Calcium phosphate ion cluster, composite bioplastic film and preparation method and application thereof

Abstract

This application provides a calcium phosphate ion cluster, a composite bioplastic film, its preparation method, and its application. The preparation method of the calcium phosphate ion cluster includes: adding sodium tripolyphosphate solution to a calcium chloride solution, adjusting the pH to 9-11, then adding trisodium phosphate solution, maintaining the pH at 9-11, and stirring for 1-3 hours to obtain the calcium phosphate ion cluster. In the bioplastic preparation process, by modifying the surface of the calcium phosphate ion cluster onto the hydroxyl groups of bacterial cellulose to form a functionalized composite fiber, and then adding sodium alginate to the composite fiber, a composite structure is finally constructed with bacterial cellulose as a rigid skeleton, sodium alginate as a flexible network, and calcium phosphate ion cluster as a buffer bridge. This increases the strength by 75% and the toughness by 300% compared to pure bacterial cellulose, exhibiting excellent fracture strength and fracture toughness.

Description

Technical Field

[0001] This application relates to the field of materials technology, and in particular to a calcium phosphate ion cluster, a composite bioplastic film, its preparation method and application. Background Technology

[0002] Cellulose is the most abundant polysaccharide macromolecule in nature. Each β-D-glucose unit in a cellulose chain is linked by a β-1,4-glycosidic bond and rotates 180°, forming a highly rigid molecular structure. Simultaneously, the high hydroxyl content of cellulose allows its parallel chains to tightly arrange themselves through hydrogen bonds, forming microfibrils, further enhancing its rigidity. These properties endow cellulose materials with high mechanical strength and a certain degree of hydrophobicity, making them an ideal material as a plastic alternative.

[0003] However, excessive rigidity results in weak strain capacity and insufficient toughness of cellulose microfilaments, limiting their potential as a plastic alternative.

[0004] Therefore, researchers have developed composite cellulose materials by introducing another biomacromolecule, such as sodium alginate and chitosan, to toughen cellulose, thus overcoming the shortcomings of traditional cellulose materials in terms of insufficient toughness. However, sodium alginate and chitosan, which are also polysaccharides, have similar molecular structures to cellulose and easily form a dense hydrogen bond network with cellulose, which limits the toughening effect. In addition, the introduction of flexible polymers reduces the strength of cellulose materials to some extent.

[0005] To further enhance the synergistic effect of cellulose's toughness and strength, researchers have attempted to introduce inorganic reinforcing phases, including carbon nanotubes and iron oxide nanoparticles, into the cellulose network. However, some inorganic materials exhibit poor dispersion and insufficient interaction forces within the cellulose network, leading to interfacial defects such as phase separation, which in turn hinders the synergistic improvement of strength and toughness. Therefore, addressing the issues of insufficient and discontinuous bonding between the inorganic toughening phase and cellulose materials to construct cellulose bioplastics with both high strength and high toughness remains a significant challenge.

[0006] Given the problems with existing technologies, it is essential to develop a new type of material.

[0007] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the Invention

[0008] This application provides a calcium phosphate ion cluster, a composite bioplastic film, a method for preparing the same, and its application, in order to solve or alleviate one or more of the technical problems mentioned above.

[0009] In a first aspect, this application provides a method for preparing calcium phosphate ion clusters, the method comprising: Add sodium tripolyphosphate solution to calcium chloride solution to adjust pH to 9-11, then add trisodium phosphate solution to maintain pH at 9-11, and keep stirring for 1-3 h to obtain calcium phosphate ion clusters.

[0010] Preferably, the concentration of the calcium chloride solution is 0.136-0.168 mol / L; Preferably, based on 1 mol of calcium chloride added to the calcium chloride solution, the amount of sodium tripolyphosphate added to the sodium tripolyphosphate solution is 0.060-0.070 mol; Preferably, the pH adjustment to 9-11 uses a pH adjuster; Preferably, the pH adjuster comprises: a 1M sodium hydroxide aqueous solution, a 1M potassium hydroxide aqueous solution, and a 1M ammonia aqueous solution; Preferably, the concentration of the trisodium phosphate solution is 0.091-0.112 mol / L; Preferably, the stirring rate is 600-800 rpm.

[0011] Preferably, the preparation method further includes post-processing the mixture obtained after stirring; Preferably, the post-processing is performed 1-5 times; Preferably, the post-processing includes solid-liquid separation and washing; Preferably, the solid-liquid separation method is centrifugation, and the centrifugation rate is 5000-7000 rpm for 1-10 min; Preferably, the cleaning solvent is deionized water.

[0012] Secondly, this application prepares calcium phosphate ion clusters according to the preparation method described in the first aspect.

[0013] Thirdly, this application provides a method for preparing a composite bioplastic film, the method comprising: The calcium phosphate ion clusters prepared in the first aspect were added to the bacterial cellulose dispersion and stirred to obtain a composite cellulose dispersion. Subsequently, sodium alginate solution was added to crosslink the mixture to obtain a composite bioplastic film.

[0014] Preferably, based on an addition amount of 1.0 g of calcium phosphate ion cluster, the addition amount of bacterial cellulose dispersion is 5.0-10.0 g, and the addition amount of sodium alginate solution is 5.0-10.0 g; Preferably, the stirring rate is 1000-1500 rpm and the time is 4-8 h; Preferably, the preparation method further includes removing air bubbles from the crosslinked mixture and drying it; Preferably, the method for removing air bubbles is ultrasound; Preferably, the drying temperature is 10-40°C.

[0015] Fourthly, this application provides a bioplastic film prepared according to the preparation method described in the third aspect.

[0016] Preferably, the tensile strength of the composite bioplastic film is 330-360 MPa; Preferably, the composite bioplastic membrane has a fracture toughness of 60-65 MJ / m. -3 .

[0017] Fifthly, this application provides an application of the bioplastic film according to the fourth aspect in the fields of biomedicine, agriculture, or the environment.

[0018] The embodiments of this application employing the above-described technical solution may have the following advantages: In the preparation of bioplastic films, surface modification with calcium phosphate clusters occupies most of the hydroxyl groups on the surface of bacterial cellulose. Multiple organic-inorganic interactions replace the strong intermolecular hydrogen bonds of polysaccharides, ultimately constructing a composite structure with bacterial cellulose as the rigid framework, sodium alginate as the flexible network, and calcium phosphate clusters as buffering bridges. Compared to bacterial cellulose films, the tensile strength and strain capacity are significantly enhanced, and the toughness is increased by up to 300%. Furthermore, by adjusting the amount of bacterial cellulose and sodium alginate added (5.0-10.0 g), bacterial cellulose composite films with different strengths and toughnesses can be obtained. Attached Figure Description

[0019] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments disclosed in this application and should not be construed as limiting the scope of this application.

[0020] Figure 1 This is a flowchart illustrating the preparation process of the composite bioplastic membrane in Example 1; Figure 2 This is an image of the composite bioplastic membrane provided in Embodiment 1 of this application; Figure 3 This is an image of the composite bioplastic film provided in Embodiment 1 of this application after being folded and shaped; Figure 4 These are transmission electron microscope images of the surface-modified composite cellulose and bioplastic slurry provided in Example 1 of this application; Figure 5These are test diagrams of the tensile strength of the bioplastic film provided in Example 1 of this application and the comparative films prepared in Comparative Examples 1-2; Figure 6 These are fracture toughness test diagrams of the bioplastic film provided in Example 1 of this application and the comparative films prepared in Comparative Examples 1-2. Detailed Implementation

[0021] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, and elements, as well as their relative dimensions, may be exaggerated. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0022] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0023] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0026] This application provides a calcium phosphate ion cluster, a composite bioplastic membrane, its preparation method, and its application. Details are provided below.

[0027] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0028] This application provides a method for preparing calcium phosphate ion clusters, the method comprising: Add sodium tripolyphosphate solution to calcium chloride solution to adjust pH to 9-11 (e.g., 9, 9.5, 10, 10.5 or 11), then add trisodium phosphate solution to maintain pH at 9-11 (e.g., 9, 9.5, 10, 10.5 or 11), and keep under stirring for 1-3 h (e.g., 1 h, 1.5 h, 2 h, 2.5 h, 3 h), to obtain calcium phosphate ion clusters.

[0029] In this application, by controlling the reaction pH to an alkaline environment of 9–11 and using sodium tripolyphosphate (STTP) as a stabilizer, excessive crystallization and aggregation of calcium phosphate are effectively suppressed, forming ultra-small (approximately 1.7 nm) calcium phosphate ion clusters. This structure possesses high specific surface area and good reactivity, laying the foundation for subsequent surface modification of bacterial cellulose.

[0030] The calcium phosphate ion clusters obtained in this application have an amorphous structure and an ultra-high specific surface area, which can effectively form hydrogen bonds with bacterial cellulose (BC) to form a surface-modified structure, providing multiple strong and weak interactions and enhanced mechanical properties for composite bioplastic films.

[0031] In some embodiments, the concentration of the calcium chloride solution is 0.136-0.168 mol / L (e.g., 0.136 mol / L, 0.140 mol / L, 0.147 mol / L, 0.153 mol / L, 0.157 mol / L, 0.162 mol / L, 0.168 mol / L, etc.). In some embodiments, with the amount of calcium chloride added to the calcium chloride solution being 1 mol, the amount of sodium tripolyphosphate added to the sodium tripolyphosphate solution is 0.060-0.070 mol (e.g., 0.060 mol / L, 0.064 mol / L, 0.067 mol / L, 0.070 mol / L, etc.). In some embodiments, the pH adjuster used to adjust the pH to 9-11 (e.g., 9, 9.5, 10, 10.5, or 11, etc.) includes: 1M sodium hydroxide aqueous solution, 1M potassium hydroxide aqueous solution, and 1M ammonia aqueous solution; In some embodiments, the concentration of the trisodium phosphate solution is 0.091-0.112 mol / L (e.g., 0.091 mol / L, 0.100 mol / L, 0.107 mol / L, 0.110 mol / L, 0.112 mol / L, etc.). In some embodiments, the stirring rate is 600-800 rpm (e.g., 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, etc.).

[0032] In some embodiments, the preparation method further includes post-processing the mixture obtained after stirring; In some embodiments, the number of post-processing steps is 1-5 (e.g., 1, 2, 3, 4, 5). In some embodiments, the post-processing includes solid-liquid separation and washing; In some embodiments, the solid-liquid separation is performed by centrifugation at a speed of 5000-7000 rpm (e.g., 5000 rpm, 5500 rpm, 6000 rpm, 6500 rpm, 7000 rpm, etc.) for a time of 1-10 min (e.g., 1 min, 3 min, 5 min, 7 min, 10 min, etc.). In some embodiments, the cleaning solvent is deionized water.

[0033] In some embodiments, this application provides a method for preparing a composite bioplastic film, the method comprising: adding the calcium phosphate ion clusters prepared above to a bacterial cellulose dispersion, stirring, and then adding a sodium alginate solution to obtain a composite bioplastic film.

[0034] In this application, calcium phosphate ion clusters are mixed with bacterial cellulose (BC) dispersion and then vigorously stirred to promote the uniform dispersion of inorganic ion clusters on the surface of organic cellulose, forming a surface-modified structure. Subsequently, sodium alginate solution is added and vigorously stirred to ultimately construct a composite structure with bacterial cellulose as a rigid framework, sodium alginate as a flexible network, and calcium phosphate ion clusters as buffer bridges. This structure solidifies during drying through hydrogen bonding, coordination, and physical cross-linking, endowing the bioplastic film with higher initial strength and toughness.

[0035] In some embodiments, based on an addition amount of 1.0 g of calcium phosphate ion cluster, the addition amount of bacterial cellulose dispersion is 5.0-10.0 g (e.g., 5.0 g, 5.6 g, 6.1 g, 6.8 g, 7.3 g, 7.9 g, 8.1 g, 9.0 g, 10.0 g, etc.), and the addition amount of sodium alginate solution is 5.0-10.0 g (e.g., 5.0 g, 5.6 g, 6.1 g, 6.8 g, 7.3 g, 7.9 g, 8.1 g, 9.0 g, 10.0 g, etc.). In some embodiments, the rate of vigorous stirring is 1000-1500 rpm (e.g., 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, etc.), and the total time is 4-8 h (e.g., 4 h, 5 h, 6 h, 7 h, 8 h, etc.). In some embodiments, the preparation method further includes removing air bubbles from the crosslinked mixture and drying it; In some embodiments, the method of removing bubbles is ultrasound; In some embodiments, the drying temperature is 10-40°C (e.g., 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc.).

[0036]

Example 1

[0037] This embodiment also provides a method for preparing a composite bioplastic film, such as... Figure 1 As shown, it includes: The calcium phosphate ion clusters obtained above were added to 120 g of bacterial cellulose dispersion with a concentration of 0.8 wt%, and the mixture was shaken evenly. The emulsion was then transferred to a 300 mL beaker and stirred vigorously for 3 hours at a stirring rate of 1200 rpm for surface modification. Subsequently, 120 g of sodium alginate aqueous solution with a concentration of 0.8 wt% was added, shaken evenly, and transferred to a 300 mL beaker. The emulsion was then stirred vigorously for 3 hours at a stirring rate of 1200 rpm for cross-linking. Finally, the homogeneous emulsion was ultrasonically degassed and transferred to a 13 cm × 13 cm culture dish and dried at room temperature (25 °C). The dried composite film was then peeled off from the culture dish.

[0038] Figure 2 The image shows an optical photograph of the bioplastic film prepared in Example 1. It can be seen that the bioplastic film has a uniform appearance and is semi-transparent.

[0039] Figure 3 The image shows an optical photograph of the bioplastic membrane prepared in Example 1 folded and shaped into a pentagram, demonstrating that the bioplastic membrane possesses good toughness and plasticity.

[0040] Figure 4The images show transmission electron microscopy (TEM) images of the surface-modified composite cellulose and the emulsion after ultrasonic degassing prepared in Example 1. The left bar is 20 nm and the right bar is 50 nm. It can be seen that calcium phosphate ion clusters are uniformly modified on the surface of bacterial cellulose, and the emulsion has a uniform composite structure.

[0041] Comparative Example 1 This comparative example discloses a film comprising: drying 120 grams of bacterial cellulose dispersion with a concentration of 0.8 wt% from Example 1 to obtain comparative film 1.

[0042] Comparative Example 2 This comparative example discloses a film comprising: 120 g of a bacterial cellulose dispersion with a concentration of 0.8 wt% and 120 g of a sodium alginate aqueous solution with a concentration of 0.8 wt% were shaken evenly and transferred to a 300 mL beaker. The emulsion was then vigorously stirred for 3 hours at a stirring rate of 1200 rpm to carry out a crosslinking composite process. Finally, the homogeneous emulsion was ultrasonically degassed and transferred to a 13 cm × 13 cm culture dish, dried at room temperature of 25 °C, and finally peeled off from the culture dish to obtain comparative film 2.

[0043] Figure 5 The images show the tensile strength test results of the composite bioplastic film prepared in Example 1 and the comparative films prepared in Comparative Examples 1-2. The comparison shows that the composite bioplastic film formed by bacterial cellulose, sodium alginate and calcium phosphate ion clusters has a higher tensile strength (346.5 MPa) than bacterial cellulose alone, or the combination of bacterial cellulose and sodium alginate.

[0044] Figure 6 The images show the fracture toughness test results of the composite bioplastic film prepared in Example 1 and the comparative films prepared in Comparative Examples 1-2. The comparison shows that the bioplastic film formed by bacterial cellulose, sodium alginate, and calcium phosphate ion clusters exhibits higher fracture toughness (63.8 MJ / m²) compared to bacterial cellulose alone, or the combination of bacterial cellulose and sodium alginate. -3 ).

[0045]

Example 2

[0046]

Example 3

[0047] The bioplastic film prepared in this application was tested using the same method as in Example 1. The bioplastic film also exhibited high strength (352.5 MPa) and high toughness (64.7 MJ / m²). -3 ).

[0048] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The directional terms "inner" and "outer" refer to the inside or outside relative to the outline of the component itself. For example, if a device in the drawings is inverted, a device described as "above" or "on top of" other devices or structures will subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0049] It should also be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this application refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0050] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0051] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A method for preparing calcium phosphate ion clusters, characterized in that, The preparation method includes: Add sodium tripolyphosphate solution to calcium chloride solution to adjust pH to 9-11, then add trisodium phosphate solution to maintain pH at 9-11, and keep stirring for 1-3 h to obtain calcium phosphate ion clusters.

2. The preparation method according to claim 1, characterized in that, The concentration of the calcium chloride solution is 0.136-0.168 mol / L; Preferably, based on 1 mol of calcium chloride added to the calcium chloride solution, the amount of sodium tripolyphosphate added to the sodium tripolyphosphate solution is 0.060-0.070 mol; Preferably, the pH adjustment to 9-11 uses a pH adjuster; Preferably, the pH adjuster comprises: a 1M sodium hydroxide aqueous solution, a 1M potassium hydroxide aqueous solution, and a 1M ammonia aqueous solution; Preferably, the concentration of the trisodium phosphate solution is 0.091-0.112 mol / L; Preferably, the stirring rate is 600-800 rpm.

3. The preparation method according to claim 1, characterized in that, The preparation method further includes post-processing the mixture obtained after stirring; Preferably, the post-processing is performed 1-5 times; Preferably, the post-processing includes solid-liquid separation and washing; Preferably, the solid-liquid separation method is centrifugation, and the centrifugation rate is 5000-7000 rpm for 1-10 min; Preferably, the cleaning solvent is deionized water.

4. Calcium phosphate ion clusters are prepared according to any one of claims 1-3.

5. A method for preparing a composite bioplastic film, characterized in that, The preparation method includes: The calcium phosphate ion clusters prepared according to any one of claims 1-3 are added to the bacterial cellulose dispersion and stirred to obtain a composite cellulose dispersion. Then, sodium alginate solution is added to crosslink the mixture to obtain a composite bioplastic film.

6. The preparation method according to claim 5, characterized in that, Based on an addition amount of 1.0 g of calcium phosphate ion cluster, the addition amount of the bacterial cellulose dispersion is 5.0-10.0 g, and the addition amount of the sodium alginate solution is 5.0-10.0 g; Preferably, the stirring rate is 1000-1500 rpm and the stirring time is 4-8 h.

7. The preparation method according to claim 5, characterized in that, The preparation method further includes removing air bubbles from the crosslinked mixture and drying it; Preferably, the method for removing air bubbles is ultrasound; Preferably, the drying temperature is 10-40°C.

8. A composite bioplastic film is prepared by the preparation method according to any one of claims 5-7.

9. The composite bioplastic membrane according to claim 8, characterized in that, The tensile strength of the composite bioplastic film is 330-360 MPa; The fracture toughness of the composite bioplastic film is 60-65 MJ / m. -3 .

10. The application of the composite bioplastic film according to claim 8 or 9 in the fields of biomedicine, agriculture or environment.

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