An apparatus and method for preparing thermotropic hydrogels

Abstract

This invention belongs to the field of thermotropic hydrogel synthesis technology, specifically relating to a preparation apparatus and method for thermotropic hydrogels. This invention discloses a preparation apparatus that integrates polymerization and water washing into the same reaction device, and a method for preparing thermotropic hydrogels using this apparatus. Through the design of an integrated purification plug on the reaction vessel, the production efficiency of thermotropic hydrogel products is improved, while production losses and costs are reduced, establishing a method for the continuous and automated production of thermotropic hydrogel products.

Description

Technical Field

[0001] This invention belongs to the field of thermotropic hydrogel synthesis technology, specifically relating to a thermotropic hydrogel preparation apparatus and preparation method. Background Technology

[0002] Thermogels are temperature-sensitive physical gels that have been widely studied and applied in the field of biomedical materials due to their excellent biocompatibility and biodegradability. The main component of thermogels is an aqueous solution of an amphiphilic polyester-polyether block copolymer. At low temperatures, they spontaneously form micelles with hydrophilic outer halos of polyether segments and hydrophobic cores of polyester segments, thus exhibiting a macroscopically flowable liquid appearance. However, as the temperature rises to body temperature, the hydrophilicity of the polyether segments decreases, and the micelles spontaneously aggregate under the drive of hydrophobic interactions to form a percolation micelle network, resulting in a macroscopically non-flowing gel state. This liquid-solid phase transition behavior adapted to human body temperature makes thermogels particularly suitable for minimally invasive injectable medical applications, showing great industrialization potential whether used as a standalone medical device or in combination with a drug. The industry has begun exploring industrial production methods for this material.

[0003] The production of thermotropic hydrogels is mainly achieved through the ring-opening polymerization of cyclic ester monomers initiated by polyether initiators. The main process involves ring-opening reactions, which can be carried out in solution polymerization with the addition of organic solvents such as tetrahydrofuran, toluene, and DMF, or in bulk polymerization without additional solvents. Post-treatment of the polymerization product primarily involves two methods: ether precipitation and hot water washing. To prepare aqueous solutions of specific concentrations, the polymerization product usually requires freeze-drying after post-treatment to obtain a pure polymer bulk.

[0004] Current technologies lack specialized equipment for the production of thermotropic hydrogels. To avoid the use of large amounts of organic solvents, the synthesis process primarily employs bulk polymerization. After the raw materials have completely reacted in a standard reaction vessel, they need to be transferred in bulk form to another vessel for post-processing. This process requires manual operation, is time-consuming and labor-intensive, and due to the viscoelasticity of the polymer, the polymerized product tends to adhere to the vessel walls during transfer, resulting in significant waste and being difficult to clean. Considering that diethyl ether is a controlled chemical, the post-processing of the polymerized product tends to use hot water washing methods, and the large amount of residual water in the system is usually removed by freeze-drying, which is energy-intensive. These technical problems significantly reduce the production efficiency of thermotropic hydrogels, leading to a substantial increase in production costs.

[0005] Therefore, there is an urgent need to find a suitable preparation device and method for continuous and automated production, in order to improve production efficiency and reduce energy consumption by avoiding material loss and optimizing the process flow, effectively save costs and ensure product safety, and meet the green production requirements of biomedical materials. Summary of the Invention

[0006] In view of this, the first objective of the present invention is to provide a continuous and automated thermogenic hydrogel preparation apparatus to address the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A thermotropic hydrogel preparation apparatus, the apparatus comprising a polymerization reactor and an auxiliary reactor, wherein the discharge end of the auxiliary reactor is connected to the feed end of the polymerization reactor via a pipeline; the polymerization reactor comprises a reaction vessel (1), the top of the reaction vessel (1) is closed and sealed by a lid (2), a stirring component (3) is fixedly installed in the center of the top of the lid (2), and a plug-in mounting hole (6) is provided on the upper part of the reactor for connecting plug-ins; the plug-ins include a purification plug-in, the purification plug-in including a support (7), a transmission mechanism (8) and a bent tube (9), the support (7) is connected to the plug-in mounting hole (6), and the transmission mechanism (8) located on the support (7) drives the bent tube (9) to move vertically up and down inside the reaction vessel.

[0009] It is worth noting that, due to the amphiphilic nature of thermotropic hydrogels, the separation interface between the purified crude product and the purified waste liquid may vary significantly between batches and even between different purification processes. This can result in the purified crude product and the purified waste liquid not being effectively separated through the outlet of a standard reaction vessel.

[0010] Therefore, by setting up the bend (9) in the purification plug, the present invention uses the vertically lifting bend (9) inside the reaction vessel to find the separation interface between the crude product after solvent purification and the purification waste liquid. On the one hand, the waste liquid is sucked out by the bend (9), realizing the effective separation of the purification waste liquid and the crude product; on the other hand, the vertical lifting function is used to simultaneously meet the needs of different separation interface heights for products of different specifications and different equivalents without disassembling any components.

[0011] Furthermore, the bend (9) is a hollow pipe and is connected to the waste liquid outlet of the reactor via a pipe and is equipped with a valve.

[0012] Furthermore, the bent pipe (9) is connected to the washing liquid inlet of the reactor via a pipeline.

[0013] It is worth noting that the purification plugin may be one or multiple independent plugins.

[0014] During operation, open the valve at the connection between the bent pipe (9) and the inlet of the reaction vessel washing liquid, add the washing liquid to begin the purification process of the polymerization product. After purification, let it stand for a certain period of time to separate the purified waste liquid from the crude product. Close the valve at the connection between the bent pipe (9) and the inlet of the reaction vessel washing liquid, and open the transmission mechanism (8) located on the support (7) to drive the bent pipe (9) to move vertically up and down inside the reaction vessel. After the lower end of the bent pipe (9) is at a suitable height, open the valve at the connection between the bent pipe (9) and the outlet of the reaction vessel waste liquid to extract the purified waste liquid. Repeat this process several times to complete the purification process.

[0015] Furthermore, the reactor also includes a viewing window (10), which is disposed on the outer wall of the reactor and parallel to the vertical lifting path of the bend (9).

[0016] Considering that different products have different specifications and equivalents, the separation interface height between the purified crude product and the purified waste liquid is also different. Therefore, this invention patent sets a viewing window (10) on the outer wall of the reactor, parallel to the vertical lifting path of the bent tube (9), to ensure that the lower end of the bent tube (9) is flush with the separation interface.

[0017] Furthermore, the device also includes a homogenizing insert, the homogenizing function of which includes one or more combinations of stirring, high-speed shearing, fluid jetting, and ultrasound.

[0018] Preferably, the homogenization function includes fluid jetting and ultrasound.

[0019] Preferably, the homogenizing function is ultrasound.

[0020] It is worth noting that the homogenizing module is a device independent of the main stirring component of the reactor. Its function is to significantly accelerate the mixing of the washing solution and the precipitate during the purification and dissolution stages, thereby improving production efficiency. Furthermore, the homogenizing module significantly assists in the automated cleaning of the purification, dissolution, and polymerization reactors, further enhancing production efficiency.

[0021] Based on the need for production process automation, this invention can also achieve automated cleaning of polymerization reactors. Cleaning water containing polymeric surfactants is sequentially added to the auxiliary vessel and the polymerization reactor until full. Stirring is used to clean the reactor with the cleaning water. Wastewater is discharged and fresh cleaning water is added, completing one cleaning cycle. After repeated washing, fresh water is added to rinse the cleaning water away, completing the cleaning of the polymerization reactor. The use of a homogenizing insert on the reactor lid further improves the efficiency of post-processing and cleaning, and further reduces production costs. Furthermore, the device also includes a regulating tank, the inlet of which is connected to the outlet of either the reactor or the auxiliary vessel via pipelines.

[0022] In some embodiments, from the feed end to the discharge end, the auxiliary vessel, the polymerization reactor, and the regulating tank are connected in sequence via pipelines.

[0023] In other embodiments, the auxiliary vessel, polymerization reactor, and regulating tank are connected sequentially via pipelines from the feed end to the discharge end. At the same time, the discharge end of the auxiliary vessel is also connected to the feed end of the regulating tank via a pipeline.

[0024] It is worth noting that, considering the reaction equivalence and production efficiency, the aforementioned auxiliary vessel, polymerization reactor, and regulating tank can be one or more to meet different production needs.

[0025] When there are multiple auxiliary vessels, each auxiliary vessel can be connected to a different polymerization reactor or to the same polymerization reactor; each auxiliary vessel can be connected to a different regulating tank or to the same regulating tank.

[0026] When there are multiple polymerization reactors, each polymerization reactor can be connected to different auxiliary reactors or to the same auxiliary reactor; each polymerization reactor can be connected to different regulating tanks or to the same regulating tank.

[0027] When multiple regulating tanks are used, each regulating tank can be connected to a different auxiliary vessel or to the same auxiliary vessel; each regulating tank can be connected to a different polymerization reactor or to the same polymerization reactor. It is worth noting that the device also includes a reaction monitoring module, which includes an internally and externally double-closed airtight valve and a sampling rod. Adding the reaction monitoring module allows for the collection of small samples during the reaction process to monitor the progress of the reaction, helping to ensure batch-to-batch stability of the product and reduce production losses.

[0028] A second objective of this invention is to address the problems existing in the prior art by providing a continuous, solvent-free, low-energy-consumption, high-efficiency, safe, and environmentally friendly method for preparing thermotropic hydrogels. This preparation method can be achieved using the preparation apparatus described above.

[0029] To achieve the above objectives, the present invention adopts the following technical solution:

[0030] A method for preparing a thermotropic hydrogel includes a polymerization reaction, a water washing process, a crude product dissolution process, and a product output process, wherein the polymerization reaction, the water washing process, and the crude product dissolution process are all continuous, same-stage reactions.

[0031] It is worth noting that existing technologies for synthesizing thermotropic hydrogels mainly employ bulk polymerization. After the raw materials have completely reacted in a standardized reaction vessel, they need to be transferred in bulk form to another vessel for post-processing. This process requires manual operation, is time-consuming and labor-intensive, and due to the viscoelasticity of the polymer, the polymerized product will adhere to the vessel walls during the transfer, resulting in significant waste and being difficult to clean. Therefore, to avoid material loss and increased production costs caused by vessel transfer, this invention integrates the polymerization reaction, water washing, and crude product dissolution into a continuous co-reactor reaction, effectively improving the yield and production efficiency of thermotropic hydrogel products in industrial production.

[0032] Furthermore, the preparation method of the thermotropic hydrogel includes the following steps:

[0033] S1, Polymerization reaction:

[0034] Initiators are added to the polymerization reactor and auxiliary reactor according to the component equivalents. Vacuum is drawn and the temperature inside the reactor is raised to 40-120 ℃ using a temperature control device. After removing impurities contained in the initiator, nitrogen gas is introduced to restore the pressure inside the reactor to normal pressure. Then, one or more polymerizable monomers are added sequentially according to the formula, and impurities contained in the monomers are removed by vacuuming. Nitrogen gas is then introduced again to restore the pressure inside the reactor to normal pressure. Finally, the temperature inside the reactor is raised to 80-180 ℃, and an appropriate amount of catalyst is added to start the polymerization reaction until the reaction is completed.

[0035] S2. Water washing treatment:

[0036] Hot water at 30-100 ℃ is pumped into the polymerization reactor and auxiliary vessel respectively by a metering pump. The temperature inside the vessel is controlled within a suitable range by a temperature control device, and stirring is turned on. After stirring for a suitable time, the mixture is allowed to stand and settle for a period of time. The supernatant is then extracted and an appropriate amount of fresh hot water is added again, which is considered to complete one water wash. The water wash is repeated several times. The amount of fresh hot water added and the amount of supernatant extracted are measured for each water wash. The precipitate is retained in the polymerization reactor and auxiliary vessel for later use.

[0037] S3. Crude product dissolution:

[0038] Fresh water was added to the polymerization reactor and the auxiliary reactor respectively, so that the precipitate obtained by water washing was dissolved into an aqueous solution of a certain concentration. A portion of the aqueous solution in the auxiliary reactor was transferred to the polymerization reactor to make the precipitate in the polymerization reactor dissolve more completely. The remaining portion of the aqueous solution was left in the auxiliary reactor for disposal.

[0039] S4. Product Transfer and Export:

[0040] After the polymerization product is fully dissolved in the polymerization reactor, the resulting aqueous solution is transferred to a regulating tank, and the solution is purified during the transfer process. After the aqueous solution is transferred to the regulating tank, its actual gelling properties are measured, and the temperature is adjusted by adding fresh water until the gelling temperature reaches a suitable range. The aqueous solution is then output to subsequent processes, which is the thermotropic hydrogel product.

[0041] After polymerization, and / or during water washing, and / or during crude product dissolution, and / or after product transfer and before product output, small samples of semi-finished / finished products are taken from each process container in the process flow to test and adjust the product's gelation properties in real time.

[0042] It is worth noting that, firstly, the method for preparing thermotropic hydrogels disclosed in this invention avoids the use of large amounts of organic solvents through bulk polymerization, especially by controlling the use of organic solvents, which can significantly reduce environmental costs while improving raw material utilization. Secondly, this invention also employs an integrated reaction device, concentrating the polymerization reaction and water washing treatment in the same device, and successfully transferring materials between various process equipment in a fluid form through dissolution, avoiding material loss and manpower costs caused by bulk transfer. Furthermore, this invention monitors quality control indicators such as the yield of the water-washed product, the water content of the water-washed product, and the gelling properties of the thermotropic hydrogel product in real time during the production process. This not only avoids the extremely energy-intensive process of freeze-drying and re-dissolving, but also allows for real-time adjustment of the gelling properties of the produced product, thereby ensuring product yield and batch stability, significantly improving production efficiency and reducing energy consumption, resulting in a substantial reduction in production costs.

[0043] Considering material transfer efficiency and equipment wear, the material transfer between each process step is carried out in fluid form. The water washing treatment is performed 1-10 times. Furthermore, the initiator includes one or more of polyethylene glycol, polyethylene glycol monomethyl ether, aminated polyethylene glycol, aminated polyethylene glycol monomethyl ether, mercapto polyethylene glycol, or mercapto polyethylene glycol monomethyl ether; the polymerized monomer includes one or more of lactide, glycolide, caprolactone, valerate, and trimethylene carbonate.

[0044] Furthermore, the suitable range for the gelation temperature is 10 ℃ to 40 ℃.

[0045] It is worth noting that, based on the requirements of fully automated production, the aqueous solution to be treated in the auxiliary vessel can be used to achieve automated cleaning of the polymerization reactor. The aqueous solution to be used in the auxiliary vessel and fresh water are mixed in a certain proportion to form cleaning water, which is then added to the polymerization reactor until it is full. Stirring is then started, allowing the cleaning water to thoroughly rinse the reactor walls and all covered areas. The cleaning water is then drained and new cleaning water is added, which is considered to complete one cleaning cycle. After repeating this washing process multiple times, fresh water is added to rinse the cleaning water off completely, which is considered to complete the cleaning of the polymerization reactor.

[0046] Considering the diverse product demands of the market, the raw material composition and the ratio of semi-finished / finished product output between the polymerization reactor and the auxiliary reactor can be changed according to the performance requirements of the final product, so as to realize the pre-adjustment of product performance in real time.

[0047] The pre-adjustment is relative to the precise adjustment in step S4. That is, the performance adjustment of the pre-adjustment is fast but not precise enough, while the precise adjustment can ensure that the final output product meets the expected performance requirements.

[0048] It is worth noting that the aforementioned production process and reactor are not limited to combined use; they can also significantly improve the production efficiency of thermotropic hydrogel products when used alone. Furthermore, the combined use of the aforementioned production process and reactor can maximize the production efficiency of thermotropic hydrogel products.

[0049] In some embodiments, depending on specific process requirements, the apparatus for preparing thermotropic hydrogels may have different equipment combinations, and the raw material ratios of different polymerization reactors and different auxiliary reactors may be different. The general implementation method is as follows:

[0050] An apparatus for preparing thermotropic hydrogels includes a synthesis reactor, an auxiliary reactor, and a regulating tank. The discharge end of the auxiliary reactor is connected to the feed end of the synthesis reactor via a pipeline, and the feed end of the regulating tank is connected to the discharge end of either the reactor or the auxiliary reactor via a pipeline.

[0051] The polymerization reactor includes a reaction vessel (1), the top of which is sealed by a lid (2). A stirring component (3) is fixedly installed in the center of the top of the lid (2). A plug-in mounting hole (6) is provided on the upper part of the reactor for connecting plug-ins. The plug-ins include a purification plug-in, which includes a support (7), a transmission mechanism (8), and a bent tube (9). The support (7) is connected to the plug-in mounting hole (6). The transmission mechanism (8) located on the support (7) drives the bent tube (9) to move vertically up and down inside the reaction vessel.

[0052] Furthermore, the bend (9) is a hollow pipe and is connected to the waste liquid outlet of the reactor through the pipe.

[0053] Furthermore, the bent pipe (9) is connected to the washing liquid inlet of the reactor via a pipeline.

[0054] Furthermore, the purification plugin may be one or multiple independent plugins.

[0055] Furthermore, the reactor also includes a viewing window (10), which is disposed on the outer wall of the reactor and parallel to the vertical lifting path of the bend (9).

[0056] Furthermore, the plug-in also includes a homogenizing plug-in, the homogenizing function of which includes one or more combinations of stirring, high-speed shearing, fluid jetting, and ultrasound.

[0057] Furthermore, the plug-in also includes a reaction monitoring plug-in, which includes an internal and external double-closed airtight valve and a sampling rod.

[0058] A method for preparing a thermotropic hydrogel based on the aforementioned preparation apparatus is as follows:

[0059] S1, Polymerization reaction:

[0060] One or more monomers and initiators are added to the polymerization reactor and auxiliary reactor in process equivalent amounts. Each reactor is evacuated and the internal temperature is raised to 40-120 °C using a temperature control device to remove impurities such as moisture from the polymerization raw materials. Then, nitrogen gas is introduced to restore the pressure inside each reactor to atmospheric pressure and place it under a nitrogen atmosphere. The internal temperature is further raised to 80-180 °C, and an appropriate amount of stannous isooctanoate catalyst is added to initiate the polymerization reaction until it is completed.

[0061] S2. Water washing treatment:

[0062] The washing process and the polymerization reaction process are integrated into the same container, namely the reactor. An appropriate amount of hot water at 30-100℃ is introduced into the reactor, and the temperature inside the reactor is controlled within a suitable range using a temperature control device while stirring is started. After stirring for a suitable time, the mixture is allowed to settle, and the supernatant is drawn into the washing wastewater tank and an appropriate amount of hot water is added again, which is considered to complete one washing cycle. After washing 1-10 times, the yield and water content of the polymerization product after washing are measured.

[0063] S3. Crude product dissolution:

[0064] Based on the measured yield and water content, appropriate amounts of fresh water were added to the polymerization reactor and the auxiliary reactor respectively, so that the precipitate obtained from water washing was dissolved into an aqueous solution of a certain concentration. A portion of the aqueous solution in the auxiliary reactor was transferred to the polymerization reactor to make the precipitate in the reactor dissolve more fully. The remaining portion of the aqueous solution was left in the auxiliary reactor for disposal.

[0065] S4. Product Transfer and Export:

[0066] For specific biomedical applications, it is necessary to monitor the gel-forming properties of thermotropic hydrogels during the production process. After the polymerization product is fully dissolved in the polymerization reactor, the gel-forming properties of the aqueous solution are rapidly detected using instruments. The solution is initially adjusted by controlling the amount of aqueous solution added to an auxiliary reactor. The resulting aqueous solution is then transferred to a conditioning tank, where the solution is purified during the transfer process. After the aqueous solution is transferred to the conditioning tank, the actual gel-forming properties are accurately measured, and the gel-forming properties are precisely adjusted by adding fresh water until the gel-forming temperature reaches a suitable range. The aqueous solution is then output for subsequent processes, resulting in the thermotropic hydrogel product.

[0067] After polymerization, and / or during water washing, and / or during dissolution and transfer, and / or after dissolution and transfer, and before outputting the product, small samples of the semi-finished / finished products in each process container in the process flow are taken to test and adjust the gelling properties of the product in real time; the gelling properties of the product are initially adjusted by controlling the amount of aqueous solution added in the auxiliary reactor in step S2, and the gelling properties of the product are precisely adjusted by adjusting the ratio of fresh water and polymer aqueous solution in the adjustment tank in step S4; after monitoring and achieving the target, a thermotropic hydrogel product with suitable gelling properties is output to the subsequent processes.

[0068] Compared with the prior art, the advantages of the present invention are as follows:

[0069] 1) By using bulk polymerization, the use of large amounts of organic solvents is avoided, which can improve the utilization rate of raw materials and significantly reduce environmental costs, enabling the production of thermotropic hydrogel products at a competitive cost.

[0070] 2) The automated process enables the integration of production and quality control. During the production process, indicators such as the yield of washed products, the water content of washed products, and the gelation performance of thermotropic hydrogel products can be monitored in real time. This not only avoids the extremely energy-intensive process of freeze-drying and re-dissolving, but also enables real-time adjustment of the gelation performance of the products, thereby ensuring the yield and batch stability of the products, greatly improving production efficiency and reducing energy consumption, and significantly reducing production costs.

[0071] 3) By integrating the water washing process into the reactor, material loss from direct transfer of the polymer body is avoided, saving labor and time costs. At the same time, the thermotropic hydrogel preparation device achieves direct interconnection of pipelines between the main equipment, providing conditions for production automation and further improving the production efficiency of thermotropic hydrogel products.

[0072] 4) The design of the purification plug on the reactor lid integrates the polymerization reaction process and the post-processing process on the reactor. The adjustable bend on the plug eliminates the need to open and close the reactor lid during the purification process, avoiding the uncertainty caused by manual operation. This not only improves the batch stability of the product but also increases operational efficiency, making the entire production process more streamlined, and thus more energy-efficient and cost-effective.

[0073] 5) Based on the requirement of fully automated production process, the polymerization reactor can be selectively automated for cleaning. The aqueous solution to be treated in the auxiliary vessel and fresh water are mixed in a certain proportion to form cleaning water, which is then added to the polymerization reactor until it is full. Stirring ensures the cleaning water thoroughly rinses the reactor walls and all parts covered by the cleaning solution. Wastewater is discharged and new cleaning water is added, completing one cleaning cycle. After repeated washing, fresh water is added to rinse the cleaning water completely, completing the cleaning of the polymerization reactor. By using a homogenizing insert on the reactor lid, the efficiency of steps S2 and S3, as well as the automated cleaning of the polymerization reactor, can be further improved, and production costs can be further reduced.

[0074] 6) Considering that the production requirements of products with different performance characteristics vary, multiple polymerization reactors and auxiliary reactors can be arranged and combined to flexibly adjust both product performance and output. Parallel connection of reactors allows for flexible adjustment of raw material ratios, thereby enabling flexible adjustment of product performance; series connection of reactors allows for flexible increase or decrease in output, avoiding the problem of batch-to-batch instability caused by fluctuations in reactor efficiency with changes in load rate. Attached Figure Description

[0075] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0076] Figure 1 This is a front-view sectional view of the polymerization reactor in the thermotropic hydrogel preparation device of the present invention. The numbers in the figure are: 1. Reaction vessel; 2. Reactor cover; 3. Stirring component; 4. Drive shaft; 5. Stirring paddle; 6. Insert mounting hole; 7. Insert bracket; 8. Transmission mechanism; 9. Hollow bend; 10. Viewing window.

[0077] Figure 2 This is a flow chart of a thermotropic hydrogel production process proposed in this invention.

[0078] Figure 3 This is a schematic diagram of a thermotropic hydrogel preparation apparatus disclosed in Embodiment 1 of the present invention.

[0079] Figure 4 This is a schematic diagram of a thermotropic hydrogel preparation apparatus disclosed in Embodiment 2 of the present invention.

[0080] Figure 5 This is a schematic diagram of a thermotropic hydrogel preparation apparatus disclosed in Embodiment 4 of the present invention.

[0081] Figure 6 This is a schematic diagram of a thermotropic hydrogel preparation apparatus disclosed in Embodiment 5 of the present invention. Detailed Implementation

[0082] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0083] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0084] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0085] In the description of this invention, it should be understood that the terms "middle", "upper", "lower", "rise", "fall", "vertical", "surface", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0086] Furthermore, the terms "A," "B," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "A," "B," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0087] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0088] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0089] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention. Example 1

[0090] An apparatus and method for preparing thermotropic hydrogels:

[0091] An apparatus for preparing thermotropic hydrogels (with attachment) Figure 3 It includes a polymerization reactor, an auxiliary reactor, and a regulating tank.

[0092] The reactor includes a reaction vessel 1, the top of which is sealed by a lid 2. A stirring component 3 is fixedly installed in the center of the top of the lid 2. A plug-in mounting hole 6 is provided on the upper part of the reactor for connecting plug-ins.

[0093] The plug-in includes a purification plug-in, which comprises a support 7, a transmission mechanism 8, and a bend 9. The support 7 is connected to the plug-in mounting hole 6, and the transmission mechanism 8, located on the support 7, drives the bend 9 to move vertically up and down inside the reaction vessel. The bend 9 is a hollow pipe and is connected to the waste liquid outlet and washing liquid inlet of the reaction vessel via a pipeline.

[0094] During operation, the reactants are added to the polymerization reactor and auxiliary vessel, the switch is turned on and the vessel lid 2 is closed. The polymerization reaction proceeds under preset reaction conditions to obtain crude polymer. Subsequent post-processing steps then begin directly in the polymerization reactor and auxiliary vessel.

[0095] When washing solution needs to be introduced, the transmission mechanism 8 is activated to raise the bent pipe 9 to near the top of the reaction vessel 1, i.e., the bottom of the vessel lid 2, allowing the washing solution to enter the reaction vessel 1. The homogenizing insert is then activated, and the crude product is cleaned using ultrasound. After cleaning, the inlet of the bent pipe 9 is adjusted via the viewing window 10 to be below the supernatant surface, close to the interface between the precipitate and the supernatant, to remove as much supernatant as possible, leaving only the precipitate, thereby improving post-processing efficiency. The installation of the insert on the vessel lid 2 integrates the polymerization reaction process and the purification process on the reaction vessel 1, thereby improving production efficiency and reducing production costs.

[0096] After the purification process is completed, fresh pure water is first introduced into both the polymerization reactor and the auxiliary reactor to dissolve the polymer precipitate into an aqueous solution. Then, the polymer aqueous solution from the auxiliary reactor is introduced into the polymerization reactor. After the crude product in the auxiliary polymerization reactor is fully dissolved, both are introduced into the regulating tank. In the regulating tank, the crude polymer aqueous solution is thoroughly mixed and adjusted to a suitable concentration to obtain the final product—a thermotropic hydrogel solution.

[0097] A method for preparing a thermotropic hydrogel, comprising:

[0098] S1, Polymerization reaction:

[0099] Add 488 g of polyethylene glycol and 1512 g of lactide monomer to the polymerization reactor; add 500 g of polyethylene glycol initiator and 800 g of lactide monomer to the auxiliary reactor; close the reactor lid and start stirring, setting the stirring speed to 300 rpm; turn on the vacuum pump to remove air from the reactor, and after the absolute pressure is <500 Pa, introduce nitrogen to complete one replacement. After three replacements, close the gas valve and maintain the vacuum state in the reactor using the vacuum pump. Turn on the temperature control device to raise the temperature of the material in the reactor to 80 ℃ and maintain it for 30 min to remove light component impurities such as moisture. Then turn off the vacuum pump and introduce nitrogen to maintain a nitrogen atmosphere in the reactor. Set the temperature control device to 140 ℃ and maintain the temperature for 30 min. Then add 4 g of stannous isooctanoate catalyst. Start timing from the time the catalyst is added. After about 3 hours of reaction, cool down to 60 ℃ to complete the polymerization reaction. All polymerization products are left in the reactor for later use.

[0100] S2. Water washing treatment:

[0101] Add hot water at 60°C to each reactor according to three times the mass of the polymerization raw materials. That is, add 6000 g of hot water to the polymerization reactor and 4000 g of hot water to the auxiliary reactor. Increase the stirring speed to 500 rpm and stir for 10 minutes. Then turn off the stirring and let it stand for 5 minutes. After standing, the water system in the reactor separates into precipitate and supernatant. Turn on the servo motor of the bending pipe lifting device and lower the lower end of the bending pipe below the supernatant liquid level. The supernatant is sucked out into the washing wastewater tank and fresh hot water is added. This is considered to complete one washing cycle. The amount of fresh hot water added and the amount of supernatant sucked out are measured for each washing cycle. After 10 washing cycles, a relatively pure water system of polymerization product is obtained and kept in the reactor for later use. Then, the solid content of the washing wastewater is tested. The yield of the polymerization product and the water content of the polymerization product water system after washing are calculated from four parameters: solid content of wastewater, total amount of wastewater sucked out, total amount of fresh hot water added, and amount of polymerization raw materials fed. In this embodiment, the yield of the polymerization product in the polymerization reactor and the water content of the water system are 93% and 30%, respectively, while the yield of the polymerization product in the auxiliary reactor and the water content of the water system are 80% and 50%, respectively.

[0102] S3. Crude product dissolution:

[0103] After adjusting the temperature inside the polymerization reactor to 25 °C using a temperature control device, 4200 g of fresh water was introduced into the reactor, and stirring was started to dissolve the polymer precipitate in the reactor into a 25 wt% aqueous solution, which was then set aside for later use. 1200 g of fresh water was introduced into an auxiliary reactor, and stirring was started. Simultaneously, the temperature inside the auxiliary reactor was gradually lowered to 25 °C using a temperature control device, causing the polymer precipitate therein to also dissolve into a 25 wt% aqueous solution. After complete dissolution, the aqueous solution from the auxiliary reactor was gradually introduced into the polymerization reactor through a transfer pump and pipeline and mixed thoroughly. The gelation temperature was monitored using a rotational rheometer. The remaining aqueous solution (approximately 15%) remained in the auxiliary reactor for further processing.

[0104] S4. Product Transfer and Export:

[0105] The uniformly mixed aqueous solution is extracted from the polymerization reactor and allowed to settle. The supernatant is then passed into a conditioning tank. The expected gelation temperature of the product is 35 °C. The actual gelation properties of the aqueous solution in the conditioning tank are measured using a rotational rheometer. If the actual gelation temperature of the aqueous solution is within the predetermined range, i.e., between 34 °C and 36 °C, the aqueous solution is directly output as a thermotropic hydrogel product for subsequent processes. If the gelation properties are below 34 °C, an appropriate proportion of fresh water and the aqueous solution in the auxiliary reactor are added to the conditioning tank, mixed thoroughly, and the gelation temperature is measured again. This operation is repeated until the gelation temperature of the aqueous solution in the conditioning tank is within the predetermined range, i.e., between 34 °C and 36 °C.

[0106] Example 2

[0107] An apparatus and method for preparing thermotropic hydrogels:

[0108] An apparatus for preparing thermotropic hydrogels (with attachment) Figure 4 It includes a polymerization reactor, an auxiliary reactor, and a regulating tank.

[0109] The reactor includes a reaction vessel 1, the top of which is sealed by a lid 2. A stirring component 3 is fixedly installed in the center of the top of the lid 2. A plug-in mounting hole 6 is provided on the upper part of the reactor for connecting plug-ins.

[0110] The plug-in includes a purification plug-in, which comprises a support 7, a transmission mechanism 8, and a bend 9. The support 7 is connected to the plug-in mounting hole 6, and the transmission mechanism 8, located on the support 7, drives the bend 9 to move vertically up and down inside the reaction vessel. The bend 9 is a hollow pipe and is connected to the waste liquid outlet and washing liquid inlet of the reaction vessel via a pipeline.

[0111] When production demand increases to three times the maximum load of a single reactor, the number of polymerization reactors is increased to three (polymerization reactor A, polymerization reactor B, and polymerization reactor C), connected in parallel to a central pipeline. This central pipeline connects to the inlets of the three regulating tanks. The number of auxiliary reactors is increased to two (auxiliary reactor A and auxiliary reactor B), connected in parallel to a central pipeline. This central pipeline connects to the inlets of the three polymerization reactors and the three regulating tanks. The number of regulating tanks is increased to three (regulating tank A, regulating tank B, and regulating tank C), connected in parallel to a central pipeline, which connects to subsequent processes. During operation, the reactants are sequentially added to each polymerization reactor and each auxiliary reactor. The electric lifting switch is activated to close the reactor lid, and the polymerization reaction proceeds under preset conditions. During polymerization, the reaction progress is monitored by sampling through a reaction monitoring module. After polymerization, crude polymer is obtained. Subsequent post-processing processes then begin directly in the main reactor and auxiliary reactors.

[0112] When washing solution needs to be introduced, the transmission mechanism 8 is activated to raise the bent pipe 9 to near the top of the reaction vessel 1, i.e., the bottom of the vessel lid 2, allowing the washing solution to enter the reaction vessel 1. The homogenizing insert is then activated, and the crude product is cleaned using ultrasound. After cleaning, the inlet of the bent pipe 9 is adjusted via the viewing window 10 to be below the supernatant surface, close to the interface between the precipitate and the supernatant, to remove as much supernatant as possible, leaving only the precipitate, thereby improving post-processing efficiency. The installation of the insert on the vessel lid 2 integrates the polymerization reaction process and the post-processing process on the reaction vessel 1, thereby improving production efficiency and reducing production costs.

[0113] After the purification process is completed, fresh pure water is introduced. In order to accelerate production, the homogenizing plug is turned on during the precipitation and dissolution process. Under the action of ultrasound, the polymer precipitate in the polymerization reactor and the auxiliary reactor is quickly dispersed and then dissolved into a solution.

[0114] After dissolution, an appropriate amount of the polymer solution from auxiliary vessel A is first introduced into each of the three polymerization reactors to aid in the complete dissolution of the polymer. The solution is then divided into three equal portions and introduced into three regulating tanks. If the polymer solution in auxiliary vessel A is exhausted, the polymer solution from auxiliary vessel B is used. The solutions in the three regulating tanks are then thoroughly mixed and adjusted to a suitable concentration to obtain the final product—a thermotropic hydrogel solution.

[0115] A method for preparing a thermotropic hydrogel, comprising:

[0116] S1, Polymerization reaction:

[0117] Three polymerization reactors and two auxiliary reactors were set up to increase production. Add 400g of initiator, aminated polyethylene glycol monomethyl ether, and 1600g of a 1:1:1 mixture of lactide / glycolic acid / valerolactone monomers to three polymerization reactors respectively. Add 400g of initiator, mercapto polyethylene glycol monomethyl ether, and 800g of a 1:1:1 mixture of lactide / trimethylene carbonate / caprolactone monomers to two auxiliary reactors respectively. After closing the reactor lids, start stirring at 300rpm. Turn on the vacuum pump to remove air from the reactors. After the absolute pressure is <500Pa, nitrogen is introduced to complete one purging. After three purgings, close the gas valve and maintain the vacuum state in the reactors using the vacuum pump. Turn on the temperature control device to raise the temperature of the material in the reactors to 80℃ and maintain it for 30min to remove light component impurities such as moisture. Then turn off the vacuum pump and introduce nitrogen to maintain a nitrogen atmosphere in the reactors. Set the temperature control device to 120℃ and maintain it for 30min. Then add the catalyst, stannous isooctanoate 6. g, the timer starts when the catalyst is added. After about 12 hours, the temperature is lowered to 80 °C, and the polymerization reaction ends. All polymerization products are left in the reactor for later use.

[0118] S2. Water washing treatment:

[0119] Add hot water at 80°C to each reactor at three times the mass of the polymerization raw materials, i.e., add 6000 g of hot water to each of the three polymerization reactors and 3600 g of hot water to each of the two auxiliary reactors. Increase the stirring speed to 500 rpm and stir for 10 minutes, then turn off the stirring and let it stand for 5 minutes. After standing, the water system in the reactors separates into precipitate and supernatant. Turn on the servo motor of the bending pipe lifting device and lower the lower end of the bending pipe below the supernatant liquid level. Use the suction pump to suck the supernatant into the washing wastewater tank and add fresh hot water. This is considered to complete one washing cycle. The amount of fresh hot water added and the amount of supernatant extracted are measured for each washing cycle. After one washing cycle, a relatively pure water system of polymerization product is obtained and retained in the reactor for later use. Then, samples are taken to test the solid content in the washing wastewater. The yield of the polymerization product and the water content of the polymerization product water system after washing are calculated from four parameters: solid content of wastewater, total amount of wastewater extracted, total amount of fresh hot water added, and amount of polymerization raw materials fed. In this embodiment, the yield of the polymerization product in the polymerization reactor and the water content of the water system are 80% and 40%, respectively, while the yield of the polymerization product in the auxiliary reactor and the water content of the water system are 60% and 40%, respectively.

[0120] S3. Crude product dissolution:

[0121] After adjusting the internal temperature of the three polymerization reactors to 20 °C using a temperature control device, 5300 g of fresh water was introduced into each reactor, and stirring was started to dissolve the polymer precipitate in all three reactors into a 20 wt% aqueous solution, which was then set aside for later use. 2400 g of fresh water was introduced into the two auxiliary reactors, and stirring was started. Simultaneously, the temperature in the auxiliary reactors was gradually lowered to 20 °C using a temperature control device, causing the polymer precipitate therein to also dissolve into a 20 wt% aqueous solution. After complete dissolution, the aqueous solution from the auxiliary reactors was gradually introduced into the polymerization reactors via a transfer pump and pipeline, and mixed thoroughly to ensure complete dissolution of the precipitate in the polymerization reactors. The gelation temperature was monitored using a rotational rheometer. The remaining aqueous solution (approximately 20%) was left in the auxiliary reactors for further processing.

[0122] S4. Product Transfer and Export:

[0123] The uniformly mixed aqueous solution is extracted from the polymerization reactor, centrifuged, filtered, and the supernatant is passed into a conditioning tank. The expected gelation temperature of the product is 25 °C. The actual gelation properties of the aqueous solution in the conditioning tank are measured using a rotational rheometer. If the actual gelation temperature of the aqueous solution is within the predetermined range, i.e., between 24 °C and 26 °C, the aqueous solution is directly output as a thermotropic hydrogel product for subsequent processes. If the gelation properties are below 24 °C, an appropriate proportion of fresh water and the aqueous solution in the auxiliary reactor are added to the conditioning tank, mixed evenly, and the gelation temperature is measured again. This operation is repeated until the gelation temperature of the aqueous solution in the conditioning tank is within the predetermined range, i.e., between 24 °C and 26 °C.

[0124] Example 3

[0125] A method for preparing thermotropic hydrogels

[0126] S1, Polymerization reaction:

[0127] Add 333 g of polyethylene glycol (PEG) initiator and 1200 g of a 4:1 molar ratio of lactide / glycolic acid mixed monomers to the polymerization reactor. Add 333 g of PEG initiator and 1200 g of a 4:1 molar ratio of lactide / glycolic acid mixed monomers to the auxiliary reactor. After closing the reactor lid, start the stirrer at 300 rpm. Turn on the vacuum pump to remove air from the reactor. After evacuating to an absolute pressure < 500 Pa, purge with nitrogen to complete one purging. After three purgings, close the gas valve and maintain a vacuum in the reactor using the vacuum pump. Turn on the temperature control device to raise the temperature of the material in the reactor to 120 °C and maintain it for 30 min to remove light impurities such as moisture. Then turn off the vacuum pump and purge with nitrogen to maintain a nitrogen atmosphere in the reactor. Set the temperature control device to 160 °C and maintain it for 30 min. Add 2 g of stannous isooctanoate catalyst. Start timing from the time the catalyst is added. After approximately 6 hours of reaction, cool down to 80 °C. At ℃, the polymerization reaction ends, and the polymerization products remain in the reactor for later use.

[0128] S2. Water washing treatment:

[0129] Hot water at 80°C was added to each reactor at four times the mass of the polymerization raw materials, i.e., 6000 g of hot water was added to reactor A and 6000 g of hot water was added to reactor B. The stirring speed was increased to 500 rpm and stirred for 5 minutes. Then the stirring was turned off and the mixture was allowed to stand for 1 minute. After standing, the water system in the reactor separated into precipitate and supernatant. The servo motor of the bending pipe lifting device was turned on and the lower end of the bending pipe was lowered below the supernatant liquid level. The supernatant was sucked out into the washing wastewater tank by the suction pump and fresh hot water was added. This was considered to complete one washing cycle. The amount of fresh hot water added and the amount of supernatant sucked out were measured for each washing cycle. After 5 washing cycles, a relatively pure water system of polymerization product was obtained and kept in the reactor for later use. Then, the solid content of the washing wastewater was sampled and tested. The yield of the polymerization product and the water content of the polymerization product water system after washing were calculated from four parameters: solid content of wastewater, total amount of wastewater sucked out, total amount of fresh hot water added, and amount of polymerization raw materials fed. In this embodiment, the yield of the polymerization product in the polymerization reactor and the water content of the water system are 90% and 60%, respectively, and the yield of the polymerization product in the auxiliary reactor and the water content of the water system are 90% and 60%, respectively.

[0130] S3. Crude product dissolution:

[0131] After adjusting the temperature inside the polymerization reactor to 5 ℃ using a temperature control device, 5750 g of fresh water is introduced into it, and stirring is turned on to dissolve the polymer precipitate into a 15 wt% aqueous solution. 5750 g of fresh water is then introduced into the auxiliary vessel, and stirring is turned on. Simultaneously, the temperature inside the auxiliary vessel is gradually reduced to 5 ℃ using a temperature control device, so that the polymer precipitate in the auxiliary vessel also dissolves into a 15 wt% aqueous solution. After complete dissolution, the entire aqueous solution from the auxiliary vessel is introduced into the polymerization reactor for later use.

[0132] S4. Product Transfer and Export:

[0133] The uniformly mixed aqueous solution is extracted from the polymerization reactor and subjected to sedimentation, centrifugation, and filtration. The supernatant is then passed into a conditioning tank. The expected gelation temperature of the product is 15 °C. The actual gelation properties of the aqueous solution in the conditioning tank are measured using a rotational rheometer. If the actual gelation temperature of the aqueous solution is within the predetermined range, i.e., between 14 °C and 16 °C, the aqueous solution is directly output as a thermotropic hydrogel product for subsequent processes. If the gelation properties are below 14 °C, an appropriate amount of fresh water is added to the conditioning tank, mixed thoroughly, and the gelation temperature is measured again. This operation is repeated until the gelation temperature of the aqueous solution in the conditioning tank is within the predetermined range, i.e., between 14 °C and 16 °C.

[0134] Example 4

[0135] An apparatus for preparing thermotropic hydrogels (with attachment) Figure 5It includes a polymerization reactor, an auxiliary reactor, and a regulating tank.

[0136] The reactor includes a reaction vessel 1, the top of which is sealed by a lid 2. A stirring component 3 is fixedly installed in the center of the top of the lid 2. A plug-in mounting hole 6 is provided on the upper part of the reactor for connecting plug-ins.

[0137] The plug-in includes a purification plug-in, which comprises a support 7, a transmission mechanism 8, and a bend 9. The support 7 is connected to the plug-in mounting hole 6, and the transmission mechanism 8, located on the support 7, drives the bend 9 to move vertically up and down inside the reaction vessel. The bend 9 is a hollow pipe and is connected to the waste liquid outlet and washing liquid inlet of the reaction vessel via a pipeline.

[0138] When the raw material ratio needs to be changed, the number of polymerization reactors is increased to three (polymerization reactor A, polymerization reactor B, and polymerization reactor C), connected in series from A to C. The number of auxiliary reactors is increased to two (auxiliary reactor A and auxiliary reactor B). The outlet of auxiliary reactor A is connected to the inlet of polymerization reactor A, and the outlet of auxiliary reactor B is connected to the inlet of polymerization reactor C. The number of regulating tanks is increased to three, connected in a loop to form a whole. The inlets of the regulating tanks are connected to the outlets of polymerization reactor C and auxiliary reactor B, respectively, and the outlet of the regulating tanks is connected to the pipelines of subsequent processes. During operation, the reactants are added sequentially to each polymerization reactor and each auxiliary reactor. The electric lifting switch is turned on to close the reactor lid. After polymerization under preset reaction conditions, crude polymer is obtained. Post-processing processes then begin directly in the polymerization reactors and auxiliary reactors.

[0139] When washing solution needs to be introduced, the transmission mechanism 8 is activated to raise the bent pipe 9 to near the top of the reaction vessel 1, i.e., the bottom of the vessel lid 2, allowing the washing solution to enter the reaction vessel 1. The homogenizing insert is then activated, and ultrasonic-assisted cleaning of the crude product is performed. After cleaning, the inlet of the bent pipe 9 is adjusted via the viewing window 10 to be below the supernatant surface, close to the interface between the precipitate and the supernatant, to remove as much supernatant as possible, leaving only the precipitate, thereby improving post-processing efficiency. The installation of the insert on the vessel lid 2 integrates the polymerization reaction process and the purification process on the reaction vessel 1, thereby improving production efficiency and reducing production costs.

[0140] After the post-processing steps are completed, fresh pure water is introduced to dissolve the polymer precipitate in the polymerization reactor and auxiliary reactor into aqueous solutions. First, the polymer aqueous solution in auxiliary reactor A is introduced into polymerization reactor A to help the polymer dissolve fully before being introduced into polymerization reactor B. After the polymer dissolves fully, it is then introduced into polymerization reactor C. Subsequently, an appropriate amount of polymer aqueous solution from auxiliary reactor B is introduced into polymerization reactor C to help the polymer dissolve fully before being introduced into the entire regulating tank. In this tank, the aqueous solution is thoroughly mixed and adjusted to a suitable concentration to obtain the final product—a thermotropic hydrogel solution.

[0141] Example 5

[0142] An apparatus for preparing thermotropic hydrogels (with attachment) Figure 6 ), including polymerization reactors and auxiliary reactors.

[0143] The reactor includes a reaction vessel 1, the top of which is sealed by a lid 2. A stirring component 3 is fixedly installed in the center of the top of the lid 2. A plug-in mounting hole 6 is provided on the upper part of the reactor for connecting plug-ins.

[0144] The plug-in includes a purification plug-in, which comprises a support 7, a transmission mechanism 8, and a bend 9. The support 7 is connected to the plug-in mounting hole 6, and the transmission mechanism 8, located on the support 7, drives the bend 9 to move vertically up and down inside the reaction vessel. The bend 9 is a hollow pipe and is connected to the waste liquid outlet and washing liquid inlet of the reaction vessel via a pipeline.

[0145] During operation, the reactants are added to the polymerization reactor and auxiliary vessel, and the electric lifting switch is turned on to close the vessel lid. The polymerization reaction proceeds under preset conditions to obtain crude polymer. Subsequent post-processing steps then begin directly in the polymerization reactor and auxiliary vessel.

[0146] When washing solution needs to be introduced, the transmission mechanism 8 is activated to raise the bent pipe 9 to near the top of the reaction vessel 1, i.e., the bottom of the vessel lid 2, allowing the washing solution to enter the reaction vessel 1. The homogenizing insert is then activated, and the crude product is cleaned using ultrasound. After cleaning, the inlet of the bent pipe 9 is adjusted via the viewing window 10 to be below the supernatant surface, close to the interface between the precipitate and the supernatant, to remove as much supernatant as possible, leaving only the precipitate, thereby improving post-processing efficiency. The installation of the insert on the vessel lid 2 integrates the polymerization reaction process and the purification process on the reaction vessel 1, thereby improving production efficiency and reducing production costs.

[0147] After the purification process is completed, fresh pure water is introduced to dissolve the polymer precipitate in the polymerization reactor and the auxiliary reactor into aqueous solutions. First, the polymer aqueous solution in the auxiliary reactor is introduced into the polymerization reactor to help the polymer dissolve fully. Then, the concentration is adjusted directly in the polymerization reactor and directly output to the next process.

[0148] A method for preparing a thermotropic hydrogel, comprising:

[0149] S1, Polymerization reaction:

[0150] Add 600 g of polyethylene glycol to the polymerization reactor and 500 g of initiator polyethylene glycol to the auxiliary reactor. After closing the reactor lid, start the stirrer and set the stirring speed to 100 rpm. Turn on the vacuum pump to remove air from the reactor. After evacuating to an absolute pressure < 500 Pa, introduce nitrogen to complete one purging. After three purgings, close the gas valve and maintain the vacuum state in the reactor using the vacuum pump. Turn on the temperature control device to raise the temperature of the material in the reactor to 95 ℃ and maintain it for 30 min to remove light component impurities such as moisture. Then, turn off the vacuum pump and introduce nitrogen to restore the pressure in both reactors to normal pressure. Add 1860 g of a 4 / 1 ratio of lactide / glycolic acid mixed monomers and 800 g of a 4 / 1 ratio of lactide / glycolic acid mixed monomers to the polymerization reactor. Turn on the vacuum pump to remove air from the reactor. After evacuating to an absolute pressure < 500 Pa, introduce nitrogen to complete one purging. After three purgings, close the gas valve and maintain the vacuum state in the reactor using the vacuum pump for 30 min. After removing light components such as moisture, the vacuum pump was turned off and nitrogen was introduced to fill the reactor with a nitrogen atmosphere. The temperature control device was set to 140 °C and the reactor was kept at a constant temperature for 30 min. Then, 4 g of stannous isooctanoate catalyst was added. Timing was started from the time the catalyst was added. After about 3 h, the temperature was lowered to 85 °C, and the polymerization reaction ended. All polymerization products were left in the reactor for later use.

[0151] S2. Water washing treatment:

[0152] Add hot water at 60°C to each reactor according to three times the mass of the polymerization raw materials. That is, add 6000 g of hot water to the polymerization reactor and 4000 g of hot water to the auxiliary reactor. Increase the stirring speed to 500 rpm and stir for 10 minutes. Then turn off the stirring and let it stand for 5 minutes. After standing, the water system in the reactor separates into precipitate and supernatant. Turn on the servo motor of the bending pipe lifting device and lower the lower end of the bending pipe below the supernatant liquid level. The supernatant is sucked out into the washing wastewater tank and fresh hot water is added. This is considered to complete one washing cycle. The amount of fresh hot water added and the amount of supernatant sucked out are measured for each washing cycle. After 10 washing cycles, a relatively pure water system of polymerization product is obtained and kept in the reactor for later use. Then, the solid content of the washing wastewater is tested. The yield of the polymerization product and the water content of the polymerization product water system after washing are calculated from four parameters: solid content of wastewater, total amount of wastewater sucked out, total amount of fresh hot water added, and amount of polymerization raw materials fed. In this embodiment, the yield of the polymerization product in the polymerization reactor and the water content of the water system are 93% and 30%, respectively, while the yield of the polymerization product in the auxiliary reactor and the water content of the water system are 80% and 50%, respectively.

[0153] S3. Crude product dissolution:

[0154] After adjusting the temperature inside the polymerization reactor to 25 °C using a temperature control device, 4200 g of fresh water was introduced into the reactor, and stirring was started to dissolve the polymer precipitate in the reactor into a 25 wt% aqueous solution, which was then set aside for later use. 1200 g of fresh water was introduced into an auxiliary reactor, and stirring was started. Simultaneously, the temperature inside the auxiliary reactor was gradually lowered to 25 °C using a temperature control device, causing the polymer precipitate therein to also dissolve into a 25 wt% aqueous solution. After complete dissolution, the aqueous solution from the auxiliary reactor was gradually introduced into the polymerization reactor through a transfer pump and pipeline and mixed thoroughly. The gelation temperature was monitored using a rotational rheometer. The remaining aqueous solution (approximately 15%) remained in the auxiliary reactor for further processing.

[0155] S4. Product Transfer and Export:

[0156] The uniformly mixed aqueous solution is extracted from the polymerization reactor and allowed to settle. The supernatant is then passed into a conditioning tank. The expected gelation temperature of the product is 35 °C. The actual gelation properties of the aqueous solution in the conditioning tank are measured using a rotational rheometer. If the actual gelation temperature of the aqueous solution is within the predetermined range, i.e., between 34 °C and 36 °C, the aqueous solution is directly output as a thermotropic hydrogel product for subsequent processes. If the gelation properties are below 34 °C, an appropriate proportion of fresh water and the aqueous solution in the auxiliary reactor are added to the conditioning tank, mixed thoroughly, and the gelation temperature is measured again. This operation is repeated until the gelation temperature of the aqueous solution in the conditioning tank is within the predetermined range, i.e., between 34 °C and 36 °C.

[0157] To further demonstrate the beneficial effects of the present invention and to better understand it, the technical features of the preparation method disclosed in the present invention are further illustrated by the following comparative examples, but these should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above description of the invention, without inventive effort, are also considered to fall within the protection scope of the present invention.

[0158] Comparative Example 1

[0159] A discontinuous method for preparing thermotropic hydrogels:

[0160] S1, Polymerization reaction:

[0161] Remove the auxiliary vessel and all fittings from the vessel lid. Add 488g of polyethylene glycol initiator and 1512g of lactide monomer to the polymerization reactor. After closing the vessel lid, start the stirrer and set the stirring speed to 300 rpm. Turn on the vacuum pump to remove air from the reactor. After the absolute pressure is <500 Pa, introduce nitrogen to complete one purging. After three purgings, close the gas valve and maintain the vacuum state in the reactor using the vacuum pump. Turn on the temperature control device to raise the temperature of the material in the reactor to 80 ℃ and maintain it for 30 min to remove light component impurities such as moisture. Then turn off the vacuum pump and introduce nitrogen to maintain a nitrogen atmosphere in the reactor. Set the temperature control device to 140 ℃ and maintain the temperature for 30 min. Then add 4g of stannous isooctanoate catalyst. Start timing from the time the catalyst is added. The reaction ends after about 3 hours. The polymerization product remains in the reactor for later use.

[0162] S2. Water washing treatment:

[0163] A water washing tank was installed. Two people manually poured the polymer melt from the reactor into a stainless steel container. The polymer was then transferred to the water washing tank via this container. Hot water at 60°C (3 times the mass of the polymer feed) was added to the water washing tank, i.e., 6000 g of hot water. The stirring speed of the agitator in the water washing tank was set to 500 rpm. After stirring for 10 minutes, the stirring was turned off and the mixture was allowed to stand for 5 minutes. After standing, the water system in the tank separated into precipitate and supernatant. Two people manually extracted the supernatant and added fresh hot water. This was considered as completing one water washing cycle. The amount of fresh hot water added and the amount of supernatant extracted were measured for each water washing cycle. After 10 water washing cycles, a relatively pure water system of polymer product was obtained.

[0164] S3, freeze-drying:

[0165] A freeze-drying device was installed. Two person-times were used to transfer the aqueous polymer system from the washing tank to the freeze-drying device via a stainless steel container. The freezing chamber temperature was set at -50 ℃, the absolute pressure in the sample chamber was <400 Pa, and the freeze-drying time was 96 h, allowing the aqueous polymer system to be dehydrated to obtain pure polymer. After drying, two person-times were used to transfer the polymer product from the freeze dryer. The yield of the obtained polymer product was 80%. The total power of the freeze-drying device was 10 kW, and the total energy consumption of the freeze-drying process was 960 kW·h.

[0166] S4. Prepare the hydrogel solution:

[0167] Two manual laborers transferred the freeze-dried polymer product to a regulating tank, added 6400 g of fresh water, turned on the stirring device of the regulating tank, and stirred for 96 h to dissolve the polymer product in water into a 25 wt% aqueous solution. Due to the lack of components generated by the auxiliary reactor for auxiliary dissolution, the polymer product was not completely dissolved, and its properties were relatively viscous with precipitation. The approximately 10 wt% aqueous solution remaining at the bottom of the regulating tank will be discharged as waste liquid.

[0168] S5. Output Products:

[0169] The gelling properties of the aqueous solution in the conditioning tank were measured using a rotational rheometer. The expected gelling temperature was 35 °C. If the actual gelling temperature of the aqueous solution was within the predetermined range, i.e., between 34 °C and 36 °C, the aqueous solution could be used as a thermotropic hydrogel product for the sterilization process. If the gelling properties were below 34 °C, one person was used to add an appropriate amount of fresh water, and the stirring device was turned on for 24 hours. The gelling temperature was measured again. This operation was repeated until the gelling temperature of the aqueous solution in the conditioning tank was within the predetermined range, i.e., between 34 °C and 36 °C.

[0170] Compared to Example 1, the yield of Comparative Example 1 decreased from 11,000 g to 5,760 g, the hydrogel yield decreased from 83% to 72%, required 10-13 more person-times, consumed 960 kWh more energy, and took 192-268 hours more. With the same amount of raw materials, the production efficiency of Comparative Example 1 was significantly reduced and the production cost was significantly increased. Due to the excessive human intervention, the risk of batch-to-batch instability in product performance also increased significantly.

[0171] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a thermotropic hydrogel, comprising polymerization reaction, water washing treatment, crude product dissolution, and product output, characterized in that, The polymerization reaction, water washing treatment, and crude product dissolution are all continuous reactions in the same reactor. The preparation apparatus used in the preparation method includes a polymerization reactor and an auxiliary reactor. The discharge end of the auxiliary reactor is connected to the feed end of the polymerization reactor through a pipeline. The polymerization reactor includes a reaction vessel (1), the top of which is sealed by a lid (2). A stirring component (3) is fixedly installed in the center of the top of the lid (2). A plug-in mounting hole (6) is provided on the upper part of the reactor for connecting plug-ins. The plug-ins include a purification plug-in, which includes a support (7), a transmission mechanism (8), and a bent pipe (9). The support (7) is connected to the plug-in mounting hole (6). The transmission mechanism (8) located on the support (7) drives the bent pipe (9) to move vertically up and down inside the reaction vessel. The bent pipe (9) is a hollow pipe and is connected to the waste liquid outlet of the reactor through a pipe. The bent pipe (9) is also connected to the washing liquid inlet of the reactor through a pipe. Includes the following steps: S1, Polymerization reaction: Initiators are added to the polymerization reactor and auxiliary reactor according to the component equivalents. Vacuum is drawn and the temperature inside the reactor is raised to 40-120 ℃ using a temperature control device. After removing impurities contained in the initiator, nitrogen is introduced to restore the pressure inside the reactor to normal pressure. Then, one or more monomers are added sequentially according to the ratio, and impurities contained in the monomers are removed by vacuuming. Nitrogen is then introduced to restore the pressure inside the reactor to normal pressure. Finally, the temperature inside the reactor is raised to 80-180 ℃, and an appropriate amount of stannous isooctanoate catalyst is added to start the polymerization reaction until the reaction is completed. S2. Water washing treatment: Hot water at 30-100 ℃ is pumped into the polymerization reactor and auxiliary reactor by metering pump. The temperature inside the reactor is controlled within a suitable range by temperature control device and stirring is turned on. After stirring for a suitable time, the mixture is allowed to stand and settle for a period of time. The valve at the connection between the bent pipe (9) and the waste liquid outlet of the reactor is opened to extract the supernatant. The valve at the connection between the bent pipe (9) and the washing liquid inlet of the reactor is opened to add an appropriate amount of fresh hot water. This is considered as completing one water washing. Repeat the water washing process multiple times, measuring the amount of fresh hot water added and the amount of supernatant removed in each wash. The precipitate is retained in the polymerization reactor and auxiliary reactor for later use. S3. Crude product dissolution: Fresh water is added to the polymerization reactor and the auxiliary reactor respectively to dissolve the precipitate obtained from water washing into an aqueous solution of a certain concentration. A portion of the aqueous solution in the auxiliary reactor is transferred to the polymerization reactor to make the precipitate in the polymerization reactor dissolve more completely. The remaining portion of the aqueous solution is left in the auxiliary reactor for further processing. S4. Product Transfer and Output: After the polymerization product is fully dissolved in the polymerization reactor, the obtained aqueous solution is transferred to a regulating tank, and the solution is purified during the transfer process. After the aqueous solution is transferred to the regulating tank, its actual gelling properties are measured, and the temperature is adjusted by adding fresh water until the gelling temperature reaches a suitable range. Then, the aqueous solution is output to the subsequent process to obtain the thermotropic hydrogel. After polymerization, and / or during water washing, and / or during crude product dissolution, and / or after product transfer, and before product output, Small samples of semi-finished / finished products were taken from each process container in the process flow to test the gelation properties of the products and make immediate adjustments.

2. The method for preparing the thermotropic hydrogel according to claim 1, characterized in that, The initiator includes one or more of polyethylene glycol, polyethylene glycol monomethyl ether, aminated polyethylene glycol, aminated polyethylene glycol monomethyl ether, mercapto polyethylene glycol, or mercapto polyethylene glycol monomethyl ether; the polymerizing monomer includes one or more of lactide, glycolide, caprolactone, valerate, and trimethylene carbonate.

3. The method for preparing the thermotropic hydrogel according to claim 1, characterized in that, The suitable range for the gelation temperature is 10 ℃ to 40 ℃.

4. An apparatus for preparing a thermotropic hydrogel using the preparation method according to any one of claims 1-3, characterized in that, The preparation apparatus includes a polymerization reactor and an auxiliary reactor, wherein the discharge end of the auxiliary reactor is connected to the feed end of the polymerization reactor via a pipeline; The polymerization reactor includes a reaction vessel (1), the top of which is sealed by a lid (2). A stirring component (3) is fixedly installed in the center of the top of the lid (2). A plug-in mounting hole (6) is provided on the upper part of the reactor for connecting plug-ins. The plug-ins include a purification plug-in, which includes a support (7), a transmission mechanism (8), and a bent tube (9). The support (7) is connected to the plug-in mounting hole (6). The transmission mechanism (8) located on the support (7) drives the bent tube (9) to move vertically up and down inside the reaction vessel. The bend (9) is a hollow pipe and is connected to the waste liquid outlet of the reactor through the pipe. The bend (9) is also connected to the washing liquid inlet of the reactor through the pipe.

5. The preparation apparatus according to claim 4, characterized in that, The reactor also includes a viewing window (10), which is located on the outer wall of the reactor and is parallel to the vertical lifting path of the bend (9).

6. The preparation apparatus according to claim 4, characterized in that, The plug-in also includes a homogenizing plug-in, whose homogenizing function includes one or more combinations of stirring, high-speed shearing, fluid jetting, and ultrasound.

7. The preparation apparatus according to claim 4, characterized in that, It also includes a regulating tank, the inlet of which is connected to the outlet of the reaction vessel or auxiliary vessel via a pipeline.

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