Degradable dialdehyde polysaccharide modified mycelium material and preparation method thereof

Abstract

The invention relates to a degradable dialdehyde polysaccharide modified mycelium material and a preparation method thereof, the preparation method comprises the following steps: sequentially carrying out inactivation, deacetylation pretreatment, chemical modifier padding, plastification, hot pressing and drying on mycelia subjected to solid state fermentation culture to prepare the degradable dialdehyde polysaccharide modified mycelium material; the chemical modifier is a dialdehyde polysaccharide compound solution, and the mass concentration of the dialdehyde polysaccharide compound solution is 1-20%; the porosity of the mycelium subjected to solid state fermentation culture is 78-83%, and the porosity of the degradable dialdehyde polysaccharide modified mycelium material is 5-11%; after the degradable dialdehyde polysaccharide modified mycelium material is buried in soil for 20 days, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 58.3-59.8%. The preparation method is simple and easy to implement, the dialdehyde polysaccharide compound is adopted for crosslinking modification, the mechanical property of the product is effectively improved on the premise that degradability is guaranteed, and the tensile strength and the elongation at break of the product are excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of new materials and relates to a degradable dialdehyde polysaccharide modified mycelium material and a preparation method thereof. Background Art

[0002] Leather is a durable and flexible textile product. Due to its unique wear resistance, natural beauty and comfortable touch, it has become popular in the clothing, footwear, furniture and automotive interior industries. However, there are the following problems in leather production: 1) the impact of toxic chemicals in the leather making process on the human body and the environment; 2) large amounts of greenhouse gas emissions in the leather making process; 3) land use issues such as deforestation; 4) ethical issues caused by animal cruelty. Artificial leather production also requires the use of non-environmentally friendly chemicals and has poor biodegradability. Researchers are committed to the dual green preparation of raw materials and tanning agents to replace animal-based or artificial leather to a certain extent. In recent years, the use of mycelium to prepare degradable materials has received widespread attention.

[0003] The literature (Flexible Fungal Materials: Shaping the Future. Trends in Biotechnology 2021, 39 (12), 1321-1331) records that common methods of culturing mycelium include liquid fermentation and solid fermentation. Liquid fermentation has a fast growth rate and more uniform growth, but is easily contaminated by bacteria and is suitable for the production of thinner paper-like film materials. Solid-state fermentation has slow growth, low culture cost, low pollution risk, and thicker mycelium, so this method mainly produces green and degradable leather substitutes with similar properties to animal leather. In addition, the raw materials used for preparing mycelium by solid-state fermentation are waste or agricultural by-products, which reduces resource waste and makes the preparation process green and environmentally friendly. However, the pure mycelium material obtained by solid-state fermentation has problems such as poor mechanical properties and is difficult to use directly. The mycelium is hard and brittle, and its use is limited. To solve this problem, related research has been addressed from the following angles:

[0004] (I) Physical modification:

[0005] Common physical modifications include heat pressing and freeze drying.

[0006] 1. Hot pressing treatment: Under a certain temperature and pressure, the mycelium will be entangled or adhered to each other, which will improve its mechanical properties to a certain extent. However, direct hot pressing of untreated mycelium will cause some of its internal structures to be destroyed, and the improvement of mechanical properties will be limited.

[0007] 2. Freeze drying: Under vacuum conditions, the water inside the mycelium is sublimated to form a porous structure. This porous structure not only maintains its own lightweight characteristics, but also enhances its own mechanical properties. However, freeze drying is time-consuming, energy-intensive, and costly. The strength improvement by freeze drying alone is very limited.

[0008] (II) Chemical cross-linking modification:

[0009] Common cross-linking agents: glutaraldehyde, glyoxal, etc., although they have high reactivity, they are toxic chemical reagents and it is difficult for them to effectively fill the pores of the material like macromolecular or polymer cross-linking agents.

[0010] (III) Surface coating:

[0011] Coating a layer of polymer or other materials with good mechanical properties, such as polylactic acid, polyvinyl alcohol, etc., on the surface of the mycelium to form a composite structure can improve the overall mechanical properties. However, the bonding force between most coatings and the mycelium is weak, and there is a risk of falling off during use. At the same time, the coating also has a certain impact on the good air permeability and biodegradability of the mycelium itself.

[0012] Therefore, it is of great significance to study a degradable dialdehyde polysaccharide modified mycelium material and a preparation method thereof to solve the problems existing in the prior art. Summary of the invention

[0013] The purpose of the present invention is to solve the problems existing in the prior art and to provide a degradable dialdehyde polysaccharide modified mycelium material and a preparation method thereof.

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

[0015] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, characterized in that: mycelium cultured by solid-state fermentation is sequentially inactivated, pre-treated by deacetylation, impregnated with a chemical modifier (experiments show that impregnation is difficult for the chemical modifier to penetrate well into the mycelium, and impregnation can promote better penetration of the chemical modifier into the mycelium), plasticized, hot-pressed and dried to obtain a degradable dialdehyde polysaccharide modified mycelium material;

[0016] The chemical modifier is a dialdehyde polysaccharide compound solution, and the mass concentration of the dialdehyde polysaccharide compound solution is 1 to 20%;

[0017] The porosity of the mycelium cultured by solid-state fermentation is 78-83%, and the porosity of the degradable dialdehyde polysaccharide modified mycelium material is 5-11%.

[0018] As the preferred technical solution:

[0019] In the preparation method of the degradable dialdehyde polysaccharide modified mycelium material as described above, the temperature of the impregnation chemical modifier is 25-50°C, the liquid rate after impregnation is 50-150%, and the material is naturally dried (i.e., placed at room temperature until dry) or baked after impregnation.

[0020] The method for preparing a degradable dialdehyde polysaccharide modified mycelium material as described above, wherein the dialdehyde polysaccharide compound is obtained by reacting a polysaccharide compound with sodium periodate, the reaction temperature is 10 to 50° C., and the reaction time is 5 to 20 hours;

[0021] The polysaccharide compound is one or more of sodium carboxymethyl cellulose, chitosan, cyclodextrin, microcrystalline cellulose, starch, dextran, galacturonic acid, glycogen, pectin, chitin and hyaluronic acid;

[0022] The molar ratio of the polysaccharide compound to sodium periodate is 1:1-5.

[0023] In the method for preparing a degradable dialdehyde polysaccharide modified mycelium material as described above, the mycelium is the mycelium of Ganoderma lucidum, Pleurotus ostreatus, Pleurotus eryngii, Pleurotus eryngii or Hericium erinaceus.

[0024] According to the method for preparing a degradable dialdehyde polysaccharide modified mycelium material as described above, the mycelium obtained by solid-state fermentation is inactivated at a temperature of 60 to 160° C. for 20 to 120 minutes; the deacetylation agent used in the deacetylation pretreatment is ethanol, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate or potassium hydroxide, and the deacetylation pretreatment is specifically carried out using an aqueous solution of these compounds, preferably an ethanol aqueous solution with a mass fraction of 75%, and the deacetylation pretreatment refers to soaking in the deacetylation agent at 30° C. for 12 to 72 hours, then washing with water to remove excess deacetylation agent, and naturally drying or baking.

[0025] In the method for preparing the degradable dialdehyde polysaccharide modified mycelium material as described above, the solid-state fermentation culture conditions are: temperature 10-60° C., relative humidity 30-100%, and fermentation period 3-30 days.

[0026] The preparation method of the degradable dialdehyde polysaccharide modified mycelium material as described above, wherein the plasticizer used for plasticization is one or more of ethylene glycol, glycerol, polyethylene glycol, citric acid, sorbitol, urea and salicylic acid, specifically, the material is immersed in a solution of a plasticizer with a mass concentration of 1 to 15%, ultrasonically treated at 25 to 50° C. for 20 to 120 minutes, then washed with water to remove excess plasticizer, and naturally dried or baked.

[0027] In the method for preparing the degradable dialdehyde polysaccharide modified mycelium material as described above, the hot pressing temperature is 50 to 180° C. and the time is 0.5 to 10 minutes.

[0028] In the method for preparing a degradable dialdehyde polysaccharide modified mycelium material as described above, drying refers to natural air drying or oven drying.

[0029] The present invention also provides a degradable dialdehyde polysaccharide modified mycelium material prepared by the preparation method as described in any one of the above items. After being buried in the soil for 20 days, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 58.3-59.8%, which is equivalent to the degradation rate of the unmodified mycelium material (the degradation rate of the unmodified mycelium material is 59.4-60.1%).

[0030] The degradable dialdehyde polysaccharide modified mycelium material has a tensile strength of 3.59-3.88 MPa and an elongation at break of 27.8-32.6%, and has excellent mechanical properties while ensuring degradability.

[0031] Principle of the invention:

[0032] The present invention first inactivates the mycelium, then converts the chitin in the mycelium into chitosan by deacetylation, releases the amino group as a chemical reaction site, and then further improves the mechanical properties of the mycelium material by chemical crosslinking, plasticization, hot pressing and other technical means. The polysaccharide compound is of natural origin, has good biocompatibility and is degradable. The dialdehyde polysaccharide compound is prepared by oxidation, and can react chemically with the amino group, hydroxyl group and the like in the mycelium to form covalent crosslinking, thereby enhancing the mechanical strength of the mycelium; in addition, the dialdehyde polysaccharide compound itself can also undergo crosslinking polymerization to form a polymer deposited in the pores of the mycelium, and through the mechanical friction between the polymer and the mycelium fiber, or the hydrogen bonding between the hydroxyl group in the polymer and the polar groups such as the hydroxyl group and the amino group in the mycelium fiber, the relative mobility of the fiber can be hindered, thereby further improving its mechanical strength.

[0033] The mycelium itself has good biocompatibility and biodegradability. The dialdehyde polysaccharide compound itself is a polysaccharide with good biocompatibility. After the dialdehyde polysaccharide compound is cross-linked with the mycelium, it will not affect the biodegradability of the mycelium (experiments have shown that the degradation performance of the mycelium material modified with the dialdehyde polysaccharide compound is equivalent to that of the unmodified mycelium material).

[0034] Beneficial effects:

[0035] (1) The present invention provides a method for preparing a degradable dialdehyde polysaccharide modified mycelium material, which is based on preparing a relatively stable dialdehyde polysaccharide compound cross-linking agent by oxidizing the polysaccharide compound through sodium periodate, and using the cross-linking agent to treat the mycelium. The tensile strength and elongation at break of the mycelium are enhanced through deacetylation of the mycelium, modification of the dialdehyde polysaccharide compound, plasticization, hot pressing and other processing.

[0036] (2) The present invention provides a method for preparing a degradable dialdehyde polysaccharide modified mycelium material. The dialdehyde polysaccharide compound used can react with amino groups, hydroxyl groups, etc. in the deacetylated mycelium to form covalent crosslinks, thereby effectively improving the mechanical properties.

[0037] (3) The degradable dialdehyde polysaccharide modified mycelium material of the present invention has a green and environmentally friendly processing process, is degradable, and has a degradation rate comparable to that of unmodified mycelium materials. It also has excellent mechanical properties while ensuring degradability, and can be widely used in the fields of clothing fabrics, shoe uppers, packaging, furniture, leather bags, and automobile interiors. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 FTIR spectra of the raw material (CMC) and the chemical modifier (DCMC) in Example 2;

[0039] Figure 2 These are SEM photos of the cross-section of the mycelium in Example 2; (a) is the mycelium cultured by solid-state fermentation, and (b) is the mycelium modified by DCMC. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0041] The test methods involved in the performance indicators of the present invention are as follows:

[0042] Tensile strength and elongation at break: According to “QB / T 2710-2018 Determination of tensile strength and elongation of leather physical and mechanical tests”, the tensile strength and elongation at break of mycelium materials are tested.

[0043] Degradability: Take a portion of mycelium material and dry it at 50°C to constant weight, record the sample mass, and bury it in the soil 30 cm below the surface under natural conditions. Take it out after 20 days, wash it with clean water, dry it to constant weight, and calculate the weight loss rate.

[0044] Sources of some substances of the present invention:

[0045] Cottonseed hulls: Manufacturer: Shandong Dezhou Edible Fungi Research Institute.

[0046] Corn cob: Manufacturer: Shandong Dezhou Edible Fungi Research Institute.

[0047] Alkaline lignin: Shanghai Titan Technology Co., Ltd., CAS No.: 8068-05-1.

[0048] Sodium carboxymethyl cellulose: Shanghai Myrel Chemical Technology Co., Ltd., CAS No.: 9004-32-4.

[0049] Chitosan: Shanghai Titan Technology Co., Ltd., CAS No.: 9012-76-4.

[0050] Cyclodextrin: Shanghai Titan Technology Co., Ltd., CAS No.: 7585-39-9.

[0051] Microcrystalline cellulose: Sinopharm Chemical Reagent Co., Ltd., CAS No.: 9004-34-6.

[0052] Starch: Sinopharm Chemical Reagent Co., Ltd., CAS No.: 9005-84-9.

[0053] Dextran: Sinopharm Chemical Reagent Co., Ltd., CAS No.: 9004-54-0.

[0054] Chitin: Sinopharm Chemical Reagent Co., Ltd., CAS No.: 1398-61-4.

[0055] Hyaluronic acid: Sinopharm Chemical Reagent Co., Ltd., CAS No.: 9004-61-9.

[0056] Ganoderma lucidum: Cangzhou Jinkelifeng Seedling Co., Ltd., pure first generation.

[0057] Black Oyster Mushroom: Cangzhou Jinkelifeng Seedling Co., Ltd., pure first generation.

[0058] Hericium erinaceus: Cangzhou Jinkelifeng Seedling Co., Ltd., pure first generation.

[0059] Example 1

[0060] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, the specific steps are as follows:

[0061] (1) preparing mycelium for solid-state fermentation culture;

[0062] Cottonseed hulls, corn cobs and alkaline lignin were prepared into a solid culture medium in a mass ratio of 5:4:1, and the mixture was evenly stirred and placed in a polypropylene fermentation bag. The solid culture medium was sterilized in a sterilizer at 121° C. for 30 min, and then Ganoderma lucidum was inoculated into the fermentation bag to prepare a fungus bag, which was placed in an incubator and cultured at 30° C. and a relative humidity of 50% for 15 days to obtain a solid-state fermentation cultured mycelium with a porosity of 80.2%;

[0063] (2) inactivating the mycelium cultured by solid-state fermentation at 60°C for 30 minutes;

[0064] (3) deacetylation pretreatment;

[0065] At 30° C., soaking the product of step (2) in a 75% by mass ethanol aqueous solution for 24 hours, then washing with water to remove excess ethanol reagent, and naturally drying to obtain deacetylated mycelium;

[0066] (4) preparing chemical modifiers;

[0067] Microcrystalline cellulose (MCC) was added to a sodium periodate aqueous solution with a mass concentration of 10% at a molar ratio of 1:2, reacted at 30°C in the dark for 12 hours, dialyzed in a dialysis bag with a molecular weight cutoff of 14 kDa at room temperature for 24 hours, and then freeze-dried at -50°C for 48 hours to obtain dialdehyde microcrystalline cellulose (DMCC), i.e., a chemical modifier;

[0068] (5) Padding chemical modifier;

[0069] The deacetylated mycelium was immersed in a DMCC aqueous solution with a mass concentration of 5%, and the mixture was immersed and rolled twice by a padder, and the liquid carrying rate after immersion and rolling was controlled to be 100%, and the mixture was dried naturally;

[0070] (6) Plasticization;

[0071] The product of step (5) was immersed in a glycerol aqueous solution with a mass concentration of 1.5%, and ultrasonically treated at room temperature of 25° C. for 30 minutes, then washed with water to remove excess glycerol, and dried naturally;

[0072] (7) hot pressing at 80° C. for 10 minutes and naturally drying to obtain a biodegradable dialdehyde polysaccharide modified mycelium material.

[0073] The porosity of the finally prepared degradable dialdehyde polysaccharide modified mycelium material is 6.1%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 59.4%, and the degradation rate of the unmodified mycelium material is 59.6%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.64MPa, and the elongation at break is 28.3%.

[0074] Comparative Example 1

[0075] A method for preparing a dialdehyde polysaccharide modified mycelium material is basically the same as that of Example 1, except that the deacetylation pretreatment in step (3) is omitted.

[0076] The porosity of the dialdehyde polysaccharide modified mycelium material finally obtained is 78.6%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 58.6%, and the degradation rate of the unmodified mycelium material is 58.9%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 1.22MPa, and the elongation at break is 15.7%.

[0077] By comparing Comparative Example 1 with Example 1, it can be found that whether deacetylation is performed or not has little effect on the degradation rate, but has a greater effect on the porosity after modification. This is because amino groups will be generated on the mycelium as cross-linking sites only after deacetylation, so that the cross-linking will be sufficient and the porosity after modification will be reduced. In addition, the process of deacetylation to generate amino groups, in addition to covalent cross-linking with aldehyde groups, can also generate more hydrogen bonds with hydroxyl groups or other polar groups on the surrounding adjacent molecular chains, thereby enhancing the interaction force between the molecular chains. When stretched by external force, a large force is required to make the molecular chains slide relatively or break. Therefore, after deacetylation is omitted, the tensile strength and elongation at break of the product will decrease.

[0078] Example 2

[0079] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, the specific steps are as follows:

[0080] (1) preparing mycelium for solid-state fermentation culture;

[0081] Cottonseed hulls, corn cobs and alkaline lignin were prepared into a solid culture medium in a mass ratio of 5:4:1, and the mixture was evenly stirred and placed in a polypropylene fermentation bag. The solid culture medium was sterilized in a sterilizer at 121° C. for 30 minutes, and then Ganoderma lucidum was inoculated into the fermentation bag to prepare a bacterial bag, which was placed in an incubator and cultured at 30° C. and a relative humidity of 50% for 15 days to obtain a solid-state fermentation cultured mycelium with a porosity of 80.6%.

[0082] (2) inactivating the mycelium cultured by solid-state fermentation at 60°C for 30 minutes;

[0083] (3) deacetylation pretreatment;

[0084] At 30° C., soaking the product of step (2) in a 75% by mass ethanol aqueous solution for 24 hours, then washing with water to remove excess ethanol reagent, and naturally drying to obtain deacetylated mycelium;

[0085] (4) preparing chemical modifiers;

[0086] Sodium carboxymethyl cellulose (CMC) was added to a sodium periodate aqueous solution with a mass concentration of 10% at a molar ratio of 1:2, reacted at 30°C in the dark for 12 hours, dialyzed in a dialysis bag with a molecular weight cutoff of 14 kDa at room temperature for 24 hours, and then freeze-dried at -50°C for 48 hours to obtain dialdehyde sodium carboxymethyl cellulose (DCMC), i.e., a chemical modifier;

[0087] like Figure 1 The Fourier transform infrared spectrum (FTIR) shown shows that the –1 The new absorption band that appeared at corresponds to the C=O peak of the aldehyde group in DCMC, indicating the successful preparation of DCMC;

[0088] (5) Padding chemical modifier;

[0089] The deacetylated mycelium was immersed in a DCMC aqueous solution with a mass concentration of 6%, and the padder was used to dip and roll twice, and the liquid rate after dipping and rolling was controlled to be 100%, and the mycelium was naturally dried;

[0090] (6) Plasticization;

[0091] The product of step (5) was immersed in a glycerol aqueous solution with a mass concentration of 1.5%, and ultrasonically treated at room temperature of 25° C. for 30 minutes, then washed with water to remove excess glycerol, and dried naturally;

[0092] (7) hot pressing at 120° C. for 3 minutes and naturally drying to obtain a degradable dialdehyde polysaccharide modified mycelium material.

[0093] The porosity of the finally prepared degradable dialdehyde polysaccharide modified mycelium material is 5%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 59.8%, and the degradation rate of the unmodified mycelium material is 60.0%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.88MPa, and the elongation at break is 32.6%.

[0094] like Figure 2 As shown, Figure (a) is the unmodified mycelium, with many pores between the fibers; Figure (b) is the mycelium modified by DCMC, with more polymers between the fiber pores, which basically fill the pores between the fibers; there are fillers in the mycelium pores, which are polymers formed by self-polymerization of DCMC, which play a role in polymer deposition and have a bonding effect on the mycelium fibers, further improving the strength of the mycelium. DCMC molecules contain hydroxyl groups, aldehyde groups, etc., and can undergo cross-linking reactions; if they do not react, DCMC will be washed away by subsequent cleaning processing, and then no filling substances can be observed in the pores between the fibers.

[0095] The degradation performance of the mycelium material modified by DCMC (i.e., the degradable dialdehyde polysaccharide modified mycelium material) is equivalent to that of the unmodified mycelium material. After being buried in the soil for 20 days, the degradation rates of both are about 60%, and the degradation performance is good. In general, the mycelium leather material prepared by the present invention has good degradation performance and can be completely biodegraded in the natural environment.

[0096] Comparative Example 2

[0097] A method for preparing mycelium material is basically the same as that of Example 2, except that step (4) and step (5) are omitted.

[0098] The porosity of the final mycelium material is 78.2%; after 20 days of landfill in the soil, the degradation rate of the mycelium material is 58.5%, and the degradation rate of the unmodified mycelium material is 58.9%; the tensile strength of the mycelium material is 1.26MPa, and the elongation at break is 21.4%.

[0099] By comparing Comparative Example 2 with Example 2, it can be found that the use of chemical modifiers has little effect on the degradation rate, but has a greater effect on the porosity. This is because after deacetylation, the amino group is exposed and forms a Schiff base structure with the chemical modifier to form a covalent bond. Combined with the tensile strength and electron microscopy data, it can be seen that the chemical modifier has sufficient penetration, so the porosity is high if no chemical modifier is used. In addition, the chemical modifier in Example 2 reacts chemically with the mycelium to form covalent crosslinks, which connect the molecular chains together. When the mycelium is subjected to external force, it will be evenly dispersed throughout the mycelium to avoid local force. In addition, in addition to covalent crosslinks, there are also non-covalent interactions such as hydrogen bonds and van der Waals forces to improve the overall mechanical properties.

[0100] Example 3

[0101] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, the specific steps are as follows:

[0102] (1) preparing mycelium for solid-state fermentation culture;

[0103] Cottonseed hulls, corn cobs and alkaline lignin were prepared into a solid culture medium in a mass ratio of 5:4:1, and the mixture was evenly stirred and placed in a polypropylene fermentation bag. The solid culture medium was sterilized in a sterilizer at 121° C. for 30 minutes, and then Ganoderma lucidum was inoculated into the fermentation bag to prepare a bacterial bag, which was placed in an incubator and cultured at 30° C. and a relative humidity of 50% for 15 days to obtain a solid-state fermentation cultured mycelium with a porosity of 81.3%;

[0104] (2) inactivating the mycelium cultured by solid-state fermentation at 60°C for 30 minutes;

[0105] (3) deacetylation pretreatment;

[0106] At 30° C., soaking the product of step (2) in a 75% by mass ethanol aqueous solution for 24 hours, then washing with water to remove excess ethanol reagent, and naturally drying to obtain deacetylated mycelium;

[0107] (4) preparing chemical modifiers;

[0108] Chitosan (CS) was added to a sodium periodate aqueous solution with a mass concentration of 10% at a molar ratio of 1:2, reacted at 30°C in the dark for 12 hours, dialyzed in a dialysis bag with a molecular weight cutoff of 14 kDa at room temperature for 24 hours, and then freeze-dried at -50°C for 48 hours to obtain dialdehyde chitosan (DCS), i.e., a chemical modifier;

[0109] (5) Padding chemical modifier;

[0110] The deacetylated mycelium was immersed in a DCS aqueous solution with a mass concentration of 3%, and the padder was used to dip and roll twice, and the liquid rate after dipping and rolling was controlled to be 100%, and the mycelium was naturally dried;

[0111] (6) Plasticization;

[0112] The product of step (5) was immersed in a glycerol aqueous solution with a mass concentration of 1.5%, and ultrasonically treated at room temperature of 25° C. for 30 minutes, then washed with water to remove excess glycerol, and dried naturally;

[0113] (7) hot pressing at 150° C. for 2 minutes and naturally drying to obtain a degradable dialdehyde polysaccharide modified mycelium material.

[0114] The porosity of the finally prepared degradable dialdehyde polysaccharide modified mycelium material is 8.2%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 59.3%, and the degradation rate of the unmodified mycelium material is 59.8%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.59 MPa, and the elongation at break is 27.8%.

[0115] Comparative Example 3

[0116] A method for preparing mycelium material is basically the same as that of Example 3, except that step (4) and step (5) are omitted.

[0117] The porosity of the final mycelium material is 79.8%; after being buried in the soil for 20 days, the degradation rate of the mycelium material is 58.6%, and the degradation rate of the unmodified mycelium material is 59.2%; the tensile strength of the mycelium material is 1.28MPa, and the elongation at break is 19.3%.

[0118] Example 4

[0119] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, the specific steps are as follows:

[0120] (1) preparing mycelium for solid-state fermentation culture;

[0121] Cottonseed hulls, corn cobs and alkaline lignin were prepared into a solid culture medium in a mass ratio of 5:4:1, and the mixture was evenly stirred and placed in a polypropylene fermentation bag. The solid culture medium was sterilized in a sterilizer at 121° C. for 30 minutes, and then Ganoderma lucidum was inoculated into the fermentation bag to prepare a bacterial bag, which was placed in an incubator and cultured at 30° C. and a relative humidity of 50% for 15 days to obtain a solid-state fermentation cultured mycelium with a porosity of 82.3%;

[0122] (2) inactivating the mycelium cultured by solid-state fermentation at 60°C for 30 minutes;

[0123] (3) deacetylation pretreatment;

[0124] At 30° C., soaking the product of step (2) in a 75% by mass ethanol aqueous solution for 24 hours, then washing with water to remove excess ethanol reagent, and naturally drying to obtain deacetylated mycelium;

[0125] (4) preparing chemical modifiers;

[0126] Cyclodextrin (CD) was added to a sodium periodate aqueous solution with a mass concentration of 10% at a molar ratio of 1:2, reacted at 30°C in the dark for 12 hours, dialyzed in a dialysis bag with a molecular weight cutoff of 1000 Da at room temperature for 24 hours, and then freeze-dried at -50°C for 48 hours to obtain dialdehyde cyclodextrin (DCD), i.e., a chemical modifier;

[0127] (5) Padding chemical modifier;

[0128] The deacetylated mycelium was immersed in a DCD aqueous solution with a mass concentration of 4%, and the padder was used to dip and roll twice, and the liquid rate after dipping and rolling was controlled to be 100%, and the mycelium was naturally dried;

[0129] (6) Plasticization;

[0130] The product of step (5) was immersed in a glycerol aqueous solution with a mass concentration of 1.5%, and ultrasonically treated at room temperature of 25° C. for 30 minutes, then washed with water to remove excess glycerol, and dried naturally;

[0131] (7) hot pressing at 180° C. for 1 minute and naturally drying to obtain a degradable dialdehyde polysaccharide modified mycelium material.

[0132] The porosity of the finally prepared degradable dialdehyde polysaccharide modified mycelium material is 11%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 59.1%, and the degradation rate of the unmodified mycelium material is 59.8%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.75MPa, and the elongation at break is 29.4%.

[0133] Comparative Example 4

[0134] A method for preparing mycelium material is basically the same as Example 4, except that step (4) and step (5) are omitted.

[0135] The porosity of the final mycelium material is 78.2%; after 20 days of landfill in the soil, the degradation rate of the mycelium material is 58.9%, and the degradation rate of the unmodified mycelium material is 59.5%; the tensile strength of the mycelium material is 1.32MPa, and the elongation at break is 20.8%.

[0136] Comparative Example 5

[0137] A method for preparing a mycelium material is basically the same as that of Example 4, except that steps (4) to (7) are omitted.

[0138] The porosity of the mycelium material finally obtained is 83.0%; after being buried in the soil for 20 days, the degradation rate of the mycelium material is 59.6%, and the degradation rate of the unmodified mycelium material is 60.1%; the tensile strength of the mycelium material is 1.19MPa, and the elongation at break is 16%.

[0139] By comparing Comparative Example 5 with Example 4, it can be found that only deacetylation without subsequent cross-linking, plasticization, hot pressing and other processes has a greater impact on the porosity. This is because the filling effect is better after the chemical modifier is cross-linked. Combined with the subsequent plasticization and hot pressing, on the one hand, the plasticizer will also have a certain wrapping effect on the inside of the mycelium. Combined with hot pressing, the porosity will be further reduced. In addition, Comparative Example 5 is only deacetylated, and the mechanical properties are limitedly improved. There is no chemical reaction inside, and there is almost no interaction force inside the mycelium to overcome the relative movement caused by external forces. Therefore, the tensile strength and elongation at break are relatively low.

[0140] Comparative Example 6

[0141] A method for preparing a mycelium material is basically the same as that of Example 4, except that step (4), step (5) and step (7) are omitted.

[0142] The porosity of the final mycelium material is 80.6%; after 20 days of landfill in the soil, the degradation rate of the degradable mycelium material is 58.6%, and the degradation rate of the unmodified mycelium material is 59.7%; the tensile strength of the mycelium material is 1.26MPa, and the elongation at break is 21.4%.

[0143] By comparing Comparative Example 6 with Example 4, it can be found that if the cross-linking and plasticizing processes are omitted and only hot pressing is used, the degradation rate is not greatly affected, but the porosity of the mycelium is greatly affected. This is because after hot pressing, under the action of external force, the three-dimensional network structure inside the mycelium itself will be more tightly entangled with each other, so that the gap between the mycelia is reduced, thereby affecting the porosity. The cross-linking process will provide covalent binding force and non-covalent force, which plays a major role in the strong effect. In addition, during the hot pressing process, heat and pressure can intensify the movement of some molecular chains in the mycelium and reduce the molecular distance, which is conducive to the formation of more intermolecular forces such as hydrogen bonds and van der Waals forces, so that the molecular chains are more tightly bound, thereby improving the tensile strength. At the same time, after hot pressing, the flexibility of the molecular chains increases, and internal rotation becomes easier, which can produce a greater elongation deformation before breaking, thereby improving the elongation at break.

[0144] Example 5

[0145] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, the specific steps are as follows:

[0146] (1) preparing mycelium for solid-state fermentation culture;

[0147] Cottonseed hulls, corn cobs and alkaline lignin were prepared into a solid culture medium in a mass ratio of 5:4:1, and the mixture was evenly stirred and placed in a polypropylene fermentation bag. The solid culture medium was sterilized in a sterilizer at 121° C. for 30 minutes, and then Ganoderma lucidum was inoculated into the fermentation bag to prepare a bacterial bag, which was placed in an incubator and cultured at 10° C. and a relative humidity of 100% for 30 days to obtain a solid-state fermentation cultured mycelium with a porosity of 80.1%;

[0148] (2) inactivating the mycelium cultured by solid-state fermentation at 60°C for 120 minutes;

[0149] (3) deacetylation pretreatment;

[0150] At 25° C., soaking the product of step (2) in a 75% by mass sodium carbonate aqueous solution for 12 hours, then washing with water to remove excess sodium carbonate, and naturally drying to obtain deacetylated mycelium;

[0151] (4) preparing chemical modifiers;

[0152] A mixture of starch and glucan (molar ratio of starch to glucan is 1:1) is added to a sodium periodate solution with a mass concentration of 5% in a molar ratio of 1:1, reacted at 10°C in the dark for 20 hours, dialyzed in a dialysis bag with a molecular weight cutoff of 14 kDa at room temperature for 24 hours, and then freeze-dried at -50°C for 48 hours to obtain a mixed cross-linking agent (DA) of dialdehyde starch and glucan, i.e., a chemical modifier;

[0153] (5) Padding chemical modifier;

[0154] The deacetylated mycelium was immersed in a DA aqueous solution with a mass concentration of 8%, and the padder was used to dip and roll twice, and the liquid rate after dipping and rolling was controlled to be 50%, and the mycelium was naturally dried;

[0155] (6) Plasticization;

[0156] The product of step (2) is immersed in an aqueous solution of ethylene glycol having a mass concentration of 1%, and subjected to ultrasonic treatment at 25° C. for 120 minutes, and then washed with water to remove excess ethylene glycol, and dried naturally;

[0157] (7) hot pressing at 50° C. for 10 minutes and naturally drying to obtain a degradable dialdehyde polysaccharide modified mycelium material.

[0158] The porosity of the finally prepared degradable dialdehyde polysaccharide modified mycelium material is 5.9%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 59.2%, and the degradation rate of the unmodified mycelium material is 59.8%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.64MPa, and the elongation at break is 28.6%.

[0159] Example 6

[0160] A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, the specific steps are as follows:

[0161] (1) preparing mycelium for solid-state fermentation culture;

[0162] Cottonseed hulls, corn cobs and alkaline lignin were prepared into a solid culture medium in a mass ratio of 5:4:1, and the mixture was evenly stirred and placed in a polypropylene fermentation bag. The solid culture medium was sterilized in a sterilizer at 121°C for 30 minutes, and then Ganoderma lucidum was inoculated into the fermentation bag to prepare a fungus bag, which was placed in an incubator and cultured at 60°C and 30% relative humidity for 3 days to obtain a solid-state fermentation cultured mycelium with a porosity of 81.3%;

[0163] (2) inactivating the mycelium cultured by solid-state fermentation at 160°C for 20 minutes;

[0164] (3) deacetylation pretreatment;

[0165] At 25° C., soaking the product of step (2) in a 75% by mass potassium hydroxide aqueous solution for 12 hours, then washing with water to remove excess potassium hydroxide, and naturally drying to obtain deacetylated mycelium;

[0166] (4) preparing chemical modifiers;

[0167] A mixture of chitin and hyaluronic acid (chitin and hyaluronic acid molar ratio of 1:5) was added to a sodium periodate solution with a mass concentration of 15% at a molar ratio of 1:5, reacted at 50° C. in the dark for 5 hours, dialyzed in a dialysis bag with a molecular weight cutoff of 14 kDa at room temperature for 48 hours, and then freeze-dried at -50° C. for 48 hours to obtain a dialdehyde chitin and hyaluronic acid mixed cross-linking agent (DB), i.e., a chemical modifier;

[0168] (5) Padding chemical modifier;

[0169] The deacetylated mycelium was immersed in a DB aqueous solution with a mass concentration of 10%, and the padder was used to dip and roll twice, and the liquid rate after dipping and rolling was controlled to be 150%, and the mixture was dried naturally;

[0170] (6) Plasticization;

[0171] The product of step (2) is immersed in a mixed aqueous solution of urea and salicylic acid (mass ratio 1:1) with a mass concentration of 1%, and ultrasonically treated at 50° C. for 20 minutes, then washed with water to remove excess urea and salicylic acid, and dried naturally;

[0172] (7) hot pressing at 180° C. for 0.5 min and naturally drying to obtain a degradable dialdehyde polysaccharide modified mycelium material.

[0173] The porosity of the finally prepared degradable dialdehyde polysaccharide modified mycelium material is 6.6%; after 20 days of landfill in the soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material is 59.4%, and the degradation rate of the unmodified mycelium material is 60.0%; the tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.66MPa, and the elongation at break is 28.4%.

Claims

1. A method for preparing a degradable dialdehyde polysaccharide modified mycelium material, characterized in that: The mycelium cultured by solid-state fermentation is sequentially inactivated, pre-treated by deacetylation, impregnated with a chemical modifier, plasticized, hot-pressed and dried to obtain a degradable dialdehyde polysaccharide modified mycelium material; The chemical modifier is a dialdehyde polysaccharide compound solution, and the mass concentration of the dialdehyde polysaccharide compound solution is 1 to 20%; The porosity of the mycelium cultured by solid-state fermentation is 78-83%, and the porosity of the degradable dialdehyde polysaccharide modified mycelium material is 5-11%.

2. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: The temperature of the chemical modifier for padding is 25-50°C, and the liquid rate after padding is 50-150%.

3. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 2, characterized in that: The dialdehyde polysaccharide compound is obtained by reacting a polysaccharide compound with sodium periodate, the reaction temperature is 10 to 50° C., and the reaction time is 5 to 20 hours; The polysaccharide compound is one or more of sodium carboxymethyl cellulose, chitosan, cyclodextrin, microcrystalline cellulose, starch, dextran, galacturonic acid, glycogen, pectin, chitin and hyaluronic acid; The molar ratio of the polysaccharide compound to sodium periodate is 1:1-5.

4. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: The mycelium is the mycelium of red ginseng, black oyster mushroom, black mushroom, phoenix tail mushroom or hericium erinaceus.

5. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: The mycelium obtained by solid-state fermentation is inactivated at a temperature of 60-160° C. for 20-120 minutes; the deacetylation agent used in the deacetylation pretreatment is ethanol, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate or potassium hydroxide.

6. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: The conditions for solid-state fermentation culture are: temperature 10-60°C, relative humidity 30-100%, and fermentation period 3-30 days.

7. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: The plasticizer used for plasticization is one or more of ethylene glycol, glycerol, polyethylene glycol, citric acid, sorbitol, urea and salicylic acid.

8. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: The temperature of hot pressing is 50 to 180° C., and the time is 0.5 to 10 minutes.

9. The method for preparing a degradable dialdehyde polysaccharide modified mycelium material according to claim 1, characterized in that: Drying means air drying or tumble drying.

10. The degradable dialdehyde polysaccharide modified mycelium material prepared by the preparation method according to any one of claims 1 to 9, characterized in that: After 20 days of landfill in soil, the degradation rate of the degradable dialdehyde polysaccharide modified mycelium material was 58.3-59.8%; The tensile strength of the degradable dialdehyde polysaccharide modified mycelium material is 3.59-3.88 MPa, and the elongation at break is 27.8-32.6%.

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