Polymer-based two-dimensional topological material and preparation method and application thereof
阅读说明：本技术 一种聚合物基二维拓扑材料及其制备方法和应用 (Polymer-based two-dimensional topological material and preparation method and application thereof ) 是由 徐坚 杨萌 赵宁 于 2018-07-12 设计创作，主要内容包括：本发明提供了一种聚合物基二维拓扑材料及其制备方法和应用,其是以聚合物纳米片为结构单元,是一种新型柔性二维拓扑结构,所述聚合物纳米片理化性质、尺寸及搭接方式的充分可调节性,而表现出特殊的光、声、热、液体浸润等表界面性能。本发明的包括上述聚合物基二维拓扑结构的复合材料是聚合物基二维拓扑材料增强或功能化的具体体现并伴生丰富应用。所述的方法对不同种类的聚合物体系具有广泛的普适性；相分离微观结构可调节性较强,可产生丰富变化,所得多孔聚合物材料可具备多种功能；所述聚合物基二维拓扑材料及包括该材料的复合材料可以广泛应用于辐射降温,或用于高性能浮力材料、油性污染物的去除、隔热、声波阻尼、催化剂载体等领域中。(The invention provides a polymer-based two-dimensional topological material, and a preparation method and application thereof, wherein a polymer nano sheet is taken as a structural unit, the polymer-based two-dimensional topological material is a novel flexible two-dimensional topological structure, and the polymer nano sheet has sufficient adjustability in physical and chemical properties, size and lap joint mode, and shows special surface interface performances such as light, sound, heat, liquid infiltration and the like. The composite material comprising the polymer-based two-dimensional topological structure is embodied by enhancing or functionalizing the polymer-based two-dimensional topological material and is associated with abundant application. The method has wide universality on different polymer systems; the phase separation microstructure has strong adjustability and can generate abundant changes, and the obtained porous polymer material can have multiple functions; the polymer-based two-dimensional topological material and the composite material comprising the same can be widely applied to radiation cooling, or can be used in the fields of high-performance buoyancy materials, oily pollutant removal, heat insulation, sound wave damping, catalyst carriers and the like.)
1. A polymer-based two-dimensional topological material with the apparent density of 10 orders of magnitude-2～102mg/cm3(ii) a And the structural unit of the two-dimensional topological material is a polymer-based two-dimensional nanosheetThe dimension of the nano-sheet is micron-sized, and the thickness is less than or equal to 100 nm.
2. The topological material according to claim 1, wherein said polymer-based two-dimensional nanoplatelets satisfy at least one of the following properties: (a) the diameter-thickness ratio of the polymer-based two-dimensional nanosheets is greater than or equal to 40; (b) the porosity of the polymer-based two-dimensional nanosheet is 0-40%; (c) if the porosity of the polymer-based two-dimensional nanosheet is not 0%, the surface of the polymer-based two-dimensional nanosheet comprises pores, and the pore diameter of the pores is within the nanoscale range.
Preferably, the porosity of said polymer-based two-dimensional topological material is higher than 95%; the pore size distribution of the polymer-based two-dimensional topological material is between 20nm and 20 μm, and preferably, the pore size distribution of the polymer-based two-dimensional topological material can be concentrated between 1 and 20 μm and is in micron-scale distribution, and can also be between 20nm and 20 μm and is in wide distribution.
Preferably, the specific surface area of the polymer-based two-dimensional topological material is greater than or equal to 30m2/g。
Preferably, the polymer forming the polymer-based two-dimensional topology material is a homopolymer and/or a copolymer, and illustratively, the polymer is a homopolymer, or a copolymer, or a mixture of homopolymers, or a mixture of copolymers, or a mixture of a homopolymer and a copolymer, or a mixture of homopolymers and copolymers, and the like;
preferably, the homopolymer is ultra-high molecular weight polyethylene (UHMWPE), common polyethylene (NPE), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), polyethylene oxide (PEO), Polystyrene (PS), high molecular weight polypropylene (HMWPP), poly (4-methylpentene) (TPX), or the like; the copolymer is poly (ethylene-co-norbornene) (COC) and poly (styrene-b-butadiene-b-styrene) (SBS).
Preferably, the polymer-based two-dimensional topological material has at least one of the following properties: (1) the compressive modulus of the polymer-based two-dimensional topological material is between 1 and 200 kPa; (2) the reflectivity of the polymer-based two-dimensional topological material with the thickness of 50 mu m to visible light near 600nm is higher than 60%; (3) the polymer-based two-dimensional topological material has heat preservation and insulation properties, and the room-temperature thermal conductivity of the material is lower than 50 mW/(m.K); (4) the polymer-based two-dimensional topological material has a multi-stage micro-nano structure similar to the surface of a peanut leaf; (5) the polymer-based two-dimensional topological material has hydrophilic and hydrophobic adhesion properties of different degrees, and the adhesion force is greater than 100 mu N.
3. The method for preparing a polymer-based two-dimensional topological material according to claim 1 or 2, wherein the method comprises the following steps:
step 1: dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2: performing pre-forming treatment on the homogeneous solution in the step 1 under the condition of phase separation temperature higher than that of the homogeneous solution system in the step 1;
and step 3: reducing the temperature of the preformed system in the step (2) to be below the solidification temperature of the small-molecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain a polymer-based gel skeleton taking the solid small-molecule good solvent as a dispersion medium;
and 4, step 4: and removing the solid micromolecule good solvent to obtain the polymer-based two-dimensional topological material.
4. The preparation method according to claim 3, wherein in the step 1, the good small molecular solvent has a molecular weight of 10 to 103g/mol. The good solvent is selected from paraffin, camphene, tertiary butanol, m-cresol, dimethyl sulfoxide, water, stearic acid and the like.
Preferably, in the step 1, a nucleating agent can be further added into the homogeneous solution system; the nucleating agent is preferably a nucleating agent compatible with the polymer system, and is illustratively selected from dibenzylidene sorbitol (DBS) and derivatives thereof, stearates, organophosphates, and the like when the polymer is polypropylene or polyethylene.
Preferably, in step 2, the preforming treatment may be dropping, dipping, silk-screening, casting, spinning, inkjet printing, roll coating, spray painting, spray coating, spin coating, extruding, and the like.
Preferably, in step 3, the rate of temperature reduction is greater than 0 and less than or equal to 300 ℃/min. Illustratively, the rate of temperature reduction is greater than or equal to 5 and less than or equal to 200 ℃/min.
Preferably, in step 3, the temperature reduction rate can be regulated in a segmented manner, for example, when the system temperature is between 150 ℃ and 120 ℃, the temperature reduction rate is 5-20 ℃/min, and when the system temperature is between 120-90 ℃, the temperature reduction rate is 50-100 ℃/min.
Preferably, in step 3, the system preformed in step 2 may be subjected to gradient cooling, that is, the cooling rates of different parts of the system preformed in step 2 are subjected to gradient design, and for example, the cooling rate of the top surface of the system preformed in step 2 is set to 6 ℃/min, and the cooling rate of the bottom surface is set to 100 ℃/min.
Preferably, step 3 further comprises a forming process; such as cutting, grinding, carving.
Preferably, in step 4, the solid good small molecule solvent can be directly dried and removed, for example, a combination of one or more methods such as drying under normal pressure, drying under reduced pressure, freeze drying or supercritical drying is adopted; the solid good solvent can be replaced by other solvents, and then the replaced other solvents are dried and removed, for example, cyclohexane is removed by a freeze drying method after the solid good solvent is replaced by cyclohexane.
5. Use of the polymer-based two-dimensional topological material of claim 1 or 2 for passive cooling of a human body, or in the fields of high-performance buoyancy materials, removal of oily pollutants, thermal insulation, acoustic wave damping, catalyst carriers, and the like.
6. A composite material comprising the polymer-based two-dimensional topology material of claim 1 or 2.
Preferably, the composite material comprises the polymer-based two-dimensional topological material and the functional filler, wherein the composite material is the functional filler/3D-NFLs polymer composite material, and the functional filler is adsorbed or bonded in pores of the polymer-based two-dimensional topological material.
Preferably, the functional filler is selected from silica aerogel microspheres, glass beads, titanium dioxide powder, aluminum sesquioxide powder, ferric oxide powder, vanadium dioxide powder, graphene, carbon nanotubes, silica fibers and the like.
Preferably, in the functional filler/3D-NFLs polymer composite material, the mass percentage of the functional filler is more than 0 and less than or equal to 80 wt%.
Preferably, the porosity of the functional filler/3D-NFLs polymer composite is greater than 95%.
7. The composite material according to claim 6, wherein the composite material comprises the polymer-based two-dimensional topology material and the fiber felt matrix according to claim 1 or 2, and the composite material is a fiber felt matrix/3D-NFLs polymer composite material, and the composite material has a double skeleton structure formed by mutually penetrating and connecting the inner parts of the composite material.
Preferably, the fiber mat is selected from glass fiber mat, carbon fiber mat, aluminum silicate fiber mat, and the like.
Preferably, in the fiber felt matrix/3D-NFLs polymer composite material, the mass percentage of the polymer-based two-dimensional topological material is greater than or equal to 0 and less than 50 wt%.
Preferably, the porosity of the fiber mat matrix/3D-NFLs polymer composite is greater than 90%.
8. The composite material according to claim 6, wherein the composite material comprises the polymer-based two-dimensional topology material according to claim 1 or 2 and an elastic substrate, i.e. an elastic substrate/3D-NFLs polymer composite material, wherein the elastic substrate/3D-NFLs polymer composite material is a macroscopic double-layer structure.
Preferably, the elastic substrate is selected from silicone rubber, ethylene propylene rubber, SBS, etc.
Preferably, the elastic substrate is capable of being sufficiently swollen by a volatile solvent and has a linear expansion higher than 20%. The volatile solvent is selected from ethanol, acetone, cyclohexane, toluene, tert-butanol, ethyl acetate, and the like.
Preferably, the thickness ratio of the elastic substrate to the polymer-based two-dimensional topological material layer is between 0.2 and 5.
9. A method for preparing the composite material according to any one of claims 6 to 8; the composite material comprises the polymer-based two-dimensional topological material and a functional filler according to claim 6; the method comprises the following steps:
step 1): dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2): adding a functional filler into the homogeneous solution obtained in the step 1), and fully stirring to form a filler uniform dispersion system; the content of the functional filler in the dispersion system is less than or equal to 20 wt%;
step 3): performing the preforming treatment on the filler homodisperse system in the step 2) under the condition that the phase separation temperature of the filler homodisperse system in the step 2) is higher than;
step 4): reducing the temperature of the preformed system in the step 3) to be below the solidification temperature of the micromolecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain the functional filler/polymer-based gel skeleton taking the solid micromolecule good solvent as a dispersion medium.
Step 5): and removing the solid micromolecule good solvent to obtain the functional filler/3D-NFLs polymer composite material.
Preferably, the composite material comprises the polymer-based two-dimensional topology material of claim 7 and a fiber felt matrix; the method comprises the following steps:
step 1'): dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2'): casting the homogeneous solution obtained in the step 1) into a preformed fiber felt matrix under the condition of the phase separation temperature of the homogeneous solution system in the step 1') to enable the preformed fiber felt matrix to be in a fully-infiltrated state;
step 3'): reducing the temperature of the preformed system in the step 2') to be below the solidification temperature of the micromolecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain the fibrofelt matrix/polymer-based gel skeleton taking the solid micromolecule good solvent as a dispersion medium.
Step 4'): and removing the solid micromolecule good solvent to obtain the fiber felt matrix/3D-NFLs polymer double-network composite material.
Preferably, the composite material comprises the polymer-based two-dimensional topological material of claim 8 and an elastic substrate; the method comprises the following steps:
step 1 "): dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2 "): performing sheet-shaped preforming treatment on the homogeneous solution obtained in the step 1) under the condition of a phase separation temperature higher than that of the homogeneous solution system in the step 1';
step 3 "): reducing the temperature of the preformed system in the step 2') to be lower than the solidification temperature of the micromolecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain a polymer-based gel skeleton taking the solid micromolecule good solvent as a dispersion medium;
step 4 "): removing the solid micromolecule good solvent to obtain a 3D-NFLs porous polymer sheet layer;
step 5 "): fully swelling the sheet-like elastic substrate with a volatile solvent;
step 6 "): placing the 3D-NFLs porous polymer sheet layer obtained in the step 4 ') on the sheet-like elastic substrate obtained in the step 5') after sufficient swelling;
step 7 "): and volatilizing the solvent to obtain the elastic substrate/3D-NFLs polymer double-layer composite material.
10. Use of the composite material according to any one of claims 6 to 8 for radiation cooling, or in the fields of high performance buoyancy materials, removal of oily contaminants, thermal insulation, acoustic damping, catalyst supports, and the like.
Technical Field
The invention relates to the technical field of porous polymer material processing, in particular to a polymer-based two-dimensional topological material, a composite material comprising the material, and preparation methods and applications of the polymer-based two-dimensional topological material and the composite material.
Background
Two-dimensional Nanosheets (NFLs) are very interesting due to the characteristics of high specific surface area and high active site exposure degree, and have wide application in the fields of energy, catalysis, environmental protection, biological medicine and the like. Common nanosheet materials are generally obtained by controlling the crystal growth mode or by adopting a special preparation process, such as graphene, phospholene, boron nitride, MOFs and the like, and the common nanosheet materials are obtained by controlling the crystal growth mode or adopting a special preparation process, such as metals and oxides thereof, transition metals and compounds thereof and the like. Furthermore, a three-dimensional porous skeleton (3D-NFLs) is constructed based on the two-dimensional nanosheets, namely a two-dimensional topological material, so that the two-dimensional material can be endowed with abundant macroscopic properties and has a wider application prospect; there are some limitations. Firstly, a special sacrificial template or a chemical crosslinking structure is required to be introduced for preparing a two-dimensional topological material, and the preparation is complex and has no universality; secondly, except for graphene, the mechanical properties, dispersibility and crosslinkability of NFLs are limited, and the final porous structure is difficult to realize the double advantages of specific surface area and mechanical properties. In addition, the high preparation cost of the two-dimensional nano material greatly hinders the practical application of the two-dimensional nano material. Soluble crystalline polymers, especially ultra high molecular weight polyolefins, have unique advantages in this regard.
Because the thickness of the wafer obtained by solution crystallization is nano-scale, the polymer-based 3D-NFLs material can be directly obtained by regulating and controlling the Thermally Induced Phase Separation (TIPS) condition, but the performance needs to be further optimized, and related research is less. Although there is a long history of development of porous polymer materials from early foaming materials to later aerogels, the 3D-NFLs structure is rarely reported. The main reason is that it is difficult to control the thickness of the polymer sheet within 100nm (even lower) only by foaming or in-situ curing, and it is more difficult to obtain a functional material with good mechanical properties at a low solid content (the solid content is the weight fraction of the polymer relative to the initial solution system before the material is formed or cured); whereas the geometric structural units of the polymeric aerogels are generally nanoparticles or fibers. Therefore, the research and preparation of high-performance polymer-based two-dimensional topological materials remain extremely challenging.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a polymer-based two-dimensional topological material, and a preparation method and application thereof.
The invention also provides a composite material, a preparation method and application thereof, wherein the composite material comprises the polymer-based two-dimensional topological material.
The inventor finds that based on thermally induced phase separation, the significant difference of viscoelasticity of high molecules and small molecules and the difference of temperature responsiveness are utilized, and the solvent is selected by combining with the temperature reduction rate and gradient regulationChanging the phase separation state can be carried out at a lower initial polymer solid content (which can be as low as 10)-5In the order of wt%) to construct a continuous polymer-based two-dimensional topology. Compared with the existing process for preparing the porous polymer material by the thermally induced phase separation method, the solid solvent selected by the method has higher molecular weight, can be subjected to adhesion promotion, solidification or freezing in the thermally induced phase separation process, and has stronger acting force with polymer molecules, so that the influence of thermally induced phase separation temperature change on the structure is strengthened, and the time required by thermally induced phase separation to tend to balance is greatly prolonged.
The structure and the performance of the obtained polymer-based two-dimensional topological material have sufficient adjusting space. The method mainly relates to the following aspects that firstly, the size, the lap joint mode, the orientation and the material aperture size of the two-dimensional nanosheets forming the polymer-based two-dimensional topological structure have higher responsiveness to preparation conditions; secondly, thermally induced phase separation methods (TIPs) are general methods, and different polymer systems can be selected according to expected functions; thirdly, the obtained polymer-based two-dimensional topological material is easy to realize the introduction of various functional groups or the loading of functional materials. Therefore, the polymer-based two-dimensional topological material prepared by the invention not only can be used as a functional material for thermal management, adsorption separation and the like, but also can be used as a universal flexible carrier or template.
The selection of the solid solvent (the solvent which is in a solid state when the thermal phase separation of the polymer concentrated phase and the polymer dilute phase in a solution system is ended) also brings great convenience for the preparation of the material, firstly, the polymer framework is supported and protected in the post-treatment processes of solvent replacement, drying and the like, and the volume shrinkage rate is reduced; secondly, the material is endowed with more abundant processability due to the existence of the intermediate state of the solid gel; the thermally induced phase separation process can be delayed and frozen in a specific transition state, particularly a bicontinuous phase separation form, through self-adhesion and solidification in the temperature reduction process so as to obtain a desired design structure. Based on the above-mentioned ideas, the technical solution of the present invention is completed.
Specifically, the invention provides the following technical scheme:
a kind ofPolymer-based two-dimensional topological material with apparent density of 10-2～102mg/cm3(ii) a And the structural unit of the two-dimensional topological material is a polymer-based two-dimensional nanosheet, the planar size of the polymer-based two-dimensional nanosheet is micron-sized, and the thickness of the polymer-based two-dimensional nanosheet is less than or equal to 100 nm.
According to a preferred embodiment of the present invention, the polymer-based two-dimensional nanoplatelets may satisfy at least one of the following properties: (a) the diameter-thickness ratio of the polymer-based two-dimensional nanosheets is greater than or equal to 40; (b) the porosity of the polymer-based two-dimensional nanosheet is 0-40%; (c) if the porosity of the polymer-based two-dimensional nanosheet is not 0%, the surface of the polymer-based two-dimensional nanosheet comprises pores, and the pore diameter of the pores is within the nanoscale range.
According to a preferred embodiment of the invention, the porosity of said polymer-based two-dimensional topological material is higher than 95%; the pore size distribution of the polymer-based two-dimensional topological material is between 20nm and 20 μm, and preferably, the pore size distribution of the polymer-based two-dimensional topological material can be concentrated between 1 and 20 μm and is distributed in a micrometer scale, and can also be distributed between 20nm and 20 μm in a wide range.
According to a preferred embodiment of the invention, the specific surface area of the polymer-based two-dimensional topological material is greater than or equal to 30m2/g。
According to a preferred embodiment of the present invention, the polymer forming the polymer-based two-dimensional topology material is a homopolymer and/or a copolymer, and illustratively, the polymer is a homopolymer, or a copolymer, or a mixture of homopolymers, or a mixture of copolymers, or a mixture of a homopolymer and a copolymer, or a mixture of homopolymers and copolymers, and the like;
preferably, the homopolymer is ultra-high molecular weight polyethylene (UHMWPE), common polyethylene (NPE), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), polyethylene oxide (PEO), Polystyrene (PS), high molecular weight polypropylene (HMWPP), poly (4-methylpentene) (TPX), or the like; the copolymer is poly (ethylene-co-norbornene) (COC) and poly (styrene-b-butadiene-b-styrene) (SBS).
According to a preferred embodiment of the present invention, the polymer-based two-dimensional topological material has at least one of the following properties: (1) the compressive modulus of the polymer-based two-dimensional topological material is between 1 and 200 kPa; (2) the reflectivity of the polymer-based two-dimensional topological material with the thickness of 50 mu m to visible light near 600nm is higher than 60%; (3) the polymer-based two-dimensional topological material has heat preservation and insulation properties, and the room-temperature thermal conductivity of the material is lower than 50 mW/(m.K); (4) the polymer-based two-dimensional topological material has a multi-stage micro-nano structure similar to the surface of a peanut leaf; (5) the polymer-based two-dimensional topological material has hydrophilic and hydrophobic adhesion properties of different degrees, and the adhesion force is greater than 100 mu N.
The invention also provides a preparation method of the polymer-based two-dimensional topological material, which comprises the following steps:
step 1: dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2: performing pre-forming treatment on the homogeneous solution obtained in the
and step 3: reducing the temperature of the preformed system in the step (2) to be below the solidification temperature of the small-molecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain a polymer-based gel skeleton taking the solid small-molecule good solvent as a dispersion medium;
and 4, step 4: and removing the solid micromolecule good solvent to obtain the polymer-based two-dimensional topological material.
According to a preferable scheme of the invention, in the
According to a preferred embodiment of the present invention, in
According to a preferred embodiment of the present invention, in step 2, the preforming process may be dropping, dipping, silk-screening, casting, spinning, inkjet printing, roll coating, spray painting, spray coating, spin coating, extruding, and the like.
According to a preferable embodiment of the present invention, in step 3, the rate of temperature reduction is greater than 0 and equal to or less than 300 ℃/min. Illustratively, the rate of temperature reduction is greater than or equal to 5 and less than or equal to 200 ℃/min.
According to a preferred embodiment of the present invention, in step 3, the temperature reduction rate can be regulated in a segmented manner, for example, when the system temperature is between 150 ℃ and 120 ℃, the temperature reduction rate is 5-20 ℃/min, and when the system temperature is between 120-90 ℃, the temperature reduction rate is 50-100 ℃/min.
According to a preferred embodiment of the present invention, in step 3, the system preformed in step 2 may be subjected to gradient cooling, that is, the cooling rates of different parts of the system preformed in step 2 are subjected to gradient design, and for example, the cooling rate of the top surface of the system preformed in step 2 is set to 6 ℃/min, and the cooling rate of the bottom surface is set to 100 ℃/min.
According to a preferred scheme of the invention, step 3 further comprises a further forming processing process; such as cutting, grinding, carving.
According to a preferred embodiment of the present invention, in step 4, the solid-state good small molecule solvent can be directly dried and removed, for example, by one or more methods selected from drying under normal pressure, drying under reduced pressure, freeze drying, or supercritical drying; the solid good solvent can be replaced by other solvents, and then the replaced other solvents are dried and removed, for example, cyclohexane is removed by a freeze drying method after the solid good solvent is replaced by cyclohexane.
The invention also provides application of the polymer-based two-dimensional topological material, which is used for passive cooling of a human body or used in the fields of high-performance buoyancy materials, removal of oily pollutants, heat insulation, sound wave damping, catalyst carriers and the like.
The invention also provides a composite material, which comprises the polymer-based two-dimensional topological material.
According to a preferable scheme of the invention, the composite material comprises the polymer-based two-dimensional topological material and the functional filler, the composite material is a functional filler/3D-NFLs polymer composite material, and the functional filler is adsorbed or bonded in pores of the polymer-based two-dimensional topological material.
According to a preferred embodiment of the present invention, the functional filler is selected from silica aerogel microspheres, glass beads, titanium dioxide powder, aluminum trioxide powder, ferroferric oxide powder, vanadium dioxide powder, graphene, carbon nanotubes, silica fibers, and the like.
According to a preferable scheme of the invention, in the functional filler/3D-NFLs polymer composite material, the mass percentage of the functional filler is more than 0 and less than or equal to 80 wt%.
According to a preferred embodiment of the present invention, the porosity of the functional filler/3D-NFLs polymer composite is greater than 95%.
According to a preferable scheme of the invention, the composite material comprises the polymer-based two-dimensional topological material and the fiber felt matrix, the composite material is a fiber felt matrix/3D-NFLs polymer composite material, and the composite material internally presents a double-skeleton structure which is mutually connected in a penetrating way.
According to a preferred embodiment of the invention, the fiber mat is selected from glass fiber mats, carbon fiber mats, aluminum silicate fiber mats and the like.
According to a preferable scheme of the invention, in the fiber felt matrix/3D-NFLs polymer composite material, the mass percentage of the polymer-based two-dimensional topological material is more than or equal to 0 and less than 50 wt%.
According to a preferred embodiment of the present invention, the porosity of the fiber mat matrix/3D-NFLs polymer composite is greater than 90%.
According to a preferable scheme of the invention, the composite material comprises the polymer-based two-dimensional topological material and the elastic substrate, the composite material is an elastic substrate/3D-NFLs polymer composite material, and the elastic substrate/3D-NFLs polymer composite material is a macroscopic double-layer structure.
According to a preferred embodiment of the present invention, the elastic substrate is selected from the group consisting of silicone rubber, ethylene propylene rubber, SBS, etc.
According to a preferred embodiment of the present invention, the elastic substrate is capable of being sufficiently swelled with a volatile solvent and has a linear expansion rate higher than 20%. The volatile solvent is selected from ethanol, acetone, cyclohexane, toluene, tert-butanol, ethyl acetate, and the like.
According to a preferred embodiment of the invention, the ratio of the thickness of the elastic substrate to the thickness of the polymer-based two-dimensional topological material layer is between 0.2 and 5.
The invention also provides the application of the composite material, which is used for radiation cooling, or is used in the fields of high-performance buoyancy materials, removal of oily pollutants, heat insulation, sound wave damping, catalyst carriers and the like.
The invention has the beneficial effects that:
1. the polymer-based two-dimensional topological material takes the polymer nano-sheet as a structural unit, is a novel flexible two-dimensional topological structure, and shows special surface interface performances such as light, sound, heat, liquid infiltration and the like due to the full adjustability of the structural unit, namely the physical and chemical properties, the size and the lap joint mode of the polymer nano-sheet.
2. The composite material comprising the polymer-based two-dimensional topological structure is embodied by enhancing or functionalizing a polymer-based two-dimensional topology material and is associated with abundant application.
3. The method of the invention has the following advantages:
1) the method has wide universality on different polymer systems;
2) the phase separation microstructure has strong adjustability and can generate abundant changes, and the obtained porous polymer material can have multiple functions;
3) the preparation route is suitable for various molding processing technologies, so that materials with various shapes and functions such as porous fibers, porous membranes, blocky profiled bars and the like can be obtained;
4) the porous composite material can be processed and formed by simple solution blending or solution casting;
5) the introduction of the solid solvent can effectively improve the through-hole rate of the porous polymer material and reduce the volume shrinkage rate of the porous polymer material in the drying process, such as reducing the apparent density of 3D-NFLs UHMWPE with the same initial solid content by 47%;
6) the preparation process has a solid gel intermediate state, so that the appearance of the porous polymer material is easy to design;
7) chemical crosslinking can not be introduced, and subsequent functionalization of the material is facilitated.
4. The polymer-based two-dimensional topological material and the composite material comprising the polymer-based two-dimensional topological material can be widely applied to radiation cooling, or can be applied to the fields of high-performance buoyancy materials, oily pollutant removal, heat insulation, sound wave damping, catalyst carriers and the like.
Drawings
FIG. 1.3 Scanning Electron Microscope (SEM) images of polymer materials of the D-NFLs. Typical microscopic morphology and different shapes of (A) fibers and (C) films of 3D-NFLs UHMWPE porous polymer material; the micro-morphology of other 3D-NFLs polymer, (D) HMWPP, and (E) COC.
FIG. 2 is SEM image of the micro-morphology of 3D-NFLs UHMWPE with a solid content of 0.005 wt%.
FIG. 3 is an SEM image of the surface of super-hydrophobic adhesion 3D-NFLs polymer material of a peanut leaf. Wherein (A-C) the surface topography of the peanut blade with different magnification factors (Yang S., et al. Small,2014,10(2): 294-; the surface appearance and the contact angle of the 3D-NFLs UHMWPE porous polymer material before (E) and after the nucleating agent (D) is added.
FIG. 4 SEM images of 3D-NFLs polymer material with graded pore size. (A) A low cooling rate surface; (B) high cooling rate surface.
FIG. 5 is a schematic structural diagram of a 3D-NFLs polymer porous composite material. (A)3D-NFLs porous polymers; (B) functional filler/3D-NFLs composite material; (C) the fiber felt matrix/3D-NFLs double-network composite material; (D) elastic substrate/3D-NFLs bilayer composites.
Detailed Description
[ Polymer-based two-dimensional topology Material ]
As previously mentioned, the present invention provides a polymer-based two-dimensional topology material having an apparent density on the order of 10-2～102mg/cm3(ii) a And the structural unit of the two-dimensional topological material is a polymer-based two-dimensional nanosheet, the planar size of the polymer-based two-dimensional nanosheet is micron-sized, and the thickness of the polymer-based two-dimensional nanosheet is less than or equal to 100 nm.
According to a preferred embodiment of the present invention, the polymer-based two-dimensional nanoplatelets may satisfy at least one of the following properties: (a) the diameter-thickness ratio of the polymer-based two-dimensional nanosheets is greater than or equal to 40; the diameter-thickness ratio in the range can provide a polymer-based two-dimensional topological material with larger porosity and lighter apparent density, and the flexibility of the prepared polymer-based two-dimensional topological material is improved; (b) the porosity of the polymer-based two-dimensional nanosheet is 0-40%; (c) if the porosity of the polymer-based two-dimensional nanosheet is not 0%, the surface of the polymer-based two-dimensional nanosheet comprises pores, and the pore diameter of the pores is within the nanoscale range; the introduction of the holes can improve the visible light transmittance of the polymer-based two-dimensional topological material.
According to a preferred embodiment of the present invention, the macro-topographic structure of the polymer-based two-dimensional topological material is not particularly limited, and may be any one known to those skilled in the art, and may be selected according to the application environment thereof, and may be, for example, a nanosheet, a microsphere, a porous fiber, a porous membrane, a bulk profile, and the like.
According to the preferable scheme of the invention, pores exist among the structural units in the polymer-based two-dimensional topological material, the porosity and the pore size distribution of the polymer-based two-dimensional topological material are not particularly limited, and the prepared polymer-based two-dimensional topological material has the properties of ultra-light weight, flexibility and the like; preferably, the porosity of said polymer-based two-dimensional topological material is higher than 95%; the pore size distribution of the polymer-based two-dimensional topological material is between 20nm and 20 μm, and preferably, the pore size distribution of the polymer-based two-dimensional topological material can be concentrated between 1 and 20 μm and is distributed in a micron-scale mode, and can also be distributed between 20nm and 20 μm in a wide mode.
According to a preferred embodiment of the present invention, the specific surface area of the polymer-based two-dimensional topological material is not particularly limited, and may be any specific surface area known to those skilled in the art, and it is required to satisfy the characteristics of ultra lightness and flexibility, and preferably, the specific surface area of the polymer-based two-dimensional topological material is greater than or equal to 30m2/g。
According to a preferred embodiment of the present invention, the polymer forming the polymer-based two-dimensional topology material is not particularly limited, and may be any polymer known to those skilled in the art. Preferably, the polymer is at least one of a homopolymer and a copolymer, and illustratively, the polymer is one homopolymer, or one copolymer, or a mixture of homopolymers, or a mixture of copolymers, or a mixture of one homopolymer and one copolymer, or a mixture of homopolymers and copolymers, and the like. If the polymer is a multi-monomer copolymer or a mixture of multiple monomers, the mass percentage of each component is not particularly limited, and the polymer-based two-dimensional topological structure can be prepared. Preferably, the homopolymer is ultra-high molecular weight polyethylene (UHMWPE), common polyethylene (NPE), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), polyethylene oxide (PEO), Polystyrene (PS), high molecular weight polypropylene (HMWPP), poly (4-methylpentene) (TPX), or the like; the copolymer is poly (ethylene-co-norbornene) (COC), poly (styrene-b-butadiene-b-styrene) (SBS) and the like.
Wherein the ultra-high molecular weight polyethylene (UHMWPE) refers to homopolyethylene with a molecular weight of more than 100 ten thousand; the ordinary polyethylene (NPE) is the general polyethylene sold in the market, and the molecular weight is between tens of thousands and hundreds of thousands; the high molecular weight polypropylene (HMWPP) refers to a homo isotactic polypropylene with a molecular weight of more than 50 ten thousand;
according to a preferred embodiment of the present invention, the molecular weight of the polymer forming the polymer-based two-dimensional topology material is preferably above 10 ten thousand.
According to a preferred embodiment of the present invention, the polymer forming the polymer-based two-dimensional topology material has solubility.
According to a preferred embodiment of the present invention, the polymer forming the polymer-based two-dimensional topology material is semi-crystalline.
According to a preferred embodiment of the present invention, the polymer-based two-dimensional topological material has at least one of the following properties: (1) the compressive modulus of the polymer-based two-dimensional topological material is between 1 and 200kPa, and the material shows better flexibility; (2) the reflectivity of the polymer-based two-dimensional topological material with the thickness of 50 mu m to visible light near 600nm is higher than 60%, and the polymer-based two-dimensional topological material has excellent visible light scattering performance; (3) the polymer-based two-dimensional topological material has heat preservation and insulation properties, and the room-temperature thermal conductivity of the material is lower than 50 mW/(m.K); (4) the polymer-based two-dimensional topological material has a multi-stage micro-nano structure similar to the surface of a peanut leaf, shows hydrophilic and hydrophobic adhesion performances in different degrees, has the adhesion force of more than 100 mu N, and has a static contact angle which is obviously changed along with the variety of the polymer.
[ preparation method of Polymer-based two-dimensional topology Material ]
As mentioned above, the present invention also provides a preparation method of the polymer-based two-dimensional topological material, which comprises:
step 1: dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2: performing pre-forming treatment on the homogeneous solution obtained in the
and step 3: reducing the temperature of the preformed system in the step (2) to be below the solidification temperature of the small-molecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain a polymer-based gel skeleton taking the solid small-molecule good solvent as a dispersion medium;
and 4, step 4: and removing the solid micromolecule good solvent to obtain the polymer-based two-dimensional topological material.
According to a preferable scheme of the invention, in the
According to a preferred embodiment of the present invention, in
According to a preferred embodiment of the present invention, in
According to a preferred embodiment of the present invention, in step 2, the preforming process may be any one known by those skilled in the art, or may be selected according to a macro topography required by the prepared polymer-based two-dimensional topology material, and may be, for example, processes such as dropping, dipping, silk-screening, casting, spinning, ink-jet printing, roll coating, painting, spray coating, spin coating, and extruding; for example: the casting can be carried out by selecting moulds with different shapes and carrying out preforming by a solution casting method to obtain blocky profiled bars; the spinning can select spinning nozzles with different apertures, and porous fibers with different diameters are obtained through solution spinning preforming; different substrate materials such as tinfoil paper, metal plates, silicon wafers, polytetrafluoroethylene plates, glass sheets and the like can be selected by dripping, dipping, silk-screen printing, ink-jet printing, roller coating, spray painting, spray coating or spin coating, and the like, and the corresponding polymer porous membrane is obtained after membrane removal.
According to a preferable embodiment of the present invention, in step 3, the rate of temperature reduction is greater than 0 and equal to or less than 300 ℃/min. Illustratively, the rate of temperature reduction is greater than or equal to 5 and less than or equal to 200 ℃/min.
According to a preferred embodiment of the present invention, in step 3, the temperature reduction rate can be regulated in a segmented manner, for example, when the system temperature is between 150 ℃ and 120 ℃, the temperature reduction rate is 5-20 ℃/min, and when the system temperature is between 120-90 ℃, the temperature reduction rate is 50-100 ℃/min.
According to a preferred embodiment of the present invention, in step 3, the system preformed in step 2 may be subjected to gradient cooling, that is, the cooling rates of different parts of the system preformed in step 2 are subjected to gradient design, and for example, the cooling rate of the top surface of the system preformed in step 2 is set to 6 ℃/min, and the cooling rate of the bottom surface is set to 100 ℃/min.
According to a preferred scheme of the invention, step 3 further comprises a further forming processing process; the molding process is based on the fact that the polymer-based gel skeleton which is prepared in the step 3 and takes the solid-state micromolecule good solvent as the dispersion medium has good easy processing performance, the obtained polymer-based gel skeleton which takes the solid-state micromolecule good solvent as the dispersion medium is further molded and processed, such as cutting, polishing, carving and the like according to the using state and the application place of the polymer-based two-dimensional topological material, and the application field of the polymer-based gel skeleton is expanded due to the characteristic of easy processing.
According to a preferred embodiment of the present invention, in step 4, the solid-state good small molecule solvent can be directly dried and removed, for example, by one or more methods selected from drying under normal pressure, drying under reduced pressure, freeze drying, or supercritical drying; the solid good solvent can be replaced by other solvents, and then the replaced other solvents are dried and removed, for example, cyclohexane is removed by a freeze drying method after the solid good solvent is replaced by cyclohexane. [ use of Polymer-based two-dimensional topology Material ]
As mentioned above, the invention also provides the application of the polymer-based two-dimensional topological material, which is used for passive cooling of human body, or used in the fields of high-performance buoyancy materials, removal of oily pollutants, heat insulation, acoustic wave damping, catalyst carriers and the like.
[ composite Material ]
As mentioned above, the present invention also provides a composite material comprising the above polymer-based two-dimensional topology material.
According to a preferable scheme of the invention, the composite material comprises the polymer-based two-dimensional topological material and the functional filler, the composite material is a functional filler/3D-NFLs polymer composite material, and the functional filler is adsorbed or bonded in pores of the polymer-based two-dimensional topological material; as shown in a and B of fig. 4, the microstructure of the functional filler/3D-NFLs polymer composite material is represented by using the 3D-NFLs polymer as a basic skeleton, and the functional filler is adsorbed or bonded thereon to perform catalytic or mid-infrared ray emission and the like.
According to a preferred embodiment of the present invention, the selection of the functional filler is not particularly limited, and may be any one of the functional fillers known to those skilled in the art to be suitable for the polymer-based two-dimensional topological material of the present invention, and exemplarily, the functional filler is selected from silica aerogel microspheres, glass microspheres, titanium dioxide powder, aluminum oxide powder, ferroferric oxide powder, vanadium dioxide powder, graphene, carbon nanotubes, silica fibers, and the like.
According to a preferable scheme of the invention, in the functional filler/3D-NFLs polymer composite material, the mass percentage of the functional filler is more than 0 and less than or equal to 80 wt%.
According to a preferred embodiment of the present invention, the porosity of the functional filler/3D-NFLs polymer composite is greater than 95%.
According to a preferable scheme of the invention, the composite material comprises the polymer-based two-dimensional topological material and a fiber felt matrix, the composite material is a fiber felt matrix/3D-NFLs polymer composite material, and the composite material is internally provided with a double-framework structure which is mutually connected in a penetrating way; as shown in a and C in fig. 4, the fiber felt matrix/3D-NFLs polymer composite material has a double-skeleton structure inside, which is interconnected through, so as to improve the overall mechanical properties, thermal conductivity and the like of the material.
According to a preferred embodiment of the present invention, the selection of the type of the fiber mat matrix is not particularly limited, and may be any fiber mat matrix known to those skilled in the art to be suitable for the polymer-based two-dimensional topology material of the present invention, and the fiber mat is exemplarily selected from a glass fiber mat, a carbon fiber mat, an aluminum silicate fiber mat, and the like.
According to the preferable scheme of the invention, in the fiber felt matrix/3D-NFLs polymer composite material, the mass percentage of the polymer-based two-dimensional topological skeleton is more than or equal to 0 and less than 50 wt%.
According to a preferred embodiment of the present invention, the porosity of the fiber mat matrix/3D-NFLs polymer composite is greater than 90%.
According to a preferred scheme of the invention, the composite material comprises the polymer-based two-dimensional topological material and an elastic substrate, the composite material is an elastic substrate/3D-NFLs polymer composite material, and the elastic substrate/3D-NFLs polymer composite material is a macroscopic double-layer structure; as shown in a and D of fig. 4, wherein the elastic substrate/3D-NFLs polymer composite is a macroscopic double layer structure, i.e., the 3D-NFLs polymer layer is adhered to the elastic substrate to obtain the tensile compression resilience and other functions.
According to a preferred embodiment of the present invention, in the elastic substrate/3D-NFLs polymer composite material, the selection of the type of elastic substrate is not particularly limited, and may be any elastic substrate known to those skilled in the art to be suitable for the polymer-based two-dimensional topology material of the present invention, and illustratively, the elastic substrate is selected from silicone rubber, ethylene propylene rubber, SBS, etc.
According to a preferred embodiment of the present invention, the elastic substrate has a tensile or compressive modulus that is more closely matched to the 3D-NFLs polymer material that is intended to be compounded.
According to a preferred embodiment of the present invention, the elastic substrate is capable of being sufficiently swelled with a volatile solvent and has a linear expansion rate higher than 20%. The volatile solvent is selected from ethanol, acetone, cyclohexane, toluene, tert-butanol, ethyl acetate, and the like. The volatile solvent capable of swelling the elastomeric substrate is capable of wetting the polymer-based two-dimensional topology material intended to be compounded.
According to a preferred embodiment of the invention, the ratio of the thickness of the elastic substrate to the thickness of the polymer-based two-dimensional topological material layer is between 0.2 and 5.
[ method for producing composite Material ]
As mentioned above, the present invention also provides a method for preparing the above composite material; the composite material comprises the polymer-based two-dimensional topological material and a functional filler; the method comprises the following steps:
step 1): dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2): adding a functional filler into the homogeneous solution obtained in the step 1), and fully stirring to form a filler uniform dispersion system; the content of the functional filler in the dispersion system is less than or equal to 20 wt%;
step 3): performing the preforming treatment on the filler homodisperse system in the step 2) under the condition that the phase separation temperature of the filler homodisperse system in the step 2) is higher than;
step 4): reducing the temperature of the preformed system in the step 3) to be below the solidification temperature of the small molecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain the functional filler/polymer-based gel skeleton taking the solid small molecule good solvent as a dispersion medium.
Step 5): and removing the solid micromolecule good solvent to obtain the functional filler/3D-NFLs polymer composite material.
As mentioned above, the present invention also provides a method for preparing the above composite material; the composite material comprises the polymer-based two-dimensional topological material and a fiber felt matrix; the method comprises the following steps:
step 1'): dissolving a polymer in a micromolecular good solvent to form a homogeneous solution system; the solid content of the polymer in the homogeneous solution system is less than or equal to 5 wt%;
step 2'): casting the homogeneous solution obtained in the step 1) into a preformed fiber felt matrix under the condition of the phase separation temperature of the homogeneous solution system in the step 1') to enable the preformed fiber felt matrix to be in a fully-infiltrated state;
step 3'): reducing the temperature of the preformed system in the step 2') to be below the solidification temperature of the micromolecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain the fibrofelt matrix/polymer-based gel skeleton taking the solid micromolecule good solvent as a dispersion medium.
Step 4'): and removing the solid micromolecule good solvent to obtain the fiber felt matrix/3D-NFLs polymer double-network composite material.
As mentioned above, the present invention also provides a method for preparing the above composite material; the composite material comprises the polymer-based two-dimensional topological material and an elastic substrate; the method comprises the following steps:
step 2 "): performing sheet-shaped preforming treatment on the homogeneous solution obtained in the step 1) under the condition of higher phase separation temperature than the homogeneous solution system in the step 1);
step 3 "): reducing the temperature of the preformed system in the step 2') to be lower than the solidification temperature of the micromolecule good solvent, and carrying out thermally induced phase separation on the preformed system to obtain a polymer-based gel skeleton taking the solid micromolecule good solvent as a dispersion medium;
step 4 "): removing the solid micromolecule good solvent to obtain a 3D-NFLs porous polymer sheet layer;
step 5 "): fully swelling the sheet-like elastic substrate with a volatile solvent;
step 6 "): placing the 3D-NFLs porous polymer sheet layer obtained in the step 4 ') on the sheet-like elastic substrate obtained in the step 5') after sufficient swelling;
step 7 "): and volatilizing the solvent to obtain the elastic substrate/3D-NFLs polymer double-layer composite material. [ use of composite Material ]
As mentioned above, the invention also provides the application of the composite material, which is used for radiation cooling, or is used in the fields of high-performance buoyancy materials, oily pollutant removal, heat insulation, sound wave damping, catalyst carriers and the like.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that various changes or modifications can be made by those skilled in the art after reading the disclosure of the present invention, and such equivalents also fall within the scope of the invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
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