Degradable flexible conductive mycelium material and preparation method thereof

Abstract

The application discloses a kind of degradable flexible conductive mycelium material method, belong to new material technical field.The application utilizes deep fermentation to prepare mycelium nanoparticle composite fermentation liquor, and is combined with solid fermentation, and the resistance value of the conductive mycelium material prepared is 30-40 Ω / cm, with excellent conductive performance, and after repeatedly stretching 100 times, resistance value fluctuation is about 10%, and the stability of guide point is excellent;In addition, degradation rate reaches about 70%, and can be recycled, compared with traditional conductive material, it will not produce a large number of electronic garbage, and reduce the dependence on earth resources, will not cause harm to the environment.Meanwhile, the breaking strength of the flexible conductive mycelium material prepared by the application reaches more than 25MPa, and the contact angle is >90°.Therefore, the conductive mycelium material prepared by the application is similar to leather in appearance, and the conductivity and flexibility are good, which can promote the development of intelligent textiles.

Description

Technical Field

[0001] This invention relates to a method for developing a biodegradable, flexible, and conductive mycelial material, belonging to the field of new materials technology. Background Technology

[0002] Traditional textile materials, such as cotton, silk, wool, and nylon, are typically insulators and cannot effectively conduct electric current. To increase the conductivity of textiles, methods such as coating or chemical deposition are often used, but these methods reduce the textiles' durability and comfort. Furthermore, some chemical processing methods may generate harmful substances, posing potential hazards to human health and the environment, thus limiting the sustainable development of smart textiles. On the other hand, conductive materials used in textiles are difficult to recycle, resulting in electronic waste that wastes resources and severely pollutes the environment.

[0003] Existing research (DAMATZKY A, GANDIAA, CHIOLERIO A. Towards fungal sensing skin[J]. Fungal Biology and Biotechnology, 2021, 8(1)) has confirmed that inactivated mycelium possesses certain conductivity or photosensitivity, and can be used to prepare flexible sensors. However, active mycelium materials are difficult to preserve, are prone to mold and decay, and cannot be practically applied. To improve their preservation, the inactivated mycelium materials, after processing, no longer possess conductivity. Therefore, it is necessary to develop a method for preparing conductive mycelium materials so that the inactivated mycelium materials possess conductivity without affecting the material's durability. Summary of the Invention

[0004] Traditional textile materials lack electrical conductivity, and composite conductive materials can negatively impact the softness and wearability of textiles. Currently available conductive fibers with conductive or photosensitive effects still exhibit high resistance, insufficient sensitivity, and are difficult to recycle or degrade, generating electronic waste.

[0005] To address the aforementioned issues, this invention utilizes mycelium and nanoparticles to prepare biodegradable flexible conductive materials, thereby resolving problems such as unstable conductivity and easy coating peeling in existing technologies, and providing new ideas for the development of smart textiles.

[0006] The first technical solution provided by this invention is a method for preparing mycelial nanocomposite fermentation broth, comprising the following steps: adding nanoparticles with a mass fraction of 2-3% to a liquid culture medium, stirring evenly, inoculating with edible fungi spawn, culturing for 5-7 days at a temperature of 20-28℃ and a rotation speed of 110-140 r / min to obtain mycelial nanocomposite fermentation broth.

[0007] In some embodiments, the edible fungi include one or more of the following: enoki mushroom, golden ear fungus, silver ear fungus, wood ear fungus, tea tree mushroom, white jade mushroom, morel mushroom, king oyster mushroom, reishi mushroom, shiitake mushroom, oyster mushroom, button mushroom, lion's mane mushroom, white lingzhi mushroom, straw mushroom, button mushroom, and matsutake mushroom.

[0008] In some embodiments, the nanoparticles include one or more of the following: silver nanoparticles, carbon nanotubes, silica nanoparticles, graphene, gold nanoparticles, iron oxide, copper nanoparticles, zinc oxide, iron oxide, and polythiophene nanoparticles. The nanoparticles are prepared into a solution with a concentration of 20%-50% and then added to a liquid culture medium.

[0009] In some embodiments, the liquid culture medium is a mixture of 15 g / L potato starch, 20 g / L glucose, 1.5 g / L calcium carbonate, 1.5 g / L trace elements, 1.5 g / L peptone, and water.

[0010] The second technical solution provided by this invention is a nano-mycelium composite fermentation broth prepared using the method described in the first technical solution.

[0011] The third technical solution provided by the present invention is a method for preparing a flexible conductive mycelium material, comprising the following steps: uniformly spreading the mycelium nanocomposite fermentation broth described in the second technical solution on a solid culture medium, covering it with a substrate, and culturing it at 20-28℃ for 10-14 days to harvest the mycelium pad and obtain a flexible conductive mycelium membrane.

[0012] In some embodiments, the solid culture medium comprises, by weight percentage, 40% corn cob, 20% wheat bran, 20% sawdust, 20% flour, 1% potassium dihydrogen phosphate, 1% calcium carbonate, 10% glucose, and 1% magnesium sulfate.

[0013] In some embodiments, the substrate is one or more of carbon fiber, cotton fiber, hemp fiber, viscose fiber, polyester fiber, stainless steel fiber, regenerated cellulose fiber, wool fiber, and microfiber.

[0014] In some embodiments, the method further includes post-processing the flexible conductive mycelial membrane to obtain a conductive mycelial pad, the post-processing including the following steps: tanning and hot pressing. This post-processing imparts good wearability to the material while maintaining its conductivity.

[0015] In some embodiments, the tanning process involves soaking the food in a 2% to 10% tanning agent, which includes one or more of the following: alcohol-soluble protein, tannin, linseed oil, glutaraldehyde, genipin, formaldehyde, tyrosinase, acetic anhydride, sodium tripolyphosphate, formamide, urea, sodium nitrate, salicylic acid, thiocyanate, glycerol, sorbitol, ethylene glycol, and DES.

[0016] In some embodiments, the hot pressing process involves a temperature of 50°C, a pressure of 1 MPa, and a time of 3 minutes.

[0017] In some embodiments, the method further includes coating the conductive mycelial pad to obtain biodegradable leather.

[0018] In some embodiments, the coating agent used in the coating process is one or more of the following: WPU coating, PVC coating, acrylic resin, phenolic resin coating, grease, paraffin wax, silicone oil, and shellac.

[0019] The fourth technical solution provided by the present invention is a flexible conductive mycelium material, which is a flexible conductive mycelium membrane, a conductive mycelium pad, or a biodegradable leather prepared by the method described in the third technical solution.

[0020] The fifth technical solution provided by this invention is the application of the method described in the first technical solution, the nano-mycelium composite fermentation broth described in the second technical solution, the method described in the third technical solution, or the flexible conductive mycelium material described in the fourth technical solution in the field of smart textiles.

[0021] In some embodiments, the smart textiles include clothing, home furnishings, medical devices, etc.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention utilizes submerged fermentation to prepare a mycelium-nanoparticle composite fermentation broth. Submerged fermentation yields a larger quantity of mycelium and a shorter cultivation cycle. During mycelial growth, the nanoparticles can be coated by the liquid vibration. Combined with solid-state fermentation, the prepared conductive mycelium material has a resistivity of 30-40 Ω / cm, exhibiting excellent conductivity. Furthermore, after repeated stretching 100 times, the resistance fluctuation is only around 10%, demonstrating excellent conductivity stability.

[0024] (2) The conductive mycelium material prepared by the present invention has a degradation rate of about 70% and can be recycled. Compared with traditional conductive materials, it does not generate a large amount of electronic waste, reduces dependence on earth resources, and does not cause harm to the environment.

[0025] (3) The fracture strength of the flexible conductive mycelium material prepared by the present invention reaches more than 25 MPa and the contact angle is >90°, indicating that the performance meets the application requirements of traditional leather, has excellent waterproof performance to protect the material, and has stable conductivity.

[0026] (4) The conductive mycelium material prepared by the present invention is similar in appearance to leather and has good conductivity and flexibility, which can promote the development of smart textiles. Attached Figure Description

[0027] Figure 1 This is an image of the conductive flexible mycelium material of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] Test method:

[0030] 1. Conductivity test

[0031] Lay the fabric flat on an insulated table without applying pressure. Take 100mm lengths of the material from three points on the left, center, and right. Use a digital multimeter to test the resistance value of each piece of material at different locations. Test three times at each location and take the average value as the resistance value of that piece of fabric.

[0032] 2. Conductivity stability test

[0033] The rate of change of electrical resistance R' of the material after being repeatedly stretched 100 times within a stretch range of 50% was measured.

[0034] R'=ΔR / R0

[0035] ΔR is the difference between the resistance of the material after stretching and the resistance of the material before stretching; R0 is the resistance value before stretching.

[0036] 3. Mechanical property testing

[0037] The test was conducted in accordance with GB / T 38610—2020 "Test Methods for Tensile Load and Elongation at Break of Artificial Leather and Synthetic Leather". Specifically, a sample with a length of 100 mm and a width of 10 mm was cut into a dumbbell shape, the distance between the clamps was set to 50 mm, and the constant elongation rate was set to 200 mm / min.

[0038] 4. Degradability test

[0039] Three 5×5cm material samples were buried in a grassy area with vigorous plant growth. After one month, they were taken out, weighed, and their weight loss rate was calculated. The average value was then taken.

[0040] Weight loss rate = (M0-M1) / M0 × 100%

[0041] Where M0 is the mass of the plastic sample before landfilling; M1 is the mass of the plastic sample after landfilling.

[0042] 5. Contact angle test:

[0043] Refer to GB / T 30693-2014 "Measurement of the contact angle between plastic film and water".

[0044] Specifically, the sample is placed on the instrument's sample stage, and 1-2 μL of water is added to the material surface using a needle. The angle θ between the solid-liquid interface is measured using software.

[0045] Example 1

[0046] A method for preparing conductive flexible mycelial material includes the following steps:

[0047] (1) Preparation of nanoparticle culture medium:

[0048] Take 200g of potatoes, add them to 500ml of boiling water and cook for 10 minutes. Add 15g of corn flour and continue cooking for 20 minutes. Filter the mixture and add 2% sucrose, 1% glucose, 0.2% peptone, 0.01% potassium dihydrogen phosphate, 1% calcium chloride, and 3% copper nanoparticles to the filtrate. Add water to 500ml and stir well.

[0049] (2) Preparation of nano-mycelium composite fermentation broth:

[0050] Dispense the above culture medium into 250ml Erlenmeyer flasks, sterilize them, and then inoculate with oyster mushroom spawn. Place the inoculated Erlenmeyer flasks in a shaker, setting the temperature to 25-28℃ and the rotation speed to 130 rpm. After 10 days of incubation, remove the fermentation broth.

[0051] (3) Preparation of solid culture medium:

[0052] In an incubator, 40% corn cob, 20% wheat bran, 20% sawdust, 20% flour, 1% potassium dihydrogen phosphate, 1% calcium carbonate, 10% glucose, and 1% magnesium sulfate are mixed evenly and sterilized. After cooling, the mixture is poured into the nano-mycelium composite fermentation broth obtained in step (2).

[0053] (4) Preparation of flexible conductive mycelium material:

[0054] The viscose fiber was immersed in the culture medium without copper nanoparticles in step (1). The reason for this operation is that if the viscose fiber is not immersed in the culture medium, the mycelial growth is relatively slow. If nanoparticles are added, the proportion of nanoparticles will be large during the entire culture process, which will inhibit the growth of the fungus. After 12 hours, it was taken out and sterilized. After cooling, it was spread evenly in the solid culture medium in step (3) and placed in an environment of 28°C. After 14 days, the flexible conductive mycelial membrane was taken out.

[0055] After drying, the flexible conductive mycelium membrane is immersed in a 5% alcohol-soluble protein / 10% PEG-600 mixed solution for tanning for 12 hours. It is then removed, dried, and hot-pressed at 80℃ and 1MPa for 1 minute to obtain a conductive mycelium pad. 10% WPU is then evenly sprayed onto the material surface and dried to obtain a biodegradable flexible conductive mycelium material, which can degrade leather, such as… Figure 1As shown.

[0056] Example 2

[0057] The concentration of copper nanoparticles in step (1) of Example 1 was adjusted to 1%, 2%, and 4%, while other aspects remained the same as in Example 1, to obtain conductive mycelium material (biodegradable leather).

[0058] The obtained materials were tested, and the test results are shown in Table 1 below:

[0059] Table 1 shows that the material exhibits the best conductivity and the shortest growth cycle (time required for mycelia to fully colonize the substrate) when the copper nanoparticle concentration is 3%. When the copper nanoparticle concentration is less than 3%, the mycelia harvested through deep fermentation are coated with fewer nanoparticles. This is partly due to the low concentration of added particles and partly because it is difficult for particles to adhere to the bottle wall during shaker operation, thus preventing the mycelia from coating with nanoparticles. When the nanoparticle concentration is greater than 3%, the copper nanoparticles cause greater damage to the fungal cell wall, inhibiting mycelial growth.

[0060] Table 1

[0061] Copper nanoparticle concentration / % Resistance value (Ω / cm) Growth cycle / d 1 ≥100 8 2 56.8 8 3 34.6 10 4 ≥100 17

[0062] Example 3

[0063] Adjust the rotation speed in step (2) of Example 1 to 0 r / min, 110 r / min, 120 r / min, and 140 r / min, while keeping the other speeds the same as in Example 1, to obtain conductive mycelium material.

[0064] The obtained materials were tested, and the test results are shown in Table 2 below:

[0065] As can be seen from Table 2, the material exhibits the best electrical conductivity and electrical stability at a rotation speed of 130 r / min.

[0066] When the rotation speed is greater than 0 and less than 130 r / min, the mycelium does not fully absorb nutrients, grows slowly, has a small amount of mycelium, and the nanoparticles are easily deposited at the bottom of the bottle and are not covered by the mycelium. When the rotation speed is greater than 130 r / min, the oxygen content in the culture medium will be too high due to the high rotation speed. Under such conditions, the mycelium grows in a flocculent manner, and is small in size but abundant, making it difficult to cover the nanoparticles.

[0067] When the rotation speed is 0, the fermentation mode of the inoculated conical flask under static culture conditions is changed to shallow fermentation. The mycelium forms a mycelium film on the surface of the culture medium. The mycelium balls in the lower layer of the culture medium grow less due to insufficient oxygen, and the accumulation of nanoparticles at the bottom of the flask will affect the growth of mycelium. As a result, the concentration of nanoparticles coated by the harvested mycelium is low and insufficient to prepare conductive materials.

[0068] Table 2

[0069] Rotational speed (r / min) Resistance value (Ω / cm) Resistance change rate / % 0 Non-conductive —— 110 ≥100 7.6 120 80.8 17.4 130 34.6 7.4 140 30.2 32.7

[0070] Example 4

[0071] The PEG-600 in step (4) of Example 1 was adjusted to glycerol and sorbitol, while the rest remained the same as in Example 1, to obtain conductive mycelium material.

[0072] The obtained materials were tested, and the test results are shown in Table 3 below:

[0073] As can be seen from Table 3, the material exhibits the best mechanical properties when the tanning agent is alcohol-soluble protein / PEG-600.

[0074] Table 3

[0075] Tanning agents Resistance value (Ω / cm) Resistance change rate / % Fracture strength / MPa Gliadin / PEG-600 34.6 7.4 28.18 Glycoprotein / glycerol 32.9 8.2 26.73 Gliadin / Sorbitol 36.2 7.8 27.79

[0076] Example 5

[0077] The WPU in step (4) of Example 1 was adjusted to be paraffin wax, PVC, and acrylic resin, while the rest remained the same as in Example 1, to obtain conductive mycelium material.

[0078] The obtained materials were tested, and the test results are shown in Table 4 below:

[0079] Table 4 shows that paraffin wax and WPU have the best waterproof performance when used as coatings. Acrylic resin and PVC have a greater impact on the tensile strength and feel of the material when used as coatings. Paraffin wax has a significant impact on the conductivity of the material when used as a coating.

[0080] Table 4

[0081] coating Resistance value (Ω / cm) Resistance change rate / % Fracture strength / MPa Contact angle / ° feel Uncoated 32.1 21.6 27.56 76.3 smooth WPU 34.6 7.4 28.18 96.5 smooth PVC 52.6 8.2 21.2 68.4 plastic texture acrylic resin 49.4 9.5 24.6 81.2 Cheap light sensor paraffin ≥100 —— 25.3 98.1 sticky

[0082] Comparative Example 1

[0083] The copper nanoparticles in step (1) of Example 1 were adjusted to graphene carbon nanoparticles, zinc oxide nanoparticles, and iron oxide nanoparticles. The results showed that, since graphene nanoparticles are soluble in water and cannot be coated by mycelia, nano-mycelia composite fermentation broth could not be prepared; zinc oxide and iron oxide nanoparticles would inhibit the growth of fungi, resulting in shorter mycelia and thus preventing the preparation of nano-mycelia composite fermentation broth.

[0084] Comparative Example 2

[0085] Adjust the rotation speed in step (2) of Example 1 to less than 100 r / min, and keep the rest the same as in Example 1. Most of the nanoparticles are deposited at the bottom of the conical flask, and the mycelium grows on the surface of the culture medium. Since the nanoparticles cannot be coated, the nano-mycelium composite fermentation broth cannot be obtained.

[0086] Comparative Example 3

[0087] The oyster mushroom in step (1) of Example 1 was changed to enoki mushroom, shiitake mushroom, or king oyster mushroom, while the rest remained the same as in Example 1, to obtain mycelial material.

[0088] The obtained materials were tested, and the test results are shown in Table 5 below:

[0089] As can be seen from Table 5, enoki mushrooms and king oyster mushrooms have the worst electrical conductivity when used as spawn, while shiitake mushrooms have relatively poor mechanical properties when used as spawn.

[0090] Table 5

[0091] strains Resistance value (Ω / cm) Resistance change rate / % Fracture strength / MPa Oyster mushrooms 34.6 7.4 28.18 Enoki mushrooms 118.4 —— 23.51 King oyster mushroom 133.7 —— 28.42 mushroom 68.4 —— 21.61

[0092] Comparative Example 4

[0093] The viscose fiber in step (4) of Example 1 was changed to polyester fiber, while the rest remained the same as in Example 1, to obtain mycelial material.

[0094] The obtained materials were tested, and the test results are shown in Table 6 below:

[0095] As can be seen from Table 6, the electrical conductivity of the materials is very poor when polyester and cotton fibers are used as the substrate, and the degradation rate is low within the same time period.

[0096] Table 6

[0097] Substrate Resistance value (Ω / cm) Resistance change rate / % Fracture strength / MPa Degradation rate / % adhesive 34.6 7.4 28.18 85 Polyester ≥100 —— 31.4 45 cotton 124.2 —— 30.1 72

[0098] Comparative Example 5

[0099] If the alcohol-soluble protein in step (4) of Example 1 is changed to tannin, flaxseed oil or glutaraldehyde, and the rest is kept the same as in Example 1, the resulting mycelial material will feel hard or greasy and will not meet the requirements for consumption.

[0100] Currently, there are still significant differences between this invention and other nano-conductive materials based on microbial biofilms. Firstly, in terms of material selection, fungi have shorter growth cycles than bacteria, and their hyphae are rich in proteins and glucans, which can, to some extent, mimic the texture of genuine leather. Bacterial biofilms, on the other hand, are cellulose materials. This invention uses copper nanoparticles, which have much lower resistance than the carbon nanoparticles used in existing patents. The resulting material exhibits better conductivity, extending its applications beyond smart textiles to include low-resistance materials such as breadboards made from traditional organic materials.

[0101] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a mycelial nanocomposite fermentation broth, characterized in that, The process includes the following steps: adding 2-3% copper nanoparticles by mass to a liquid culture medium, stirring evenly, inoculating with oyster mushroom spawn, culturing for 10 days at a temperature of 20-28℃ and a rotation speed of 110-140 r / min to obtain mycelial nanocomposite fermentation broth.

2. A mycelium nanocomposite fermentation broth prepared using the method described in claim 1.

3. A method for preparing a flexible conductive mycelium material, characterized in that, The process includes the following steps: uniformly spreading the mycelium nanocomposite fermentation broth of claim 2 onto a solid culture medium, covering it with a substrate, and culturing it at 20-28℃ for 10-14 days. The substrate with mycelium growth is then harvested to obtain a flexible conductive mycelium membrane, wherein the substrate is viscose fiber.

4. The method for preparing the flexible conductive mycelium material according to claim 3, characterized in that, The method further includes post-processing the flexible conductive mycelium membrane to obtain a conductive mycelium pad, the post-processing including the following steps: tanning and hot pressing.

5. A flexible conductive mycelium material, characterized in that, Flexible conductive mycelium membrane, conductive mycelium pad, or biodegradable leather prepared by the method described in any one of claims 3 to 4.

6. The preparation method of the mycelium nanocomposite fermentation broth according to claim 1, the mycelium nanocomposite fermentation broth according to claim 2, the preparation method of the flexible conductive mycelium material according to any one of claims 3 to 4, or the application of the flexible conductive mycelium material according to claim 5 in the field of smart textiles.

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