Preparation method and application of temperature and pH response actuating film with full-biomass-based Janus structure

Abstract

The invention discloses a preparation method and application of a temperature and pH response actuating film of a full-biomass-based Janus structure, and belongs to the technical field of flexible actuating materials. The invention provides a bio-based polysaccharide-cellulose nanocrystalline-Ca < 2 + > / bio-based polysaccharide-gelatin composite film which has a Janus structure and has good responsiveness to temperature and pH based on the synergistic effect and asymmetric structure design of components. The composite membrane provided by the invention has rapid response to pH and temperature, and in water of 60 DEG C, the composite membrane can be rapidly curled from a flat state to a bio-based polysaccharide-gelatin side; and in a solution with the pH value of 1-13, the bending amplitude of the composite membrane is gradually reduced. In addition, the temperature and pH response actuating film of the full-biomass-based Janus structure, provided by the invention, is used as an actuator, and a plastic sheet can be taken out from water at 60 DEG C and released at 20 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of flexible actuation materials technology, and particularly relates to a method for preparing and applying a temperature- and pH-responsive actuation film with an all-biomass-based Janus structure. Background Technology

[0002] Stimulus-responsive hydrogels and polymer films have attracted widespread research interest in soft robotics and biomedicine due to their ability to translate environmental signals (such as temperature, pH, or light) into programmable mechanical motion. In particular, soft actuators capable of performing complex tasks such as grasping, manipulating, and controlled release in aquatic environments show great potential in applications such as minimally invasive surgery, targeted drug delivery, and underwater micromanipulation.

[0003] Currently, facing the urgent need for global sustainable development, the design of next-generation smart materials must not only possess responsiveness to the external environment but also consider their environmental friendliness throughout their entire life cycle. Biomass, as an abundant renewable carbon source on Earth, possesses advantages such as wide availability, low cost, and environmental friendliness, and is considered one of the ideal alternatives to fossil resources. In recent years, driven by continuous advancements in bioprocessing and catalysis technologies, the development and application of bio-based functional materials in advanced materials, chemical synthesis, and auxiliaries have shown rapid growth. In view of this, a thin film with a fully biomass-based Janus structure that is simple to process, exhibits excellent performance, and possesses superior mechanical properties and temperature and pH-responsive actuation has become an important research direction in the field of flexible actuation materials. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method for preparing and applying a temperature- and pH-responsive actuated thin film with an all-biomass-based Janus structure.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a temperature- and pH-responsive actuated film with a fully biomass-based Janus structure, wherein the temperature- and pH-responsive actuated film with a fully biomass-based Janus structure is a bio-based polysaccharide-cellulose nanocrystal-Ca 2+ / Bio-based polysaccharide-gelatin composite membrane.

[0007] Furthermore, the bio-based polysaccharide-cellulose nanocrystals-Ca 2+ The bio-based polysaccharide-gelatin composite film contains bio-based polysaccharides selected from hyaluronic acid, starch, chitosan, sodium carboxymethyl cellulose, or sodium alginate.

[0008] This invention provides a method for preparing a temperature- and pH-responsive actuated thin film with a fully biomass-based Janus structure as described above, comprising the following steps:

[0009] (1) Prepare bio-based polysaccharide-cellulose nanocrystal gel membrane;

[0010] (2) Pour the mixed solution of bio-based polysaccharide and gelatin onto the bio-based polysaccharide-cellulose nanocrystal gel membrane, and evaporate the solvent to obtain a bio-based polysaccharide-cellulose nanocrystal / bio-based polysaccharide-gelatin composite membrane;

[0011] (3) Spray CaCl2 solution onto the bio-based polysaccharide-cellulose nanocrystal side of the bio-based polysaccharide-cellulose nanocrystal / bio-based polysaccharide-gelatin composite film, and after drying, obtain bio-based polysaccharide-cellulose nanocrystal-CaCl2 solution. 2+ / Bio-based polysaccharide-gelatin composite membrane, namely a temperature- and pH-responsive actuated membrane with a fully biomass-based Janus structure.

[0012] Further, in step (1), the preparation method of the bio-based polysaccharide-cellulose nanocrystal gel membrane includes: mixing the cellulose nanocrystal solution with the bio-based polysaccharide solution and stirring to obtain a suspension; pouring the suspension into a mold and placing it to obtain the bio-based polysaccharide-cellulose nanocrystal gel membrane.

[0013] Furthermore, the cellulose nanocrystals in the cellulose nanocrystal solution have a diameter of 4-10 nm and a length of 100-500 nm;

[0014] The concentration of the bio-based polysaccharide solution is 1.5 wt%; the concentration of the cellulose nanocrystal solution is 4 wt%; and the mass ratio of the bio-based polysaccharide solution to the cellulose nanocrystal solution is 9:1.

[0015] Further, in step (2), the method for preparing the mixed solution of bio-based polysaccharide and gelatin includes: mixing the bio-based polysaccharide solution and the gelatin solution, and stirring to obtain the mixed solution of bio-based polysaccharide and gelatin;

[0016] The concentration of the bio-based polysaccharide solution is 1.5 wt%; the concentration of the gelatin solution is 10 wt%; and the mass ratio of the bio-based polysaccharide solution to the gelatin solution is 3:7.

[0017] The stirring temperature is 45°C, and the stirring time is 1 hour.

[0018] Further, in step (2), the amount of the mixed solution of bio-based polysaccharide and gelatin poured is such that the gelatin accounts for a certain percentage of the bio-based polysaccharide-cellulose nanocrystal-Ca 2+ / Based on 25-75% of the dry weight of the bio-based polysaccharide-gelatin composite film.

[0019] Further, in step (3), the concentration of the CaCl2 solution is 2wt%; the spraying amount of the CaCl2 solution is 1g / cm³. 2 .

[0020] Further, in step (3), the bio-based polysaccharide-cellulose nanocrystals-Ca 2+ The thickness of the bio-based polysaccharide-gelatin composite film is ≤200μm.

[0021] The present invention also provides an application of the temperature- and pH-responsive actuation film of the all-biomass-based Janus structure described above in an actuator.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] Based on the synergistic effect of components and asymmetric structural design, this invention provides a bio-based polysaccharide-cellulose nanocrystal-Ca nanocrystal with a Janus structure and good responsiveness to temperature and pH. 2+ / Bio-based polysaccharide-gelatin composite membrane; Bio-based polysaccharide serves as the continuous phase matrix, utilizing its abundant hydroxyl and carboxyl groups to construct a hydrogen bond network, endowing the membrane with good biocompatibility. Its inherent pH-sensitive properties provide a chemical response basis for actuation; Cellulose nanocrystals serve as the nano-reinforcing phase, significantly improving the mechanical strength of the membrane due to their high crystallinity and high modulus. Simultaneously, the hydroxyl groups on the surface of cellulose nanocrystals can form hydrogen bonds with the polysaccharide, and their chiral arrangement can induce structural anisotropy, promoting directional actuation; Ca ions form coordination crosslinks with the carboxyl groups of the polysaccharide through electrostatic interactions. A reversible dynamic ionic bond network is constructed—when pH changes, carboxyl protonation leads to crosslinking dissociation, causing a change in the intralayer swelling rate, thus achieving pH-responsive actuation; gelatin utilizes its thermosensitive triple helix-random coil transition characteristics to produce reversible conformational changes and volume shrinkage under temperature stimulation, endowing the film with temperature-responsive functionality; the Janus structure design gives the two sides of the film differentiated modulus and swelling behavior. When the ambient pH or temperature changes, the mismatch between the response rate and degree on both sides generates an internal stress gradient, driving the film to bend or curl in a specific direction, thus achieving intelligent actuation.

[0024] The temperature- and pH-responsive actuated membrane with a fully biomass-based Janus structure provided by this invention exhibits rapid response to pH and temperature. In water at 60°C, the composite membrane can rapidly curl from a flat state towards the bio-based polysaccharide-gelatin side; in solutions with pH values ​​of 1-13, the bending amplitude of the composite membrane gradually decreases. Furthermore, using the temperature- and pH-responsive actuated membrane with a fully biomass-based Janus structure provided by this invention as an actuator, it can remove a plastic sheet from water at 60°C and release it at 20°C.

[0025] This invention prepares bio-based polysaccharide-cellulose nanocrystals-Ca using a layer-by-layer casting method. 2+ Bio-based polysaccharide-gelatin composite membranes are simple to process, easy to operate, and can be prepared in large quantities. Attached Figure Description

[0026] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 The large-scale SA-CNC suspension, SA-GEL mixed solution, and SA-CNC-Ca prepared in Example 1 2+ The image shows a physical sample of the SA-GEL composite membrane, where a is a mixture of SA-CNC suspension and SA-GEL solution, and b is a mixture of SA-CNC and Ca2+. 2+ / SA-GEL composite membrane;

[0028] Figure 2 SA-CNC-Ca prepared in Example 1 2+ Cross-sectional SEM image of the SA-GEL composite membrane;

[0029] Figure 3 SA-CNC-Ca prepared in Example 1 2+ EDS diagram of SA-GEL composite membrane;

[0030] Figure 4 SA-CNC-Ca prepared in Examples 1-3 2+ Mechanical properties of SA-GEL composite membrane;

[0031] Figure 5 SA-CNC-Ca prepared in Example 1 2+ Physical images of the driving behavior of the SA-GEL composite membrane in solutions with different pH values;

[0032] Figure 6 A physical image of the driving behavior of the monolayer SA-GEL film prepared for Comparative Example 1 in water at 60°C;

[0033] Figure 7 SA-CNC-Ca prepared in Example 1 2+ Physical images of the driving behavior of the SA-GEL composite membrane in water at 60℃ and 20℃, where a is 60℃ and b is 20℃;

[0034] Figure 8 SA-CNC-Ca prepared in Example 1 2+The image shows an SA-GEL composite membrane used as an actuator to grab a plastic sheet from water at 60°C and release it at 20°C. In the image, a represents 60°C and b represents 20°C.

[0035] Figure 9 Bio-based polysaccharide-cellulose nanocrystals-Ca prepared in Examples 1 and 4 2+ / A physical image of a bio-based polysaccharide-gelatin composite film;

[0036] Figure 10 Bio-based polysaccharide-cellulose nanocrystals-Ca prepared in Examples 1 and 4 2+ / Comparative mechanical properties of bio-based polysaccharide-gelatin composite membranes. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] This invention provides a temperature- and pH-responsive actuated film with a fully biomass-based Janus structure, wherein the temperature- and pH-responsive actuated film with a fully biomass-based Janus structure is a bio-based polysaccharide-cellulose nanocrystal-Ca 2+ / Bio-based polysaccharide-gelatin composite membrane.

[0040] In a preferred embodiment, the bio-based polysaccharide-cellulose nanocrystals-Ca 2+ The bio-based polysaccharide-gelatin composite film contains bio-based polysaccharides selected from hyaluronic acid, starch, chitosan, sodium carboxymethyl cellulose, or sodium alginate, with sodium alginate (SA) being a more preferred option.

[0041] This invention provides a method for preparing a temperature- and pH-responsive actuated thin film with a fully biomass-based Janus structure as described above, comprising the following steps:

[0042] (1) Prepare bio-based polysaccharide-cellulose nanocrystal gel membrane;

[0043] (2) Pour the mixed solution of bio-based polysaccharide and gelatin onto the bio-based polysaccharide-cellulose nanocrystal gel membrane, and evaporate the solvent to obtain a bio-based polysaccharide-cellulose nanocrystal / bio-based polysaccharide-gelatin composite membrane;

[0044] (3) Spray CaCl2 solution onto the bio-based polysaccharide-cellulose nanocrystal side of the bio-based polysaccharide-cellulose nanocrystal / bio-based polysaccharide-gelatin composite film, and after drying, obtain bio-based polysaccharide-cellulose nanocrystal-CaCl2 solution. 2+ / Bio-based polysaccharide-gelatin composite membrane, namely a temperature- and pH-responsive actuated membrane with a fully biomass-based Janus structure.

[0045] In a preferred embodiment, step (1) involves preparing the bio-based polysaccharide-cellulose nanocrystal gel membrane by mixing a cellulose nanocrystal solution with a bio-based polysaccharide solution and stirring to obtain a suspension; pouring the suspension into a mold and placing it to obtain the bio-based polysaccharide-cellulose nanocrystal gel membrane.

[0046] In a preferred embodiment, during the preparation of the bio-based polysaccharide-cellulose nanocrystal gel membrane, the cellulose nanocrystals in the cellulose nanocrystal solution have a diameter of 4-10 nm and a length of 100-500 nm.

[0047] In a preferred embodiment, during the preparation of the bio-based polysaccharide-cellulose nanocrystal gel membrane, the cellulose nanocrystal solution is further subjected to an ultrasonication step before being mixed with the bio-based polysaccharide solution; the ultrasonication time is 15 minutes.

[0048] In a preferred embodiment, during the preparation of the bio-based polysaccharide-cellulose nanocrystal gel membrane, the concentration of the bio-based polysaccharide solution is 1.5 wt%; the concentration of the cellulose nanocrystal solution is 4 wt%; and the mass ratio of the bio-based polysaccharide solution to the cellulose nanocrystal solution is 9:1.

[0049] In a preferred embodiment, during the preparation of the bio-based polysaccharide-cellulose nanocrystal gel membrane, the stirring temperature is room temperature, the stirring time is 2 hours, and the stirring method is magnetic stirring.

[0050] In a preferred embodiment, during the preparation of the bio-based polysaccharide-cellulose nanocrystal gel membrane, the placement specifically involves placing it in a constant temperature and humidity chamber at 25°C and 50% relative humidity for 7 hours.

[0051] In a preferred embodiment, step (2) involves preparing the mixed solution of bio-based polysaccharide and gelatin by mixing the bio-based polysaccharide solution and the gelatin solution and stirring to obtain the mixed solution of bio-based polysaccharide and gelatin.

[0052] In a preferred embodiment, during the preparation of the mixed solution of bio-based polysaccharide and gelatin, the concentration of the bio-based polysaccharide solution is 1.5 wt%; the concentration of the gelatin solution is 10 wt%; and the mass ratio of the bio-based polysaccharide solution to the gelatin solution is 3:7.

[0053] In a preferred embodiment, during the preparation of the mixed solution of bio-based polysaccharides and gelatin, the stirring temperature is 45°C and the stirring time is 1 hour.

[0054] In a preferred embodiment, in step (2), the amount of the mixed solution of bio-based polysaccharide and gelatin poured is such that the gelatin accounts for a percentage of the bio-based polysaccharide-cellulose nanocrystal-Ca 2+ / Based on 25-75% of the dry weight of the bio-based polysaccharide-gelatin composite film.

[0055] In a preferred embodiment, in step (2), the solvent evaporates at a temperature of 25°C and a relative humidity of 50%.

[0056] In a preferred embodiment, in step (3), the concentration of the CaCl2 solution is 2 wt%; the spraying amount of the CaCl2 solution is 1 g / cm³. 2 .

[0057] In a preferred embodiment, in step (3), the bio-based polysaccharide-cellulose nanocrystals-Ca 2+ The thickness of the bio-based polysaccharide-gelatin composite film is ≤200μm.

[0058] The present invention also provides an application of the temperature- and pH-responsive actuation film of the all-biomass-based Janus structure described above in an actuator.

[0059] In this embodiment of the invention, room temperature refers to "25±2℃".

[0060] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0061] Example 1

[0062] A temperature- and pH-responsive actuated film with a fully biomass-based Janus structure, composed of sodium alginate-cellulose nanocrystals-Ca 2+ Sodium alginate-gelatin composite film (SA-CNC-Ca) 2+ / SA-GEL composite membrane);

[0063] The specific steps for preparing the above-mentioned temperature- and pH-responsive actuated thin film with a fully biomass-based Janus structure are as follows:

[0064] (1) The cellulose nanocrystal solution (CNC) was sonicated for 15 min. 9 g of sodium alginate solution (SA) with a concentration of 1.5 wt% and 1 g of CNC solution with a concentration of 4 wt% were taken, mixed and magnetically stirred at room temperature for 2 h to obtain SA-CNC suspension. The obtained SA-CNC suspension was poured into a silicone mold and placed in a constant temperature and humidity chamber at 25 ℃ and 50% relative humidity for 7 h to obtain sodium alginate-cellulose nanocrystal gel membrane (SA-CNC gel membrane). The diameter of the cellulose nanocrystals in the cellulose nanocrystal solution was 4-10 nm and the length was 100-500 nm.

[0065] (2) Take 3g of 1.5wt% SA solution and 7g of 10wt% gelatin solution (GEL), mix them, and stir in a water bath at 45℃ for 1h to obtain sodium alginate-gelatin (SA-GEL) mixed solution; with gelatin accounting for the SA-CNC-Ca 2+ Based on 75% of the dry weight of the SA-GEL composite membrane, the obtained SA-GEL mixed solution was directly poured onto the SA-CNC gel membrane obtained in step (1), and placed in a constant temperature and humidity chamber at 25°C and 50% relative humidity until it was completely dried to obtain sodium alginate-cellulose nanocrystal / sodium alginate-gelatin composite membrane (SA-CNC / SA-GEL composite membrane).

[0066] (3) Take a 2wt% calcium chloride solution and apply it at a concentration of 1g / cm³. 2 The coating amount was uniformly sprayed onto the SA-CNC side of the SA-CNC / SA-GEL composite film obtained in step (2). After complete drying, a SA-CNC-Ca film with a thickness of 200 μm was obtained. 2+ / SA-GEL composite membrane is a temperature- and pH-responsive actuated membrane with a fully biomass-based Janus structure.

[0067] Example 2

[0068] A temperature- and pH-responsive actuated film with a fully biomass-based Janus structure, differing from Example 1 only in that, in step (2), gelatin is used to account for SA-CNC-Ca 2+ Based on 25% of the dry weight of the SA-GEL composite membrane, the obtained SA-GEL solution was directly poured onto the SA-CNC gel membrane obtained in step (1), and the rest was the same as in Example 1.

[0069] Example 3

[0070] A temperature- and pH-responsive actuated film with a fully biomass-based Janus structure, differing from Example 1 only in that, in step (2), gelatin is used to account for SA-CNC-Ca 2+Based on 50% of the dry weight of the SA-GEL composite membrane, the obtained SA-GEL solution was directly poured onto the SA-CNC gel membrane obtained in step (1), and the rest was the same as in Example 1.

[0071] Example 4

[0072] A temperature- and pH-responsive actuated film with a fully biomass-based Janus structure, differing from Example 1 only in that sodium alginate in steps (1) and (2) is replaced with equal masses of hyaluronic acid (HA), starch (AMY), chitosan (CS), or sodium carboxymethyl cellulose (CMC-Na), while the rest is the same as in Example 1.

[0073] Comparative Example 1

[0074] A method for preparing a single-layer sodium alginate-gelatin (SA-GEL) film:

[0075] Take 3g of 1.5wt% SA solution and 7g of 10wt% gelatin solution (GEL), mix them and stir in a water bath at 45℃ for 1h to obtain sodium alginate-gelatin (SA-GEL) mixed solution; pour the obtained SA-GEL mixed solution into a silicone mold and place it in a constant temperature and humidity chamber at 25℃ and 50% relative humidity until it is completely dried to obtain a single layer of sodium alginate-gelatin (SA-GEL) film.

[0076] Figure 1 The large-scale SA-CNC suspension, SA-GEL mixed solution, and SA-CNC-Ca prepared in Example 1 2+ The image shows a physical sample of the SA-GEL composite membrane, where a is a mixture of SA-CNC suspension and SA-GEL solution, and b is a mixture of SA-CNC and Ca2+. 2+ / SA-GEL composite membrane. From Figure 1 As can be seen from part a, both the SA-CNC suspension and the SA-GEL mixed solution are stable suspensions; from Figure 1 As can be seen from part b, in Example 1, a Janus film with a size of 100cm × 28cm was obtained by coating layer by layer using a film scraper.

[0077] Figure 2 SA-CNC-Ca prepared in Example 1 2+ Cross-sectional SEM image of the SA-GEL composite membrane. Figure 2 It can be seen that the SA-CNC-Ca prepared by the layer-by-layer casting method in Example 1... 2+ The SA-GEL composite membrane has a Janus structure.

[0078] Figure 3 SA-CNC-Ca prepared in Example 12+ EDS diagram of the SA-GEL composite membrane. From Figure 3 It can be seen that the SA-CNC-Ca prepared in Example 1 2+ In the SA-GEL composite film, the nitrogen element contained in the gelatin is concentrated on one side of the film.

[0079] Figure 4 SA-CNC-Ca prepared in Examples 1-3 2+ Mechanical properties of SA-GEL composite membranes. From... Figure 4 It can be seen that with the increase of gelatin content, the mechanical properties of the composite film gradually increase. The SA-CNC-Ca prepared in Example 1... 2+ The tensile strength of the SA-GEL composite film reaches 79 MPa, and the elongation at break reaches nearly 60%.

[0080] SA-CNC-Ca prepared in step 1 2+ The SA-GEL composite membrane was cut into a cross shape and placed in solutions with pH values ​​of 1, 3, 5, 7, 9, 11, and 13 obtained by mixing hydrochloric acid and sodium hydroxide solutions. The driving behavior of the composite membrane was observed, and the results are shown in [Figure number missing]. Figure 5 .

[0081] Figure 5 SA-CNC-Ca prepared in Example 1 2+ Physical images showing the driving behavior of the SA-GEL composite membrane in solutions at different pH values. Figure 5 It can be seen that as the solution pH increases from 1 to 13, SA-CNC-Ca 2+ The deformation of the SA-GEL composite membrane gradually decreases; at 120s, the deformation of the SA-CNC-Ca composite membrane gradually decreases. 2+ The SA-GEL composite membrane exhibited maximum deformation in solutions with pH values ​​of 1, 3, and 5.

[0082] The monolayer SA-GEL film prepared in Comparative Example 1 was cut into strips and placed in water at 60°C. The driving behavior of the film was observed, and the results are shown in [Figure 1]. Figure 6 .

[0083] Figure 6 A photograph showing the driving behavior of the monolayer SA-GEL film prepared for Comparative Example 1 in water at 60°C. Figure 6 It can be seen that within the time frame of 0-120s, the monolayer SA-GEL film prepared in Comparative Example 1 did not exhibit curling behavior in water at 60℃.

[0084] The SA-CNC-Ca prepared in Example 1 2+The SA-GEL composite membrane was cut into strips, first placed in water at 60℃, then in water at 20℃, and the driving behavior of the composite membrane was observed. The results are shown in [the table below]. Figure 7 .

[0085] Figure 7 SA-CNC-Ca prepared in Example 1 2+ Physical images showing the driving behavior of the SA-GEL composite membrane in water at 60℃ and 20℃, where a represents 60℃ and b represents 20℃. Figure 7 It can be seen that the SA-CNC-Ca prepared in Example 1 2+ The SA-GEL composite membrane can bend 120.36° in 9 seconds in water at 60°C and completely curls up in 12 seconds. After being placed in water at 20°C, the composite membrane gradually recovers and fully recovers in 140 seconds.

[0086] The SA-CNC-Ca prepared in Example 1 2+ The SA-GEL composite membrane was cut into a cross shape. The cut membrane was then used as an actuator to grasp and release plastic sheets from deionized water. The results are shown below. Figure 8 .

[0087] Figure 8 SA-CNC-Ca prepared in Example 1 2+ A photograph showing an SA-GEL composite membrane acting as an actuator to grip a plastic sheet from water at 60°C and release it at 20°C. In the figure, a represents 60°C and b represents 20°C. Figure 8 It can be seen that when the cross-shaped composite membrane is placed in deionized water at 60°C, it can bend completely and grasp the plastic sheet well within 16 seconds; when the composite membrane that has grasped the plastic sheet is put back into deionized water at 20°C, the robotic arm that has fully formed the composite membrane gradually opens and releases the plastic sheet, indicating that the temperature and pH responsive actuation film of the all-biomass-based Janus structure provided by the present invention has potential application scenarios in the field of flexible robots.

[0088] Figure 9 Bio-based polysaccharide-cellulose nanocrystals-Ca prepared in Examples 1 and 4 2+ / A physical image of a bio-based polysaccharide-gelatin composite film. From Figure 9 It can be seen that composite membranes can be prepared by using hyaluronic acid, starch, chitosan, sodium carboxymethyl cellulose, or sodium alginate as bio-based polysaccharides.

[0089] Figure 10 Bio-based polysaccharide-cellulose nanocrystals-Ca prepared in Examples 1 and 4 2+ / Comparison of mechanical properties of bio-based polysaccharide-gelatin composite films. From Figure 10It can be seen that composite membranes made using hyaluronic acid, starch, chitosan, sodium carboxymethyl cellulose, or sodium alginate as bio-based polysaccharides all have good mechanical properties.

[0090] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A fully biomass-based Janus structured temperature, pH responsive actuating film, characterized in that, The temperature, pH responsive actuating thin film of the full-biomass-based Janus structure is a bio-based polysaccharide-cellulose nanocrystal-Ca 2+ / bio-based polysaccharide-gelatin composite film.

2. The fully biomass-based Janus structured temperature and pH responsive actuating film according to claim 1, wherein, The bio-based polysaccharide-cellulose nanocrystals-Ca 2+ The bio-based polysaccharide in the bio-based polysaccharide-gelatin composite film is selected from hyaluronic acid, starch, chitosan, sodium carboxymethyl cellulose or sodium alginate.

3. A method for preparing the all-biomass-based Janus structured temperature and pH responsive actuating film according to any one of claims 1-2, characterized in that, The method comprises the following steps: (1) preparing a bio-based polysaccharide-cellulose nanocrystal gel film; (2) pouring a mixed solution of bio-based polysaccharide and gelatin on the bio-based polysaccharide-cellulose nanocrystal gel film, and evaporating the solvent to obtain a bio-based polysaccharide-cellulose nanocrystal / bio-based polysaccharide-gelatin composite film; (3) spraying CaCl2 solution on the side of the bio-based polysaccharide-cellulose nanocrystal of the bio-based polysaccharide-cellulose nanocrystal / bio-based polysaccharide-gelatin composite film, and drying to obtain a bio-based polysaccharide-cellulose nanocrystal-Ca 2+ / bio-based polysaccharide-gelatin composite film, which is a Janus structure temperature and pH responsive actuating film based on full biomass.

4. The production method according to claim 3, characterized by, In step (1), the preparation method of the bio-based polysaccharide-cellulose nanocrystal gel film comprises: mixing a cellulose nanocrystal solution and a bio-based polysaccharide solution, stirring to obtain a suspension; pouring the suspension into a mold, and placing to obtain the bio-based polysaccharide-cellulose nanocrystal gel film.

5. The preparation method according to claim 4, characterized in that, The cellulose nanocrystals in the cellulose nanocrystal solution have a diameter of 4-10 nm and a length of 100-500 nm; The concentration of the bio-based polysaccharide solution is 1.5 wt%; the concentration of the cellulose nanocrystal solution is 4 wt%; and the mass ratio of the bio-based polysaccharide solution to the cellulose nanocrystal solution is 9:

1.

6. The preparation method according to claim 3, characterized in that, In step (2), the preparation method of the mixed solution of bio-based polysaccharide and gelatin comprises: mixing a bio-based polysaccharide solution and a gelatin solution, and stirring to obtain the mixed solution of bio-based polysaccharide and gelatin; The concentration of the bio-based polysaccharide solution is 1.5 wt%; the concentration of the gelatin solution is 10 wt%; and the mass ratio of the bio-based polysaccharide solution to the gelatin solution is 3:7; The stirring temperature is 45°C, and the stirring time is 1 h.

7. The preparation method according to claim 3, characterized in that, In step (2), the amount of the mixed solution of the biobased polysaccharide and the gelatin to be poured is 25 to 75% based on the dry weight of the biobased polysaccharide-gelatin composite film. 2+ / biobased polysaccharide-gelatin composite film.

8. The preparation method according to claim 3, characterized in that, In step (3), the concentration of the CaCl2 solution is 2 wt%; the spraying amount of the CaCl2 solution is 1 g / cm2. 2 .

9. The preparation method according to claim 3, characterized in that, In step (3), the bio-based polysaccharide-cellulose nanocrystals-Ca 2+ The thickness of the bio-based polysaccharide-gelatin composite film is ≤ 200 μm.

10. Use of the full-biomass-based Janus structure temperature and pH responsive actuating film according to any one of claims 1-2 in an actuator.

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