40 hours) of piperazine with allyl chloride in warm ethanol in the presence of sodium bicarbonate. In the second step, the obtained monoquaternized triallyl intermediate can undergo a second quaternization with allyl chloride under heat in a pressurized vessel for an extended period (e.g., greater than 72 hours), resulting in an overall yield of greater than 70% for the two-step synthesis.

[0063] Depending on the desired properties and application of the ionomer in the composite material, different crosslinking agents can be used. While different allyl or divinyl crosslinking agents can produce more rigid and stable polymer structures, the interchain distance within the polymer can alter the hygroscopic capacity of the ionomer. Figure 5 In an illustrative example, another poly-DADMAC ionomer material is synthesized via polymerization of DADMAC monomer, tetraallyl ammonium crosslinking agent, and 2,2'-azobis(2-methylpropanediamine) dihydrochloride free radical initiator, which can reduce the interchain distance and thereby reduce the hygroscopicity of the ionomer material.

[0064] As another illustrative example, Figure 6A The synthesis of a long-chain tetraallyl-substituted diamidinium crosslinking agent from diallylamine and N,N'-bis(epoxyethylenemethyl)-N,N,N',N'-tetramethyl-1,6-hexanediamine onium dichloride is described. This agent can be used in polymerization reactions to form hydroxyammonium onium-functionalized poly-DADMAC ionomers, specifically 2-hydroxyethyl-N,N-dimethylamine onium methyl-functionalized poly-DADAMAC containing... Figure 6B The long-chain tetraallyl-substituted crosslinking agent shown is used to modify the poly-DADMAC polymer chains by functionalizing them to include additional quaternary ammonium groups that increase cationic charge density and hydroxyl groups that increase hydrophilicity. Furthermore, the long-chain crosslinking agent increases the interchain distance (e.g., forming “cages” between the poly-DADMAC polymer chains that accommodate more water molecules) to further increase the hygroscopic capacity of the ionomer material.

[0065] Cationic polymeric materials based on modified polysaccharides (particularly chitosan) are now provided as another exemplary ionomer material that can be used in hygroscopic polymeric composites of this technology. Figure 8A In the example shown in -C, preparation Figure 8A The ammonium-functionalized chitosan material shown is such that the permanently positively charged quaternary ammonium groups are substituted at the 2-amino / 2-acetamino positions in the polymer.

[0066] Figure 8AAn ammonium-functionalized chitosan ionomer precursor material is described, produced by substitution with trimethylammonium glycidyl chloride. In this illustrative example, the high molecular weight chitosan is unsubstituted to leave one available amino group (-NH2) per 15 monomer units. Figure 8C The ionomer material containing cross-linked ammonium-functionalized chitosan shown can be used... Figure 8A Ammonium-functionalized chitosan and diamineonium diepoxide crosslinking agent, such as Figure 8B The polymerization synthesis of the N,N'-bis(epoxyethylenemethyl)-N,N,N',N'-tetramethyl-1,6-hexanediamine dichloride crosslinking agent shown. Figure 8B The diamineonium diepoxide crosslinking agent is provided as an example; however, other straight-chain, branched, and / or heterocyclic diepoxides may be used.

[0067] In the exemplary synthesis methods of the dicyclic oxide crosslinking agents that can be used herein, Figure 8B The diamineonium diepoxide crosslinking agent can be produced in aqueous solution from commercially available N,N,N',N'-tetramethyl-1,6-diaminohexane. The aqueous solution of N,N,N',N'-tetramethyl-1,6-diaminohexane can be cooled (e.g., via an ice bath), and a 3-molar excess of epichlorohydrin can be added dropwise. The resulting emulsion can be stirred in a water bath for an extended period (e.g., more than 19 hours) until the emulsion becomes a clear solution. The mixture can be extracted once or multiple times with ethyl acetate to remove excess epichlorohydrin to produce an aqueous solution of N,N'-bis(epoxyethylenemethyl)-N,N,N',N'-tetramethyl-1,6-hexanediamineonium dichloride.

[0068] In some embodiments, the composite material may include filler materials, such as fibrous materials, clay materials, molecular sieves, silicates, polysaccharides, or combinations thereof. As an illustrative example, hygroscopic salts and clay fillers may be included in a composite material containing… Figure 8C In the exemplary cross-linked ammonium-functionalized chitosan composite material shown, the first synthesis step or operation may include reacting trimethylammonium glycidyl chloride and chitosan in an aqueous solution by heating (e.g., > 80°C) and stirring to form Figure 8A Ammonium-functionalized chitosan ionomer precursor. Figure 8AAmmonium-functionalized chitosan ionomer precursors, hygroscopic salts (e.g., calcium chloride), and clay materials (e.g., montmorillonite clay) can be reacted in an aqueous solution in a single step by heating (e.g., > 80°C) and stirring to form an ionomer material containing clay material filler and incorporating hygroscopic salts. The composite material can then be prepared by mixing the hygroscopic salt-incorporated ionomer material containing clay material filler with a component of a water vapor permeable polymer material. For example, the water vapor permeable polymer component can be provided as a polyisocyanurate foam by reacting a first component containing an isocyanate and a second component containing a polyol.

[0069] The composition or relative amount of each component in the composite material can be set according to the desired hygroscopicity and the application or use. Typically, the composition of the composite material may contain 20 to 50 wt% (w / w) of a water vapor permeable polymer. As another example, the amount of ionomer material in the composite material may range from 20% to 50% by weight (e.g., poly-DADMAC, modified chitosan), 10% to 40% by weight of a hygroscopic salt (if present), and 20% to 50% by weight of a filler (if present).

[0070] In the hygroscopic polymer composites of this technology, the water vapor permeable or supporting polymer material may include a chemical, structural, and / or pore distribution to support the ionomer material and hygroscopic salt (if present), such that water obtained by the ionomer material and / or hygroscopic salt across a range of water contents and / or relative humidity is contained within the supporting polymer matrix without leaching liquid water from the composite material. In some implementations, the water vapor permeable or supporting polymer material is configured as a polymer foam formed around the ionomer material and hygroscopic salt (if present).

[0071] Exemplary polymer foam materials based on polyisocyanurate or polyurethane are provided herein; however, a variety of other supporting polymer materials can be used in the hygroscopic polymer composites of this technology, and logical, chemical, compositional, and other changes can be made without departing from the spirit and scope of this disclosure. Various supporting polymer materials based on polyisocyanurate, polyurethane, polyimide, phenolic resin, etc., can be used in the hygroscopic polymer composites of this technology.

[0072] The amount of water vapor permeable polymer material in hygroscopic polymer composites can vary based on one or more specific ionomer materials and / or hygroscopic salts (if present). However, the composition range of composites of this technology is typically between 15 wt% and 70 wt% of water vapor permeable polymer, and / or 10 wt.% to 50 wt.% of ionomer polymer, and / or 5 wt.% to 40 wt.% of hygroscopic salts (if present).

[0073] In some implementations, the water vapor permeable polymer material can be selected, modified, or functionalized depending on the application or use of the composite material. In one instance, the water vapor permeable polymer material can be provided as or include a hydrophobic polymer and can at least partially resist water adsorption in order to maintain the structural integrity of the composite material when exposed to moisture. Some exemplary hydrophobic polymer foams that can be included in the composite material include polyurethane (PU) foam, polyisocyanurate (PIR), polyethylene (PE) foam, polypropylene (PP) foam, polystyrene (PS) foam, polyvinyl chloride (PVC) foam, derivatives thereof, or combinations thereof.

[0074] Various methods can be employed to manufacture the aforementioned hygroscopic polymer composite material. In some implementations, the ionomer material, and in some embodiments incorporating hygroscopic or deliquescent salts, can be produced separately and then mixed with or otherwise combined with the water vapor permeable polymer material. In other implementations, the ionomer material, the water vapor permeable polymer material, and the precursors and / or monomers of the hygroscopic salt (if present) can be synthesized or reacted simultaneously.

[0075] In one example, a water vapor permeable polymer foam can be formed around a portion (e.g., fragments, particles, clumps, etc.) of an ionomer material (which may or may not have hygroscopic salts bound therein). In this implementation, the ionomer material can be provided in a super-swollen state (which may or may not have hygroscopic salts bound therein), and a water vapor permeable polymer foam can be formed around the super-swollen ionomer material. The super-swollen state can be described as having such a high water content that water saturates the ionomer polymer (and, if present, hygroscopic salts) beyond the maximum equilibrium water absorption under atmospheric conditions (e.g., 30%, 60%, or 90% RH at 25°C). When in the super-swollen state, the ionomer material (and the bound hygroscopic salts, if present) can have so much water that it swells or expands, such that when water is lost to equilibrium, the composite material including the support material has an open pore volume to allow airflow through the hygroscopic polymer composite material. When the ionomer material (and any associated hygroscopic salts, if present) is dried to, for example, an equilibrium swollen or shrunken state, permeable pores can be formed within the water vapor-permeable polymer foam of the hygroscopic polymer composite.

[0076] Ionomeric materials (including bound hygroscopic salts, if present) can be placed in different swelling states or degrees of swelling during the preparation or manufacture of the composite material. When exposed to air at a predetermined relative humidity (%RH) and temperature, the ionomeric material can reach a predetermined equilibrium swelling state. Furthermore, during manufacturing operations, the ionomeric material can be pushed beyond its equilibrium swelling state, such that the degree of swelling or volume change is greater than that achieved by absorbing atmospheric water vapor (e.g., via contact with liquid or aqueous solutions). In the method of preparing the composite material, the operation may include contacting the ionomeric material with a hygroscopic salt solution until a super-swelling state is reached. A predetermined super-swelling state, saturating the ionomeric material under atmospheric conditions beyond its maximum equilibrium water absorption rate, can be set to ensure sufficient space is provided in the composite pores to allow airflow through the composite material.

[0077] In another exemplary method for preparing or manufacturing the composite material, the ionomer (which may or may not have a hygroscopic salt incorporated therein) can be anchored to the water vapor permeable polymer material, for example, by copolymerization of the monomers of the ionomer (or its polymer) with the supporting polymer material. In this implementation, the monomers of the ionomer (or its polymer) may contain functional groups reactive to the supporting polymer material. For example, the functional groups of the monomers of the ionomer (or its polymer) may be selected from the group of nucleophilic groups, such as primary or secondary amines, primary or secondary alcohols, primary or secondary thiols, or combinations thereof. As another example, the supporting polymer material may be selected from the group of electrophilic groups: isocyanates, epoxides, activated carboxyl groups, active haloalkanes, or combinations thereof. Furthermore, the method may include reacting a first monomer of the ionomer containing the hygroscopic salt with a second ionomer or non-ionomer monomer.

[0078] Water vapor permeable polymer materials or supporting polymer materials can be prepared by reacting a first component containing an isocyanate (e.g., methylene diphenyl diisocyanate (MDI)) with a second component containing a polyol. In embodiments where the supporting polymer material is polyurethane foam, the amount of the isocyanate component is less than or equal to 105% of the stoichiometric amount of the polyol component, while polyisocyanurate supporting polymer materials can be prepared at a greater ratio (e.g., the isocyanate component is greater than 105% relative to the polyol component). In some preparation methods, a foaming agent used in the preparation process can generate and stabilize the porous matrix of the supporting polymer material by producing bubbles. The foaming agent can be a physical and / or chemical foaming agent, such as water, carbon dioxide, carbonates such as sodium bicarbonate or ammonium bicarbonate, hydrogen-producing metals such as aluminum, azodicarbonamide (ADC), hydrochlorofluorocarbons (HCFCs), and / or hydrofluorocarbons (HFCs) can be used in the production of this composite material. Furthermore, various catalysts and / or surfactants can be used to form the supporting polymer material. Depending on the desired performance and specific application, various preparative modifications can be used, such as temperature variations between catalyst type, thermally activated polymerization (e.g., > 80°C), and room temperature polymerization.

[0079] The mixture of isocyanate and polyol components can be referred to as a support material precursor mixture, which can be combined with the ionomer material in a stepwise or one-step manner. In a preferred synthetic method for preparing the composite material of the present invention, for example, water vapor-permeable polymer synthesis (e.g., polymerization) is carried out while the ionomer polymer (and the hygroscopic salt therein, if present) is in a super-swollen state, in order to construct a porous matrix of the composite material to allow for airflow and / or porous structural framework that promote reversible adsorption / desorption cycles during normal operation or use.

[0080] This hygroscopic polymer composite material can be manufactured with a porous structure, which, depending on the application, may include hierarchical porosity, a network of pores, etc. In some implementations, the production method may include the use of foaming agents, blowing agents, or aerating agents and / or physical molding or templates. Depending on the surrounding environment at the planned use and / or installation location, the formulation of the hygroscopic polymer composite material can be modified and may include various additives to adjust porosity, mechanical strength, thermal conductivity, and / or the stability of water vapor adsorption / desorption reversibility for a specific environment and / or application.

[0081] The porosity of water vapor permeable or supported polymer materials can be adjusted by the water content during synthesis, the amount of ionomer material present, the reaction temperature, one or more foaming agents, and / or by including one or more surfactants. Depending on the application, the pore size of the composite material and / or water vapor permeable or supported polymer material can range from 50 micrometers (µm) to 3 millimeters (mm). Furthermore, the composite material and / or water vapor permeable polymer material can have a pore structure that can be hierarchically porous (e.g., microporous, mesoporous, and / or microporous), with pore sizes from about < 2 nm (micropores) to about 50 µm (mesopores) and up to the millimeter scale (macropores).

[0082] In some embodiments, agents for controlled bubble formation, foaming, and / or mixture expansion may be used. For example, foaming agents, bubbling agents, aerators, or expanding agents may include one or more materials to control the dispersion of components in the mixture, bubble size, and / or the expansion of the mixture. In examples, surfactants (e.g., anionic surfactants, cationic surfactants, nonionic surfactants, functionalized polymers, etc.) may be combined with another foaming agent to act as stabilizers. In various examples, agents for controlling bubble formation may include nonionic surfactants (e.g., cocoamides, ethoxylates, or alkoxylates, polyethylene oxides), anionic surfactants (e.g., gluconates, sulfonates, or sulfates), or cationic surfactants (e.g., alkylammonium chloride-based surfactants). Surfactants may be provided during mixing to form foam or pre-foamed surfactants may be provided before mixing with other components of the composite material.

[0083] As an example Figure 9A A photograph is shown of a hygroscopic polymer composite comprising a functionalized chitosan-based ionomer material and a polyisocyanurate-based supporting polymer material including a microporous matrix. As another illustrative example, Figure 9BA photograph is shown of a hygroscopic polymer composite body comprising a poly-DADMAC-based ionomer and a polyisocyanurate-based supporting polymer, wherein the poly-DADMAC-based ionomer is incorporated with calcium chloride salt, and the supporting polymer includes a microporous / microporous matrix and central template pores or voids.

[0084] Figure 9B -D shows a photograph of a hygroscopic polymer composite containing a poly-DADMAC-based ionomer material incorporating calcium chloride salt and a polyisocyanurate-based supported polymer material. To illustrate the possible variations in the formation of larger pores or pore sizes within the hygroscopic polymer composite, Figure 9B This illustrates airflow passing through a single central pore of the hygroscopic polymer composite body. Figure 9C This illustrates how multiple pores or voids are formed using template pins (black), and Figure 9D This illustrates a hierarchical porous hygroscopic polymer composite body containing large pores or voids after the template pins have been removed.

[0085] Figure 10 Enlarged photographs are shown of hygroscopic polymer composites comprising functionalized chitosan-based ionomers and polyisocyanurate-based supporting polymers. (See also...) Figure 10 As can be seen, the supporting polymer material 130 is a polymer foam formed around the ionomer material 120 to support volume changes (e.g., from transition to a swollen to a contracted state) during water absorption and release.

[0086] The density or weight of porous moisture-absorbing composites can be preferably minimized, for example, by changing the composition and / or adjusting the pore structure. In different embodiments, porous moisture-absorbing composites exhibit values ​​ranging from 50 to 800 kg / m³. 3 Between 100-500 kg / m 3 Between and less than 800 kg / m 3 Less than 500 kg / m 3 Less than 400 kg / m 3 and / or less than 200 kg / m 3 The density. In examples, a lower density threshold can be set by determining the minimum composite density based on water adsorption or retention capacity (e.g., measured from isotherms) to determine the minimum desired water mass absorption or adsorption capacity for a specific purpose or application. For example, the supporting polymer content can be varied between 20-50 wt.% to set the density from 450 kg / m³. 3 Up to 150 kg / m 3 .

[0087] The water absorption rate and capacity of a composite material can be modified based on its formulation. This ionomer material can rapidly absorb and retain large amounts of water, even exceeding its own weight (e.g., from minutes to hours, depending on the specific formulation, particle size, pore structure, thickness, etc.). However, it is possible that the formulation of this composite material can be modified to include hygroscopic or deliquescent salts (e.g., to increase its water storage capacity). As an illustrative example, Figure 11 The water adsorption isotherm measurements at 25°C are shown for A) a 2 mol% crosslinked poly-DADMAC ionomer material and B) the same poly-DADMAC ionomer material bound with 80 wt.% calcium chloride. The isotherm plots show the equilibrium water content of the composites at a specific relative humidity of the ambient environment. The shrinkage state of the composites can be defined relative to the shrinkage state at a higher water content (e.g., in…). Figure 11 The swelling state defined by a higher %RH on the isotherm has a lower or reduced water content (e.g., at...). Figure 11 The state of being at a lower %RH on the isotherm.

[0088] like Figure 11 As shown, the addition of hygroscopic salts can double or even double the water storage capacity of the composite material while maintaining mechanical integrity without leakage. Even with high levels of calcium chloride in the composite material, it is noteworthy that the composite material can maintain a balanced water content (through the three-dimensional polymer network of the ionomer and supporting polymer materials) without leakage, seepage, formation, or loss of liquid water, even at high equilibrium water contents. In some applications, an upper limit for the hygroscopic salt content can be preferably set; for example, for systems or devices exposed to greater than 90% RH, the hygroscopic salt content in the composite material can be set to 60 wt.% or less.

[0089] The hygroscopic polymer composite of this technology can retain a large amount of water in a highly reversible manner, ensuring that the composite does not leak, seep out, or lose liquid water (and / or hygroscopic salt solutions, if present) during water vapor adsorption / desorption cycles across a range of environmental conditions. To illustrate the water adsorption capacity of the exemplary poly-DADMAC composite described herein, Figure 12 The diagram shows the reversible water vapor adsorption cycle of (A) the hygroscopic polymer composite material relative to (B) its constituent ionomer material and (C) its constituent supporting polymer material at 60% RH and 25°C. Figure 12 (A) The hygroscopic polymer composite material exhibits properties close to Figure 12 (B) shows the water absorption capacity of the individual ionomer material while having the characteristic mechanical integrity provided by the supporting polymer material.

[0090] The reversible water adsorption capacity and cycling behavior can be tuned by adjusting the composition of the ionomer material, the supporting polymer, and the hygroscopic salt (if present), depending on the application and use of the composite material. For example, depending on the chosen composition, the hygroscopic polymer composite of this technology can exhibit reversible water adsorption capacities exceeding 10%, 20%, 40%, or 60% (m / m0) by mass of the composite material at 60% RH and 25°C. To illustrate the adjustability in the adsorption / desorption cycle, Figure 13A An exemplary hygroscopic polymer composite material is shown for water vapor adsorption or water absorption at 60% RH and 25°C. This composite material contains hygroscopic salts incorporated in a poly-DADMAC ionomer material supported by (A) 20 wt% polyisocyanurate foam-supported polymer and (B) 30 wt% polyisocyanurate foam-supported polymer. Higher amounts of ionomer material (and hygroscopic salts, if present) relative to the supporting polymer in the composite material can increase water adsorption capacity; however, a trade-off may exist regarding mechanical integrity. Therefore, the composition of this composite material can be varied depending on the desired application, use, environmental conditions, and / or cycle life.

[0091] As another example, to illustrate the tunable water adsorption properties of the composite material described herein, Figure 13B The illustration shows water vapor adsorption or water absorption at 60% RH and 25°C for exemplary hygroscopic polymer composites (A) with calcium chloride hygroscopic salt and (B) in the absence of hygroscopic salt (i.e., composites containing poly-DADMAC ionomer material and polyisocyanurate foam-supported polymer). As another example illustrating the tunability of composite composition, Figure 13C Exemplary hygroscopic polymer composites (A) and (B) incorporating ionomer materials (poly-DADMAC) with 20 wt.% supporting polymer (polyisocyanurate foam) and 60 wt.% hygroscopic salt (calcium chloride) are shown for water vapor adsorption or water absorption at 60% RH and 25°C.

[0092] To provide additional characteristic properties of the composite material described herein, the swelling rate of the composite material can be defined as the sample weight, %RH, or water content at a given time divided by the initial dry sample weight. Due to the composite structure including a porous support polymer matrix that supports the volume change of the ionomer material during water adsorption cycling, the composite material of this technology can exhibit a swelling rate of less than 0.01%, 0.1%, 0.5%, 1%, and / or 5% by weight when exposed to 90%RH for at least 12, 24, 48, and / or 72 hours. As another exemplary feature of the composite material of this technology, the composite material can lose (e.g., through leakage, seepage, elution) less than 0.01%, 0.1%, 0.5%, 1%, and / or 5% by weight of liquid water and / or hygroscopic salt solution (if present) at 90%RH for at least 24, 48, and / or 72 hours. However, the composite material of this technology can be designed and does not exhibit leakage or salt migration during cycling.

[0093] The mechanical strength of hygroscopic polymer composites can be adjusted based on the surrounding environment at the end-use and / or installation location. The supporting polymer material can be provided as or comprise a semi-rigid or rigid polymer foam. In examples, the supporting polymer material can exhibit an elastic modulus between 60 and 700 MPa, between 60 and 700 MPa, between 68 and 690 MPa, and / or greater than 60 MPa. Furthermore, the supporting polymer material can exhibit compressive strengths of 100 to 1000 kPa, 100 to 200 kPa, 110 to 172 kPa, and / or greater than 100 kPa.

[0094] The hygroscopic polymer composites of this technology can exhibit mechanical stability, enabling them to be independent, self-supporting, or self-supporting under both dry and wet conditions. While the water vapor permeable polymer material in the hygroscopic polymer composites can provide mechanical stability during adsorption cycles and thus act as a supporting polymer, some compositions may include mechanical reinforcement materials such as reinforcing fibers like carbon fibers, glass fibers, woven fibers, mats, etc.

[0095] This disclosure relates to a new class of hygroscopic polymer composites with unique water vapor adsorption and desorption properties, providing stable performance without leakage under a range of environmental conditions. Therefore, these materials can be deployed in a wide range of applications, such as thermal management or passive cooling systems, humidity control systems, air-derived water generation systems, and / or dehumidifiers. The materials and compositions of this technology can be deployed in both established and novel applications that can benefit from effective thermal insulation, passive cooling, thermal regulation, mechanical strength, and / or stable and reversible water vapor adsorption and desorption properties.

[0096] This document provides various illustrative applications of the described hygroscopic polymer composites, such as coatings for passive cooling of solar panels and water generation systems. However, the hygroscopic polymer composites of the present invention can be deployed in a variety of other systems that can benefit from reversible water adsorption / desorption without leakage under a range of environmental conditions without departing from the spirit and scope of this disclosure.

[0097] Figure 14A A cross-sectional view of a solar panel 200 comprising multiple solar cells 202 is shown. Each solar cell may include a front side facing the sun during daytime operation to convert solar radiation irradiated thereon into electricity and heat, and a back side opposite the front side. The solar panel 200 may include a transparent cover 202 above or on the front side of the solar cells 202, the transparent cover may include glass or a transparent polymer material. A backplate 206 may be disposed on or facing the back of the solar cells 202. A sealant 208 may bond the solar cells 202, the transparent cover 204, and the backplate 206 together in a protective encapsulation. The solar panel 200 may further include a tile or coating 210 located on the back of the panel, the tile or coating comprising a hygroscopic polymer composite material of the present technology. Since the latent heat of water evaporation can be used to absorb the heat generated by the solar panel during operation (e.g., during daytime operation), the water evaporated by the hygroscopic polymer composite of the tile or coating 210 can improve the efficiency of the solar panel, thereby reducing its operating temperature.

[0098] The hygroscopic polymer composite tile or coating 210 may include an ionomer material and a water vapor permeable polymer material, and the water vapor permeable polymer material may support the volume change of the ionomer material (and hygroscopic salts, if present) between a first state (e.g., a contracted or low-moisture-content state) and a second state (e.g., a swollen or high-moisture-content state). The hygroscopic polymer composite tile or coating 210 may receive heat generated by solar panels during daytime operation, causing water to evaporate from the hygroscopic polymer composite tile or coating 210 into the surrounding environment as it transitions from a swollen state to a contracted state.

[0099] In some implementations, the hygroscopic polymer composite tile or coating 210 may include one or more additives to increase thermal conductivity. For example, a variety of fillers, fibers, or other additives to increase thermal conductivity can be provided, such as metal powders, particles, microparticles, or nanoparticles (e.g., aluminum, copper, silver), metal oxides (e.g., alumina, zinc oxide, boron nitride), carbon-based materials (e.g., graphite, graphene, carbon nanotubes, carbon fibers), ceramic materials (e.g., aluminum nitride, silicon carbide, boron nitride), polymer fibers or whiskers (e.g., polyaramid, polyester), or combinations thereof. The amount of thermally conductive additives can range from 2 wt.% to 50 wt.% or 5 wt.% to 40 wt.% of the composite material, depending on the desired application. As an illustrative application, the hygroscopic polymer composite of this technology can be used to cool photovoltaic panels to reduce operating temperatures and increase efficiency. In such applications, it may be preferred to include one or more thermally conductive additives in amounts at the higher end of this range, such as greater than 10 wt% in the composite material, greater than 20 wt% in the composite material and / or greater than 30 wt% in the composite material.

[0100] Figure 14BAnother example is shown, in which the solar panel 200 includes a multilayer coating on a backsheet 206. An inner layer 212 may contact or be applied to the solar panel backsheet 206, and an outer layer 214 may contact or be applied to the inner layer 212, such that the outer layer 214 is exposed to the surrounding environment. The outer layer 214 may comprise an ionomer material (and hygroscopic salts, if present) and a water vapor-permeable polymer material, such that the outer layer 214 absorbs water vapor from ambient air during nighttime and receives heat generated by the solar cells 202 during daytime operation. In one example, the inner layer 212 may have a higher thermal conductivity than the outer layer 214. The outer layer 214 may receive heat generated by the solar cells 202 during daytime operation via the inner layer 212 to reduce the operating temperature of the solar panel 200, thereby increasing the operating efficiency of the solar panel. In this implementation, the inner layer 212 may comprise a thermally conductive material. The inner layer 212 may comprise a polymer material including fillers, fibers, or other additives to increase its thermal conductivity. Non-limiting examples of fillers, fibers, or other additives that increase thermal conductivity include metal powders, particles, microparticles, or nanoparticles (e.g., aluminum, copper, silver), metal oxides (e.g., alumina, zinc oxide, boron nitride), carbon-based materials (e.g., graphite, graphene, carbon nanotubes, carbon fibers), ceramic materials (e.g., aluminum nitride, silicon carbide, boron nitride), polymer fibers or whiskers (e.g., polyaramid, polyester), or combinations thereof. The inner layer 212 and outer layer 214 may comprise similar polymeric materials (e.g., both layers may comprise a hygroscopic polymer composite). In other implementations, the inner layer 212 and outer layer 214 may comprise different polymeric materials (e.g., the inner layer 212 comprises an epoxy-based thermally conductive binder containing conductive fillers and the outer layer 214 comprises a hygroscopic polymer composite of the present technology).

[0101] Solar or photovoltaic (PV) panels typically include an outer backsheet layer (e.g., layer 206) that comprises a core or inner layer of a fluoropolymer (e.g., polyvinylidene fluoride (PVF), polyvinylidene fluoride (PVDF)) and often includes polyethylene terephthalate (PET) or ethylene vinyl acetate (EVA). EVA is also commonly used as a sealant, for example, as a sealant layer 208.

[0102] Solar or photovoltaic (PV) panels degrade over time due to a variety of factors related to their operation in the field. These factors include prolonged exposure to ultraviolet radiation, which leads to degradation of panel materials, including sealants and backsheets, and temperature cycling, which causes constant expansion and contraction, resulting in panel stress that can lead to microcracks and / or delamination of the encapsulation and backsheet layers. Furthermore, solar cells may degrade over time due to environmental factors, potential-induced degradation (PID), or other electrical degradation mechanisms that may cause corrosion, increased resistance, or shunt currents that may reduce overall panel performance over time.

[0103] As an illustrative example, Figure 15A A photograph shows a hygroscopic polymer composite material formed as a layer (e.g., a tile or coating that can be applied to the back surface of a solar cell or panel), the layer comprising a polyDADMAC ionomer material and a PEBA-based water vapor permeable polymer material dispersed on a carbon fiber reinforcement material. Figure 15B Enlarged photographs depict a hygroscopic polymer composite layer comprising polyDADMAC ionomer and PEBA-based water vapor permeable polymer dispersed on carbon fiber material. For reference, Figure 15B The carbon fibers in the composite material have an average diameter of 10 micrometers (µm). The carbon fiber material can provide mechanical stability to the layer, for example, by passively cooling the PV cell or panel through water adsorption (i.e., at night) and desorption (i.e., during the day) cycles, thereby increasing the power output of the PV cell or panel.

[0104] To experimentally demonstrate the PV cooling function of the exemplary composite material of this technology, Figure 16 It shows 1000 W / m at room temperature 2 18 cm under irradiance tested for 6 hours 2 The power output of the crystalline silicon solar cell is measured in milliwatts (mW). Solar cell (A) comprises a hygroscopic polymer composite material of this technology adhered to its back surface and is compared to a similar solar cell (B) without any back coating. During a 6-hour test, solar cell A generated approximately 7% more energy than solar cell B due to a cooling effect, where water in the back coating of the hygroscopic polymer composite material (e.g., water captured during the previous night's circulation) evaporates via heat generated by the solar cell during solar radiation. Therefore, this experiment demonstrates the ability of the hygroscopic polymer composite material of this technology to improve the efficiency of solar cells and panels, as the latent heat of water evaporation can be utilized to absorb heat generated during operation.

[0105] While hygroscopic polymer composites, tiles, or coatings can be applied to solar cell modules during manufacturing, there is an opportunity to improve the performance of solar cell modules that are already operating in the art and degrading over time due to various degradation mechanisms. For example, a coating of a hygroscopic polymer composite material incorporating the present technology can be provided or applied (e.g., by spraying or roller coating the back surface of a solar panel such as a backsheet).

[0106] In some implementations, adhesion of the applied coating can be improved, for example, by removing the top or surface layer of the backsheet before applying the hygroscopic polymer composite coating, when applied to a solar module that has been aged or operated for an extended period. For example, mechanical methods (e.g., sanding, blasting), chemical stripping (e.g., dissolving or softening the solvent of the top layer), thermal methods (e.g., heat gun, laser), and / or ozone decomposition stripping can be employed. Where the outer or back layer of the solar panel has poor thermal conductivity or poor adhesion for applying the hygroscopic polymer composite coating (e.g., due to chemical and / or aging), an inner or intermediate layer can be applied before the hygroscopic polymer composite coating. For example, an inner layer 212 can be provided to improve the adhesion of the hygroscopic polymer composite coating to the backsheet 206.

[0107] In another exemplary application, the hygroscopic polymer composite material described herein can be used as an adsorbent material in a water generation device. This adsorbent material captures or retains (e.g., absorbs, adsorbs) water vapor from ambient air under a first condition (e.g., at night) and releases the absorbed water under a second condition (e.g., during the day via solar thermal energy) (e.g., through temperature fluctuations, humidity fluctuations, pressure fluctuations). The released water vapor can then be condensed (e.g., via a condenser in the water generation system) to produce liquid water from atmospheric humidity. The reversible hygroscopic properties of the hygroscopic polymer composite material enable material regeneration without leakage, allowing water to be consistently generated for the user (e.g., as drinking water for the user's consumption). Therefore, various embodiments relate to systems and methods for generating water from the air using hygroscopic polymer composite materials.

[0108] Figure 17 A perspective cross-sectional view of a water generation system 300 comprising a hygroscopic polymer composite material is shown. The water generation system 300 can generate liquid water from a process gas containing water vapor (e.g., ambient air at atmospheric temperature and pressure). The system 300 includes a solar thermal unit, which is configured, for example, as a top cover and / or enamel layer 312 attached to a housing 302, such that the outer top surface is exposed to the surrounding environment to collect solar radiation. The system 300 may optionally include a solar power generation unit, such as a photovoltaic (PV) panel or layer 314. In some embodiments, the water generation system may also include at least one gap layer (e.g., 316) beneath the top cover layer (e.g., 312) to improve solar radiation collection.

[0109] The water generation system disclosed herein converts solar radiation into thermal energy by transferring energy from sunlight to a regenerated gas, endothermic gas, or working gas (e.g., air in a closed loop) flowing through the system. In some embodiments, the water generation system converts solar radiation into both thermal and electrical energy, for example, via a solar cell comprising one or more glazed layers and one or more photovoltaic layers.

[0110] The top cover layer 312 includes an outer surface exposed to ambient air and an inner surface opposite the outer surface. The top cover or glaze layer may include a transparent material (e.g., glass) that allows solar radiation to enter the interior of the water generation system 100. In some embodiments, the top cover layer may include one or more photovoltaic panels comprising PV cells for converting solar radiation into electrical energy. Additionally, one or more gap layers may include an assembly comprising one or more photovoltaic (PV) panels or layers for converting solar radiation into electrical energy, one or more glaze layers (e.g., a transparent layer, a glass layer), or a combination thereof. In some embodiments, the optional gap glass layer may be a layer different from the one or more photovoltaic layers (e.g., separated by gaps), for example... Figure 17 As shown (i.e., the interstitial enamel layer 316 is located above and spaced apart from the photovoltaic layer 314). However, in other embodiments, the interstitial layer may be integrally formed or comprise enamel portions (e.g., glass) and photovoltaic units or portions (e.g., photovoltaic cells), among other components (e.g., encapsulation materials, wires, etc.). In some embodiments, the water generation system of this disclosure may include a photovoltaic panel or layer 314 located below and spaced apart from the top cover layer 312, without any interstitial layers.

[0111] In some embodiments, these water generation systems may be configured as one or more glazed or unglazed solar collectors to convert radiant solar energy into heat energy, and thereby heat the porous moisture-absorbing compound and / or regeneration gas. Furthermore, some water generation systems may include hybrid solar collectors or photovoltaic-thermal solar collectors that convert solar radiation into both heat and electricity, such that the generated heat is transferred to the porous moisture-absorbing compound and / or regeneration gas and the generated electricity powers components of the water generation system (e.g., fans, compressors, controllers, and / or the like).

[0112] The water generation system 300 includes an absorption unit, a body, or a layer 318 comprising a hygroscopic polymer composite material of the present technology. The absorption layer 318 is configured to capture (e.g., adsorb, absorb) water vapor from the treatment gas as it flows through and / or through the treatment gas (e.g., ambient air at atmospheric pressure), for example during adsorption cycles (e.g., nighttime hours). Furthermore, the absorption layer 318 may be configured to transfer heat from the water vapor and / or heat to the regeneration or working gas during unloading, release, or desorption operation cycles.

[0113] The absorption layer can be configured to receive heat from at least one heat source, such as regenerated gas, solar radiation, photovoltaic cells, heaters, heat exchangers, condensers of vapor compression refrigeration units, and / or the like. Furthermore, when a moisture-absorbing material is included, the regenerated gas can accumulate heat and / or water vapor as it flows through or passes through the absorption layer. Figure 17 In this configuration, the absorber layer 318 is located below and spaced apart from the enamel layer 312 and the interstitial photovoltaic layer 314; however, other configurations are possible without departing from the spirit and scope of this disclosure.

[0114] like Figure 17 As depicted, the water generation system 100 further includes a heat exchange assembly 330 for increasing the relative humidity and / or partial pressure of water vapor in the regenerated gas to drive the condensation of water vapor from the regenerated gas during desorption mode or circulation. The heat exchange assembly 330 can be configured to reduce the temperature of the regenerated gas by discharging heat to the surrounding environment and / or another heat-absorbing fluid (e.g., a refrigerant). The heat exchange assembly 330 can be configured as a single unit, provided as an assembly of multiple components (e.g., all components including a refrigeration unit or loop) or as a component of a larger refrigeration or heat transfer unit or loop (e.g., some components including a refrigeration loop, a heat exchanger, and / or the like).

[0115] In one example, heat exchange assembly 330 includes a refrigeration unit or circuit configured to circulate refrigerant via refrigerant lines or conduits in a closed refrigerant circuit comprising a refrigerant evaporator (e.g., configured as part of or integrated with a liquid water condenser), a refrigerant compressor, a refrigerant condenser, and a refrigerant expansion device (e.g., an expansion valve or capillary). In some implementations, the heat exchange assembly (e.g., 330) includes a refrigeration circuit integrated with an absorption unit (e.g., 318), such that the refrigerant condenser of the refrigeration circuit transfers heat (i.e., acts as a heat source) to the absorption layer (e.g., 318) during desorption mode or circulation. Furthermore, the refrigerant evaporator of the refrigeration circuit may be configured as part of or integrated with a liquid water condenser, i.e., serving as a heat exchanger to transfer heat from the regeneration gas (and / or the latent heat of condensation of water vapor from the regeneration gas) to the refrigerant circulating through the refrigerant evaporator of the refrigeration circuit.

[0116] In various embodiments, the heat exchange assembly 330 includes a liquid water condenser configured to provide a high surface area for heat transfer, allowing for the condensation of water vapor from the regeneration gas with minimal pressure drop as it flows through or across the regeneration gas. In one example, the liquid water condenser may include a radiator and / or a heat transfer surface (e.g., a heat dissipation surface, fins, ridges, ribs, protrusions, flaps, passive radiators, etc.) to dissipate heat from the regeneration gas to the surrounding environment. In some embodiments, the heat exchange assembly 330 and / or the liquid water condenser may form an external portion of the housing 302 to dissipate heat to the surrounding environment. In other embodiments, the heat exchange assembly may be entirely located within the housing.

[0117] In various embodiments, the absorbent unit or layer (e.g., 318) comprises or is formed of a hygroscopic polymer composite layer, material, composite material, body, or component, which is configured to capture and release water vapor upon exposure to a process gas (e.g., ambient air), and the absorbent unit or layer (e.g., 318) can have various compositions and structures. The absorbent unit or layer (e.g., 318) can be configured as one or more hygroscopic polymer composite bodies or layers, which can be porous to allow airflow through them. The terms 'porous' or 'porosity' used herein with respect to water generation systems can describe flow-through implementations relative to flow-through or plate implementations of the absorbent unit. While overflow or plate implementations can be employed (e.g., by coating a surface with a hygroscopic polymer composite), it is preferable to maintain a small boundary layer with high permeability, for example, as can be provided in a porous flow body, unit, or layer.

[0118] The hygroscopic polymer composite material, composite component, or layer can be further configured to absorb thermal energy (e.g., radiant solar thermal energy) and release captured water vapor into the working or regenerating gas, for example, during desorption / release operating modes or cycles. In one embodiment, the hygroscopic polymer composite material can be arranged within a flow distributor, such as, but not limited to, a grid structure, top and bottom rigid perforated plates, internal corrugated fluid channels, interdigitated fluid channels, and / or woven and fiber webs, to maintain back pressure and distribute the flow. The hygroscopic polymer composite material of this technology can be further configured as a composite component such that its structure provides structural properties, pressure drop, flow path, and / or thermal properties to the system.

[0119] This disclosure also provides molded or molded composite materials, wherein the hygroscopic polymer composite material is produced or formed into blocks or panels that can be deployed in various systems or structures where high mechanical strength, highly efficient thermal regulation properties, and / or stable water vapor adsorption / desorption properties without leakage are desired, such as in air-derived water generation systems, dehumidifiers, thermal management systems, humidity control systems, passive cooling, etc. The hygroscopic polymer composite material can be provided in any number of shape factors of various sizes and thicknesses. The hygroscopic polymer composite material has the advantage of being easy to form or mold into the desired shape factor, handle, transport, and even cut or adjust in size (e.g., with a saw), for example, at the installation or deployment site.

[0120] Not bound by any specific theory, the hygroscopic polymer composite material described herein can provide a thermal buffering effect via the evaporation of water as latent heat (e.g., along the diurnal cycle of ambient temperature and humidity changing over a 24-hour period), thus releasing heat when adsorbing ambient moisture (e.g., under nighttime conditions with lower ambient temperature and / or higher ambient relative humidity) and consuming heat during water vapor desorption (e.g., under daytime conditions with higher ambient temperature and / or lower ambient relative humidity).

[0121] The hygroscopic polymer composite of this technology can be used in a variety of potential thermal energy storage applications to store and release thermal energy through a phase change process involving the absorption and desorption of water vapor by the hygroscopic polymer composite. During adsorption, absorption, or “charging” operations, the hygroscopic polymer composite undergoes an adsorption process to absorb and retain moisture, thereby storing thermal energy as latent heat. During storage operations or states, the hygroscopic polymer composite effectively stores latent heat and moisture without leakage. During desorption, release, or “emission” operations, the hygroscopic polymer composite releases thermal energy and moisture as water vapor, for example, by exposure to a drier environment and / or heating to release the stored latent heat. This process can provide a thermal energy source for different applications, and the hygroscopic material returns to its original dry state.

[0122] These hygroscopic polymer composites offer innovative approaches to efficient and sustainable energy management, applicable in applications where temperature and / or humidity regulation is critical. Depending on the end use or application, the hygroscopic polymer composites can be configured to improve interaction with the surrounding environment and / or facilitate the adsorption and desorption of ambient humidity. In various embodiments, the hygroscopic polymer composites can be sprayed, coated, formed, or molded into a bulk or layer that may include larger air channels or voids (e.g., via a template mold that is removed after polymerization, coagulation, and / or curing). In one embodiment, the hygroscopic polymer composite can be coated or sprayed onto a surface. In another embodiment, the hygroscopic polymer composite can be formed as a porous fluid, such as a pore structure with a range of pore sizes (e.g., a multi-peak or bi-peak pore size distribution, wherein smaller voids or pores are formed during synthesis and / or larger air voids or channels are formed via a template mold). In many embodiments, smaller pore diameters can range from 0.1 to 5 mm, while larger channel or pore diameters can range from about 5 mm to 10 mm.

[0123] The hygroscopic polymer composites of this technology can be manufactured or produced by various methods, including but not limited to polymerization, copolymerization, wet mixing, dry mixing, blending, spraying, impregnation, initial wet impregnation, drying, heating, curing, autoclaving, template, molding or similar derivative methods and combinations thereof.

[0124] refer to Figure 18 Flowchart 1000 depicts a method for producing a hygroscopic polymer composite material according to embodiments of the present disclosure. The methods depicted in the disclosed flowchart are merely exemplary and are not limited to the embodiments presented herein. The disclosed flowchart can be used in many different embodiments or embodiments not specifically depicted or described herein. In some embodiments, the operations or activities of the method flowchart are performed in the presented order. In other embodiments, the operations or activities of the method flowchart can be performed in any other suitable order. In other embodiments, one or more operations or activities in the method flowchart can be combined or skipped. Furthermore, operations or activities with dashed outlines indicate optional operations or activities.

[0125] In activity or operation 1010, the method of manufacturing a hygroscopic polymer composite material includes preparing an ionomer material.

[0126] For example, operation 1010 may include polymerizing monomers of a water vapor permeable or supportive polymer material to form a porous network or foam in a super-swollen state around a hygroscopic salt-bound ionomer material.

[0127] In optional activity or operation 1012, the method includes contacting the ionomer material with a hygroscopic salt solution until it reaches a swollen or super-swollen state.

[0128] In optional activity or operation 1014, the method includes drying a hygroscopic polymer composite material comprising hygroscopic salts and a water vapor permeable polymer material bound within a crosslinked network of an ionomer material. In operation 1014, drying the ionomer material bound with hygroscopic salts within the water vapor permeable polymer material to an equilibrium swelling or shrinkage state can create pores within the hygroscopic polymer composite material.

[0129] In activity or operation 1012, the method includes an activity or operation of preparing a water vapor permeable polymer material to support the ionomer material within a porous matrix of the water vapor permeable polymer material, such that the porous matrix of the water vapor permeable polymer material supports the volume change of the ionomer material between a contracted state and a swollen state.

[0130] The foregoing specification and examples provide a complete description of the structure and use of illustrative embodiments. While certain embodiments have been described above to a certain degree or with reference to one or more individual examples, those skilled in the art can make many changes to the disclosed embodiments without departing from the scope of the invention. Accordingly, the different illustrative embodiments of the methods and systems are not intended to be limited to the specific forms disclosed. Rather, they include all modifications and substitutions falling within the scope of the claims, and embodiments other than those shown may include some or all of the features of the depicted embodiments. For example, elements may be omitted or combined into an integral structure, and / or connections may be replaced. Furthermore, suitable aspects of any of the above embodiments may be combined with aspects of any of the other examples described to form other examples having comparable or different characteristics and / or functions and solving the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments.

[0131] The claims are not intended to include, and should not be construed as including, means plus function or steps plus function limitations, unless such limitations are expressly stated in the given claims using the phrases “means for…” or “steps for…” respectively. As used herein, the terms “about” or “substantially” are intended to include minor deviations rather than defining precise values.

Claims

1. A composite material comprising: Ionomer materials having an ionized polymer matrix to maintain equilibrium water content; and Water vapor can permeate polymer materials; in, The water vapor permeable polymer material supports the volume change of the ionomer material between a shrinkage state with a first equilibrium water content and a swelling state with a second equilibrium water content, wherein the second equilibrium water content is greater than the first equilibrium water content.

2. The composite material according to claim 1, further comprising: A reinforcing material is provided to support the volume change between the ionomer material and the water vapor permeable polymer material in the contracted state and the swollen state.

3. The composite material according to claim 1, wherein, The water vapor permeable polymer material includes a porous matrix that facilitates water vapor permeation and provides a rigid framework to support volume changes of the ionomer material between the contracted state and the swollen state.

4. The composite material according to claim 1, wherein, The water vapor permeable polymer material is an elastomer to facilitate water vapor permeation; and exhibits an elastic volume change between the contracted state and the swollen state.

5. The composite material according to claim 1, wherein, The ionomer material has a crosslinking degree of 1 mol% - 5 mol%.

6. The composite material according to claim 1 further comprises: a hygroscopic salt incorporated into the ionized polymer matrix of the ionomer material.

7. The composite material according to claim 6, wherein, The ionomer material incorporating the hygroscopic salt is supported within the water vapor permeable polymer material, and wherein the composite material maintains the equilibrium moisture content absorbed by the ionomer material incorporating the hygroscopic salt within the water vapor permeable polymer material.

8. The composite material according to claim 7, wherein, The ionomer material incorporating the hygroscopic salt is supported within the porous matrix of the water vapor permeable polymer material; and wherein the composite material maintains the equilibrium moisture content absorbed by the ionomer material incorporating the hygroscopic salt within the porous matrix of the water vapor permeable polymer material.

9. The composite material according to claim 6, wherein, The ionomer material and the hygroscopic salt form a homogeneous gel in a swollen state without leakage.

10. The composite material according to claim 6, wherein, The ionomer material incorporating the hygroscopic salt forms a homogeneous gel in a swollen state at a relative humidity of up to 80% RH without leakage.

11. The composite material according to claim 6, wherein, The hygroscopic salt is present in an amount of 5% to 60% by weight of the ionomer material.

12. The composite material according to claim 6, wherein, The hygroscopic salt is present in an amount greater than 20% by weight of the ionomer material.

13. The composite material according to claim 6, wherein, When subjected to 90% RH for at least 72 hours, the composite material loses less than 0.1 wt.% of the hygroscopic salt.

14. The composite material according to claim 6, wherein, The hygroscopic salts include calcium chloride, calcium bromide, magnesium chloride, ammonium chloride, lithium bromide, lithium chloride, zinc bromide, sodium bromide, lithium iodide, sodium iodide, potassium iodide, potassium carbonate, potassium iodide, potassium sulfate, potassium acetate, zinc sulfate, or combinations thereof.

15. The composite material according to claim 1, wherein, In the absence of leakage, the porous matrix of the water vapor permeable polymer material supports the volume change of the ionomer material between the contracted and swollen states.

16. The composite material according to claim 1, wherein, In the absence of leakage, at 60% RH and 25°C, the composite material exhibits a reversible water adsorption capacity that is 20% by weight higher than the composite material mass.

17. The composite material according to claim 1, wherein, The composite material includes pores in both the contracted state and the swollen state.

18. The composite material according to claim 1, wherein, The water vapor permeable polymer material includes semi-rigid or rigid polymer foams.

19. The composite material according to claim 1, wherein, The water vapor permeable polymer material includes a porous matrix, wherein the porous matrix of the water vapor permeable polymer material supports the volume change of the ionomer material.

20. The composite material according to claim 1, wherein, The water vapor permeable polymer material is provided as foam, which is configured to form around the ionomer material in a super-swollen state, such that pores exist when the ionomer material is in the contracted state or both the swollen and contracted states.

21. The composite material according to claim 1, wherein, The water vapor permeable polymeric material includes polyisocyanurate foam, polyurethane foam, polyimide foam, phenolic foam, or combinations thereof.

22. The composite material according to claim 1, wherein, The ionomer material includes hydrophilic polymers.

23. The composite material according to claim 1, wherein, The water vapor permeable polymer material includes hydrophobic polymers.

24. The composite material according to claim 1, wherein, The water vapor permeable polymer material exhibits compressive strength ranging from 100 kPa to 1000 kPa.

25. The composite material according to claim 1, wherein, The water vapor permeable polymer material exhibits a compressive strength greater than 100 kPa.

26. The composite material according to claim 1, wherein, The water vapor permeable polymer material exhibits an elastic modulus of 60 MPa to 700 MPa.

27. The composite material according to claim 1, wherein, The water vapor permeable polymer material exhibits an elastic modulus greater than 60 MPa.

28. The composite material according to claim 1, wherein, The composite material contains 15% to 70% by weight of a water vapor permeable polymer.

29. The composite material according to claim 1, wherein, The composite material contains 20% to 50% by weight of a water vapor permeable polymer.

30. The composite material according to claim 1, wherein, The ionomer material includes cationic polymer materials and halogen anions.

31. The composite material according to claim 1, wherein, The ionomer material includes polyamide, polyacrylamide, polysaccharide, polycarbonate, polyisocyanate, polyepoxide, polyurethane, peptide, alginate, or a combination thereof.

32. The composite material according to claim 1, wherein, The ionomer material includes polydiallyl dimethylammonium chloride (poly-DADMAC), modified chitosan material, or a combination thereof.

33. The composite material according to claim 1, wherein, The monomers of the ionomer material include hydrophilic functional groups selected from hydroxyl, carbonyl, aldehyde, ketone, carboxyl, carboxylic acid, amino, amide, mercapto, thiol, phosphate ester or combinations thereof.

34. The composite material according to claim 1, further comprising a filler material.

35. The composite material according to claim 34, wherein, The filler material includes clay materials, polysaccharide materials, or combinations thereof.

36. The composite material according to claim 1 further comprises clay material, molecular sieve, silicate or combination thereof.

37. The composite material according to claim 1 further comprises activated carbon, perlite, vermiculite, palygorskite clay, bentonite, montmorillonite clay, chitosan material, or combinations thereof.

38. The composite material according to claim 1, wherein, When exposed to 90% RH for at least 24 hours, the composite material exhibits a swelling rate of less than 1-5%.

39. A hygroscopic polymer composite material, comprising: Hygroscopic salts; and Ionic polymer materials, in, When water is present, the hygroscopic salt is incorporated into the crosslinked network of the ionomer material.

40. The composite material according to claim 39, further comprising a water vapor permeable polymer material, wherein, The volume change of the ionomer material incorporating the hygroscopic salt between a shrinkage state with a first equilibrium moisture content and a swelling state with a second equilibrium moisture content is supported by the water vapor permeable polymer material without leakage, wherein the second equilibrium moisture content is greater than the first equilibrium moisture content.

41. A method for preparing a hygroscopic polymer composite material, comprising: Preparation of ionomer materials; as well as A water vapor permeable polymer material is prepared to support the ionomer material between a shrinkage state and a swelling state, wherein the swelling state has a higher water content than the shrinkage state.

42. The method of claim 41, further comprising: The ionomer material is brought into contact with a hygroscopic salt solution until it reaches a super-swelling state; The ionomer material containing hygroscopic salts is dried within the water vapor-permeable polymer material to form breathable pores within the hygroscopic polymer composite material.

43. The method of claim 41, further comprising: The ionomer material is anchored to the water vapor permeable polymer material via copolymerization. The ionomer material includes functional groups that are reactive to the supporting polymer material.

44. The method according to claim 43, wherein, The functional groups of the ionomer material include nucleophilic groups, which are selected from: primary amines, secondary amines, primary alcohols, secondary alcohols, primary thiols, secondary thiols, or combinations thereof; and The water vapor permeable polymer material includes electrophilic groups selected from isocyanates, epoxides, activated carboxyl groups, haloalkanes, or combinations thereof.

45. The method according to claim 41, wherein, The preparation of the ionomer material includes: The monomer diallyl dimethyl ammonium chloride (DADMAC) is functionalized using functional groups selected from hydroxyl, amine, quaternary ammonium, or combinations thereof.

46. ​​The method according to claim 41, wherein, The preparation of the ionomer material includes: The diallyl dimethyl ammonium chloride (DADMAC) monomer is polymerized with a crosslinking agent selected from the group consisting of tetraallyl ammonium crosslinking agents, tetraallyl piperazineonium crosslinking agents, diamineonium diepoxide crosslinking agents, or combinations thereof.

47. The method according to claim 41, wherein, The preparation of the water vapor permeable polymer material includes: A first component, including isocyanate, and a second component, including polyol, are reacted to form polyurethane or polyisocyanurate foam.

48. A layer comprising: A hygroscopic polymer composite material comprising an ionomer material and a water vapor permeable polymer material, wherein the water vapor permeable polymer material supports the volume change of the ionomer material between a shrinkage state and a swelling state, wherein the swelling state has a higher water content than the shrinkage state; in, The hygroscopic polymer composite material receives heat from its surface, causing water to evaporate from the hygroscopic polymer composite material into the surrounding environment as it transitions from the swollen state to the contracted state.

49. The layer according to claim 48, wherein, The layer is configured to receive heat generated by the solar panel during daytime operation, such that water evaporates from the hygroscopic polymer composite material into the surrounding environment when the material transitions from the swollen state to the contracted state.

50. The layer according to claim 48, wherein, The layer includes: Inner layer, which contacts the back side of the solar panel; An outer layer exposed to the surrounding environment, the outer layer comprising the ionomer material and the water vapor permeable polymer material. The outer layer absorbs water vapor from the surrounding air during nighttime hours, and The outer layer receives heat generated by the solar panel during daytime operation via the inner layer to reduce the operating temperature of the solar panel, thereby improving the operating efficiency of the solar panel.

51. The layer according to claim 50, wherein, The inner layer contains a thermally conductive material.

52. The layer according to claim 51, wherein, The thermally conductive material includes an epoxy polymer with a thermally conductive filler.

53. The layer according to claim 50, wherein, The inner layer includes an adhesive material to adhere the outer layer to the back side of the solar panel.

54. A solar panel, comprising: Multiple solar cells, each solar cell comprising: The front side, which faces the sun during daytime operation, converts solar radiation incident upon it into electrical energy and heat. The back side opposite to the front side; A transparent cover, the transparent cover being above the front side of the solar cell; A backsheet, the backsheet being located on the back side of the solar cell; A layer comprising a hygroscopic polymer composite material is provided for receiving heat generated by the plurality of solar cells during daytime operation, such that water evaporates from the hygroscopic polymer composite material into the surrounding environment when transitioning from a first state to a second state, the second state having a lower moisture content than the first state.

55. A method comprising: A layer comprising a hygroscopic polymer composite material is applied to a solar panel. The layer is configured to receive heat generated by the solar panel during daytime operation, such that water evaporates from the layer into the surrounding environment when transitioning from a first state to a second state, the second state having a lower water content than the first state.

56. The method of claim 55, further comprising: Before applying the layer, remove the top layer of the backsheet.

57. A system for producing liquid water, comprising: A solar energy unit configured to convert solar radiation irradiating it into heat and electrical energy; A hygroscopic polymer composite material configured to capture water vapor from the surrounding air during an adsorption cycle and to receive heat generated by the solar cell during a desorption cycle. The hygroscopic polymer composite material comprises ionomer materials and water vapor permeable polymer materials. In this process, a water vapor-permeable polymer material supports the volume change of the ionomer material between a contracted state and a swollen state, wherein the swollen state has a higher water content than the contracted state. A heat exchange assembly configured to increase the partial pressure of water vapor in the regenerated gas as it flows through it, thereby driving water vapor to condense from the regenerated gas to form liquid water during the desorption cycle.

58. A method for producing water from air, comprising: During the adsorption cycle, process gas is passed through a hygroscopic polymer composite material to capture water vapor from the process gas. The hygroscopic polymer composite material comprises an ionomer material and a water vapor permeable polymer material; wherein the water vapor permeable polymer material supports the volume change of the ionomer material between a shrinkage state and a swelling state, and the swelling state has a higher water content than the shrinkage state; The cycle transitions from adsorption to desorption; During the analysis cycle, regenerated gas is allowed to flow in a regenerated flow path configured to direct the regenerated gas to the solar cell to accumulate heat therefrom, and to flow through the hygroscopic polymer composite material to accumulate water vapor and heat therefrom. During the desorption cycle, water vapor is condensed from the regeneration gas in the regeneration flow path to produce liquid water.

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