阅读说明：本技术 源自细菌的纳米纤维素纺织物材料 (Bacterial-derived nanocellulose textile materials ) 是由 W·查贾 E·施瓦茨 D·英塞尔曼 于 2020-04-09 设计创作，主要内容包括：本公开涉及一种浸油细菌纳米纤维素(BNC)材料,该浸油BNC材料包括：多孔主体,该多孔主体包括限定多个互连孔的三维细菌纳米纤维素纤维网络；以及浸渍在多个孔内的油。本公开另外描述了一种制备浸油BNC材料的方法,该方法包括将细菌发酵以形成细菌纳米纤维素纤维的多孔主体,该多孔主体具有限定多个互连孔的三维网络；机械按压多孔主体；使多孔主体脱水；以及用包含油的浸油流体浸渍多孔主体,以便将油截留在多孔主体的孔中,从而形成浸油BNC材料。(The present disclosure relates to an oil-impregnated Bacterial Nanocellulose (BNC) material, the oil-impregnated BNC material comprising: a porous body comprising a three-dimensional bacterial nanocellulose fiber network defining a plurality of interconnected pores; and oil impregnated in the plurality of pores. The present disclosure additionally describes a method of making an oil-impregnated BNC material, the method comprising fermenting bacteria to form a porous body of bacterial nanocellulose fibers, the porous body having a three-dimensional network defining a plurality of interconnected pores; mechanically pressing the porous body; dehydrating the porous body; and impregnating the porous body with an oil-impregnated fluid comprising oil so as to entrap the oil in the pores of the porous body, thereby forming an oil-impregnated BNC material.)

1. An oil-impregnated Bacterial Nanocellulose (BNC) material, said oil-impregnated BNC material comprising:

a porous body comprising a three-dimensional bacterial nanocellulose fiber network defining a plurality of interconnected pores; and the number of the first and second groups,

an oil impregnated within the plurality of pores.

2. The oil-impregnated BNC material of claim 1, wherein said porous body comprises never-dried bacterial nanocellulose.

3. The oil-impregnated BNC material of any of claims 1 or 2, wherein said porous body comprises pure bacterial nanocellulose.

4. The oil-impregnated BNC material of any of the preceding claims, wherein said porous body is fully dehydrated.

5. The oiled BNC material according to any of the preceding claims, wherein said nanocellulose fibers have a crystallinity of at least 65% as measured by XRD.

6. The oil-impregnated BNC material of any one of the preceding claims, wherein said porous body has a thickness of about 15mg/cm²To about 40mg/cm²Cellulose content within the range.

7. The oil-impregnated BNC material of any of the preceding claims, wherein said oil-impregnated BNC material has a thickness in the range of about 1mm to about 10 mm.

8. The oil-impregnated BNC material of any of the preceding claims, wherein said oil comprises at least 70 weight% of the total weight of said oil-impregnated BNC material.

9. The oil-impregnated BNC material of any of the preceding claims, wherein said oil comprises about 70% to about 95% by weight of the total weight of said oil-impregnated BNC material.

10. The oil-impregnated BNC material of any one of the preceding claims, wherein said oil-impregnated BNC material has a thickness of about 275N/cm²To about 2100N/cm²Tensile strength in the range.

11. The oil-impregnated BNC material of any of the preceding claims, wherein said oil-impregnated BNC material has a tensile load to failure value in the range of about 50N to about 150N.

12. The oil-impregnated BNC material of any of the preceding claims, wherein said oil-impregnated BNC material has a suture pullout failure load in the range of about 5N to about 40N.

13. The oil-impregnated BNC material of any of the preceding claims, further comprising one or more dyes or sealants.

14. A textile material, comprising:

oil-impregnated Bacterial Nanocellulose (BNC) material, the BNC material comprising:

a porous body comprising a three-dimensional bacterial nanocellulose fiber network defining a plurality of interconnected pores; and the number of the first and second groups,

an oil impregnated within the plurality of pores.

15. The textile material of claim 14, wherein the textile material comprises a single piece of oil-impregnated BNC material.

16. The textile material of claim 14, wherein the textile material comprises a plurality of pieces of oil-impregnated BNC material.

17. The textile material of claim 14, wherein the textile material comprises a plurality of oil-impregnated BNC materials in the form of ribbons, strands, or fibers, or combinations thereof, and wherein each of the ribbons, strands, or fibers, or combinations thereof, are interconnected or interwoven to another of the ribbons, strands, fibers, or combinations thereof.

18. A method of preparing oil-impregnated Bacterial Nanocellulose (BNC) material, said method comprising:

fermenting bacteria to form a porous body of bacterial nanocellulose fibers, the porous body having a three-dimensional network defining a plurality of interconnected pores;

mechanically pressing the porous body;

dehydrating the porous body; and the number of the first and second groups,

impregnating the porous body with an oil-impregnated fluid comprising an oil so as to entrap the oil in the pores of the porous body and form an oil-impregnated BNC material.

19. The method of claim 18, wherein the fermenting step comprises fermenting at a temperature in the range of about 30 ℃ ± 2 ℃.

20. The method of claim 18 or 19, wherein the fermenting step is performed at a pH range of about 4.1 to about 4.6.

21. The method of any one of claims 18 to 20, wherein the fermenting step comprises fermenting for a period of time ranging from about 5 days to about 30 days.

22. The method of any one of claims 18 to 21, further comprising purifying the porous body after fermentation.

23. The method of any one of claims 18 to 22, wherein dehydrating the porous body comprises using a solvent comprising one or more water-miscible organic solvents.

24. The method of claim 23, wherein the solvent is heated to boiling.

25. The method according to any one of claims 23 or 24, wherein the weight to volume ratio of the nanocellulose fibers to the solvent in mg/ml is in the range of about 15:1 to about 8: 1.

26. The method of any one of claims 18 to 25, wherein the immersion fluid is heated during the immersing step.

27. The method of any one of claims 18 to 26, wherein the weight to volume ratio of the nanocellulose fibers to the immersion fluid in mg/ml is in the range of about 15:1 to about 1: 1.

28. The method of any one of claims 18 to 27, wherein the oil-impregnated fluid comprises an emulsifier.

29. The method of claim 28, wherein the emulsifier is a water-miscible organic solvent.

30. The method of claim 28 or 29, wherein the oil-impregnated fluid has an oil to emulsifier volume ratio in the range of about 90:10 to about 10: 90.

31. The method of any one of claims 18-30, further comprising drying said oil-impregnated BNC material.

Technical Field

The present disclosure relates to oil impregnated bacterial nanocellulose materials for use as fabrics and textiles and methods for making the same.

Background

The leather industry is an industry that produces values in excess of $ 1000 billion that produces unique textile materials with desirable physical and handling characteristics (when compared to other textile materials) by mechanically and chemically treating animal hides and skins. The leather industry has developed at a rate that exceeds the demand for leather products over the meat industry. The demand for animal meat rises at a rate of about 3%, which closely reflects the growth rate of the population, while the demand for leather products increases at a rate of 4% to 7%. Due to this increase in demand, suppliers of leather materials have to look for other livestock to meet the increasing demand for fur materials.

Tanning of leather requires the consumption of large amounts of water, exposes workers to chemicals, and results in soil and water contamination, and the generation of large amounts of organic waste. For each ton (about 1,000kg) of hide material processed, 200kg of finished product is expected to result. The remaining material is organic waste that is currently of no commercial value.

Although synthetic leather materials provide an alternative with less environmental and livestock impact, synthetic leather has poor handling characteristics, durability, and aesthetics, which make it unacceptable. Although synthetic leather provides some properties that are superior to real leather textiles, its plastic-like texture and a consistent look are perceived as being inexpensive and therefore less popular by the fashion industry, which prefers the random properties and texture provided by animal hides, including the smell and feel of the dermis.

Another complaint of the synthetic leather industry is that its processing is not environmentally closed. Although the leather tanning industry has a serious impact on the environment, it is widely accepted that leather products are susceptible to decomposition over time and to biodegradation, whereas synthetic leather products are not biodegradable and may release toxins, dioxins and phthalates into the environment many years after their end of service life. Many raw materials used to produce synthetic leather also have negative environmental effects when mined or preprocessed, such as polyurethanes, solvents, plasticizers, and polyvinyl chloride.

Furthermore, not only is synthetic leather inferior in durability to leather, but its abrasive properties are also undesirable when compared to natural materials. The dermal material may actually become more desirable as it develops a worn-out appearance and a weakened texture as it ages. Synthetic leathers begin to delaminate and peel when worn, which is an undesirable aesthetic feature.

The current options for the use by consumers of leather and artificial leather products represent complex tradeoffs that require a compromise between value and quality. The market is open for natural materials that do not require compromises between ethic, environmental impact and product performance.

Disclosure of Invention

It would be beneficial to use materials for textile and textile applications that reduce the environmental impact in raw material harvesting, as well as the negative impact of both production and degradation, while maintaining aesthetic qualities that mimic the desirable attributes of natural leather.

Cellulose from various sources has proven to be a versatile biomaterial for a variety of applications. Cellulose synthesized by almost every type of plant and a selected number of microorganisms (such as certain yeasts and bacteria) is an all natural, renewable, biocompatible, and degradable polymer for use in a wide variety of applications including paper products, food products, electronic devices, pharmaceutical coatings, and bandages.

Cellulose formed by bacteria, i.e. Bacterial Nanocellulose (BNC), represents a naturally occurring material with high strength, conformability and handling properties. The cellulose derived from the bacteria forms a porous three-dimensional network of cellulose nanofibers that can, under certain conditions, mimic some of the physical and mechanical properties of natural hides (e.g., leather), such as grain texture and flexibility.

Accordingly, the present disclosure relates to an oil-impregnated Bacterial Nanocellulose (BNC) material, the oil-impregnated BNC material comprising: a porous body having a three-dimensional bacterial nanocellulose fiber network, wherein the nanocellulose fiber network defines a plurality of interconnected pores; and oil impregnated in the plurality of pores.

In certain embodiments, the oil-impregnated BNC material comprises a porous body of never-dried bacterial nanocellulose. In certain embodiments, the porous body is a pure BNC material. In certain additional embodiments, the porous body is fully dehydrated.

According to certain embodiments, the nanocellulose fibers have a crystallinity of at least 65% as measured by x-ray diffraction (XRD). In certain embodiments, the porous body has a porosity of at about 20mg/cm²To about 30mg/cm²Cellulose content within the range. In other embodiments, the oil-impregnated BNC material has a thickness in the range of about 1mm to about 10 mm.

According to some embodiments, the oil comprises at least 70 wt% of the total weight of the oiled BNC material. In other embodiments, the oil comprises from about 70 wt% to about 95 wt% of the total weight of the oiled BNC material.

According to certain embodiments, the oil-impregnated BNC material has a particle size of at about 275N/cm²To about 2100N/cm²Tensile strength in the range. According to further embodiments, the oil-impregnated BNC material has a tensile load to failure value in the range of about 50N to about 150N. According to further embodiments, the oil-impregnated BNC material has a suture pullout failure load in the range of about 5N to about 40N.

According to certain embodiments, the oil-impregnated BNC material further comprises one or more dyes or sealants.

According to the present disclosure, a textile material or fabric material is described comprising oil impregnated BNCs as previously detailed.

In certain embodiments, the textile or fabric material comprises a single piece of oil-impregnated BNCs. In certain further embodiments, the textile material comprises a plurality of pieces of oil-impregnated BNCs; in other words, a multilayered oil-impregnated BNC textile material. In certain additional embodiments, the sheet may comprise a plurality of oil-impregnated BNC strips, strands or fibers or combinations thereof, woven or knitted or braided, or other known interlacing or interconnection methods generally known to those of skill in the art. In an alternative embodiment, the oil-impregnated sheet is a continuous, uniform monolithic structure.

The present disclosure further describes a method of preparing an oil-impregnated Bacterial Nanocellulose (BNC) material, the method comprising the steps of:

fermenting bacteria to form a porous body of bacterial nanocellulose fibers, the porous body having a three-dimensional network defining a plurality of interconnected pores;

mechanically pressing the porous body;

dehydrating the porous body;

impregnating the porous body with an oil-impregnated fluid comprising oil so as to entrap the oil in the pores of the porous body, thereby forming an oil-impregnated BNC material.

According to certain embodiments, the fermenting step comprises fermenting at a temperature in the range of about 30 ℃ +/-2 ℃. According to additional embodiments, the fermenting step comprises fermenting for a period of time ranging from about 5 days to about 30 days. In certain embodiments, the fermentation is conducted at a pH in the range of about 4.1 to about 4.6. In certain embodiments, the method may comprise purifying the porous body after fermentation.

According to certain embodiments, dehydrating the porous body comprises using a solvent comprising one or more water-miscible organic solvents. In certain embodiments, the solvent is heated to boiling. In further embodiments, the weight to volume ratio of nanocellulose fibers to solvent in mg/ml may be in the range of about 15:1 to about 8: 1.

According to certain embodiments, the immersion fluid is heated during the immersion step. According to further embodiments, the weight to volume ratio of the nanocellulose fibers to the oil immersion fluid in mg/ml ranges from about 1:1 to about 1: 10.

According to certain embodiments, the oil immersion fluid comprises an emulsifier. In further embodiments, the emulsifier comprises a water-miscible organic solvent. According to further embodiments, the oil-impregnated fluid has an oil to emulsifier volume ratio in the range of about 90:10 to about 10: 90.

According to further embodiments, the method of the present invention may further comprise the step of drying the oil-impregnated BNC material.

Drawings

FIGS. 1A to 1C are photographic images (numbers 1 to 10, FIG. 1A; numbers 11 to 20, FIG. 1B; and numbers 21 to 30, FIG. 1C) of samples used in the tensile strength test as described below; and the number of the first and second electrodes,

fig. 2A to 2C are photographic images (No. 1 to 10, fig. 2A; No. 11 to 20, fig. 2B; and No. 21 to 30, fig. 2C) of samples used in the suture thread pullout test as described below.

Detailed Description

In this document, unless otherwise indicated, the terms "a" or "an" are used to include one or more than one, and the term "or" is used to refer to a non-exclusive "or". Also, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. In addition, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as if individually incorporated by reference. In the event of inconsistent usages between this document and those documents incorporated by reference, the usage in the incorporated references should be considered supplementary to that of this document; for incongruous inconsistencies, the usage in this document controls. When a range of values is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. All ranges are inclusive and combinable. In addition, reference to values stated in ranges includes each and every value within that range. It is also to be understood that certain features of the invention, which are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination.

In accordance with the present disclosure, oil-impregnated Bacterial Nanocellulose (BNC) materials and methods of forming the same are described. One type of bacterial cellulose particularly suitable for use in the present disclosure is synthesized by the bacteria Acetobacter xylinum (reclassified as Gluconacetobacter and/or colatobacter). Cellulose produced by this bacterium is characterized by a highly crystalline three-dimensional network consisting of pure cellulose nanofibers (i.e., cellulose fibers having cross-sectional dimensions in the nanometer range) that are stabilized by hydrogen bonds between and within. Such fibrous networks exhibit high strength, flexibility and large nanofiber surface area. These cellulose nanofibers define an interconnected heterogeneous pore network with high void space (i.e., porosity) that allows for the entrapment and retention of the secondary filler material. These properties make this material ideally suited as a substitute for natural leather products formed from a three-dimensional network of protein collagen. According to certain embodiments, the bacterial nanocellulose is "pure bacterial nanocellulose" in that it is cellulose synthesized solely from bacterial sources. In other words, there are no other types of microorganisms, such as yeasts, that contribute to the cellulose synthesis process or to the overall structure and appearance of the final product. In certain embodiments, the pure bacterial nanocellulose is synthesized solely from an acetobacter source (e.g., gluconacetobacter spp.).

According to certain embodiments, whenThe bacterial nanocellulose fibers have a crystallinity of at least 65%, preferably at least 80%, up to and including at least 95%, as measured by XRD. According to further embodiments, the porous body has a pore volume (i.e., porosity) of at least 75%, at least 80%, or at least 90%. According to additional embodiments, the porous body has a porosity of at about 15mg/cm²To about 40mg/cm²Ranges (such as, for example, about 20 mg/cm)²To about 30mg/cm²Range) of cellulose content. The cellulose content as measured herein will be further described below.

According to the present disclosure, an oil-impregnated BNC material is described comprising a porous body of bacterial nanocellulose fibers and an oil component, wherein the oil component is entrapped within the pore network of the porous body. As used herein, "oil" includes mineral oils and waxes, as well as natural oils, fats and waxes of vegetable and animal origin, and synthetic derivatives thereof. Oils and waxes known to be useful in the fatliquoring process of animal hides are considered suitable for use in this disclosure. The oil component may include pure oil compositions, as well as compositions in which a majority by weight includes oil, or a combination or mixture of oils. In certain embodiments, the oil component may include a minor portion of an emulsifier to aid in penetration of the oil into the porous network of the porous body. Suitable emulsifiers may include, for example, water-miscible organic solvents, such as will be described in more detail below.

Mineral oils and waxes:

mineral oils and waxes are by-products derived from crude oil and typically comprise a mixture of many alkanes and cycloalkanes separated by distillation. Mineral oils are generally immiscible with water and can provide some degree of water-repellency. They are available in a variety of viscosities and generally have a lighter density than water. Mineral waxes may include, for example, paraffin wax, montan wax, and ozokerite wax. This list is not intended to be exclusive.

Natural oils, fats and waxes:

generally, most oils and fats in animals, fish and plants are fatty acid glycerides. These fatty acids are mainly water insoluble and range from very mobile oily liquids to greasy pastes and hard waxy materials.

Fatty acids can be classified as saturated or unsaturated. Saturated fatty acids are generally more viscous or hard, do not darken upon exposure to sunlight, and generally resist oxidation upon exposure to air and moisture. Unsaturated fatty acids are more mobile (less viscous), darken under the action of sunlight, and can become sticky or tacky when oxidized by air.

Most naturally occurring fatty acids have an even number of C atoms. Shorter chain saturated fatty acids (such as C-6, C-8 and C-10) are present in coconut and palm oils, milk fat and other softer oils. C-12 (i.e., lauric acid) is present in sperm oil. C-16 and C-18 saturated fatty acids are common to animal fats and many vegetable oils. The C-24 and C-25 classes are present in waxes, such as carnauba wax and beeswax.

Unsaturated fatty acids with more than 1 double bond can be classified as drying oils, such as linseed oil or cottonseed oil. Some contain-OH groups such as palmitic acid (C-16 hydroxyl, saturated) present in lanolin (or anhydrous lanolin) and ricinoleic acid (C-18 hydroxyl, unsaturated) present in castor oil.

Exemplary animal oils and fats may include: cod liver oil, menhaden oil, salmon oil, sardine oil, japanese fish oil, menhaden oil, whale oil (e.g., sperm oil), beef tallow, mutton tallow, lanolin and anhydrous lanolin, stearin, stearic acid, milk fat (or milk fat), and neatsfoot oil. Exemplary vegetable oils may include: coconut oil, cottonseed oil, olive oil, palm kernel oil, castor oil, linseed oil, and soybean oil. Exemplary natural waxes may include carnauba wax, candelilla wax, and beeswax.

According to further embodiments, the porous body is fully dehydrated. As used herein, "fully dehydrated" means that the porous body contains less than 5% by weight free water molecules, and in certain embodiments, may contain less than 1% by weight free water molecules. It is understood that some degree of hydrogen bonding occurs in and between the nanocellulose polymer chains of the porous body, such that a percentage of water molecules may be bound via hydrogen bonding in the polymer network, and thus are not "free" (as that term is understood in the art).

According to certain embodiments of the present disclosure, the porous body is "never dried" from synthesis to its final state. As used herein, "never dried" when referring to a porous body means that at least 80%, preferably 90% and most preferably 95% or more of the total volume of void space defined by the porous network of bacterial nanocellulose fibers is continuously occupied by liquid from fermentation through to the final oil-impregnated BNC material embodiments described herein. In certain embodiments in which the term is specified, "never dried" means that 95% or more of the total volume of void space in the porous body or the oil-impregnated BNC material is continuously occupied by liquid from the beginning of fermentation.

It should also be noted that the terms "dehydrated" and "dried" as used herein are not intended to encompass the same scope. Dehydration involves a process of removing water, which in some cases may include drying. Drying involves a process in which liquid (of any type) is removed from the pores of a porous body and the pore spaces are filled with a gas or vapor (e.g., air or CO)₂) The process of occupation.

The beneficial effects of a porous body of bacterial nanocellulose "never dried" may be relevant for potential use in the textile industry. Although cellulose-based materials have been considered for textile manufacturing, a significant disadvantage is that the cellulosic sheet may lose some of its preferred qualities when dried. Cellulose in its naturally hydrated (i.e., "wet") state exhibits many of the characteristics of textile materials. However, when wet cellulose is exposed to the environment, water occupying the pore spaces defined by the network of fibers begins to evaporate. This results in the breaking of crosslinks from both intra-chain crosslinks in the polysaccharide chains and inter-chain crosslinks provided by hydrogen bonding from water molecules in the porous network. When this loss of cross-linking occurs, the pores previously occupied by water collapse, which reduces the available pore space and pore size, and hinders access to the remaining pore voids. The result is a densely collapsed cellulose product with undesirable handling characteristics, and a reduced ability to manipulate the remaining reduced pore space.

Thus, unlike animal hides which can be conditioned after drying, the drying of the porous body consisting of bacterial nanocellulose fibers is irreversible, to the extent that the porous structure collapses, causing thinning and densification of the material, which hinders any subsequent attempt to impregnate the material with the conditioner. The bacterial nanocellulose porous bodies, which remain in an never-dried state, can be stabilized over a wide range of environmental conditions when subsequently impregnated with oil, and have handling and mechanical properties very similar to animal leather. Impregnation of oils, fats and waxes into a porous body of bacterial nanocellulose cannot be effectively achieved using traditional fatliquoring techniques for animal hides. According to embodiments of the present disclosure, oiling a porous body of never-dried bacterial nanocellulose can produce a completely natural and environmentally degradable product with leather-like properties, durability and appearance, with the additional benefit of eliminating the use of aggressive chemical treatments, animal slaughter and environmental pollution.

According to embodiments of the present disclosure, the oil-impregnated BNC material may have a thickness in the range of about 1mm to about 20mm, such as in the range of about 1mm to about 10mm, such as in the range of about 1mm to about 5 mm. According to further embodiments, the oil comprises at least 70 wt%, up to and including at least about 95%, such as in the range of about 75% to about 95%, about 75% to about 90%, about 80% to about 95%, about 80% to about 90%, about 80% to 85%, about 85% to about 90%, and any subcombination of the ranges disclosed herein, of the total weight of the oil-impregnated BNC material.

According to an embodiment of the present disclosure, the oil-impregnated BNC material has a BNC density of at about 275N/cm²To about 2100N/cm²Tensile strength in the range. According to further embodiments, the oil-impregnated BNC material has a tensile load to failure value of about 50N to about 150N. According to further embodiments, the oil-impregnated BNC material has a suture pull-out failure load of about 5N to about 40N.

According to the present disclosure, a textile material or fabric material is described comprising oil impregnated BNCs as previously detailed. In certain embodiments, the textile or fabric material comprises a single piece of oil-impregnated BNCs. In certain further embodiments, the textile material comprises a plurality of pieces of oil-impregnated BNCs; in other words, a multilayered oil-impregnated BNC textile material. In certain additional embodiments, the sheet may comprise a plurality of oil-impregnated BNC strips, strands or fibers or combinations thereof, woven or knitted or braided, or other known interlacing or interconnection methods generally known to those of skill in the art. In an alternative embodiment, the oil-impregnated sheet is a continuous, uniform monolithic structure.

According to the present disclosure, a method of preparing an oil-impregnated BNC material comprises:

fermenting bacteria to form a porous body of bacterial nanocellulose fibers, the porous body having a three-dimensional network defining a plurality of interconnected pores;

mechanically pressing the porous body;

dehydrating the porous body;

impregnating the porous body with an oil-impregnated fluid comprising oil so as to entrap the oil in the pores of the porous body, thereby forming an oil-impregnated BNC material; and the number of the first and second groups,

the oil-impregnated BNC material was dried.

Growth of cellulose pellicle

In preparing the oil-impregnated BNC material of the present disclosure, bacterial cells, in this case acetobacter xylinum, are cultured/incubated in a bioreactor containing a liquid nutrient medium. Changes in the liquid nutrient medium can affect the resulting quality and quantity of cellulose produced by the cultured bacteria. The medium used for cellulose growth typically comprises a sugar source and a nitrogen source, as well as additional nutrient additives. Suitable sugar sources may include both monosaccharides such as glucose, fructose and galactose as well as disaccharides such as sucrose and maltose, and any combination thereof. Suitable nitrogen sources may include ammonium salts and amino acids. Corn steep liquor is a preferred medium component that provides both a nitrogen source and additional desirable additives including vitamins and minerals. Suitable nutritional additives may additionally include, for example, sodium phosphate, magnesium sulfate, citric acid, and acetic acid.

Increasing the total sugar content of the medium can result in higher amounts of cellulose being produced. Varying the type of sugar added, or in the case of multiple sugars, their respective ratios, can also result in variations in the yield of cellulose obtained. For example, according to one embodiment, a blend of sugar sources comprising glucose and fructose may have a higher ratio of glucose to fructose, which may result in a lower strength of the cellulosic material. Alternatively, according to another embodiment, a higher ratio of fructose to glucose may result in the cellulosic material exhibiting higher strength. In another embodiment, increasing the amount of nitrogen source can increase the amount of cellulose produced.

In certain embodiments, the medium is maintained at an acidic pH, e.g., about 4.0 to 4.5. In some cases, increasing the medium pH to greater than 5.0 or higher may result in reduced bacterial cell growth. In certain embodiments, the temperature of the medium is maintained above room temperature, for example in the range of about greater than 25 ℃ to about 35 ℃. In a preferred embodiment, the medium is in the range of about 30 ℃. In some cases, adjustment of the incubation temperature can affect the growth of the cellulosic material. According to one embodiment, increasing the incubation temperature may increase the amount of cellulose produced. Alternatively, lowering the incubation temperature may reduce the amount of cellulosic material produced. According to one embodiment, the bacterial cells are cultured for about 1 to 4 days before starting the fermentation process.

Once a suitable amount of bacteria has been propagated, the fermentation process begins. The medium is typically poured into the bioreactor tray to start the fermentation process. According to certain embodiments, a higher amount of bacterial cells in the culture medium results in a higher amount of cellulose produced. According to certain embodiments, the fill weight of the medium is in the range of about 1.5L to about 15L, for example in the range of about 4L to about 8L or about 5L to about 10L. The fermentation process is typically carried out in a shallow bioreactor with a cover to reduce evaporation. Such systems can provide oxygen-limiting conditions that help ensure the formation of a uniform cellulose pellicle. The size of the bioreactor may vary depending on the desired shape, size, thickness and yield of the synthesized cellulose.

In a preferred embodiment, the fermentation process is conducted at about 30 ℃ ± 2 ℃ in an acidic environment having a pH of about 4.1 to about 4.6, and under static conditions for about 5 days to 30 days.

In certain embodiments, the fermentation step may be performed at a temperature in the range of about 20 ℃ to about 40 ℃, such as, for example, 20 ℃ to 30 ℃, 30 ℃ to 40 ℃, 25 ℃ to 35 ℃, 28 ℃ to 32 ℃, 28 ℃ to 30 ℃, and 30 ℃ to 32 ℃. In a preferred embodiment, the fermentation is carried out in the range from 28 ℃ to 32 ℃ and more particularly preferably at about 30 ℃.

The fermentation may be carried out at an acidic pH, for example in the range of from about 3.3 to about 7.0, such as for example in the range of from about 3.5 to about 6.0 or 4.0 to about 5.0. In a preferred embodiment, the fermentation is carried out at a pH in the range of about 4.1 to about 4.6.

The time period of fermentation may vary. According to embodiments of the present disclosure, fermentation may be carried out for about 5 days to about 60 days, depending on the desired growth of the cellulose pellicle. For example, fermentation may be carried out for about 5 days to about 10 days, about 5 days to about 30 days, about 10 days to about 50 days, about 10 days to about 25 days, about 20 days to about 60 days, about 20 days to about 50 days, about 20 days to about 30 days, and combinations falling within the ranges indicated herein. According to certain embodiments, a longer fermentation results in a higher amount of cellulose produced, while, alternatively, a shorter fermentation time results in a lower amount of cellulose produced. Depending on the desired thickness and/or cellulose yield, the fermentation may be stopped, at which point the cellulose pellicle (i.e., the porous body of cellulose) may be harvested from the fermentation tray bioreactor.

Cellulose purification

After fermentation and harvesting are completed, according to certain embodiments, the porous body of nanocellulose may be subjected to a purification process, wherein the porous body is rendered free of microorganisms; that is, the porous body is chemically treated to remove bacterial by-products and residual culture medium. Any living organisms and pyrogens (endotoxins) produced during fermentation are removed from the porous body using a caustic solution, preferably sodium hydroxide, preferably at a concentration in the range of about 0.1M to 4M. Treatment times of about 1 hour to about 12 hours in sodium hydroxide have been investigated in conjunction with temperature changes of about 30 ℃ to about 100 ℃ to optimize the process. The preferred or recommended treatment temperature is 70 ℃ or close to 70 ℃. The treated porous body may be rinsed with filtered water to reduce microbial contamination (bioburden) and to achieve a neutral pH. In addition, the porous body may be treated with a dilute acetic acid solution to neutralize the remaining sodium hydroxide.

According to further embodiments of the present disclosure, after harvesting, the porous body may be subjected to one or more mechanical presses (before or after purification (where purification is utilized)) to remove excess water, reduce the overall thickness, and increase the cellulose density of the porous body. If desired, according to certain embodiments, the porous body may be reprocessed for about 1 to 30 days by thermal modification via freezing and dewatering at a temperature in the range of about-5 to-80 ℃, which may further reduce the thickness and increase the cellulose density.

Solvent dehydration of porous bodies

According to further embodiments of the present disclosure, after harvesting the cellulose pellicle, most commonly after initial mechanical pressing of the porous body to physically remove a substantial amount of water and compress the thickness, the porous body may be treated with a water-miscible organic solvent for one up to several cycles to further dehydrate the porous body. If desired, the porous body may be subjected to further mechanical pressing after completion of the solvent exchange dehydration step.

Exemplary water-miscible organic solvents may include, for example, acetaldehyde, acetic acid, acetone, acetonitrile, 1, 2-butanediol, 1, 3-butanediol, 1, 4-butanediol, 2-butoxyethanol, butyric acid, diethanolamine, diethylenetriamine, dimethylformamide, dimethoxyethane, dimethylsulfoxide, 1, 4-dioxane, ethanol, ethylamine, ethylene glycol, formic acid, furancarbinol, glycerol, methanol, methyldiethanolamine, methylisonitrile, N-methyl-2-pyrrolidone, 1-propanol, 1, 3-propanediol, 1, 5-pentanediol, 2-propanol, propionic acid, propylene glycol, pyridine, tetrahydrofuran, and triethylene glycol. A preferred list of solvents includes methanol, ethanol, propanol, isopropanol, acetone, and mixtures thereof.

According to certain embodiments, the porous body is immersed in a solvent. According to further embodiments, the porous body may be subjected to one or more solvent exchanges during the treatment to increase dehydration of the porous body. For example, during solvent dehydration, the porous body may be immersed in one, two, three, four, five, up to about 10 solvent exchanges. According to certain embodiments, the solvent may be heated to substantially near or at its boiling point during the solvent dehydration process. In a preferred embodiment, the solvent is in a boiling state during the entire dehydration process. According to further embodiments, the weight to volume ratio of cellulose nanofibers to solvent (mg/mL) may be in the range of 15:1 or less, 12:1 or less, 10:1 or less, or 8:1 or less. In further embodiments, the solvent is mechanically agitated during the process, for example with a magnetic stirring device or other known methods. As previously described, after the solvent exchange dehydration process is completed, the porous body may again be subjected to one or more mechanical presses to remove excess solvent or to achieve a desired thickness.

Supercritical carbon dioxide drying

As an alternative to or in combination with the above solvent dehydration step, the porous body may be further dehydrated by supercritical point drying using supercritical carbon dioxide. During critical point drying, a wet porous body (with water or solvent or both entrapped within the pores) is loaded onto a holder, sandwiched between stainless steel mesh plates, and then soaked under pressure in a chamber containing supercritical carbon dioxide. The holder is designed to allow CO₂Circulating through the porous network while the mesh sheet stabilizes the porous body against deformation during the drying process. Once all the solvent (or water) has been exchanged (in the range of about 1 to 6 hours in most typical cases), the chamber is filled with a solution of waterThe temperature is raised above the critical temperature of carbon dioxide so that CO is present₂Forming a supercritical fluid/gas. Due to the fact that there is no surface tension during this transition, the resulting product is a dehydrated and dried porous body, which retains its shape, thickness and 3D nanostructure. The resulting porous body may be referred to as "critically dried" in accordance with the present disclosure.

Oil immersion method

According to the present disclosure, after dewatering the porous body via solvent drying or supercritical drying, or both, the porous body may be subjected to one or more oil-soaking steps to allow the oil component to permeate the porous body and be trapped within the network of pores so as to form an oil-soaked BNC material. Typically, the porous body is completely submerged in a container containing an immersion fluid containing oil. In embodiments where the porous body is submerged in the immersion fluid, the weight to volume ratio (mg/ml) of the nanocellulose fibers to the immersion fluid is less than about 15:1 to about 1:1, such as, for example, 12:1, 10:1, 8:1, 5:1, 4:1, 3:1, 2:1, and combinations and subranges of each of the foregoing ratios. Alternatively, the oil-impregnated fluid may be applied and pressed into the porous body, such as, for example, by using a roller, brush, or pad.

According to certain embodiments, the immersion fluid comprises only an oil component. Alternatively, the immersion fluid may contain an oil component mixed with an emulsifier to facilitate impregnation of the oil component into the porous body. In certain embodiments, the oiling fluid with emulsifier and oil can increase the total amount of oil trapped in the final oiled BNC material. Suitable emulsifiers may include, for example, the previously disclosed water-miscible organic solvents suitable for use in the solvent dehydration process. According to certain embodiments, the oil-impregnated fluid may be prepared to have an oil to emulsifier volume ratio within the range of about 90:10 to about 10:90 and any subrange therein (e.g., 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, and 20: 80). In certain embodiments, a higher oil to emulsifier ratio can result in a higher concentration of trapped oil in the final oil-impregnated BNC material. According to further embodiments, the immersion fluid may be heated during the immersion process. One benefit of heating the immersion fluid is to ensure that any heavier oil components that have a melting point above ambient temperature can be melted, or at least have a reduced viscosity to aid in the formation of a suitable emulsion. According to one embodiment, the immersion fluid is heated to boiling. According to yet another embodiment, the immersion fluid is constantly stirred or otherwise mixed during the immersion process. Agitation is useful for ensuring homogeneity within the immersion fluid, such as, for example, where one or more oils are present in the oil component, or where the oil component is mixed with an emulsifier. Agitation may further facilitate penetration of the immersion fluid into the porous network of the porous body.

Post-dip treatment

According to further embodiments of the present disclosure, the oil-impregnated BNC material may be subjected to further treatment. For example, the oiled BNC material can be dried to remove any residual water or solvent that remains within the pore network. In certain embodiments, drying may be performed in a hot air oven, and may also include drum drying. The oiled BNCs can be further treated to impart aesthetic qualities, such as dyeing and/or surface treatments to alter the texture of the surface or to add designs or patterns to the surface. Alternatively, the oiled BNC material can be mechanically pressed to achieve the final desired thickness or weight, or any excess oil removed from the final BNC material. According to further embodiments, the oil-impregnated BNC material can be subjected to a sealing or finishing step that helps to keep the oil within the pore network.

Examples

Cellulose preparation

The gluconacetobacter (foal bacillus) strains were cultured in sucrose and corn steep liquor based medium (including an autoclave step) and 7.2L (4.2L medium +3L species) were poured into a fixed reactor tray for fermentation. The fermentation was continued at a temperature of about 31 ℃ and a pH in the range of 4.1 to 4.6 for 26 days. At harvest, the pellicle had an average thickness of about 5cm and weighed 5.605 kg. The porous body (i.e., the pellicle) formed at the surface has the aesthetic and tactile properties observed in natural leather hides. PureThe porous body is formed by: washed with 1% to 6% aqueous NaOH and 0.1% to 1% H₂O₂Bleached, then soaked in distilled/purified water to obtain a neutral pH. Finally, the porous body is mechanically pressed to a desired thickness. After purification and pressing, the weight of the water-impregnated porous body was 230.96g, and the porous body had approximately 22.9mg/cm²Average cellulose content of (a). The cellulose content was measured in the following manner: a sample of known area of wet porous body was taken and air dried at 55 ℃ for approximately 12 hours, resulting in a porous body comprising theoretically only nanocellulose fibers. In other words, the total weight of the dry porous body is entirely due to the nanocellulose fibers. The cellulose content was determined by dividing the weight of the dried sample by its area.

Solvent extraction

The wet-pressed porous body was then cut into 45 strips, each strip approximately 5cm by 5cm, and each strip having approximately 575mg (i.e., 22.9 mg/cm)²) Cellulose content of (a). The thickness of these wet bars at each of its four corners was measured and the average wet thickness was recorded in the table below. The strips were then randomly divided into 3 groups of 10 samples each and treated by a solvent extraction step and an oil immersion step. The solvent extraction operation for these samples was identical, including the use of boiling ethanol [ ETOH ] with a purity of 99%](about 70 ℃) in a plurality of extraction steps. The sample was placed in a flask with a mechanical stirrer operating at about 200rpm and containing about 1500mL ETOH for about 2 to 24 hours. Each of the 10 samples from groups 1,2 and 3 was individually subjected to a second extraction step with 500mL of boiling ETOH, respectively, including an agitator operating at 200rpm, for about 2 to 24 hours. After the sample was removed from the solvent extraction, it was weighed and prepared for the oil immersion step. The weight of the sample after solvent washing is reported as the "wash weight" in the table below.

Immersion oil

The group 1 samples (samples 1 to 10) were placed with constant mixing into a flask containing a heated immersion oil fluid at about 70 ℃. The oil-impregnated fluid contained 250mL of ETOH as emulsifier, and 250mL of unrefined coconut oil (emulsifier/oil ratio 50: 50). Group 2 samples (samples 11 to 20) were placed with constant mixing into a flask containing a heated immersion oil fluid at about 70 ℃. The oil-impregnated fluid contained 350mL of ETOH as emulsifier, and 150mL of unrefined coconut oil (emulsifier/oil ratio 70: 30). Group 3 samples (samples 21 to 30) were placed under constant mixing into a flask containing heated immersion oil fluid at about 70 ℃. The oil-impregnated fluid contained 150mL of ETOH as emulsifier, and 350mL of unrefined coconut oil (emulsifier/oil ratio 30: 70). Each set of samples was oil soaked for approximately 2 hours. After the oil immersion process was complete, the samples were weighed to record their weight, indicated as "immersion weight" in the table below. The samples were air dried in a fume hood for approximately 24 hours and their dry weight and average thickness were recorded. The oil weight and oil percentage of the final dry product were calculated by subtracting the known cellulose weight of the sample (approximately 575mg) from the total dry weight of the oil-impregnated BNC material. The following are tables for groups 1 to 3 showing the weight and thickness of the samples measured from the solvent washing stage through to drying.

Table 1: group 1(50:50 dip)

Table 2: group 2(70:30 dip)

Table 3: group 3(30:70 dip)

Samples of the oil impregnated BNC materials were further tested for tensile strength and suture pull-out to evaluate their suitability as textile materials.

Tensile strength

The samples were tested on MTS Insight 100(EM05), the instrument having a 250N load cell capacity and set at 50 mm/min. As can be seen from fig. 1A to 1C, the shape of the sample of each of the groups 1 to 3 was modified to be about 5cm × 1.5cm for this test, with an approximate barbell shape having a central cutout portion of about 2cm in length and 4mm to 5mm in width. The sample was placed in the grip of the instrument and the tensile load and displacement length were recorded until failure. The measured values for each of the groups 1 to 3 are shown in the following table. "tensile load" is a measure of force at failure in newtons. "tensile strength" is the tensile load at failure divided by the cross-sectional area (thickness x width) of the specimen.

Table 4: results of group 1：

Tensile Properties of untested sample 5

Table 5: results of group 2：

Table 6: results of group 3

Suture/suture pull-out

The samples were tested on MTS Insight 100(EM05), the instrument having a 250N load cell capacity and set at 300 mm/min. As can be seen in fig. 2A to 2C, the shape of the samples of each of groups 1 to 3 was modified for this test to be about 4cm x 1.0cm with a suture placed at one end about 0.5cm from each boundary. The sample is placed in one clamp and the excess suture length is grasped in the other clamp. The instrument was started and the sample displacement distance and failure load were recorded and the values are shown in the table below.

Table 7: results of group 1

Sample numbering	Pulling out load (N)	Displacement when pulled out (mm)
			1	22.4	2.69
2	13.3	2.34
			3	13.1	2.80
4	N/T	N/T
			5	15.5	1.15
6	N/T	N/T
			7	14.8	2.05
8	7.4	3.38
			9	12.0	1.07
10	18.1	1.89
			Mean value of	14.6	2.17
Standard deviation of	4 42	0 802

Table 8: results of group 2

Sample numbering	Pulling outLoad (N)	Displacement when pulled out (mm)
			11	14.4	1.10
12	13.6	1.98
			13	28.5	3.62
14	15.2	1.56
			15	13.7	2.74
16	17.1	2.92
			17	16.3	2.54
18	13.4	2.32
			19	16.3	1.20
20	17.2	2.00
			Mean value of	16.6	2.20
Standard deviation of	4.43	0.793

Table 9: results of group 3

Sample numbering	Pulling out load (N)	Displacement when pulled out (mm)
			21	26.9	4.82
22	13.5	3.37
			23	21.8	1.91
24	21.4	2.31
			25	11.1	1.33
26	19.2	1.12
			27	N/T	N/T
28	20.8	4.41
			29	36.4	4.99
30	15.2	2.51
			Mean value of	20.7	2.97
Standard deviation of	7.60	1.48

Although the present disclosure has been described in terms of several embodiments, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the disclosure, for example as specified by the appended claims. Accordingly, it should be understood that the scope of the present disclosure is not intended to be limited to the particular embodiments of the process, manufacture, composition of matter, methods and steps described herein. For example, various features described above in accordance with one embodiment may be incorporated into other embodiments unless otherwise specified. Moreover, as one of ordinary skill in the art will readily appreciate from the disclosure, processes, manufacture, compositions of matter, means, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure.