CN110922629A

CN110922629A - Reversible dynamic macroporous elastomer polymer material and preparation method and application thereof

Info

Publication number: CN110922629A
Application number: CN201911218637.7A
Authority: CN
Inventors: 崔家喜; 王宏
Original assignee: Chengdu Yuping Technology Co Ltd
Current assignee: Chengdu Yuping Technology Co Ltd
Priority date: 2019-12-03
Filing date: 2019-12-03
Publication date: 2020-03-27
Anticipated expiration: 2039-12-03
Also published as: WO2021109323A1; CN110922629B

Abstract

The invention discloses a reversible dynamic macroporous elastomer polymer material, a preparation method and application thereof. The invention mixes and stirs the polymerizable precursor or the cross-linking polymer precursor and the template liquid which is not dissolved in the precursor evenly, and solidifies the obtained emulsion to prepare the reversible dynamic macroporous elastomer polymer material. The novel elastomer polymer material with the reversible dynamic porous structure has the advantages of simple and feasible synthesis process, environmental protection, high yield, low preparation cost and easy popularization. The reversible dynamic macroporous elastomer polymer material has an adjustable reversible multi-layer porous structure, has good convertible sunlight reflection performance and infrared radiation performance, high solution storage capacity and adjustable surface roughness, belongs to a macroporous polymer material, and has wide application prospects in the aspects of radiation refrigeration solar heating and intelligent interfaces.

Description

Reversible dynamic macroporous elastomer polymer material and preparation method and application thereof

Technical Field

The invention relates to the technical field of high molecular materials, in particular to a reversible dynamic macroporous elastomer polymer material and a preparation method and application thereof.

Background

Macroporous polymers (also known as polymeric macroporous materials) are materials which are formed by taking polymers as base materials and have an interconnected or closed pore structure, and the main cavity pore diameter of the macroporous polymers is more than 50 nanometers (according to the international IUPAC standard). The macroporous polymer can combine the advantages of a macroporous material and a polymer material, has the characteristics of large surface area, adjustable aperture and the like of the macroporous material, has the characteristics of high mechanical strength, good thermal stability, good solvent resistance, easy processing, low raw material price and the like, and is widely applied to the fields of catalysis, energy storage, sound and heat insulation, gas separation, water treatment, drug delivery and the like. Meanwhile, the diversity of the polymer synthesis method can provide abundant synthesis paths to construct pore-size structures with different properties, and can provide wider application fields for macroporous materials, such as new application scenes of anti-pollution and anti-drag interfaces, reflective coatings, fluorescence detection, energy transfer, liquid storage, tissue engineering scaffolds, cell culture and the like, so that the polymer is considered to be one of porous materials with the most application prospect.

At present, there are many methods for preparing macroporous polymers, and the most important methods are a phase separation method (phase separation polymerization), a freeze-drying method (free-drying), a foaming method (gas-blowing), a template method (templating method), and the like.

The phase separation polymerization method, which was the earliest method for preparing porous polymers, is a mechanism in which a diluent compatible with a precursor in advance undergoes phase separation during polymerization or crosslinking, diluent-aggregated domains are formed in situ as cavity templates, and these domains can be removed after polymerization to obtain a permanent porous structure. A wide variety of polymerizable monomers and crosslinkable polymer precursors can be prepared by this method to give macroporous polymers. The diluent may be a solvent, a non-solvent (such as supercritical carbon dioxide), or an inert polymer, among others. The suspension polymerization process commonly used for the preparation of porous polymer beads belongs to this method. This method requires that the polymerization/crosslinking kinetics be matched to the phase separation kinetics, and the resulting pore size distribution is relatively broad, often involving relatively complex diluent removal processes.

The freeze-drying method is a method which is started in recent years, and water crystallization in the freeze-drying process is mainly utilized to drive the polymer in the system to be irreversibly aggregated, so that the porous polymer is obtained after the solvent is removed. The method has high energy consumption, and the obtained macroporous polymer has relatively poor mechanical property.

The foaming method is a method of using bubbles generated by a foaming agent in the process of curing a material as a template, and is widely used in the industries of preparing artificial leather, sponge and the like.

The templating method is a method for preparing a porous polymer using a porogen (porogen) insoluble in a polymer precursor (a mixed precursor of a monomer and a crosslinking agent or a crosslinkable polymer precursor) as a cavity template, and generally comprises three steps: firstly, dispersing a pore-forming agent into a precursor; then initiating polymerization or crosslinking to form a polymer continuous phase; and finally, leaching and eluting the pore-making agent to obtain the macroporous material. The method is suitable for various monomers and polymers, the cavity structure and the pore size can be accurately controlled through a template (which can be small molecules, micro-nano particles or a continuous framework), and a large-area sample can be conveniently prepared; however, the process is relatively complex, and particularly, the leaching process is long in time consumption and high in cost and easily causes material deformation.

In general, the current macroporous polymer preparation method usually involves volatile organic solvents or consumes a large or long amount of energy, and the prepared macroporous structure is usually permanent and cannot change the topological structure under external stimulation.

Material intellectualization is a trend of scientific research and material market in recent years, and has been receiving attention to design and synthesis of novel responsive macroporous polymerization. The properties of macroporous polymers are generally determined by both the material composition and the pore structure. At present, the strategy for preparing the intelligent macroporous polymer is mainly to select a stimulus responsive polymer as a substrate material or modify the surface of a pore through a responsive molecule, thereby achieving the purpose of changing the performance of the material; however, few methods for adjusting the performance of macroporous polymer materials by changing the pore topology structure are available, and no report is found on the case that complete opening and closing of the macroporous structure can be realized without filling with foreign substances.

The switching of the control channels is one of the most effective ways to adjust the properties of the porous material. The current method is to modify responsive molecules in pores, change the topological structure and performance of the molecules through external stimuli such as light, pH value, salt, recognition molecules, electric signals and the like, and prevent the entry and output of specific substances, thereby achieving the purpose of switching the internal performance of materials, such as catalytic property, transport capacity, optical performance and the like. However, these molecular level changes can only be used for systems with relatively small pore sizes (a few nanometers), making it difficult to open up the macroporous structure. In addition, these methods are not effective in changing macroscopic properties of the material, such as, for example, volume, surface area, light transmission, liquid storage capacity, surface roughness, etc., of the material. In response to these needs, there is currently no method for effectively and reversibly switching large pore polymeric cavities.

In summary, there is a lack of environmental friendly methods for preparing responsive macroporous polymers, and the prepared macroporous polymers cannot effectively and reversibly switch the pore structure, and thus the related applications are less explored.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a reversible dynamic macroporous elastomer polymer material, a preparation method and application thereof, and the technical scheme for solving the technical problems is as follows:

a preparation method of a reversible dynamic macroporous elastomer polymer material comprises the following steps:

(1) mixing a mixed precursor containing a polymerizable monomer and a crosslinking agent or a crosslinkable polymeric precursor with a template solution to obtain a cured precursor;

wherein the template solution is a volatile solution incompatible with the mixed precursor or a volatile solution incompatible with the cross-linkable polymeric precursor;

(2) applying the cured precursor to a substrate or a mold for curing to produce the reversible dynamic macroporous elastomeric polymeric material.

The polymerizable monomer of the invention refers to a small molecule monomer which can be polymerized under the action of a cross-linking agent. The crosslinkable polymeric precursor of the present invention refers to a polymer capable of forming covalent bonding crosslinks, optionally with the addition of a crosslinking catalyst, a free radical initiator, an oil-soluble organic pigment, and a surfactant.

The invention takes polymerizable monomer or cross-linking polymerization precursor as raw material to mix with template solution, the template solution is volatile solution incompatible with polymerizable monomer or cross-linking polymerization precursor, and the incompatibility between the template solution and the precursor (including polymerizable monomer and cross-linking polymerization precursor, the same applies hereinafter) is utilized to play a role of template for forming pore structure in the polymerization cross-linking process, and simultaneously, the template solution has volatility and can volatilize in the curing process, so that the pore structure is formed after the originally occupied space of the template solution volatilizes, and the porous and macroporous elastomer polymer is obtained. Along with the volatilization of the template liquid in the curing process, the pore structure collapses, the pore structure supported by the original template liquid becomes a collapsed solid state under the action of gravity, but the pores actually exist, and when the porous elastomer receives external stimulation, the collapsed pores are restored to be opened, so that the reversible conversion between the solid state and the porous state is realized.

In the curing process of the cured precursor, the crosslinking polymerization of the precursor and the volatilization of the template liquid can be controlled by means of controlling whether the crosslinking polymerization and the volatilization are carried out simultaneously, so that the pore structure is adjusted and controlled, and the reversible dynamic macroporous elastomer polymer materials with different properties can be obtained.

The template fluid of the present invention may be randomly distributed in the cured precursor in the form of numerous small droplets, or may be embedded in the cured precursor in a specific shape (fiber, pattern or three-dimensional array) in a manner related to the mixing of the template fluid and the precursor. For example, the template fluid may be dispersed in numerous small droplets by agitation mixing, or formed into a fibrous liquid in a solidified precursor by injection.

The manner in which the cured precursor of the present invention is applied to the substrate or mold includes, but is not limited to, casting, brushing, spraying, and spin-coating processes. Further, as another preferred embodiment, the cured precursor may be prepared directly on a substrate or a mold without being previously mixed, that is, a mixed precursor of a polymerizable monomer and a crosslinking agent or a crosslinkable polymerizable precursor is first applied to a substrate or a film and then a template liquid is introduced to obtain the cured precursor. The skilled person can select a suitable way depending on the performance requirements of the desired cellular elastomeric material.

The invention can realize the localization and the patterning of the porous structure by a sequential casting method. For example, a specific mold is obtained by casting a mixed precursor containing a polymerizable monomer and a crosslinking agent or a crosslinkable polymeric precursor on a mold, and then a mixed solution of a corresponding precursor and water is cast in a blank to obtain a monolithic material after complete curing, and after stimulation, a porous structure appears only in a specific region.

The present invention can obtain reverse phase elastomer film through casting mixed precursor containing polymerizable monomer and cross-linking agent or cross-linkable polymer precursor into the film and curing, and the transparent elastomer material is obtained through casting mixed precursor of the corresponding precursor and water and curing. Under the external stimulation, the responsive part of the material can be porous, and macroscopically shows a specific pattern.

The invention can be combined with a printing method to prepare a cavity structure with a specific geometric structure, and can also prepare only one cavity. For example, in a viscous hybrid precursor or crosslinkable polymeric precursor comprising a polymerizable monomer and a crosslinking agent, an aqueous solution is injected to print a pattern and cured to provide a transparent solid polymeric material that is porous to the outside stimulus to reveal the printed pattern. Also for example, when only one fibrous water template is printed, a channel that opens and closes under an external stimulus can be obtained. Pouring organic silica gel precursor on a substrate, injecting polyvinyl alcohol aqueous solution into the viscous precursor through a needle to form a fibrous water template penetrating through the precursor, and curing to obtain a transparent silica gel elastomer, wherein the elastomer can form a micro-channel at the position of the water template under the external stimulation.

The present invention can regulate the size of the liquid drop in the emulsion via the stirring time of the mixture of polymerizable or crosslinkable precursor and template solution to regulate the pore size of the porous elastomer polymer material. For example, the mixture of the cross-linkable polymeric precursor and water may be stirred for a period of time ranging from 5 to 50 minutes, corresponding to a drop size of 30 to 1 micron. By mixing the solidified precursors containing water droplets of different sizes in a certain ratio, a dynamic reversible porous structure with layers of different sizes can be obtained. For example, after mixing the two cured precursors with stirring for 5 minutes and stirring for 50 minutes, a macroporous material having pore diameters of both 1 micron and 30 microns can be obtained.

The invention can prepare anisotropic materials by stretching a sample orientation sample during the curing process. For example, the crosslinkable polymeric precursor is mixed with an aqueous solution of polyvinyl alcohol to give an emulsion, which is then precured for 5 to 30min under sealed conditions at 50 to 90 ℃. The resulting elastomer is stretched to varying degrees, for example, 110-. The prepared real-time polymer shows different responsiveness under different directions of stimulation.

It should be noted that, when selecting the monomers and the template solution, the monomers with a curing time longer than the time required for completely volatilizing the template solution should be selected, so that after the template solution is volatilized, the residual monomers can continue to be crosslinked and cured until the curing is completed.

Further, in a preferred embodiment of the present invention, the curing process in step (2) is performed in an open environment, and the curing temperature is room temperature or not higher than the boiling temperature of the template solution.

The curing process naturally occurs in an open room temperature environment, and the template liquid naturally volatilizes; the template solution can be heated at the temperature not higher than the boiling point of the template solution so as to promote the template solution to volatilize more quickly. In an open environment, curing and template liquid volatilization are performed simultaneously.

Further, in a preferred embodiment of the present invention, the curing process of step (2) comprises the following steps:

(21) applying a curing precursor to a substrate or a mold and pre-curing in a sealed environment in the presence of a template liquid, wherein the curing temperature is room temperature or not higher than the boiling point temperature of the template liquid, so as to obtain a pre-cured body;

(22) volatilizing and removing volatile components of the template solution in the pre-solidified body to obtain an intermediate;

(23) and finally curing the intermediate at room temperature or below 200 ℃ to obtain the reversible dynamic macroporous elastomer polymer material.

The invention divides the curing into three stages of pre-curing, volatilizing and final curing by controlling the curing conditions. The mechanism of each stage is explained below.

The pre-curing is carried out in the presence of a template fluid to form a partially permanent cross-linked polymer structure, referred to as a first network, which has a tendency to maintain the geometry of the sample in the template fluid-containing state. During the precure in the sealed state, the template liquid does not evaporate. And in the pre-curing process, the pre-curing can be carried out at room temperature or in a heating state not higher than the boiling point of the template liquid. If the pre-curing is performed by heating, the heating temperature should not be higher than the boiling point of the template solution or the volatile substances in the template solution.

And after the pre-curing is finished, completely volatilizing the template liquid or completely volatilizing the volatile substances in the template liquid in the pre-cured body in an open state or a negative pressure state. During the volatilization process, negative pressure can be generated inside the material; this negative pressure collapses the internal cavities of the material, resulting in a visually solid structure with a microscopically interface at the location of the master template fluid, where this interface is referred to as a wrinkle.

When the template liquid is completely volatilized, the remaining cured precursor is cured in a state where the internal cavities of the material are collapsed, and this portion of the crosslinked polymer, referred to as a second network, has a tendency to maintain the collapsed state of the polymer material. After the final cure is complete, the resulting material is a polymer in a collapsed state that exhibits the characteristics of a non-porous material. For example, the material can exhibit good transparency. The polymer in the collapsed state, referred to as solid polymer, is maintained in its solid state by the interaction of the second network with the wrinkle interface.

Through the three stages, the porous elastomer polymer material with the first network structure, the folds and the second network structure is obtained, and under the condition that external stimulation is applied to influence acting forces, the cavity structure is opened to obtain the macroporous polymer, wherein the state is simply referred to as porous state; the cavity structure in the porous state has geometric features close to but slightly smaller than the original template solution. When the stimulation of the external machine is eliminated, the porous structure collapses, the cavity in the porous state disappears, and the solid state is returned again. Thus, the cellular elastomeric polymeric material can be switched between a solid state and a cellular state by external stimulus conditions and is stable in the absence of a particular stimulus.

Further, in a preferred embodiment of the present invention, in the step (1), the content of the template liquid in the cured precursor is 5 to 90 wt%.

The invention can adjust the porosity of the finally obtained polymer material by controlling the content of the template liquid in the curing precursor. For example, in a cured precursor composed of a silicone precursor and an aqueous solution of polyvinyl alcohol, when the water content in the silicone precursor is between 5 and 90 wt%, the resulting porosity is between 4 and 80%.

Further, in a preferred embodiment of the present invention, the polymerizable monomer is a non-volatile monomer or a monomer having a boiling point higher than 150 ℃ or a mixture of the two.

Further, in a preferred embodiment of the present invention, the polymerizable monomer is one or more selected from the group consisting of 4-hydroxybutyl acrylate, isooctyl acrylate, poly (ethylene glycol) methyl ether acrylate, octamethylcyclotetrasiloxane, methylcyclopentadiene dimer and dicyclopentadiene;

the cross-linking agent is one or more of 1, 6-hexanediol diacrylate, 1, 6-hexanediol dimethacrylate, 1, 4-butanediol diacrylate, 1, 4-butanediol dimethacrylate, 1, 2-ethylene glycol diacrylate, 1, 2-ethylene glycol dimethacrylate, poly (ethylene glycol) diacrylate and poly (ethylene glycol) dimethacrylate;

the template solution is water, polyvinyl alcohol aqueous solution, polyethylene oxide aqueous solution, ethanol, isopropanol, diethyl ether or n-hexane.

Further, in a preferred embodiment of the present invention, the mixed precursor further comprises an initiator and/or a thickener.

The initiator and thickener may be selectively added depending on the nature of the polymerizable monomer. For example, when the polymerizable monomer is 4-hydroxybutylacrylate, an initiator and a thickener are added to the mixed precursor, the initiator may be azobisisobutyronitrile, and the thickener may be poly (4-hydroxybutylacrylate).

Further, in a preferred embodiment of the present invention, the cross-linkable polymeric precursor is one or more combinations of double-ended acrylated polypropylene, double-ended acrylated polytetrahydrofuran, double-ended acrylated polypropylene, double-ended thiolated polypropylene, double-ended acrylated polytetrahydrofuran, and double-ended thiolated polytetrahydrofuran, or an organic silica gel;

the template solution is water, polyvinyl alcohol aqueous solution, poly (N-isopropylacrylamide) aqueous solution, ethanol, isopropanol, diethyl ether or N-hexane.

The organic silica gel adopted in the embodiment of the invention can be commercially available room temperature curing AB silica gel, the components of which are mixed in a ratio of 1:1, and can also be commercially available transparent liquid silica gel.

According to the invention, silica gel is used as a cross-linkable polymerization precursor, a poly (N-isopropylacrylamide) aqueous solution is used as a template solution, and after solidification, a responsive polymer is deposited on the cavity/fold surface, so that a macroporous polymer with changeable chemical components and cavity geometric structures is formed.

Further, in a preferred embodiment of the present invention, the crosslinkable polymer precursor further comprises one or more combinations of a crosslinking catalyst, a free radical initiator, an oil-soluble organic pigment, and a surfactant, the crosslinking catalyst being a tin catalyst or a platinum catalyst.

The present invention can improve the reactivity of the silica gel precursor by adding a platinum catalyst to the silica gel, and in this case, the silica gel precursor can be cured at room temperature. In another embodiment, the reaction activity may be increased by directly heating at an elevated temperature to accelerate the curing process.

The invention is used for preparing the macroporous polymer with color by doping the oil-soluble organic pigment into the catalyst-containing silica gel precursor.

The invention controls the structure of the pores by adding a surfactant. For example, a mixture of the silicone precursor and water can be prepared to produce a closed-cell macroporous polymer, while a mixture of the silicone precursor and water containing a surfactant can be prepared to produce a macroporous polymer having an open-cell structure when the water content is greater than 40% by volume or more.

The reversible dynamic macroporous elastomer polymer material prepared by the preparation method.

The solid state and the porous state of the reversible dynamic macroporous elastomer polymer material have different material densities, light transmission properties or surface roughness. The reversible dynamic macroporous elastomeric polymeric material, when in the porous state, can be used to store a liquid in the cavity portion, exhibiting significantly higher swellability than the bulk polymeric material.

Use of a reversible dynamic macroporous elastomeric polymeric material in the preparation of a stimuli-responsive polymeric material.

Such stimulus responsiveness includes, but is not limited to, mechanical force responsiveness, humidity responsiveness, and solvent responsiveness.

Further, in the preferred embodiment of the present invention, the reversible dynamic macroporous elastomeric polymer material is applied to an energy-saving coating.

The transition of the macroporous polymer between the solid state and the porous state can be regulated when different mechanical forces are applied to the reversible dynamic macroporous elastomeric polymer material. The reversible dynamic macroporous elastomer polymer material can allow sunlight to penetrate under a solid state to realize a heating effect, and can reflect sunlight and radiate heat under a porous state, so that a refrigerating effect can be realized. Preferably, the material is applied as a coating on a coating that absorbs sunlight, and the light absorbing layer increases the heating effect in the solid state.

The reversible dynamic macroporous elastomer polymer material disclosed by the invention is prepared into a coating material, and can achieve the following excellent properties: firstly, both the solid state and the porous state can stably exist at the temperature of 200 ℃ below zero to 250 ℃; secondly, after the treatment at the temperature of 200 ℃ below zero to 250 ℃, the mechanical responsiveness can be maintained after the treatment is recovered to the room temperature; thirdly, the solid state and the porous state can stably exist in a humid environment and a rainy environment, and the mechanical responsiveness of the porous state is kept; fourthly, both the solid state and the porous state can stably exist under the irradiation of the sun, and the mechanical responsiveness of the porous material is kept.

Further, in a preferred embodiment of the present invention, the reversible dynamic macroporous elastomeric polymer material is applied to an intelligent interface.

The reversible dynamic macroporous elastomer polymer still keeps the stimulus responsiveness after the inside of the polymer is cut; the cut interface has low surface roughness in a solid state, the water contact angle is relatively low, the water drop rolling angle is high, and the interface belongs to a non-super-hydrophobic interface; after the porous state is converted, the cut interface has better surface roughness, high water contact angle and easy rolling of water drops, and belongs to a super-hydrophobic interface.

Further, in a preferred embodiment of the present invention, the use of the reversible dynamic macroporous elastomeric polymeric material described above for liquid storage and for extended surface smoothness is provided.

The polymer changes from a solid state to a porous state during the swelling process, and these cavities can be used to store the swelling liquid. A layer of liquid molecules exists on the surface of the swelled polymer, which can play a role in lubrication and form a super-smooth surface. When these liquid molecules are consumed, the liquid molecules stored in the cavity can diffuse to the surface to maintain the surface lubrication. The porous structure increases the storage of liquid molecules and thus increases the time that the surface retains lubricating properties. When the swelling polymer is subjected to external force, a large amount of liquid molecules can be released; when the external force is removed, the liquid molecules are sucked back from the new liquid.

Further, in a preferred embodiment of the present invention, the above-described reversible dynamic macroporous elastomeric polymeric material is used in a control fluid.

Macroporous elastomeric polymeric materials with communicating pores/channels do not allow fluid (gas or liquid) to pass through in the solid state, but allow fluid to pass through in the porous state.

Further, in a preferred embodiment of the present invention, the use of reversible dynamic large pore elastomeric polymeric material volume change as described above.

The macroporous elastomeric polymer material will change from solid to porous with a significant increase in volume at tangential forces, which can be used for sealing the mouth of a bottle or for securing an article. The macroporous elastomeric polymer material can absorb energy in the process of transforming from a porous state to a solid state, and plays a role in damping and protection.

The invention has the following beneficial effects:

the porous organic elastic polymer material prepared by the invention has adjustable aperture structure, integral volume and transmittance. The material has good reflection performance on sunlight, can have high transmittance on infrared light at an atmospheric window, and can realize conversion between a multi-cavity state and an entity state under the action of external mechanical force, thereby realizing the regulation and control of the optical performance of the material, realizing the reflection and absorption of responsive sunlight, and further regulating the heat absorption and heat release behaviors of the material.

The novel elastomer polymer material with the reversible dynamic porous structure has the advantages of simple and feasible synthesis process, environmental protection, high yield, low preparation cost and easy popularization. The reversible dynamic macroporous elastomer polymer material has an adjustable reversible multi-layer porous structure, has good convertible sunlight reflection performance and infrared radiation performance, belongs to a macroporous polymer, and has wide application prospect in the aspect of radiation refrigeration and solar heating.

Drawings

FIG. 1 is a schematic diagram of the fabrication of a reversible dynamic macroporous elastomeric polymeric material according to an embodiment of the present invention;

FIG. 2 is a reversible stimulus responsive hollowing behavior of a reversible dynamic macroporous elastomeric polymeric material of an embodiment of the present invention;

FIG. 3 is a sample plot of reversible dynamic cellular elastomer polymers of an embodiment of the present invention at various stages of preparation;

FIG. 4 is an optical microscope image of a reversible dynamic macroporous elastomeric polymeric material under tension or compression in accordance with an embodiment of the present invention;

FIG. 5 is a graph of the change in the reversible dynamic macroporous elastomeric polymeric material of an embodiment of the present invention before and after force/solvent stimulation by a "herringbone" pattern;

FIG. 6 is a graph of the change in the channel openability and closeability under an external stimulus for a reversible dynamic macroporous elastomeric polymeric material in accordance with an embodiment of the present invention;

FIG. 7 is a microscopic view of closed pores of a reversible dynamic macroporous elastomeric polymeric material prepared from a cured precursor having a water content of 15% according to an embodiment of the present invention;

FIG. 8 is an open pore micrograph of a reversible dynamic macroporous elastomeric polymeric material prepared from a cured precursor having a water content of 90% according to an embodiment of the present invention;

FIG. 9 is a microscopic view of a macroporous elastomeric polymer having a multi-layered pore structure in accordance with an embodiment of the present invention;

FIG. 10 is a graph of the change in the cured precursor versus porosity for different water contents of reversible dynamic macroporous elastomeric polymeric materials of an embodiment of the present invention;

FIG. 11 is a graph of the change in optical properties of anisotropic reversible dynamic macroporous elastomeric polymeric materials under different angular mechanical forces with samples stretched to 250% during final cure according to embodiments of the present invention;

FIG. 12 is a graph of the change in optical properties of reversible dynamic macroporous elastomeric polymeric materials in solid and porous states according to embodiments of the present invention;

FIG. 13 is a graph of the actual heating effect of a macroporous elastomeric polymer coating in a solid state according to an embodiment of the invention;

FIG. 14 is a graph of the actual refrigeration effect of a macroporous elastomeric polymer coating in a porous state according to an embodiment of the invention;

FIG. 15 is a density of a reversible dynamic macroporous elastomeric polymeric material in both a solid state and a porous state according to embodiments of the present invention;

FIG. 16 is a graph of the effect of reversible dynamic macroporous elastomeric polymeric materials in water in both the solid and porous states of an embodiment of the present invention;

FIG. 17 is a contact angle diagram of a water drop on the surface of a reversible dynamic macroporous elastomeric polymeric material in an embodiment of the present invention;

FIG. 18 is a graph of porosity versus swelling ratio for silicone oil for reversible dynamic macroporous elastomeric polymeric materials in accordance with embodiments of the present invention.

Detailed Description

The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

In the following examples of the present invention, a platinum catalyst solution was used at a concentration of 1 wt%, and the product information was a xylene solution of platinum (0) -1, 3-divinyl-1, 1,3, 3-tetramethyldisiloxane complex, Pt-2%.

Both AB silica gel and clear silicone gel precursors are commercially available. The concentration of the aqueous polyvinyl alcohol solution was 1 wt%.

As shown in FIG. 1, the preparation method of reversible dynamic macroporous polymer in the embodiment of the invention mixes polymerizable/cross-linking precursor (i.e. the polymerizable monomer and the cross-linkable polymeric precursor) with the template solution which is incompatible with the polymerizable/cross-linking precursor and has volatility, the monomer is subjected to curing reaction in the presence of the template solution, the template solution is continuously exerted at the same time, the space (macroporous source) originally occupied by the volatilized template solution collapses under the action of gravity to form a folded and solid state, and after the template solution is completely volatilized, the curing is continued until the final curing process is completed, and finally the reversible macroporous elastomer polymer is obtained. As shown in fig. 2, the polymer can be switched between solid and macroporous states under different stimulation conditions. FIG. 3 is a schematic flow chart of the preparation of an embodiment of the present invention, showing the sample state at different stages.

The following examples adopt different monomers and corresponding template liquids to synthesize reversible macroporous elastomer polymers with different properties, and each example also has a corresponding stimulation mode to realize reversible state due to different materials, so that the reversible macroporous elastomer polymers are applied to different places. The present invention includes, but is not limited to, the following examples, which are intended to be illustrative of the invention and are not limiting.

Example 1:

the preparation method of the reversible dynamic macroporous polymer obtained by micromolecule polymerization comprises the following steps:

20g of 4-hydroxybutyl acrylate, 0.2g of 1, 6-hexanediol diacrylate, 0.1g of azobisisobutyronitrile and 0.2g of poly (4-hydroxybutyl acrylate) were mixed in a homogeneous manner to give a viscous polymerization precursor solution. Then, the mixture was mixed with 3.1g of water containing 1% by weight of polyvinyl alcohol, and vigorously stirred to obtain an emulsion. The obtained emulsion is cured for 1 day under the conditions of room temperature, natural light and open air, and the dynamic reversible macroporous polymer in a solid state is obtained after curing.

The reversible dynamic macroporous elastomeric polymer material prepared in this example is a transparent material.

Example 2:

20g of 4-hydroxybutyl acrylate, 0.2g of 1, 6-hexanediol diacrylate, 0.1g of azobisisobutyronitrile and 0.2g of poly (4-hydroxybutyl acrylate) were mixed in a homogeneous manner to give a viscous polymerization precursor solution. Then, the mixture was mixed with 3.1g of pure water and vigorously stirred to obtain an emulsion. The obtained emulsion is pre-cured for 15 minutes under the sealing condition of 40 ℃; then the sample is put into a drying container, vacuum is carried out at room temperature until a transparent sample is obtained, the sample is taken out, and the temperature is raised to 40 again for curing for 1 day. And obtaining the dynamic reversible macroporous polymer in a solid state after curing.

Example 3:

the preparation method for preparing the reversible dynamic macroporous elastomeric polymer from the crosslinkable polymer precursor in this example comprises:

the organosilicon precursor was obtained from a mixture of 10g of A and 10g of B. Mixing and stirring the organic silicon precursor and 3g of 1 wt% polyvinyl alcohol aqueous solution for 30min, pouring the obtained emulsion on a substrate, and curing at room temperature for 6 days to obtain the reversible dynamic macroporous elastomer polymer material.

Example 4:

a1% platinum catalyst solution was added to a mixture of 20g and 2g of the silica gel precursor, and the mixture was mixed to obtain a highly reactive organosilicon precursor. Mixing and stirring the organic silicon precursor and 3.4g of 1 wt% polyvinyl alcohol aqueous solution for 30min, pouring the obtained emulsion on a substrate, and curing at room temperature for 6 days to obtain the reversible dynamic macroporous elastomer polymer material.

The reversible dynamic macroporous elastomer polymer material with the heterogeneous structure prepared by the embodiment is a transparent material.

Example 5:

the preparation method of the reversible dynamic macroporous elastomeric polymer material of the embodiment comprises the following steps:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring the organic silicon precursor and 3g of aqueous solution containing 1% of polyvinyl alcohol for 5min, pouring the obtained emulsion on a substrate, precuring for 20min at 70 ℃ to obtain an opaque film material, and continuously curing the opaque film for 2 days at 70 ℃ in an open environment to obtain the transparent reversible dynamic macroporous elastomer polymer material.

Example 6:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring the organic silicon precursor and 3g of aqueous solution containing 1 wt% of polyvinyl alcohol for 10min, pouring the obtained emulsion on a substrate, precuring for 20min at 70 ℃ to obtain an opaque film material, and continuously curing the opaque film for 2 days at 70 ℃ in an open environment to obtain the transparent reversible dynamic macroporous elastomer polymer material.

Example 7:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring an organic silicon precursor and 3g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min at 70 ℃ to obtain an opaque film material, and continuously curing for 2 days at 70 ℃ in an open environment to obtain the transparent reversible dynamic macroporous elastomer polymer material.

Example 8:

the preparation method of the reversible dynamic macroporous elastomer polymer material with a multilayer porous structure comprises the following steps:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. The organosilicon precursor and 3g of an aqueous solution containing 1% polyvinyl alcohol were mixed and stirred for 30min to obtain emulsion 1. 10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. The organosilicon precursor and 3g of an aqueous solution containing 1% polyvinyl alcohol were mixed and stirred for 1min to obtain emulsion 2. Emulsion 1 and emulsion 2 were mixed and stirred for 4 minutes to obtain a cured precursor. And pouring the curing precursor on a substrate, precuring for 20min at 70 ℃ in a closed environment to obtain an opaque film material, and curing for 2 days in an open environment at 70 ℃ to obtain the transparent reversible dynamic macroporous elastomer polymer material.

The reversible dynamic macroporous elastomer polymer material prepared by the embodiment is a transparent material

Example 9:

the preparation method of the reversible dynamic macroporous elastomeric polymer material with color of the embodiment comprises the following steps:

10g of A and 10g of B were mixed with 0.05g of an oil-soluble red organic pigment based on perylene imide to give an organosilicon precursor. Mixing and stirring an organic silicon precursor and 3g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, and precuring for 20min in a closed environment at 70 ℃ to obtain an opaque film material; the opaque film material was allowed to cure for 2 days at 70 ℃ in an open environment to produce a red, transparent, reversible dynamic macroporous elastomeric polymeric material.

The reversible dynamic macroporous elastomeric polymer material with color prepared by the embodiment is a transparent material.

Example 10:

the preparation method of the reversible dynamic macroporous elastomer polymer material with the functional pore surface comprises the following steps:

10g of A and 10g were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring an organic silicon precursor and 3g of aqueous solution containing 1% of poly (N-isopropylacrylamide) for 30min, pouring the obtained emulsion on a substrate, and precuring for 20min in a closed environment at 70 ℃ to obtain an opaque film material; and continuously curing the opaque film material in an open environment at 70 ℃ for 2 days to prepare the reversible dynamic macroporous elastomer polymer material with the functional pore surface. The sample was cut open, cold water droplets were able to wet the surface and high temperature droplets were not able to wet the surface.

The reversible dynamic macroporous elastomer polymer material with the functional pore surface prepared by the embodiment is a transparent material.

Example 11:

the preparation method of the reversible dynamic macroporous elastomer polymer material with the specific pattern comprises the following steps:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. The silicone rubber precursor was cast on a substrate, and a "herringbone" was written by injecting a pure aqueous solution containing 1 wt% of polyethylene using a syringe, and then it was cured in an open environment at 70 ℃ for 5 days to obtain a transparent solid polymer material. As shown in fig. 5, after applying a pulling force (stimulus 1), the appearance of the opaque "man" is seen, whereas by applying a pressure (stimulus 2), the opaque "man" disappears and the polymeric material returns to its original shape.

The reversible dynamic macroporous elastomeric polymer material patterned under external stimulus prepared in this example is a transparent material.

Example 12:

the preparation method of the reversible dynamic elastomer polymer material of the channel which is opened and closed under the external stimulation comprises the following steps:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. The organic silica gel precursor is poured on a substrate, a polyvinyl alcohol aqueous solution is injected into the viscous precursor through a needle to form a fibrous water template of the precursor, and then the fibrous water template is solidified for 5 days in an open environment at 70 ℃ to prepare the transparent solid polymer material. As shown in fig. 6, after applying a pulling force (stimulus 1), a channel is visible, whereas the polymeric material is restored by applying a pressure (stimulus 2).

This example produces a channel reversible dynamic elastomeric polymeric material that opens and closes under an external stimulus that is transparent.

Example 13:

the preparation method of the anisotropic reversible dynamic macroporous elastomeric polymer material of the present embodiment comprises:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring an organic silicon precursor and 3g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min at 70 ℃ in a closed environment, stretching the precured elastomer to 110%, and curing for 2 days at 70 ℃ in an open environment to prepare the 110% anisotropic transparent solid polymer material.

Example 14:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring an organic silicon precursor and 3g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min at 70 ℃ in a closed environment, stretching the precured elastomer to 170%, and curing for 2 days at 70 ℃ in an open environment to prepare the 170% anisotropic transparent solid polymer material.

Example 15:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring an organic silicon precursor and 3g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min in a closed environment at 70 ℃, stretching the precured elastomer to 250%, and curing for 2 days in an open environment at 70 ℃ to prepare the 250% anisotropic transparent solid polymer material.

Example 16:

the preparation method of the reversible dynamic macroporous elastomeric polymer material with controllable porosity of the embodiment comprises the following steps:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring the organic silicon precursor and 1g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min in a closed environment at 70 ℃, and then curing for 2 days in an open environment at 70 ℃ to obtain the transparent solid polymer material containing 5 wt% of water.

Example 17:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring the organic silicon precursor and 20g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min in a closed environment at 70 ℃, and then curing for 2 days in an open environment at 70 ℃ to obtain the transparent solid polymer material containing 50 wt% of water.

Example 18:

1g of A and 1g of B were mixed uniformly to obtain an organosilicon precursor. Mixing and stirring the organic silicon precursor and 20g of aqueous solution containing 1% of polyvinyl alcohol for 30min, pouring the obtained emulsion on a substrate, precuring for 20min in a closed environment at 70 ℃, and then curing for 2 days in an open environment at 70 ℃ to obtain the transparent solid polymer material containing 90 wt% of water.

Example 19:

the preparation method of the macroporous elastomer polymer coating with the cooling and heating adjustable functions comprises the following steps:

10g of A and 10g of B were mixed uniformly to obtain an organosilicon precursor. 8g of the organosilicon precursor and 1g of carbon black were mixed, stirred for 30 minutes to obtain a black liquid, and the liquid was brushed on a tile and cured at 70 ℃ for 4 hours to obtain a first layer. 12g of organic silicon precursor and 30g of aqueous solution containing 1% polyvinyl alcohol are mixed and stirred for 30min, the obtained emulsion is brushed on the cured first layer sample, pre-cured for 20min in a closed environment at 70 ℃, and then cured for 2 days in an open environment at 70 ℃ to obtain the double-layer material. The porous state is obtained by scraping, and the solid state is obtained by extruding.

The anisotropic reversible dynamic macroporous elastomer polymer material prepared by the embodiment is a transparent material.

Test example 1 mechanical force responsiveness of reversible dynamic macroporous elastomeric polymeric materials

Referring to fig. 4, the reversible dynamic macroporous elastomeric polymer material of the embodiment of the invention changes from a solid state to a porous state under the action of a tensile force; under the action of pressure, the porous state is converted into the solid state again, and dynamic reversibility is realized.

Test example 2 solvent responsiveness of reversible dynamic macroporous elastomeric polymeric materials

Referring to fig. 5 and 6, an elastomer material having a specific shape, such as a herringbone shape shown in fig. 5 and a straight line shape shown in fig. 6, is formed in a cured body by filling a mold liquid into the material or using a mold at the time of casting. The collapse in the initial solid state can be shown to be a corresponding pattern under the action of tensile force through force or solvent swelling, or the solvent enters the macropores to swell to form the corresponding pattern.

Test example 3 influence of template liquid content on pore Structure

Referring to fig. 7 and 8, when water is used as the template solution, the elastomer polymer material prepared from the cured precursor with 15% water content is closed pores, and the elastomer polymer prepared from the cured precursor with 90% water content is open pores. FIG. 9 is a schematic representation of the mixing of multiple cured precursors at different moisture levels to produce a macroporous elastomeric polymer having a multi-layered pore structure. As can be seen from fig. 10, the porosity increases with the increase in the water content.

Test example 4 Effect of different mechanical force stimulation angles on optical Properties

As shown in fig. 11, the transmittance of the anisotropic reversible dynamic macroporous elastomeric polymer material stretched to 250% was different under different mechanical forces at different angles. When the tension direction is 0 degrees, namely, the tension is applied to the surface of the parallel material, the light transmittance hardly changes along with the continuous increase of the tension. However, when the tension is inclined at 45 ° or 90 ° with respect to the surface of the material, the transmittance gradually decreases as the tension increases, and decreases faster than 45 ° at 90 °.

As can be seen from fig. 12, the change of the solar transmittance is stable with the increase of the cycle number, which shows that the reversible dynamic macroporous elastomeric polymer material of the present invention does not cause the performance difference in the switching between the light transmittance and the light shielding property with the increase of the cycle number, and the material performance is relatively stable.

Test example 5 refrigeration and heating effects of reversible dynamic macroporous elastomeric Polymer Material

As shown in fig. 13 and 14, fig. 13 is a solid state, the temperature inside the material is significantly higher than the ambient temperature, and the material can allow sunlight to penetrate through and can effectively play a role in heating; fig. 14 is a porous state, the internal temperature of the coating is obviously lower than the atmospheric temperature, sunlight can be reflected, heat radiation and heat dissipation can be achieved, and the effect of refrigeration can be achieved.

Test example 6 Density of reversible dynamic macroporous elastomeric Polymer Material

As shown in FIG. 15, the density of the porous elastomeric polymer material decreases with increasing porosity, and the difference in density from the solid state is significant, as shown in FIG. 16, in which the solid elastomeric polymer material sinks to the water bottom, while the porous elastomeric polymer floats on the water surface, indicating that the density of the material changes in different states. As shown in fig. 18, as the porosity increases, the silicone oil swelling ratio of the elastomeric polymer material in the porous state increases.

Test example 7 surface roughness of reversible dynamic macroporous elastomeric polymeric materials

As shown in fig. 17, the surface roughness of the elastomeric polymer material varied in different states, with a contact angle of 108 ° when solid and 152 ° when porous, with the porous state being rougher compared to the solid state surface.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A preparation method of a reversible dynamic macroporous elastomer polymer material is characterized by comprising the following steps:

wherein the template solution is a volatile solution that is incompatible with the mixed precursor or is incompatible with the cross-linkable polymeric precursor;

2. The method for preparing a reversible dynamic macroporous elastomeric polymer material as claimed in claim 1, wherein the curing process in step (2) is performed in an open environment, and the curing temperature is room temperature or not higher than the boiling temperature of the template solution.

3. The method of preparing a reversible dynamic macroporous elastomeric polymeric material of claim 1, wherein the curing process of step (2) comprises the steps of:

(21) applying the curing precursor to a substrate or a mold and carrying out pre-curing in a sealed environment in the presence of the template liquid, wherein the curing temperature is room temperature or not higher than the boiling point temperature of the template liquid, so as to obtain a pre-cured body;

4. A method for preparing a reversible dynamic macroporous elastomeric polymeric material as claimed in any one of claims 1 to 3, wherein said polymerizable monomer is a non-volatile monomer or a monomer having a boiling point higher than 150 ℃ or a mixture of both.

5. The method of making a reversible dynamic macroporous elastomeric polymeric material of claim 4, wherein the polymerizable monomer is one or more combinations of 4-hydroxybutyl acrylate, isooctyl acrylate, poly (ethylene glycol) methyl ether acrylate, octamethylcyclotetrasiloxane, methylcyclopentadiene dimer, and dicyclopentadiene;

the template solution is water, a polyvinyl alcohol aqueous solution, a polyethylene oxide aqueous solution, ethanol, isopropanol, diethyl ether or n-hexane.

6. The method of making a reversible dynamic macroporous elastomeric polymeric material of claim 4, wherein said mixed precursor further comprises an initiator and/or a thickener.

7. The method of preparing a reversible dynamic macroporous elastomeric polymeric material of any one of claims 1-3, wherein the cross-linkable polymeric precursor is one or more combinations of double-ended acrylated polypropylene, double-ended acrylated polytetrahydrofuran, double-ended acrylated polypropylene, double-ended thiolated polypropylene, double-ended acrylated polytetrahydrofuran, and double-ended thiolated polytetrahydrofuran, or is a silicone;

the template solution is water, a polyvinyl alcohol aqueous solution, a poly (N-isopropylacrylamide) aqueous solution, ethanol, isopropanol, diethyl ether or N-hexane.

8. The method of making a reversible dynamic macroporous elastomeric polymeric material of claim 7, wherein the cross-linkable polymeric precursor further comprises one or more combinations of a cross-linking catalyst that is a tin catalyst or a platinum catalyst, a free radical initiator, an oil soluble organic pigment, and a surfactant.

9. A reversible dynamic macroporous elastomeric polymeric material prepared by the method of any one of claims 1 to 8.

10. Use of the reversible dynamic macroporous elastomeric polymeric material of claim 9 in the preparation of a stimuli-responsive polymeric material.