阅读说明：本技术 一种仿生多孔聚乳酸复合材料及其制备方法与应用 (Bionic porous polylactic acid composite material and preparation method and application thereof ) 是由 徐建海 王美兰 杨智韬 邱守季 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种仿生多孔聚乳酸复合材料及其制备方法与应用。所述制备方法包括：将聚乳酸、热塑性聚合物与相容剂密炼共混,之后进行注塑处理,制得聚乳酸发泡前驱体材料；以及,将所述聚乳酸发泡前驱体材料进行二维受限超临界CO-(2)发泡处理,再经刻蚀处理,获得仿生多孔聚乳酸复合材料。本发明制备的仿生多孔聚乳酸复合材料具有仿木材的取向微纳多级多孔结构,在微米级泡孔孔壁上形成纳米级通道,使得复合材料具有良好的超疏水-超亲油的润湿性能,更好的毛细作用力和吸油能力。(The invention discloses a bionic porous polylactic acid composite material and a preparation method and application thereof. The preparation method comprises the following steps: mixing polylactic acid, a thermoplastic polymer and a compatilizer, and then carrying out injection molding treatment to prepare a polylactic acid foaming precursor material; and subjecting the polylactic acid foaming precursor material to two-dimensional limited supercritical CO 2 Foaming treatment and etching treatment to obtain the bionic porous polylactic acid composite material. The bionic porous polylactic acid composite material prepared by the invention has a wood-like oriented micro-nano multistage porous structure, and a nano-scale channel is formed on the wall of a micro-scale cell hole, so that the composite material has good super-hydrophobic-super-oleophylic wettability, and better capillary force and oil absorption capacity.)

1. A preparation method of a bionic porous polylactic acid composite material is characterized by comprising the following steps:

mixing polylactic acid, a thermoplastic polymer and a compatilizer in an internal mixing way, and then carrying out injection molding treatment to prepare a polylactic acid foaming precursor material, wherein the compatilizer comprises any one or the combination of more than two of polylactic acid-b-polypropylene, polylactic acid-b-polystyrene and polylactic acid-b-polycarbonate;

and subjecting the polylactic acid foaming precursor material to two-dimensional limited supercritical CO₂Foaming treatment and etching treatment to obtain the bionic porous polylactic acid composite material.

2. The method of claim 1, wherein: the mass ratio of the polylactic acid to the thermoplastic polymer to the compatilizer is (20-80) to (1-5).

3. The method of claim 1, wherein: the thermoplastic polymer comprises any one or the combination of more than two of polypropylene, polystyrene and polycarbonate;

and/or the compatilizer at least enables the phase region size of the bionic porous polylactic acid composite material to be refined to a nanometer level.

4. The production method according to claim 1, characterized by comprising: uniformly mixing polylactic acid, a thermoplastic polymer and a compatilizer, and then sequentially carrying out mixing blending, crushing and injection molding treatment to prepare the polylactic acid foaming precursor material, wherein the mixing blending temperature is 180-200 ℃, and the time is 10-20 min.

5. The production method according to claim 1, characterized by comprising:

placing the polylactic acid foaming precursor material in a mould;

and placing the mold in a high pressure reaction apparatus followed by CO₂In the atmosphere, two-dimensional limited supercritical CO is carried out under the conditions that the temperature is 120-150 ℃, the saturation pressure is 12-30 MPa, the saturation time is 1-3 h, and the pressure relief rate is 1-8 MPa/s₂Foaming treatment;

preferably, the mold has a groove structure, and the groove structure is used for accommodating the polylactic acid foaming precursor material; more preferably, the trench structure comprises a square trench.

6. The production method according to claim 1, characterized by comprising: will be subjected to said two-dimensional limited supercritical CO₂Placing the foamed material in an etching solvent, performing etching treatment at 20-50 ℃ for 10-24 h, and drying to obtain the bionic porous polylactic acid composite material;

preferably, the etching solvent includes toluene.

7. The bionic porous polylactic acid composite material prepared by the method of any one of claims 1 to 6, which has a micro-level and nano-level oriented open pore structure, wherein the diameter of a micro pore contained in the bionic porous polylactic acid composite material is 10-200 μm, the porosity is 85-97%, and the wall of the micro pore has a nano-pore structure smaller than 100 nm;

preferably, the specific surface area of the bionic porous polylactic acid composite material is 19-50 g/m²；

Preferably, the contact angle of the bionic porous polylactic acid composite material and water is 150-164 degrees;

preferably, the oil absorption rate of the bionic porous polylactic acid composite material is 82-155 L.h^-1·g^-1。

8. The use of the biomimetic porous polylactic acid composite material according to claim 7 in oil-water separation.

9. An oil-water separation method is characterized by comprising the following steps: the bionic porous polylactic acid composite material of claim 7 is fully contacted with an oil-water mixture, so that oil-water separation is realized.

10. An oil-water separation device, characterized by comprising the biomimetic porous polylactic acid composite material according to claim 7.

Technical Field

The invention belongs to the technical field of polylactic acid, and particularly relates to a bionic porous polylactic acid composite material and a preparation method and application thereof.

Background

The pores of tens of microns inside the natural wood are oriented, so that the wood has high porosity and low density, and the mechanical strength in the direction parallel to the pores is improved. Meanwhile, the hole wall plays a key role in the mechanical property of the wood, and the main component of the hole wall is composed of cross-linked amorphous lignin, so that the rigidity of the wood is enhanced. The multi-stage porous structure is also beneficial to the material exchange and transportation in the wood growth process, and provides a design direction for wood and wood bionic materials. As a material which has been widely used by humans at the earliest, the application of wood has been developed for thousands of years from the original building material to the present. In recent years, researchers have repositioned their eyes on the multilevel structure of wood, and developed various new wood or wood-like structures and applications, so that the traditional material will develop new vitality. The multi-level structure of the wood can be directly used as a base material, and a wood-like structure can be constructed, so that the development of the bionic structure and the performance of the wood is realized.

The Hulian and the like use wood as a substrate, carbonize and activate the wood, and then load ruthenium nanoparticles in porous micro-pore channels to construct a 'breathable' high-performance lithium-oxygen battery positive electrode material. The structure of the porous structure makes the anode material be completely soaked by electrolyte, the micro pore canal is favorable for oxygen diffusion transmission, and the electrolyte thin layer formed on the pore canal wall ensures the rapid transmission of lithium ions. Wang et al utilize chemical treatment and freeze-drying treatment of natural wood to form wave-shaped multi-layer multi-stage structure, and can implement high-efficiency and repeatedly-usable suctionOil properties. The Huliang and other people directly carry out chemical treatment on natural wood to prepare the elastic wood with high elasticity, ionic conductivity and anisotropy. The Shushuhong, etc. can be used for making controllable carbonization of natural wood surface or constructing heat-conducting layer so as to form a unique double-layer structure. The upper layer realizes the capture of light, and the lower layer carries out water transportation, thereby forming the water absorption performance imitating the plant transpiration effect, and the characteristics of quick transportation and water evaporation of the water absorption performance enable the water absorption performance to be used for efficient solar seawater desalination. The wood-like material breaks through the limitation of the components of the natural wood, researchers form oriented pore channels by adopting an ice crystal template method, various wood-like materials are created, and the performance of the wood-like multi-level structure is obtained. The aerogel with a radial grading porous structure is constructed by adopting a radial ice template method and a low-temperature in-situ free radical polymerization technology in a medium level, millimeter-level radial diffusion channels, micron-level folds and a porous molecular network are realized, and Carbon Nano Tubes (CNT) are used as a solar light absorption layer to realize long-distance transmission (more than 28cm within 190 min) and high-efficiency evaporation collection (the water evaporation rate is about 2.0 kg/m) of various kinds of water such as pure water, seawater, sewage, underground water and the like²H, energy efficiency of 85.7%). The existing preparation methods of the wood-like structure mainly comprise two types, one type is that natural wood is used as a raw material, and the wood-like structure is prepared through various treatment processes. The size and the appearance of the simulated wood structure prepared by the method mainly depend on the structure of natural wood, so the simulated wood structure is limited by wood raw materials, the batches of the wood raw materials are different, the microstructures of the wood raw materials are different, the simulated wood structure is unstable, the repeatability is poor, and the large-scale production and application are difficult; the microstructures of different parts of the wood raw material are also obviously different, the parts of the oriented hierarchical pore structure can be used for preparing the wood-like structure, but other parts cannot be used; in addition, the dimensions of the simulated wood structure are limited by the dimensions of the wood raw material. The other method breaks through the limit of wood, mainly adopts an ice crystal template method, utilizes the directional growth of ice crystals to form a template, and combines other technologies to form an imitation wood microstructure. The method needs to strictly control the directional growth of ice crystals, and then removes ice crystal templates by means of freeze drying to prevent extractionThe porous structure collapses in the drying process, so that the forming time is long, the required instruments and equipment are complex, and the large-scale preparation is difficult. Furthermore, the material needs to be water soluble or water dispersible, and thus the material is limited.

In addition, methods for producing an open-cell type microporous material mainly include a thermally induced phase separation method, a stretching method, a thermal decomposition method, a solvent etching method, and a gas foaming method. Wherein, the thermally induced phase separation method generates a phase region through the heated phase separation of the blend, and obtains a porous structure through etching, and the porous structure with oriented pore diameter is usually difficult to prepare; the stretching method is only applicable to semicrystalline polymers; the pore diameter of the polymer open pore material prepared by the thermal decomposition method is unstable under heating, and a controllable pore structure is difficult to prepare; solvent etching rules limit the porous structures that they produce by the structure of the blend phase. The gas foaming method, including supercritical carbon dioxide foaming, can adopt a directional foaming mode to prepare an oriented porous structure, and combines a solvent etching method to prepare a wood-like oriented hierarchical porous structure. The existing polylactic acid blend foaming method is used for preparing polylactic acid/polyethylene blend alloy, polylactic acid/TPU, polylactic acid/polybutylene succinate and other porous structures. The thermotropic phase separation method utilizes the blend to carry out phase separation in a heating state to generate a micro-phase region, and selectively etches away the other phase to prepare the polylactic acid open-pore structure. Usually, the phase separation of the polymer blend forms a micron-sized micro-phase region, the size of the phase region is larger, the appearance of the micro-pores formed after etching is also controlled by the appearance of the micro-phase region, and the wood-like oriented micro-nano multi-level porous structure is difficult to form. The solvent etching method is usually to etch away one phase to form a porous structure of polylactic acid, and the size and morphology of the pore diameter of the porous structure are regulated by the etched one phase. The solvent etching method comprises a salting-out method and the like, and porous materials with uniform pore diameters are generally prepared, so that the wood-like oriented micro-nano multi-level porous structure is difficult to form. Supercritical CO₂The foaming method is a common method for preparing the polylactic acid tissue engineering scaffold, and the polylactic acid is subjected to supercritical CO₂Foaming to obtain an open pore structure with the diameter of the pores of 200-400 mu m, and performing supercritical CO on the polylactic acid blend₂Foaming can effectively regulate and control the density and diameter of the foam pores to obtain the foam pores with the diameter of 10-20 mu mA porous structure. But due to the supercritical CO₂The foaming method does not control the orientation of the cells, and the foaming conditions of each cell are relatively close, so that the cells are uniform, a nano-scale communicated structure is difficult to form, and the wood-like oriented micro-nano multi-level porous structure cannot be formed.

Disclosure of Invention

The invention mainly aims to provide a bionic porous polylactic acid composite material, a preparation method and application thereof, so as to overcome the defects of the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the embodiment of the invention provides a preparation method of a bionic porous polylactic acid composite material, which comprises the following steps:

mixing polylactic acid, a thermoplastic polymer and a compatilizer in an internal mixing way, and then carrying out injection molding treatment to prepare a polylactic acid foaming precursor material, wherein the compatilizer comprises any one or the combination of more than two of polylactic acid-b-polypropylene, polylactic acid-b-polystyrene and polylactic acid-b-polycarbonate;

and subjecting the polylactic acid foaming precursor material to two-dimensional limited supercritical CO₂Foaming treatment and etching treatment to obtain the bionic porous polylactic acid composite material.

The embodiment of the invention also provides the bionic porous polylactic acid composite material prepared by the method, the bionic porous polylactic acid composite material has a micron and nanometer multistage oriented open pore structure, the aperture of a micron pore contained in the bionic porous polylactic acid composite material is 10-200 mu m, the porosity is 85-97%, and a nanometer pore structure with the size smaller than 100nm is arranged on the wall of the micron pore.

The embodiment of the invention also provides application of the bionic porous polylactic acid composite material in oil-water separation.

The embodiment of the invention also provides an oil-water separation method, which comprises the following steps: the bionic porous polylactic acid composite material is fully contacted with an oil-water mixture, so that oil-water separation is realized.

The embodiment of the invention also provides an oil-water separation device which comprises the bionic porous polylactic acid composite material.

Compared with the prior art, the invention has the beneficial effects that:

(1) the preparation method provided by the invention is suitable for wide foamable thermoplastic polymer materials, the material application range is wide, and the prepared material can be directly used; utilizing two-dimensional limited supercritical CO₂The micro-nano oriented pore structure is prepared by a foaming method, parameters of foam pores can be conveniently controlled by regulating and controlling foaming parameters, the operation is simple, the used time is short, the micro-nano oriented pore structure can be completed only by hours, and the micro-nano oriented pore structure is suitable for batch preparation;

(2) according to the invention, polylactic acid, thermoplastic polymer and compatilizer are mixed to obtain a microphase region structure with various scales of 0.1-50 μm, and open cell structures with various shapes can be prepared; the prepared bionic porous polylactic acid composite material has super-hydrophobic-super-oleophylic wettability; meanwhile, the composite material has a wood-like oriented micro-nano multistage porous structure, and a nano-scale channel is formed on the wall of the micro-scale cell hole, so that the composite material has stronger capillary force, higher oil absorption rate and stronger oil absorption capacity.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an SEM image of the oriented porous structure of the bionic porous polylactic acid composite material prepared in example 1 of the invention;

FIG. 2 is an SEM image of the pore wall surface of an oriented porous structure of the bionic porous polylactic acid composite material prepared in example 1 of the invention;

FIG. 3 is an SEM image of a pore wall section of an oriented porous structure of the bionic porous polylactic acid composite material prepared in example 1 of the invention;

FIG. 4 is an SEM image of the porous structure of the polylactic acid composite material prepared in comparative example 1 according to the present invention;

FIG. 5 is an SEM image of the porous structure of the polylactic acid composite material prepared in comparative example 2 according to the present invention;

FIG. 6 is a schematic view of an apparatus for oil-water separation in an exemplary embodiment of the invention.

Detailed Description

In view of the defects of the prior art, the inventor of the present invention has long studied and largely practiced to propose the technical solution of the present invention, which will be clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

One aspect of the embodiments of the present invention provides a method for preparing a biomimetic porous polylactic acid composite material, comprising:

mixing polylactic acid, a thermoplastic polymer and a compatilizer in an internal mixing way, and then carrying out injection molding treatment to prepare a polylactic acid foaming precursor material, wherein the compatilizer comprises any one or the combination of more than two of polylactic acid-b-polypropylene, polylactic acid-b-polystyrene and polylactic acid-b-polycarbonate;

and subjecting the polylactic acid foaming precursor material to two-dimensional limited supercritical CO₂Foaming treatment, and etching treatment to obtain the bionic porous polylactic acid composite material, wherein the compatilizer at least thins the phase region size of the bionic porous polylactic acid composite material to a nanometer level.

In particular, in supercritical CO₂In the environment, the addition of the compatilizer can further reduce the interfacial tension and promote the phase region size of the bionic porous polylactic acid composite material to be thinned to the nanometer level.

In some specific embodiments, the mass ratio of the polylactic acid to the thermoplastic polymer to the compatibilizer is (20-80) to (1-5).

In some more specific embodiments, the thermoplastic polymer includes any one or a combination of two or more of polypropylene, polystyrene, and polycarbonate, without limitation.

Further, the thermoplastic polymer includes polystyrene and/or polycarbonate, and is not limited thereto.

Further, the compatibilizer includes polylactic acid-b-polystyrene and/or polylactic acid-b-polycarbonate, and is not limited thereto.

In some more specific embodiments, the preparation method comprises: uniformly mixing polylactic acid, a thermoplastic polymer and a compatilizer, and then sequentially carrying out mixing blending, crushing and injection molding treatment to prepare the polylactic acid foaming precursor material, wherein the mixing blending temperature is 180-200 ℃, and the time is 10-20 min.

In some more specific embodiments, the preparation method comprises:

placing the polylactic acid foaming precursor material in a mould;

and placing the mold in a high pressure reaction apparatus followed by CO₂In the atmosphere, two-dimensional limited supercritical CO is carried out under the conditions that the temperature is 120-150 ℃, the saturation pressure is 12-30 MPa, the saturation time is 1-3 h, and the pressure relief rate is 1-8 MPa/s₂And (5) foaming treatment.

Further, the mold has a groove structure for accommodating the polylactic acid foaming precursor material.

Further, the trench structure includes a square trench.

In some more specific embodiments, the preparation method comprises: will be subjected to said two-dimensional limited supercritical CO₂And placing the foamed material in an etching solvent, performing etching treatment at 20-50 ℃ for 10-24 h, and drying to obtain the bionic porous polylactic acid composite material.

Further, the etching solvent includes toluene, but is not limited thereto.

In some more specific embodiments, the preparation method of the biomimetic porous polylactic acid composite material may comprise:

(1) firstly, blending polylactic acid, a thermoplastic polymer and a compatilizer by an internal mixer according to a certain proportion, crushing the blend and then performing injection molding to obtain a standard sample strip (namely a polylactic acid foaming precursor material);

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO (carbon monoxide) treatment under the conditions of the temperature of 120-150 ℃, the saturation pressure of 12-30 MPa, the saturation time of 1-3 h and the pressure release rate of 1-8 MPa/s₂Foaming; simultaneously controlling foaming parameters, promoting the movement of blending components by utilizing the gas-liquid dual properties of the supercritical CO2 fluid, namely high permeability of gas and liquid solubility and fluidity, and playing the role of a compatilizer and the supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) the foamed sample strip is soaked in toluene or the like, the blended thermoplastic polymer component is etched away, and then the sample strip is dried at 50 ℃.

The embodiment of the invention also provides a bionic porous polylactic acid composite material prepared by the method, the bionic porous polylactic acid composite material has a micron and nanometer multistage oriented open pore structure, the aperture of a micron pore contained in the bionic porous polylactic acid composite material is 10-200 mu m, the porosity is 85-97%, and the wall of the micron pore has a nanometer pore structure smaller than 100 nm.

Furthermore, the specific surface area of the bionic porous polylactic acid composite material is 19-50 g/m²。

Furthermore, the contact angle between the bionic porous polylactic acid composite material and water is 150-164 degrees.

Further, the oil absorption rate of the bionic porous polylactic acid composite material is 82-155 L.h^-1·g^-1。

The bionic porous polylactic acid composite material prepared by the invention has a wood-like oriented micro-nano multistage porous structure, and a nano-scale channel is formed on the wall of a micro-scale cell hole.

In some more specific embodiments, the biomimetic porous polylactic acid composite material comprises the following components in parts by weight: 20-80 parts of polylactic acid, 20-80 parts of thermoplastic polymer (selected from any one or combination of more than two of polypropylene, polystyrene and polycarbonate) and 1-5 parts of compatilizer (selected from any one or combination of more than two of polylactic acid-b-polypropylene, polylactic acid-b-polystyrene or polylactic acid-b-polycarbonate).

Further, the bionic porous polylactic acid composite material is prepared by limited supercritical CO₂The foaming method, the supercritical CO2 refining phase region action and the solvent etching method are combined to prepare the nano-crystalline silicon nano-particles.

Furthermore, the micron-sized pore diameter of the bionic porous polylactic acid composite material is 10-200 mu m, and pore channels with the pore diameter lower than 100nm are arranged on the pore walls of the pores.

The embodiment of the invention also provides application of the bionic porous polylactic acid composite material in oil-water separation.

Another aspect of the embodiments of the present invention also provides an oil-water separation method, including: the bionic porous polylactic acid composite material is fully contacted with an oil-water mixture, so that oil-water separation is realized.

The embodiment of the invention also provides an oil-water separation device which comprises the bionic porous polylactic acid composite material. The technical solutions of the present invention are further described in detail below with reference to several preferred embodiments and the accompanying drawings, which are implemented on the premise of the technical solutions of the present invention, and a detailed implementation manner and a specific operation process are provided, but the scope of the present invention is not limited to the following embodiments.

The experimental materials used in the examples used below were all available from conventional biochemical reagents companies, unless otherwise specified.

Example 1

(1) Carrying out banburying blending, crushing and injection molding on 70 parts of polylactic acid, 25 parts of polystyrene and 5 parts of polylactic acid-b-polystyrene to obtain a sample strip, wherein the temperature of the banburying blending is 190 ℃ and the time is 10 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 150 deg.C, saturation pressure of 14MPa, saturation time of 1h, and pressure release rate of 7MPa/s₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) soaking the foamed sample strip in toluene, etching at 50 deg.c for 10 hr to remove the blended thermoplastic polymer component, and stoving at 50 deg.c to obtain the bionic porous polylactic acid composite material.

Example 2

(1) Carrying out banburying blending, crushing and injection molding on 60 parts of polylactic acid, 35 parts of polypropylene and 5 parts of polylactic acid-b-polypropylene to obtain a sample strip, wherein the temperature of the banburying blending is 190 ℃ and the time is 10 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 130 deg.C, saturation pressure of 18MPa, saturation time of 2h, and pressure release rate of 6MPa/s₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂The micro-phase regions of all the components are fully refined by the dissolution of polymer chain segments；

(3) Soaking the foamed sample strip in toluene, etching at 50 deg.c for 10 hr to remove the blended thermoplastic polymer component, and stoving at 50 deg.c to obtain the bionic porous polylactic acid composite material.

Example 3

(1) 50 parts of polylactic acid, 45 parts of polystyrene and 5 parts of polylactic acid-b-polystyrene are subjected to banburying blending, crushing and injection molding treatment to obtain a sample strip, wherein the temperature of the banburying blending treatment is 200 ℃, and the time is 10 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 120 deg.C, 20MPa for 3 hr, and 4Pa/s for pressure release₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) soaking the foamed sample strip in toluene, performing etching treatment at 50 ℃ for 10 hours, etching off the blended thermoplastic polymer components, and drying the sample strip at 50 ℃ to obtain the bionic porous polylactic acid composite material, wherein an SEM image of an oriented porous structure of the bionic porous polylactic acid composite material prepared in the embodiment is shown in FIG. 1, and FIG. 2 is an SEM image of a pore wall surface of the oriented porous structure of the bionic porous polylactic acid composite material prepared in the embodiment; fig. 3 is an SEM image of a pore wall cross section of an oriented porous structure of the biomimetic porous polylactic acid composite material prepared in this example.

Example 4

(1) Carrying out banburying blending, crushing and injection molding on 30 parts of polylactic acid, 65 parts of polycarbonate and 5 parts of polylactic acid-b-polycarbonate to obtain a sample strip, wherein the temperature of the banburying blending is 190 ℃ and the time is 10 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 120 deg.C, saturation pressure of 30MPa, saturation time of 3h, and pressure release rate of 6MPa/s₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) soaking the foamed sample strip in toluene, etching at 50 deg.c for 10 hr to remove the blended thermoplastic polymer component, and stoving at 50 deg.c to obtain the bionic porous polylactic acid composite material.

Example 5

(1) Carrying out banburying blending, crushing and injection molding on 25 parts of polylactic acid, 70 parts of polystyrene and 5 parts of polylactic acid-b-polystyrene to obtain a sample strip, wherein the temperature of the banburying blending is 200 ℃, and the time is 15 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 150 deg.C, 12MPa of saturation pressure, 1h of saturation time and 6MPa/s of pressure release rate₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) soaking the foamed sample strip in toluene, etching at 50 deg.c for 10 hr to remove the blended thermoplastic polymer component, and stoving at 50 deg.c to obtain the bionic porous polylactic acid composite material.

Comparative example 1

(1) 50 parts of polylactic acid, 45 parts of polystyrene and 5 parts of polylactic acid-b-polystyrene are subjected to banburying blending, crushing and injection molding treatment to obtain a sample strip, wherein the temperature of the banburying blending treatment is 190 ℃ and the time is 10 min;

(2) subjecting the sample to conventional supercritical CO₂Foaming:

placing the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 120 deg.C, saturation pressure of 20MPa, saturation time of 3h, and pressure release rate of 4MPa/s₂Foaming;

(3) soaking the foamed sample strip in toluene, etching at 50 ℃ for 10h to remove the blended thermoplastic polymer components, and drying the sample strip at 50 ℃ to obtain the polylactic acid composite material, wherein an SEM image of the porous structure of the polylactic acid composite material prepared by the comparative example is shown in FIG. 4.

Comparative example 2

(1) 50 parts of polylactic acid and 50 parts of polystyrene are subjected to banburying blending, crushing and injection molding treatment to obtain a sample strip, wherein the temperature of the banburying blending treatment is 190 ℃, and the time is 10 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 120 deg.C, saturation pressure of 20MPa, saturation time of 3h, and pressure release rate of 4MPa/s₂Foaming;

(3) soaking the foamed sample strip in toluene, etching at 50 ℃ for 10h to remove the blended thermoplastic polymer components, and drying the sample strip at 50 ℃ to obtain the polylactic acid composite material, wherein an SEM image of the porous structure of the polylactic acid composite material prepared by the comparative example is shown in FIG. 5.

And (3) performance characterization:

the test results of the composite materials prepared in examples 1 to 5 and comparative examples 1 to 2 are shown in tables 1 to 2, respectively:

TABLE 1 test results of biomimetic porous polylactic acid composites prepared in examples 1-5

Table 2 test results of polylactic acid composite materials prepared in comparative examples 1 to 2

The schematic diagram of the oil-water separation device adopted in the invention is shown in fig. 6, the bionic porous polylactic acid composite material prepared in the embodiment is fixed at one port of a hose, the mass of the composite material is m (g), and the composite material is placed in an oil-water mixture; the other end of the hose is connected with a vacuum pump for pumping under higher vacuum degree. According to the volume V (L) of the oil sucked out in a certain time t (h), the oil suction rate V/(mt) is calculated.

From the test results in tables 1 and 2, it can be seen that the porous structure prepared by combining the two-dimensional limited foaming method with the effect of the compatibilizer has the characteristics of wood-like porous structure, the orientation degree of the pore diameter is higher, the pore diameter of the porous material is more uniform, the specific surface area is large, the hydrophobic and oleophilic effect of the material is stronger, the capillary effect is stronger, and the oil absorption rate is high; the orientation degree of the porous material cannot be improved by the action of the single compatilizer, so that the oil absorption rate of the porous material is obviously lower than that of the porous material prepared by two-dimensional limited foaming as shown in comparative example 1; when the compatilizer is not used, the blending components are poor in compatibility, and are easy to phase separate to form a larger phase region, even reaching a millimeter-scale phase region, which is represented by the fact that the comparative example 2 has large pores, the specific surface area is small, the surface water contact angle is 120 degrees, and the super-hydrophobic and super-oleophilic phase region is not realized, so that the oil-water separation cannot be realized.

Example 6

(1) Carrying out banburying blending, crushing and injection molding on 20 parts of polylactic acid, 80 parts of polystyrene and 3 parts of polylactic acid-b-polystyrene to obtain a sample strip, wherein the temperature of the banburying blending is 180 ℃, and the time is 20 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 120 deg.C, 12MPa of saturation pressure, 3 hr of saturation time and 1MPa/s of pressure release rate₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) soaking the foamed sample strip in toluene, etching at 20 deg.c for 24 hr to remove the blended thermoplastic polymer component, and stoving at 50 deg.c to obtain the bionic porous polylactic acid composite material.

Example 7

(1) 80 parts of polylactic acid, 20 parts of polystyrene and 1 part of polylactic acid-b-polystyrene are subjected to banburying blending, crushing and injection molding treatment to obtain a sample strip, wherein the temperature of the banburying blending treatment is 200 ℃, and the time is 10 min;

(2) subjecting the sample strip to two-dimensional limited supercritical CO₂Foaming:

placing the sample strip in a square groove die;

placing the mold carrying the sample strip in a high-pressure reaction kettle, and introducing CO₂Removing air in the kettle, and then performing supercritical CO treatment at 130 deg.C, saturation pressure of 30MPa, saturation time of 1h, and pressure release rate of 8MPa/s₂Foaming; simultaneously controlling foaming parameters by using supercritical CO₂The gas-liquid dual properties of the fluid, namely high permeability of gas and liquid solubility and fluidity, promote the movement of the blending components, play the role of a compatilizer and supercritical CO₂Fully refining the microphase regions of all the components by the dissolution of polymer chain segments;

(3) soaking the foamed sample strip in toluene, etching at 30 deg.c for 20 hr to remove the blended thermoplastic polymer component, and stoving at 50 deg.c to obtain the bionic porous polylactic acid composite material.

In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.

It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific embodiments, and all technical modifications made according to the technical solution of the present invention fall within the protection scope of the present invention without departing from the spirit of the present invention and the protection scope of the claims.