Super-hydrophobic-super-hydrophilic reversible conversion material and preparation method thereof

Abstract

The invention belongs to the technical field of material surface modification, and relates to a super-hydrophobic-super-hydrophilic reversible conversion material (sporopollen extracted from plants serves as a material matrix) and a preparation method. The invention relates to a super-hydrophobic-super-hydrophilic reversible transformation material. A matrix carrier of the reversible transformation material is sporopollen extracted from plants. The sporopollen is derived from pollen, and the pollen is selected from one or more of entomophilous pollen, aeolian pollen or natural spores. The natural microcapsule is prepared on the basis of natural substances extracted from pollen and spores, the process is simple, and the natural microcapsule has a natural core-shell structure, uniform micron size and micro-nano structure, monodisperse particle size distribution and high physical and chemical stability; and meanwhile, the natural microcapsule can realize super-hydrophobic-super-hydrophilic hydrophilic-hydrophobic reversibility of the surface under pH response.

Description

Technical Field

[0001] The invention belongs to the technical field of material surface modification, and relates to a super-hydrophobic-super-hydrophilic reversible transformation material (the material matrix is ​​sporopollenin extracted from plants) and a preparation method thereof. Background Art

[0002] Microcapsules have micron-sized, hollow core-shell structures that protect the core from external chemical and physical changes, while releasing their contents at a specific rate under specific conditions. Microencapsulation design can achieve excellent drug stability, targeting and controlled release performance, and has therefore received widespread attention in the biomedical field. Traditional polymer microcapsules are prepared by chemical synthesis, which has complex processes, high manufacturing costs, high difficulty, and poor monodispersity. In particular, this multi-step, harsh conditions, and time-consuming synthesis process greatly limits their high-precision, large-scale, and highly reproducible production. Traditional polymer microcapsules are prepared by chemical synthesis, which has complex processes, high manufacturing costs, high difficulty, and poor monodispersity. In particular, this multi-step, harsh conditions, and time-consuming synthesis process greatly limits their high-precision, large-scale, and highly reproducible production.

[0003] There is a wide interest in producing microcapsules through alternative strategies. The biosynthetic capabilities of nature have evolved over longer timescales to produce large quantities of sophisticated and complex microcapsules with high fidelity. Plant-derived materials are novel and powerful drug carriers that can improve the stability and bioavailability of active ingredients and enhance drug performance. Sporopollenin exocapsules are the outer layer of pollen shells extracted from natural pollen. They have uniform size, good mechanical and chemical stability, monodisperse size and porosity, large inner cavity, and abundant availability, thus providing an attractive, natural, and powerful drug delivery system that has attracted the interest of the scientific community. Wettability is particularly important for the application of sporopollenin spore wall microcapsules in colloid science, drug delivery, and materials science. Although there are a lot of studies on the extraction of pollen spore wall microcapsules, there are few reports on the evaluation of their wettability.

[0004] CN115400096A provides a method for preparing sporopollenin microcapsules, wherein defatting, acid hydrolysis and a series of solvent washing are used to prepare hollow sporopollenin microcapsules.

[0005] CN104941544B provides a method for preparing spore pollen microcapsules, comprising taking untreated, complete pollen or spores, soaking in any one or more selected from alcohol, alcohol solution, alkaline solution, water, acetone, acetone solution, chloroform and acid solution, filtering, washing and drying to obtain the microcapsules. The preparation method not only extracts the complete outer wall of pollen or spores for microcapsules, but also removes the biomass inside the pollen or spores.

[0006] CN111671069A provides a method for extracting pine pollen wall from broken pine pollen, comprising the following steps: (1) gelatinization, primary enzymolysis, secondary enzymolysis, and precipitation washing. The preparation method abandons the conventional method of using strong acid, strong alkali and organic reagent washing to remove the content and extract the pine pollen wall, but adopts a mild method such as enzyme treatment and water and ethanol washing to avoid the influence on the quality of the pine pollen wall to the greatest extent.

[0007] CN108434119B provides a method for preparing a protein oral microcapsule preparation, which includes three steps: preparation of sporopollenin, loading of drugs, and encapsulation of the outer wall of sporopollenin. The present invention is the first to prepare a protein oral microcapsule using sporopollenin as a capsule material, and at the same time uses zein to block the pores on the outer wall of sporopollenin, thereby reducing the degradation and release of the therapeutic protein in the stomach, so that it can pass through the stomach smoothly and be absorbed by the intestine.

[0008] CN110367542B provides a probiotic microcapsule that is slowly released in the intestine, comprising a core material and a wall material, wherein the core material is probiotics, and the wall material is composed of a first wall material coated outside the core material and a second wall material coated outside the first wall material, wherein the first wall material is sporopollenin, and the second wall material is a high molecular weight polysaccharide.

[0009] The above studies on sporopollen microcapsules all prepared clean sporopollenin, but none of them involved the study of the wettability of sporopollenin.

[0010] CN113463402A provides a method for preparing a pH-responsive super-hydrophobic-hydrophilic reversible transformation material surface, which chemically synthesizes microcapsules by selecting appropriate raw materials, and the prepared material can achieve reversible transformation from super-hydrophobic to hydrophilic.

[0011] CN109320640B provides a method for preparing an environmentally responsive super-hydrophobic-hydrophilic material surface. The prepared material can achieve reversible conversion between hydrophobic-super-hydrophobic-hydrophilic. However, the material involved is chemically synthesized, and the switching mechanism is environmental response.

[0012] From the above, it can be seen that the existing technology still cannot take into account the problems of achieving super hydrophobic-hydrophilic reversible conversion and preparing microcapsules of natural origin. Summary of the invention

[0013] In view of the deficiencies in the prior art, the object of the present invention is to provide a super-hydrophobic-super-hydrophilic reversible transformation material (the material matrix is ​​sporopollenin extracted from plants) and a preparation method thereof.

[0014] To achieve the above object, the technical solution adopted by the present invention is:

[0015] A super-hydrophobic-super-hydrophilic reversible transformation material, wherein the matrix carrier of the reversible transformation material is sporopollenin extracted from plants.

[0016] The sporopollenin is derived from pollen, and the pollen is selected from one or more of insect-pollinated pollen, wind-pollinated pollen or natural spores.

[0017] The pollen is selected from one or more of sunflower pollen, chamomile pollen, rapeseed pollen, Codonopsis pilosula pollen, Elaeagnus angustifolia pollen, Leonurus japonicus pollen, corn pollen, sesame pollen, buckwheat pollen, astragalus pollen, broad bean pollen, watermelon pollen, pumpkin pollen, citrus pollen, lotus pollen, camellia pollen, gallnut pollen, dandelion pollen, pine pollen, birch pollen, black poplar pollen, rose pollen, sorghum pollen, forget-me-not pollen, pecan pollen, rice pollen, pollen pollen, and Ganoderma lucidum spores.

[0018] A method for preparing the super-hydrophobic-super-hydrophilic reversible transformation material adopts a chemical method, an enzymatic method or a chemical-enzymatic method, and uses sporopollenin extracted from plants as a matrix carrier to prepare sporopollen microcapsules.

[0019] The sporopollenins are derived from pollen.

[0020] Specifically:

[0021] Step 1: Disperse the pollen in purified water to remove insoluble impurities

[0022] Step 2, pre-treating the pollen by defatting;

[0023] Step 3, suspending the defatted pollen in one or more of an acid solution, an alkaline solution or an enzyme solution, treating for a certain period of time, washing with and / or using different solvents, filtering or centrifuging, and drying to obtain pollen microcapsules;

[0024] Furthermore, in step 1, the pollen is selected from one or more of insect-pollinated pollen, wind-pollinated pollen or natural spores.

[0025] Furthermore, the pollen in step 1 is selected from one or more of sunflower pollen, chamomile pollen, rapeseed pollen, Codonopsis pilosula pollen, Elaeagnus angustifolia pollen, Leonurus japonicus pollen, corn pollen, sesame pollen, buckwheat pollen, Astragalus membranaceus pollen, broad bean pollen, watermelon pollen, pumpkin pollen, citrus pollen, lotus pollen, camellia pollen, gallnut pollen, dandelion pollen, pine pollen, birch pollen, black poplar pollen, rose pollen, sorghum pollen, forget-me-not pollen, pecan pollen, rice pollen, Pollen Typha, and Ganoderma lucidum spores.

[0026] Furthermore, the wind-pollinated pollen can be directly subjected to the operation of step 3.

[0027] Furthermore, in step 1, insoluble impurities are removed, the pollen is dispersed in purified water or hot water at 60°C, filtered through an 80-mesh sieve, vacuum filtered and the filter cake is washed, the filter cake is dispersed in purified water or hot water at 60°C again, and the washing is repeated until the filtrate is colorless.

[0028] Furthermore, in step 2, the defatting pretreatment uses one or more of 50% or 75% ethanol, anhydrous ethanol, acetone, ether, and n-hexane, and the filtrate is repeatedly washed until it is clear, and then dried to obtain defatted pollen.

[0029] Furthermore, the acid solution in step 3 includes any one of hydrochloric acid, acetic acid, sulfuric acid, phosphoric acid, perchloric acid, and hydrofluoric acid, or a mixture of several of them.

[0030] Furthermore, the alkaline solution in step 3 includes any one of sodium hydroxide and potassium hydroxide or a mixture of several of them.

[0031] Furthermore, the enzyme in step 3 includes one or more of α-amylase, β-amylase, acid protease, papain, cellulase, acid protease, and alkaline protease.

[0032] Furthermore, the organic solvent in step 3 is ethanol or acetone.

[0033] A method for reversibly modifying the surface of a sporopollenin-containing microcapsule, wherein the sporopollenin-containing microcapsule is extracted from a plant to obtain a microcapsule, and the wettability of the sporopollen microcapsule is induced to change from hydrophilic / superhydrophilic to hydrophobic / superhydrophobic in an acidic environment; then the surface is modified from hydrophobic / superhydrophobic to hydrophilic / superhydrophilic in an alkaline environment, and the reversible transformation of the material surface is achieved alternately in an acidic or alkaline environment.

[0034] The microcapsules are in an acidic system with a pH value less than 5.0, and the surface wettability of the sporopollen microcapsules is changed from hydrophilic / superhydrophilic to hydrophobic / superhydrophobic by acid induction;

[0035] The microcapsules are placed in an alkaline system with a pH value greater than 9.0, and the alkalinity induces the wettability of the sporopollen microcapsules to change from hydrophobicity / super-hydrophobicity to hydrophilicity / super-hydrophilicity.

[0036] The microcapsules are in an acidic system with a pH value less than 4.5, and the surface wettability of the sporopollen microcapsules is changed from hydrophilic / superhydrophilic to hydrophobic / superhydrophobic by acid induction;

[0037] The microcapsules are placed in an alkaline system with a pH value greater than 10.0, and the alkalinity induces the wettability of the sporopollen microcapsules to change from hydrophobicity / super-hydrophobicity to hydrophilicity / super-hydrophilicity.

[0038] The microcapsules are placed in an acidic system with a pH value less than 1, and the surface wettability of the sporopollen microcapsules is changed from hydrophilic / superhydrophilic to superhydrophobic by acid induction;

[0039] The microcapsules are placed in an alkaline system with a pH value greater than 13.0, and the alkalinity induces the wettability of the sporopollen microcapsules to change from hydrophobicity / superhydrophobicity to superhydrophilicity.

[0040] The beneficial effects of the present invention are:

[0041] 1. The present invention prepares natural microcapsules based on natural substances extracted from pollen and spores, has a simple process, has a natural core-shell structure, uniform micron-scale size and micro-nanostructure, monodisperse particle size distribution, and high physical and chemical stability. At the same time, the natural microcapsules can achieve reversible super-hydrophobicity-super-hydrophilicity on the surface under pH response.

[0042] 2. The material matrix of the natural microcapsules obtained by the present invention is sporopollenin extracted from plants. Sporopollenin contains carboxyl, carboxylate or pectin. Under alkali treatment, pectin can be deesterified, resulting in exposure of carboxyl groups. Carboxyl protonation and deprotonation are the key to reversible transformation. The natural micro-nano structure of sporopollenin is the basis for its adjustable wettability, and both are indispensable. Under acidic conditions, carboxyl protonates, while under alkaline conditions, carboxyl deprotonates. The protonation / deprotonation regulation of carboxyl groups can achieve reversible transformation of sporopollenin wettability. Hydrophobic / super-hydrophobic sporopollen microcapsules can be obtained by acid solution treatment, wherein the water contact angle of super-hydrophobic sporopollen microcapsules is greater than 150°; hydrophilic / super-hydrophilic sporopollen microcapsules can be obtained by alkaline solution treatment, wherein the water contact angle of super-hydrophilic sporopollen microcapsules is close to 0°.

[0043] 3. The reagents used in the preparation of natural microcapsules of the present invention are all common reagents with low prices; at the same time, the obtained natural microcapsules can be stored for a long time and can be adjusted to suitable hydrophilicity and hydrophobicity according to the needs of actual applications, which has significant economic benefits; the natural microcapsules before modification have very limited application fields due to the limitation of wettability, and can only achieve adsorption or drug loading of substances of specific properties, and their application as adsorbents or drug carriers is limited.

[0044] 4. The present invention expands the scope of use of natural microcapsules, realizes their reversible transformation from pH-responsive superhydrophobic to superhydrophilic, and the number of transformations can reach at least five times. It has strong durability and the ability to resist damage from the external environment; thereby expanding the application scope of natural microcapsules in adsorption, drug loading and other fields, and has a very broad application prospect in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 These are wettability photos of the sunflower spore pollen microcapsules prepared in Example 1 of the present invention; wherein, the left picture shows the prepared super-hydrophobic sunflower spore pollen microcapsules, the middle picture shows the alkali treatment, and the right picture shows the acid treatment.

[0046] Figure 2 These are wettability photos of the Codonopsis pilosula spore powder microcapsules prepared in Example 2 of the present invention; wherein, the left picture shows the prepared super-hydrophobic Codonopsis pilosula spore powder microcapsules, the middle picture shows the alkali treatment, and the right picture shows the acid treatment.

[0047] Figure 3 The super-hydrophobic-super-hydrophilic reversible rapeseed spore pollen microcapsules prepared in Example 3 of the present invention undergo 5 reversible cycles of wettability changes.

[0048] Figure 4 This is a wettability photograph of the wild chrysanthemum spore pollen microcapsules prepared in Example 4 of the present invention.

[0049] Figure 5 This is a wettability photograph of the pine pollen spore microcapsules prepared in Example 5 of the present invention.

[0050] Figure 6 Scanning electron microscope photos of the superhydrophobic-superhydrophilic reversible switchable sporopollen microcapsules prepared in Example 5 of the present invention before and after preparation.

[0051] Figure 7 The nitrogen content of the super-hydrophobic-super-hydrophilic sporopollen microcapsules prepared in Example 5 of the present invention.

[0052] Figure 8 This is a photograph of the water contact angle of the super hydrophobic-hydrophilic reversible sporopollen microcapsules prepared in Example 5 of the present invention.

[0053] Fig. 9 This is a wettability photograph of the Typha Chrysanthemum spore powder microcapsules prepared in Example 6 of the present invention.

[0054] Fig.10 This is a wettability photograph of rose spore pollen microcapsules prepared in Example 7 of the present invention.

[0055] Fig.11 This is a wettability photograph of the acid-treated modified sporopollen microcapsules prepared in Comparative Example 1 of the present invention. Fig.12This is a wettability photograph of the acid-treated modified sporopollen microcapsules prepared in Comparative Example 2 of the present invention.

[0056] Fig.13 This is a wettability photograph of the alkali-treated modified sporopollen microcapsules prepared in Comparative Example 3 of the present invention.

[0057] Fig.14 This is a wettability photograph of the alkali-treated modified sporopollen microcapsules prepared in Comparative Example 4 of the present invention.

[0058] Fig.15 This is a wettability photograph of the alkali-treated modified sporopollen microcapsules prepared in Comparative Example 5 of the present invention.

[0059] Fig.16 This is a wettability photograph of the alkali-treated modified sporopollen microcapsules prepared in Comparative Example 6 of the present invention. DETAILED DESCRIPTION

[0060] The specific implementation modes of the present invention are further described below in conjunction with examples. It should be noted that the specific implementation modes described here are only for illustrating and explaining the present invention, and are not limited to the present invention.

[0061] Embodiment 1:

[0062] Preparation of spore pollen microcapsules:

[0063] Step 1, disperse sunflower pollen particles in 10 times the volume of water, sieve to remove impurities that cannot pass through the sieve, filter the suspension with a vacuum filtration device, disperse the filtered and recovered pollen again in deionized water, and wash repeatedly until the filtrate is basically colorless to prepare powdered pollen.

[0064] Step 2, the pollen washed in step 1 is repeatedly washed with 10 times the volume of 50% ethanol, 75% ethanol and anhydrous ethanol in sequence until the filtrate is basically colorless, and dried to prepare defatted sunflower pollen.

[0065] Step 3, directly suspend the defatted sunflower pollen (50g) obtained in step 2 in 15 times the volume of phosphoric acid (85%, v / v), and stir at 70°C at a rate of 100rpm for 16h. Filter the suspension with a vacuum filtration device to collect the crude spore pollen microcapsules; and wash (filter) the crude spore pollen microcapsules according to the following series of steps: 1) wash twice with 750mL of 2mol / L hydrochloric acid at 40-50°C, 2) wash with 750mL of 80-100°C water until the filtrate is colorless, 3) wash five times with 750mL of 40-50°C acetone, 4) wash with 750mL of 80-100°C water until the filtrate is colorless. Each time the pollen is washed, stir and stay in the solvent for 5 minutes, and finally collect the product by vacuum filtration to obtain superhydrophobic sunflower spore pollen microcapsules (see Figure 1 left).

[0066] The microcapsules obtained above were subjected to surface reversible transformation:

[0067] Step 1, super hydrophobic sunflower spore powder microcapsules are stirred in a 2M NaOH solution with a volume of 10 times the volume thereof at 80°C for 1 hour, at which time the pH of the reaction solution is 13.48, filtered, and fully washed with anhydrous ethanol until the filtrate is colorless, and dried to obtain super hydrophilic sunflower spore powder microcapsules (see Figure 1 (middle picture).

[0068] Step 2, the super hydrophilic spore powder microcapsules obtained in step 1 are stirred at 70°C for 1 hour in 10 times the volume of 1M hydrochloric acid, at which time the pH of the reaction solution is 1.29, filtered, washed thoroughly with water, and dried to obtain super hydrophobic sunflower spore powder microcapsules (see Figure 1 right).

[0069] like Figure 1 As shown in Table 1, the sunflower spore pollen microcapsules prepared in Example 1 of the present invention achieve the transformation of the wettability of the spore pollen microcapsules from superhydrophobic-superhydrophilic-superhydrophobic; the left picture in the figure shows the prepared superhydrophobic sunflower spore pollen microcapsules, the middle picture is an alkaline environment, and the right picture is an acidic environment.

[0070] Table 1 Water contact angle of sunflower spore pollen microcapsules before and after modification

[0071] type Before modification - super hydrophobic Alkaline environment-super hydrophilic Acid environment-superhydrophobic Contact Angle 152° 3° 151°

[0072] Embodiment 2:

[0073] Preparation of spore pollen microcapsules:

[0074] Step 1, disperse the codonopsis pollen particles in 5 times the volume of 60°C water, sieve to remove impurities that cannot pass through the sieve, filter the suspension with a vacuum filtration device, disperse the filtered and recovered pollen again in deionized water, and wash repeatedly until the filtrate is basically colorless to prepare powdered pollen.

[0075] Step 2, stirring the pollen washed in step 1 at 60°C and refluxing in 5 volumes of anhydrous ethanol for 1 hour. Filtering the suspension with a vacuum filtration device, re-dispersing the recovered pollen in acetone, repeating the above operation until the filtrate is colorless, and drying to prepare defatted Codonopsis pollen.

[0076] Step 3, directly suspending the defatted Codonopsis pollen (50 g) obtained in step 2 in 15 times the volume of phosphoric acid (85%, v / v), and stirring at 100° C. at a rate of 100 rpm for 18 hours, filtering the suspension with a vacuum filtration device to collect the crude sporopollen microcapsule product; and washing (filtering) the crude sporopollen microcapsule product according to the following series of steps: 1) washing with 750 mL of 80-100° C. water until the filtrate is colorless, 2) 60-70° C. 2 mol / L NaOH 750mL washing twice, 3) 60-70℃ water 750mL washing until the filtrate is colorless, 4) 40~50℃ acetone 750mL washing 5 times, 5) 40~50℃ 2mol / L hydrochloric acid 750mL washing twice, 6) 80~100℃ water 750mL washing until the filtrate is colorless, 7) 40~50℃ acetone 750mL washing 5 times, 8) 50~60℃ ethanol 750mL washing 5 times, 9) 80~100℃ water 750mL washing until the filtrate is colorless, each time the pollen is washed, stir and stay in the solvent for 5 minutes, and finally collect the product by vacuum filtration. Obtain superhydrophobic Codonopsis pilosula spore powder microcapsules (see Figure 2 left).

[0077] The microcapsules obtained above were subjected to surface reversible transformation:

[0078] Step 1, the super hydrophobic Codonopsis pilosula spore powder microcapsules are stirred at 70°C for 1 hour in 20 times the volume of 1M KOH solution, at which time the pH of the reaction solution is 13.32, filtered, and fully washed with anhydrous ethanol until the filtrate is colorless, and dried to obtain super hydrophilic Codonopsis pilosula spore powder microcapsules (see Figure 2 middle image).

[0079] Step 2, the super hydrophilic spore powder microcapsules obtained in step 1 are stirred at 100°C for 1 hour in 15 times the volume of 17% phosphoric acid, at which time the pH of the reaction solution is 0.41, filtered, washed thoroughly with water, and dried to obtain super hydrophobic Codonopsis pilosula spore powder microcapsules (see Figure 2 right).

[0080] like Figure 2 As shown in Table 2, the Codonopsis pilosula spore powder microcapsules prepared in Example 2 of the present invention achieve the transformation of the wettability of the spore powder microcapsules from superhydrophobic-superhydrophilic-superhydrophobic; the left picture in the figure shows the prepared superhydrophobic Codonopsis pilosula spore powder microcapsules, the middle picture is an alkaline environment, and the right picture is an acidic environment.

[0081] Table 2 Water contact angle of Codonopsis pilosula powder microcapsules before and after modification

[0082] type Before modification - super hydrophobic Alkaline environment-super hydrophilic Acid environment-superhydrophobic Contact Angle 150° 2° 153°

[0083] Embodiment 3:

[0084] Preparation of spore pollen microcapsules:

[0085] Step 1, disperse rape pollen particles in 15 times the volume of water, sieve to remove impurities that cannot pass through the sieve, filter the suspension with a vacuum filtration device, disperse the filtered and recovered pollen again in deionized water, and wash repeatedly until the filtrate is basically colorless to prepare powdered pollen.

[0086] Step 2, stirring the pollen washed in step 1 at room temperature and refluxing in 5 volumes of ether for 1 hour. Filtering the suspension with a vacuum filtration device, re-dispersing the recovered pollen in ether, repeating the above operation until the filtrate is colorless, and drying to prepare defatted rapeseed pollen.

[0087] Step 3, add the defatted rapeseed pollen (50g) obtained in step 2, 900ml of sodium hydroxide solution (pH=11), and 5g of alkaline protease into a reaction bottle, stir overnight at 42°C, wash with water until neutral, resuspend in 15 times the volume of phosphoric acid (85%, v / v), and stir at 100°C at a rate of 100rpm for 5h, filter the suspension with a vacuum filtration device, and collect the crude spore pollen microcapsules. The crude product of pollen microcapsules was washed (filtered) according to the following steps: 1) 50-60℃ 2mol / L hydrochloric acid 750mL washing twice, 2) 80-100℃ water 750mL washing until the filtrate is colorless, 3) 40-50℃ acetone 750mL washing 5 times, 4) 70-80℃ ethanol 750mL washing 5 times, 5) 80-100℃ water 750mL washing until the filtrate is colorless, each time the pollen is stirred in the solvent for 5 minutes, and finally the product is collected by vacuum filtration. Super hydrophobic rapeseed pollen microcapsules are obtained.

[0088] The microcapsules obtained above were subjected to surface reversible transformation:

[0089] Step 1, stirring the super-hydrophobic rapeseed spore powder microcapsules in 20 times the volume of 1M KOH solution at 80°C for 1 hour, at which time the pH of the reaction solution is 13.39, filtering, and washing with water until the filtrate is colorless, and drying to obtain super-hydrophilic rapeseed spore powder microcapsules.

[0090] Step 2, the super hydrophilic spore pollen microcapsules obtained in step 1 are stirred in 15 times the volume of 1M sulfuric acid at 70°C for 1 hour, at which time the pH of the reaction solution is 0.68, filtered, washed thoroughly with water, and dried to obtain super hydrophobic rapeseed spore pollen microcapsules.

[0091] Then, the rapeseed spore pollen microcapsules were subjected to surface transformation treatment according to the above-mentioned steps 1 and 2 (see Figure 3 ).

[0092] Depend on Figure 3As can be seen from Table 3, the surface of the obtained rapeseed pollen microcapsules was reversibly converted between superhydrophobic and superhydrophilic. The wettability results of 5 reversible cycles show that the prepared pollen microcapsules achieved a transition from superhydrophobic to superhydrophilic during the 5 reversible cycles, thereby achieving the reversible conversion of superhydrophobic and superhydrophilic properties of the pollen microcapsules induced by pH.

[0093] Table 3 Water contact angle of rapeseed spore pollen microcapsules before and after modification

[0094] type Before modification - super hydrophobic Alkaline environment-super hydrophilic Acid environment-superhydrophobic 1 cycle 151° 4° 151° 2 cycles / 3° 152° 3 cycles / 3° 151° 4 cycles / 4° 150° 5 cycles / 3° 151°

[0095] Embodiment 4:

[0096] Preparation of spore pollen microcapsules:

[0097] Step 1, disperse wild chrysanthemum pollen particles in 20 times the volume of water, sieve to remove impurities that cannot pass through the sieve, filter the suspension with a vacuum filtration device, disperse the filtered and recovered pollen again in deionized water, and wash repeatedly until the filtrate is basically colorless to prepare powdered pollen.

[0098] Step 2, stirring the pollen washed in step 1 at room temperature and refluxing in 15 times the volume of n-hexane for 1 hour. Filtering the suspension with a vacuum filtration device, re-dispersing the recovered pollen in n-hexane, repeating the above operation until the filtrate is colorless, and drying to prepare defatted wild chrysanthemum pollen.

[0099] Step 3, add the defatted wild chrysanthemum pollen (50g) obtained in step 2, 900ml of hydrochloric acid solution (pH=3), and 5g of acid protease into a reaction bottle, stir overnight at 42°C, resuspend in 15 times the volume of phosphoric acid (85%, v / v), and stir at 100°C at a rate of 100rpm for 24h, filter the suspension with a vacuum filtration device, and collect the crude sporopollen microcapsule product; and wash (filter) the crude sporopollen microcapsule product according to the following series of steps: 1) wash with 750mL of 70-80°C water until the filtrate is colorless 2) 60-70°C 2mol / L Wash once with 750 mL of NaOH, 3) wash with 750 mL of 60-70°C water until the filtrate is colorless, 4) wash twice with 750 mL of 40-50°C acetone, 5) wash twice with 750 mL of 2 mol / L hydrochloric acid at 40-50°C, 6) wash twice with 750 mL of 70-80°C water until the filtrate is colorless, 7) wash twice with 750 mL of 40-50°C acetone, 8) wash twice with 750 mL of 50-60°C ethanol, 9) wash twice with 750 mL of 80-100°C water until the filtrate is colorless; each time the pollen is washed, stir and stay in the solvent for 5 minutes, and finally collect the product by vacuum filtration. Hydrophobic wild chrysanthemum spore powder microcapsules are obtained (see Figure 4 left).

[0100] The microcapsules obtained above were subjected to surface reversible transformation:

[0101] Step 1, stirring the hydrophobic wild chrysanthemum spore powder microcapsules in 20 volumes of 0.1M KOH solution at 80°C for 1 hour, at which time the pH of the reaction solution is 12.84, filtering, and washing with water until the filtrate is colorless, and drying to obtain hydrophilic wild chrysanthemum spore powder microcapsules (see Figure 4 middle image).

[0102] Step 2, the hydrophilic spore powder microcapsules obtained in step 1 are stirred at 70°C for 1 hour in 10 times the volume of 0.1M hydrochloric acid, at which time the pH of the reaction solution is 1.29, filtered, washed thoroughly with water, and dried to obtain hydrophobic wild chrysanthemum spore powder microcapsules (see Figure 4 center right).

[0103] like Figure 4 As shown in Table 4, the wild chrysanthemum spore pollen microcapsules prepared in Example 4 of the present invention achieve the transformation of the wettability of the spore pollen microcapsules from hydrophobic-hydrophilic-hydrophobic. The left picture in the figure shows the prepared hydrophobic wild chrysanthemum spore pollen microcapsules, the middle picture is an alkaline environment, and the right picture is an acid environment.

[0104] Table 4 Water contact angle of wild chrysanthemum spore powder microcapsules before and after modification

[0105] type Before modification - hydrophobic Alkaline environment - hydrophilic Acid environment - hydrophobic Contact Angle 141° 7° 138°

[0106] Embodiment 5:

[0107] Preparation of spore pollen microcapsules:

[0108] Natural pine pollen (50g, see Figure 5 Left) was directly suspended in 15 volumes of phosphoric acid (85%, v / v) and stirred at 70°C at a rate of 100 rpm for 16 h. The suspension was filtered with a vacuum filtration device and washed thoroughly with hot water to obtain superhydrophobic pine pollen spore microcapsules (see Figure 5-Figure 7 ).

[0109] The pH value of superhydrophobic pine pollen spore microcapsules was determined to be 2.33.

[0110] The microcapsules obtained above were subjected to surface reversible transformation:

[0111] Step 1, stirring the super-hydrophobic pine pollen spore microcapsules in 10 times the volume of 2M NaOH solution at 80°C for 0.5h, at which time the pH of the reaction solution is 13.29, filtering, and washing with anhydrous ethanol until the filtrate is colorless, and drying to obtain super-hydrophilic pine pollen spore microcapsules. The pH of the super-hydrophilic pine pollen spore microcapsules was measured to be 10.54.

[0112] Step 2, the super hydrophilic spore powder microcapsules obtained in step 1 are stirred at 70°C for 0.5h in 10 times the volume of 85% phosphoric acid solution, at which time the pH of the reaction solution is 0.32, filtered, washed with water until the filtrate is colorless, and dried to obtain super hydrophobic pine pollen spore powder microcapsules (see Figure 5-Figure 8 ).

[0113] like Figure 5 As shown, the pine pollen spore microcapsules prepared in Example 5 of the present invention achieve the transformation of the spore microcapsule wettability from super hydrophobic to super hydrophilic to super hydrophobic. The left picture in the figure shows the prepared super porous pine pollen spore microcapsules, the middle picture is an alkaline environment, and the right picture is an acid environment.

[0114] Depend on Figure 6 From the scanning electron microscope photos of the superhydrophobic-superhydrophilic pollen microcapsules before and after preparation, it can be seen that the left picture is the raw material natural pine pollen, and the middle and right pictures are the capsules after transformation. It can be seen from the pictures that the pollen microcapsules in the pollen microcapsules before and after transformation maintain a complete structure, uniform micron-scale size and micro-nano structure, in a monodisperse state, without aggregation. The preparation process of the present invention is carried out under heating conditions using strong acid and strong base, and it can be seen that the prepared pollen microcapsules have high physical and chemical stability. The water contact angle of the pollen microcapsules was further measured ( Figure 8 ) It can be seen that the water contact angle of the sporopollen microcapsules in an acidic environment can reach 151°, reaching a superhydrophobic state; while the water contact angle of the sporopollen microcapsules in an alkaline environment is close to 0°, reaching a superhydrophilic state. It can be seen that pH can adjust the wettability of sporopollen microcapsules and achieve a transition from superhydrophobic to superhydrophilic.

[0115] At the same time, the nitrogen content (N%) of the prepared pollen microcapsules and the treated super-hydrophobic pollen microcapsules and super-hydrophilic pollen microcapsules was determined (see Figure 7 ), where nitrogen content determination (N%) has been widely used to identify the proportion of protein removed during the pollen extraction process, and N% multiplied by a factor of 6.25 is used to convert it into protein content.

[0116] Depend on Figure 7 The protein content determination shows that natural pine pollen shows a protein content of about 20%, and the protein content of super-hydrophobic and super-hydrophilic pollen microcapsules is about 2-3%, indicating that the preparation process of the present invention significantly removes the protein in the pollen to obtain complete and clean pollen microcapsules.

[0117] Embodiment 6:

[0118] Preparation of spore pollen microcapsules:

[0119] Step 1: Pollen Typhae (50 g) was directly suspended in 15 volumes of phosphoric acid (85%, v / v), and stirred at 70° C. at a rate of 100 rpm for 16 h. The suspension was filtered with a vacuum filtration device to collect the crude sporopollen microcapsules; and the crude sporopollen microcapsules were washed (filtered) according to the following series of steps: 1) washing with 750 mL of 70-80°C water until the filtrate was colorless, 2) washing with 750 mL of 2 mol / L NaOH at 60-70°C once, 3) washing with 750 mL of 60-70°C water until the filtrate was colorless, 4) washing with 750 mL of 40-50°C acetone for 5 times, 5) washing with 750 mL of 2 mol / L acetic acid at 40-50°C for 2 times, 6) washing with 750 mL of 70-80°C water until the filtrate was colorless, 7) washing with 750 mL of 40-50°C acetone for 5 times, 8) washing with 750 mL of 50-60°C ethanol for 5 times, 9) washing with 750 mL of 80-100°C water until the filtrate was colorless, stirring the pollen in the solvent for 5 minutes each time, and finally collecting the product by vacuum filtration. Obtain super-hydrophobic Typha spore powder microcapsules (see Fig. 9 ).

[0120] The microcapsules obtained above were subjected to surface reversible transformation:

[0121] Step 1: Stir the super-hydrophobic Typha Chrysanthemum spore powder microcapsules in 10 times the volume of 1M KOH solution at 80°C for 1 hour, filter, and then the pH of the reaction solution is 13.21. Wash with anhydrous ethanol until the filtrate is colorless, and dry to obtain super-hydrophilic Typha Chrysanthemum spore powder microcapsules (see Fig. 9 ).

[0122] Step 2, the super hydrophilic spore powder microcapsules obtained in step 1 are stirred at 70°C for 1 hour in 14% phosphoric acid solution with a volume of 10 times, at which time the pH of the solution is 0.51, and then washed with water, filtered, and dried to obtain super hydrophobic Typha spore powder microcapsules (see Fig. 9 ).

[0123] like Fig. 9 As shown in Table 5, the Typhae spore powder microcapsules prepared in Example 6 of the present invention achieve the transformation of the wettability of the spore powder microcapsules from super-hydrophobic to super-hydrophilic to super-hydrophobic. The left picture in the figure shows the prepared super-hydrophobic Typhae spore powder microcapsules, the middle picture is an alkaline environment, and the right picture is an acid environment.

[0124] Table 5 Water contact angle of Typhus typhinatum powder microcapsules before and after modification

[0125] type Before modification - super hydrophobic Alkaline environment-super hydrophilic Acid environment-superhydrophobic Contact Angle 153° 1° 151°

[0126] Embodiment 7:

[0127] Preparation of spore pollen microcapsules:

[0128] Step 1, add rose pollen (50g), sodium hydroxide solution 900ml (pH=11), alkaline protease, papain, cellulase 2g respectively, into a reaction bottle, stir overnight at 42°C, resuspend in 15 times volume of phosphoric acid (85%, v / v), and stir at 100°C at a rate of 100rpm for 5h, filter the suspension with a vacuum filtration device, and collect the crude sporopollen microcapsule product; and wash (filter) the crude sporopollen microcapsule product according to the following series of steps: 1) wash with 750mL of 70-80°C water until the filtrate is colorless, 2) 60-70°C for 2mo 1) Wash once with 750 mL of 1 / L KOH, 3) Wash with 750 mL of 60-70°C water until the filtrate is colorless, 4) Wash with 750 mL of 40-50°C acetone for 5 times, 5) Wash twice with 750 mL of 40-50°C 2 mol / L hydrochloric acid, 6) Wash with 750 mL of 70-80°C water until the filtrate is colorless, 7) Wash with 750 mL of 40-50°C acetone for 5 times, 8) Wash with 750 mL of 50-60°C ethanol for 5 times, 9) Wash with 750 mL of 80-100°C water until the filtrate is colorless. Stir the pollen in the solvent for 5 minutes each time, and finally collect the product by vacuum filtration. Hydrophobic rose spore powder microcapsules were obtained (see Fig.10 ).

[0129] The microcapsules obtained above were subjected to surface reversible transformation:

[0130] Step 1, the hydrophobic rose spore powder microcapsules are stirred in 10 volumes of 0.05M NaOH solution at 80°C for 1 hour, at which time the pH of the reaction solution is 10.81, filtered, and fully washed with anhydrous ethanol until the filtrate is colorless, and dried to obtain hydrophilic rose spore powder microcapsules (see Fig.10 ).

[0131] Step 2: The hydrophilic spore powder microcapsules obtained in step 1 are stirred in 10 times the volume of 2M acetic acid at 70°C for 1 hour, at which time the pH of the reaction solution is 3.02, and then the hydrophobic rose spore powder microcapsules are obtained by washing with water, filtering, and drying (see Fig.10 ).

[0132] like Fig.10 As shown in Table 6, the rose spore pollen microcapsules prepared in Example 7 of the present invention achieve the transformation of the wettability of the spore pollen microcapsules from hydrophobic-hydrophilic-hydrophobic. The left picture in the figure shows the prepared hydrophobic rose spore pollen microcapsules, the middle picture is an alkaline environment, and the right picture is an acidic environment.

[0133] Table 6 Water contact angle of rose spore pollen microcapsules before and after modification

[0134] type Before modification - hydrophobic Alkaline environment - hydrophilic Acid environment - hydrophobic Contact Angle 135° 9° 132°

[0135] The performance of the reversibly transformable super-hydrophobic and super-hydrophilic sporopollen microcapsules in the above embodiment was tested:

[0136] 1) The super-hydrophobic and super-hydrophilic pollen microcapsules in only one reversible transformation process in Example 1-5 were subjected to methylene blue adsorption test, and the adsorption results are shown in Table 7. It was found that the methylene blue adsorption capacity of super-hydrophilic pollen microcapsules and super-hydrophobic microcapsules was significantly different, and the adsorption capacity of super-hydrophilic pine pollen pollen microcapsules and super-hydrophobic pine pollen pollen microcapsules differed by 25 times. It can be seen that the adsorption capacity of pollen microcapsules for water-soluble cationic substances represented by methylene blue can be significantly improved by modifying wettability.

[0137] Table 7 Results of adsorption of methylene blue by superhydrophobic and superhydrophilic spore pollen microcapsules

[0138]

[0139] 2) the super-hydrophobic and super-hydrophilic sporopollen microcapsules in the reversible transformation process in embodiment 1-5 were subjected to the adsorption test of mitoxantrone hydrochloride, and the adsorption results are shown in Table 8. It was found that the adsorption capacity of mitoxantrone hydrochloride of super-hydrophilic sporopollen microcapsules and super-hydrophobic sporopollen microcapsules was significantly different, and the adsorption capacity of super-hydrophilic chrysanthemum, sunflower, pine pollen sporopollen microcapsules and super-hydrophobic sporopollen microcapsules differed by about 38 times. It can be seen that the adsorption capacity of sporopollen microcapsules to water-soluble neutral substances represented by mitoxantrone hydrochloride can be significantly improved by the modification of wettability.

[0140] Table 8 Results of adsorption of mitoxantrone hydrochloride by superhydrophobic and superhydrophilic sporopollen microcapsules

[0141]

[0142] 3) The sporopollen microcapsules with different cycle times in Example 3 were subjected to methylene blue adsorption measurement, and the adsorption results are shown in Table 9. The results show that the number of cycles does not affect the adsorption capacity of methylene blue. It can be concluded that the sporopollen microcapsules prepared by the present invention can achieve reversible transformation of hydrophobic / super hydrophobic and hydrophilic / super hydrophilic, and the performance is not affected by the number of reversible transformations.

[0143] Table 9 Effect of reversible cycle number on methylene blue adsorption

[0144]

[0145] Comparative Example 1:

[0146] The super-hydrophobic pine pollen spore pollen microcapsules prepared in Example 5 were stirred at 80° C. for 1 h in 10 volumes of 0.001 M sodium hydroxide solution, at which time the pH of the reaction solution was 2.94. The solution was filtered and washed thoroughly with anhydrous ethanol until the filtrate was colorless and dried.

[0147] like Fig.11As shown, the wettability of the pine pollen microcapsules did not change from superhydrophobic to superhydrophilic (i.e., the original wettability was maintained) because the corresponding pH conditions were not reached in the environment. In the figure, the left picture shows the original state of the prepared microcapsules, and the right picture shows the surface transformation.

[0148] Comparative Example 2:

[0149] The super-hydrophobic pine pollen spore microcapsules prepared in Example 5 were stirred at 80° C. for 1 h in 10 volumes of 0.015 M sodium hydroxide solution, at which time the pH of the reaction solution was 8.70. The solution was filtered and washed thoroughly with anhydrous ethanol until the filtrate was colorless and dried.

[0150] like Fig.12 As shown, the wettability of the pine pollen microcapsules did not change from superhydrophobic to superhydrophilic (i.e., the original wettability was maintained) because the corresponding pH conditions were not reached in the environment.

[0151] Furthermore, from the above-mentioned Examples 1-7, Comparative Examples 1 and 2, it can be explained that when the pH value is less than 9, the wettability of the pollen microcapsules cannot be transformed from superhydrophobic to superhydrophilic, which further proves that the pH of the acid solution of the present invention must be above 9 to achieve the transformation of the wettability of the pollen microcapsules from superhydrophobic to superhydrophilic.

[0152] Comparative Example 3:

[0153] The super-hydrophobic pine pollen spore microcapsules prepared in Example 5 were reversibly converted into super-hydrophilic spore microcapsules, placed in 10 times the volume of 0.05M acetic acid solution, stirred at 70°C for 1 hour, at which time the pH of the reaction solution was 10.92, washed thoroughly with water, filtered, and dried to obtain spore microcapsules.

[0154] like Fig.13 As shown, the wettability of the pine pollen microcapsules did not change from superhydrophilic to superhydrophobic because the corresponding pH conditions were not reached in the environment (i.e., the original wettability was maintained).

[0155] Comparative Example 4:

[0156] The super-hydrophobic pine pollen spore microcapsules prepared in Example 5 were reversibly converted into super-hydrophilic spore microcapsules, placed in 10 times the volume of 0.01M hydrochloric acid solution, stirred at 70°C for 1 hour, at which time the pH of the reaction solution was 9.15, washed thoroughly with water, filtered, and dried to obtain spore microcapsules.

[0157] like Fig.14 As shown in the figure, the transition of wettability of pine pollen microcapsules from superhydrophilic to superhydrophobic was not achieved because the corresponding pH conditions were not reached in the environment.

[0158] Comparative Example 5:

[0159] The super-hydrophobic pine pollen spore microcapsules prepared in Example 5 were reversibly converted into super-hydrophilic spore microcapsules, placed in 0.085% phosphoric acid solution with 10 times its volume, and stirred at 70°C for 1 hour, at which time the pH of the reaction solution was 8.87. The spore microcapsules were fully washed with water, filtered, and dried to obtain spore microcapsules.

[0160] like Fig.15 As shown, the wettability of the pine pollen microcapsules did not change from superhydrophilic to superhydrophobic because the corresponding pH conditions were not reached in the environment (i.e., the original wettability was maintained).

[0161] Comparative Example 6:

[0162] The super-hydrophobic pine pollen spore microcapsules prepared in Example 5 were reversibly converted into super-hydrophilic spore microcapsules, and placed in 10 times the volume of 0.03M hydrochloric acid solution, stirred at 70°C for 1 hour, at which time the pH of the reaction solution was 5.21. The spore microcapsules were fully washed with water, filtered, and dried to obtain spore microcapsules.

[0163] like Fig.16 As shown, the wettability of the pine pollen microcapsules did not change from superhydrophilic to superhydrophobic because the corresponding pH conditions were not reached in the environment (i.e., the original wettability was maintained).

[0164] Furthermore, Examples 1-7 and Comparative Examples 3-6 show that when the pH value is greater than 5, the wettability of the pollen microcapsules cannot be transformed from superhydrophilic to superhydrophobic, which further proves that the pH of the acid solution of the present invention can only achieve the transformation of the wettability of the pollen microcapsules from superhydrophilic to superhydrophobic when the pH value is below 5.

Claims

1. A super-hydrophobic-super-hydrophilic reversible transformation material, characterized in that: The reversible transformation material matrix carrier is sporopollenin extracted from plants.

2. The super-hydrophobic-super-hydrophilic reversible transformation material according to claim 1, characterized in that: The sporopollenin is derived from pollen, and the pollen is selected from one or more of insect-pollinated pollen, wind-pollinated pollen or natural spores.

3. The super-hydrophobic-super-hydrophilic reversible transformation material according to claim 2, characterized in that: The pollen is selected from one or more of sunflower pollen, chamomile pollen, rapeseed pollen, Codonopsis pilosula pollen, Elaeagnus angustifolia pollen, Leonurus japonicus pollen, corn pollen, sesame pollen, buckwheat pollen, astragalus pollen, broad bean pollen, watermelon pollen, pumpkin pollen, citrus pollen, lotus pollen, camellia pollen, gallnut pollen, dandelion pollen, pine pollen, birch pollen, black poplar pollen, rose pollen, sorghum pollen, forget-me-not pollen, pecan pollen, rice pollen, pollen pollen, and Ganoderma lucidum spores.

4. A method for preparing the super-hydrophobic-super-hydrophilic reversible transformation material according to claim 1, characterized in that: The sporopollen microcapsules are prepared by using the chemical method, enzymatic method or chemical-enzymatic method and sporopollenin extracted from plants as a matrix carrier.

5. The method for preparing the super-hydrophobic-super-hydrophilic reversible transformation material according to claim 4, characterized in that: The sporopollenin is derived from pollen, and the pollen is selected from one or more of insect-pollinated pollen, wind-pollinated pollen or natural spores.

6. The method for preparing the super-hydrophobic-super-hydrophilic reversible transformation material according to claim 5, characterized in that: The pollen is selected from one or more of sunflower pollen, chamomile pollen, rapeseed pollen, Codonopsis pilosula pollen, Elaeagnus angustifolia pollen, Leonurus japonicus pollen, corn pollen, sesame pollen, buckwheat pollen, astragalus pollen, broad bean pollen, watermelon pollen, pumpkin pollen, citrus pollen, lotus pollen, camellia pollen, gallnut pollen, dandelion pollen, pine pollen, birch pollen, black poplar pollen, rose pollen, sorghum pollen, forget-me-not pollen, pecan pollen, rice pollen, pollen pollen, and Ganoderma lucidum spores.

7. A method for reversibly modifying the surface of sporopollenin-containing microcapsules, characterized in that: The microcapsules obtained by extracting sporopollenin from plants as described in claim 1 induce the wettability of the sporopollen microcapsules to change from hydrophilic / superhydrophilic to hydrophobic / superhydrophobic in an acidic environment; and then the surface modification is changed from hydrophobic / superhydrophobic to hydrophilic / superhydrophilic in an alkaline environment, and the reversible transformation of the material surface is achieved alternately in an acidic or alkaline environment.

8. The method for reversibly modifying the surface of pollen matrix microcapsules according to claim 7, characterized in that: The microcapsules are in an acidic system with a pH value less than 5.0, and the surface wettability of the sporopollen microcapsules is changed from hydrophilic / superhydrophilic to hydrophobic / superhydrophobic by acid induction; The microcapsules are placed in an alkaline system with a pH value greater than 9.0, and the alkalinity induces the wettability of the sporopollen microcapsules to change from hydrophobicity / super-hydrophobicity to hydrophilicity / super-hydrophilicity.

9. The method for reversibly modifying the surface of pollen matrix microcapsules according to claim 8, characterized in that: The microcapsules are in an acidic system with a pH value less than 4.5, and the surface wettability of the sporopollen microcapsules is changed from hydrophilic / superhydrophilic to hydrophobic / superhydrophobic by acid induction; The microcapsules are placed in an alkaline system with a pH value greater than 10.0, and the alkalinity induces the wettability of the sporopollen microcapsules to change from hydrophobicity / super-hydrophobicity to hydrophilicity / super-hydrophilicity.

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