Temperature-sensitive microcapsule wall material as well as preparation method and application thereof

Abstract

The invention provides a temperature-sensitive microcapsule wall material and a preparation method thereof, a hydrophobic monomer with a polymerizable double bond at a terminal group is used as a monomer A, a temperature-sensitive monomer is used as a monomer B, the monomer A and the monomer B are subjected to atom transfer radical polymerization to prepare an A-b-B structure, and a block high-molecular copolymer A-b-B, namely the temperature-sensitive microcapsule wall material, is obtained; the invention also provides an application of the temperature-sensitive microcapsule wall material, the temperature-sensitive microcapsule wall material is used for preparing temperature-controlled slow-release microcapsules, the temperature response sensitivity of the block high-molecular copolymer A-b-B is good, and the block high-molecular copolymer A-b-B has a good temperature-controlled slow-release effect on functional core materials in the microcapsules as the wall material. The process is simple, the temperature response sensitivity of the block high-molecular copolymer A-b-B is good, the temperature control slow-release effect of the block high-molecular copolymer A-b-B serving as a wall material is good, the prepared microcapsule can be applied to functional clothes, functional beauty makeup products or other products for human body contact, the application range is wide, and the preparation method belongs to the technical field of temperature-sensitive materials.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature-sensitive materials, and specifically relates to a temperature-sensitive microcapsule wall material and a preparation method and application thereof. Background Art

[0002] Microencapsulation technology is a technology that wraps trace substances in polymer films. It is a micro-packaging technology for storing solids, liquids, and gases. Specifically, it means that the core material is completely coated with a continuous film (wall material) of various natural or synthetic polymer compounds, without damaging the original chemical properties of the core material, and then gradually through certain external stimuli or sustained release effects, the function of the target object is presented again on the outside, or the shielding effect of the capsule wall is relied on to protect the core material. Microencapsulation technology can protect the active ingredients in the capsule core, protect the active ingredients from the influence of the external environment, and extend its shelf life. In addition, microencapsulation technology can control the release rate of active ingredients, which is very useful in the fields of drug delivery, fertilizer sustained release, etc. However, traditional microencapsulation technology has great difficulty in controlling the release of the core material. Although sustained release can be achieved, it is still challenging in terms of conditional release and precise control of release.

[0003] The Chinese invention patent with publication number CN111715157A discloses a temperature-controlled release rose essence-starch-based microcapsule and its preparation method. The preparation method of this technology is simple and suitable for large-scale production, but the technology lacks more sophisticated control means in terms of temperature control, and its sustained-release effect depends more on the increase in temperature, the acceleration of the molecular motion of the liquid capsule core material, and the expansion of the capsule wall material. The Chinese invention patent with publication number CN112280389A discloses a mosquito-repellent interior wall paint with added Chinese herbal medicine extracts and its preparation method. This technology adopts a method of coating Chinese herbal medicine extracts with thermosensitive hydrogels, and uses a compound synthesized by azobisisobutyramidine hydrochloride and propyl acrylamide as a thermosensitive hydrogel sustained-release material, achieving good temperature sensitivity. At a temperature of 25°C, the outer shell is in a contracted state, and the essential oil extracted from the wrapped Chinese herbal medicine is not easy to release. In the summer with higher temperatures, the increase in temperature accelerates the release of the essential oil extracted from the Chinese herbal medicine, achieving the effect of mosquito repellent. However, the state of the thermosensitive material in this technology is a gel state, which limits its scope of application.

[0004] Based on the above situation, developing a temperature-sensitive microcapsule material that can effectively control the flexible release of the capsule core material at a suitable temperature and has a wide range of applications is a key research and development application direction to meet the special needs of the market. Summary of the invention

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is to provide a temperature-sensitive microcapsule wall material and its preparation method and application, so as to solve the technical problems that the existing microcapsules cannot flexibly release the capsule core material at a suitable temperature and have a narrow application range.

[0006] A first aspect of an embodiment of the present invention provides a temperature-sensitive microcapsule wall material, which is a block polymer copolymer, which is prepared into an AbB structure by atom transfer radical polymerization of monomer A and monomer B, wherein monomer A is a hydrophobic monomer with a polymerizable double bond at the end group, and monomer B is a temperature-sensitive monomer.

[0007] Preferably, the monomer A includes any one of styrene, methyl methacrylate, ethyl methacrylate and hydroxyethyl methacrylate, and the monomer B includes N-isopropylacrylamide.

[0008] A second aspect of the embodiments of the present invention provides a method for preparing the temperature-sensitive microcapsule wall material described in any one of the above items, comprising the following steps:

[0009] (1) adding monomer A to anisole to dissolve it, then adding cuprous bromide and a ligand, stirring to react, then adding an initiator, heating and stirring to react, and post-treating to obtain A-Br;

[0010] (2) A-Br, cuprous bromide, and monomer B are mixed, and then anhydrous N,N-dimethylformamide is added and stirred to dissolve, and then a ligand is added, and the temperature is raised and stirred to react, and post-processed to obtain a block polymer copolymer AbB, which is a thermosensitive microcapsule wall material.

[0011] Preferably, in step (1), the mass ratio of monomer A to anisole is 4-5:1, the molar ratio of cuprous bromide to monomer A is 1%-2.5%:1, the ligand includes any one of N,N,N',N',N"-pentamethyldiethylenetriamine and 2,2'-bipyridine, the molar ratio of the ligand to cuprous bromide is 1:1, the initiator includes any one of (1-bromoethyl)benzene and ethyl α-bromopropionate, and the molar ratio of the initiator to cuprous bromide is 0.9-1:1.

[0012] Preferably, in step (1), the temperature is raised to 100-110° C. and the reaction is carried out for 0.5-3 h.

[0013] In the present invention, in step (1), the reaction is carried out under high-purity argon; the post-treatment is specifically as follows: after the reaction is completed, the temperature is lowered and cooled, the reaction liquid is filtered after settling in methanol, dried, then dissolved in tetrahydrofuran, and again precipitated in methanol after filtering, dried, and the operation is repeated three times for purification to obtain A-Br.

[0014] Preferably, in step (2), the molar ratio of A-Br, CuBr and monomer B is 1:5-10:50-300, the mass ratio of A-Br to anhydrous N,N-dimethylformamide is 1:5-10, the ligand includes any one of N,N,N',N',N"-pentamethyldiethylenetriamine and 2,2'-bipyridine, and the molar ratio of the ligand to cuprous bromide is 1:1.

[0015] Preferably, in step (2), the temperature is raised to 85-95° C. and the reaction is carried out for 12-24 hours.

[0016] In the present invention, in step (2), the reaction is carried out under high-purity argon; the post-treatment is specifically as follows: after the reaction is completed, the temperature is lowered and cooled, anhydrous N,N-dimethylformamide is added to the reaction liquid for dilution, the CuBr catalyst is removed by a neutral alumina column, the remaining liquid is precipitated in methanol, filtered, dried, then dissolved in tetrahydrofuran, precipitated in methanol again, filtered, dried, and the operation is repeated three times for purification to obtain a block polymer copolymer AbB.

[0017] A third aspect of the embodiments of the present invention provides an application of the temperature-sensitive microcapsule wall material described in any one of the above items, wherein the temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule, wherein the temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material, and the preparation method thereof comprises the following steps:

[0018] (1) dissolving the block polymer copolymer AbB and the functional core material in acetone at room temperature to obtain a mixed solution;

[0019] (2) In an ice-water bath, the mixed solution is added dropwise into deionized water under stirring to obtain a mixed system; while maintaining the ice-water bath, the mixed system is shear-dispersed to obtain an emulsion; and the emulsion is spray-dried to obtain a temperature-controlled sustained-release microcapsule.

[0020] In the present invention, the functional core material includes aromatic essential oil, anti-mosquito component, vitamins and medicine.

[0021] Preferably, in step (1), the mass ratio of the functional core material, the block polymer copolymer AbB, and acetone is 1:0.1-10:1-20.

[0022] Preferably, in step (2), the stirring speed is 500-3000rpm, the mass ratio of the mixed solution to deionized water is 1:5-100, and the dropping speed of the mixed solution is 0.02-0.2mL / min; the mixed system is sheared and dispersed using a high-speed homogenizer, the speed of the high-speed homogenizer is 8000-12000r / min, and the shear time is 10-60min; the feed rate of the spray drying is 1-5mL / min, the air inlet temperature is 180-200°C, and the air outlet temperature is 80-100°C.

[0023] The present invention provides a temperature-sensitive microcapsule wall material and a preparation method thereof. A hydrophobic monomer with a polymerizable double bond at the end group is used as monomer A, and a temperature-sensitive monomer is used as monomer B. Monomer A and monomer B are prepared into an AbB structure through atom transfer free radical polymerization to obtain a block polymer copolymer AbB, which is the temperature-sensitive microcapsule wall material. The present invention also provides an application of the temperature-sensitive microcapsule wall material for preparing temperature-controlled sustained-release microcapsules. The block polymer copolymer AbB has good temperature response sensitivity and has a good temperature-controlled sustained-release effect on a functional core material inside the microcapsule as a wall material.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention uses temperature-sensitive monomer N-isopropylacrylamide (NIPAM) as monomer B, and through the method of atom transfer radical polymerization (ATRP), NIPAM forms a homopolymer at one end of the polymer, and the temperature-sensitive monomers aggregate together, thereby improving the temperature response sensitivity of the block polymer copolymer AbB; when it is used as a microcapsule wall material, when the critical solution temperature of NIPAM is reached, the NIPAM molecules aggregate, and the microcapsule wall shrinks to form microchannels, so that the internal functional core material is efficiently released at the expected temperature, ensuring a better functional effect; when the expected use temperature is not reached, the release of the functional core material is slow, which effectively reduces the loss of functional components and prolongs the action time of the microcapsule; in addition, the block polymer copolymer AbB has a narrow molecular weight distribution and good macromolecular chain structure consistency. When stimulated by external temperature changes, the response consistency is high, the response is more efficient, and the effect is more obvious.

[0026] (2) The present invention uses a hydrophobic monomer with a polymerizable double bond at the terminal group as monomer A, which can play the role of a skeleton when polymerized with monomer B through ATRP to form a wall material, thereby maintaining the overall shape of the microcapsule; when the critical solution temperature of NIPAM is reached, the NIPAM molecules aggregate and form microchannels when the microcapsule wall shrinks, so that the functional core material inside can be efficiently precipitated. At this time, the homopolymer formed by monomer A supports the microcapsule wall, avoiding the overall collapse of the microcapsule, thereby improving the stability of the microcapsule.

[0027] The process of the present invention is simple, the block polymer copolymer AbB has good temperature response sensitivity, and its temperature control sustained release effect as a wall material is good. The prepared microcapsules can be applied to functional clothing for human body contact, functional beauty products or other products, and have a wide range of applications. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail in conjunction with the embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The raw materials and devices used in the present invention are conventional commercial products unless otherwise specified; the methods used are conventional methods unless otherwise specified.

[0029] (I) Thermosensitive microcapsule wall material and preparation method thereof

[0030] Example 1

[0031] A method for preparing a temperature-sensitive microcapsule wall material comprises the following steps:

[0032] (1) 104.14 g of styrene (St) was added to 20.8 g of anisole to dissolve, the reaction apparatus was sealed and stirred, vacuumed, and replaced with high-purity argon gas, repeated 3 times, then 2.86 g of dried cuprous bromide (CuBr) powder and 4.03 g of N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) were added, vacuumed again, replaced with high-purity argon gas, repeated 3 times, and stirred for 30 min to react; while maintaining the internal argon environment, 3.76 g of (1-bromoethyl)benzene was injected into the reaction system with a syringe, the temperature was raised to 110° C., and the reaction was carried out for 2 h;

[0033] After the reaction is completed, the reaction device is moved into a dry ice bath to cool down, the reaction liquid is precipitated in methanol, filtered, and vacuum dried, then dissolved in tetrahydrofuran, precipitated in methanol again, filtered, and vacuum dried, and the operation is repeated 3 times for purification to obtain a macromolecular initiator A-Br, named PSt-Br;

[0034] PSt-Br was detected and its Mn (GPC) was found to be 4.1k, Mw = 5.2k, and PDI = 1.27.

[0035] (2) Add 20.5 g PSt-Br, 3.6 g cuprous bromide (CuBr), and 28.3 g N-isopropylacrylamide (NIPAM) into a flask, seal it, evacuate it, and replace it with high-purity argon, repeating 3 times; then inject 123 g anhydrous N,N-dimethylformamide (DMF) into the flask with a syringe, stir to dissolve, and then inject 5.05 g N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) into the flask with a syringe, evacuate it again, and replace it with high-purity argon, repeating 3 times; maintain the internal argon environment, heat to 90°C, and react for 18 hours;

[0036] After the reaction is completed, the flask is moved into a dry ice bath to cool down, anhydrous N,N-dimethylformamide (DMF) is added to the reaction liquid in the flask for dilution, and the cuprous bromide (CuBr) catalyst is removed by a neutral alumina column. The remaining liquid is precipitated in methanol and filtered, and vacuum dried. It is then dissolved in tetrahydrofuran, precipitated in methanol again and filtered, and vacuum dried. The operation is repeated 3 times for purification to obtain a block polymer copolymer AbB, named PSt-b-PNIPAM, which is a thermosensitive microcapsule wall material;

[0037] PSt-b-PNIPAM was tested and its Mn (GPC) was measured to be 7.3k, Mw = 8.3k, and PDI = 1.14.

[0038] Example 2

[0039] A method for preparing a temperature-sensitive microcapsule wall material comprises the following steps:

[0040] (1) 125 g of methyl methacrylate (MMA) was added to 25 g of anisole to dissolve, the reaction apparatus was sealed and stirred, vacuumed, and replaced with high-purity argon gas, repeated 3 times, and then 3.59 g of dried cuprous bromide (CuBr) powder and 3.9 g of 2,2'-bipyridine were added, vacuumed again, replaced with high-purity argon gas, repeated 3 times, and stirred for 30 min to react; while maintaining the internal argon environment, 4.07 g of ethyl α-bromopropionate was injected into the reaction system with a syringe, the temperature was raised to 105° C., and the reaction was carried out for 1.5 h;

[0041] After the reaction is completed, the reaction device is moved into a dry ice bath to cool down, the reaction liquid is precipitated in methanol, filtered, and vacuum dried, then dissolved in tetrahydrofuran, precipitated in methanol again, filtered, and vacuum dried, and the operation is repeated 3 times for purification to obtain a macromolecular initiator A-Br, named PMMA-Br;

[0042] PMMA-Br was tested and found to have Mn (GPC) = 3.8k, Mw = 4.2k, and PDI = 1.11.

[0043] (2) Add 19 g PMMA-Br, 4.3 g cuprous bromide (CuBr), and 33.95 g N-isopropylacrylamide (NIPAM) into a flask, seal it, evacuate it, and replace it with high-purity argon gas, repeating 3 times; then inject 95 g anhydrous N,N-dimethylformamide (DMF) into the flask with a syringe, stir to dissolve, and then inject 6.04 g N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) into the flask with a syringe, evacuate it again, and replace it with high-purity argon gas, repeating 3 times; maintain the internal argon environment, heat to 95°C, and react for 24 hours;

[0044] After the reaction is completed, the flask is moved into a dry ice bath to cool down, anhydrous N,N-dimethylformamide (DMF) is added to the reaction liquid in the flask for dilution, and the cuprous bromide (CuBr) catalyst is removed by a neutral alumina column. The remaining liquid is precipitated in methanol and filtered, and vacuum dried. It is then dissolved in tetrahydrofuran, precipitated in methanol again and filtered, and vacuum dried. The operation is repeated 3 times for purification to obtain a block polymer copolymer AbB, named PMMA-b-PNIPAM, which is a temperature-sensitive microcapsule wall material;

[0045] PMMA-b-PNIPAM was tested and its Mn(GPC) was measured to be 7.4k, Mw=8.6k, and PDI=1.16.

[0046] Example 3

[0047] A method for preparing a temperature-sensitive microcapsule wall material comprises the following steps:

[0048] (1) 142.68 g of ethyl methacrylate (EMA) was added to 35.67 g of anisole to dissolve, the reaction apparatus was sealed and stirred, vacuumed, and replaced with high-purity argon gas, repeated 3 times, then 1.79 g of dried cuprous bromide (CuBr) powder and 2.52 g of N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) were added, vacuumed again, replaced with high-purity argon gas, repeated 3 times, and stirred for 30 min to react; while maintaining the internal argon environment, 2.04 g of ethyl α-bromopropionate was injected into the reaction system with a syringe, the temperature was raised to 100° C., and the reaction was carried out for 3 h;

[0049] After the reaction is completed, the reaction device is moved into a dry ice bath to cool down, the reaction liquid is precipitated in methanol, filtered, and vacuum dried, then dissolved in tetrahydrofuran, precipitated in methanol again, filtered, and vacuum dried, and the operation is repeated 3 times for purification to obtain a macromolecular initiator A-Br, named PEMA-Br;

[0050] PEMA-Br was tested and found to have Mn (GPC) = 4.5k, Mw = 5.1k, and PDI = 1.13.

[0051] (2) Add 22.5 g PEMA-Br, 3.59 g cuprous bromide (CuBr), and 28.3 g N-isopropylacrylamide (NIPAM) into a flask, seal it, evacuate it, and replace it with high-purity argon gas, repeating 3 times; then inject 225 g anhydrous N,N-dimethylformamide (DMF) into the flask with a syringe, stir to dissolve, and then inject 3.9 g 2,2-bipyridine into the flask with a syringe, evacuate it again, and replace it with high-purity argon gas, repeating 3 times; maintain the internal argon environment, heat to 85°C, and react for 20 hours;

[0052] After the reaction is completed, the flask is moved into a dry ice bath to cool down, anhydrous N,N-dimethylformamide (DMF) is added to the reaction liquid in the flask for dilution, and the cuprous bromide (CuBr) catalyst is removed by a neutral alumina column. The remaining liquid is precipitated in methanol and filtered, and vacuum dried. It is then dissolved in tetrahydrofuran, precipitated in methanol again and filtered, and vacuum dried. The operation is repeated 3 times for purification to obtain a block polymer copolymer AbB, named PEMA-b-PNIPAM, which is a thermosensitive microcapsule wall material;

[0053] PEMA-b-PNIPAM was tested and its Mn (GPC) was measured to be 8.8k, Mw = 10.6k, and PDI = 1.20.

[0054] Example 4

[0055] A method for preparing a temperature-sensitive microcapsule wall material comprises the following steps:

[0056] (1) 162.68 g of hydroxyethyl methacrylate (HEMA) was added to 36.15 g of anisole to dissolve, the reaction apparatus was sealed and stirred, vacuumed, and replaced with high-purity argon gas, repeated 3 times, and then 2.69 g of dried cuprous bromide (CuBr) powder and 2.93 g of 2,2'-bipyridine were added, vacuumed again, replaced with high-purity argon gas, repeated 3 times, and stirred for 30 minutes to react; while maintaining the internal argon environment, 3.39 g of ethyl α-bromopropionate was injected into the reaction system with a syringe, the temperature was raised to 110° C., and the reaction was carried out for 0.5 hours;

[0057] After the reaction, the reaction device was moved into a dry ice bath to cool down, the reaction liquid was precipitated in methanol, filtered, and vacuum dried, then dissolved in tetrahydrofuran, precipitated in methanol again, filtered, and vacuum dried, and the operation was repeated 3 times for purification to obtain a macromolecular initiator A-Br, named PHEMA-Br;

[0058] PHEMA-Br was tested and its Mn (GPC) was found to be 5.9k, Mw = 6.4k, and PDI = 1.08.

[0059] (2) Add 29.5 g PHEMA-Br, 5.38 g cuprous bromide (CuBr), and 99.02 g N-isopropylacrylamide (NIPAM) into a flask, seal it, evacuate it, and replace it with high-purity argon, repeating 3 times; then inject 220 g anhydrous N,N-dimethylformamide (DMF) into the flask with a syringe, stir to dissolve, and then inject 7.55 g N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) into the flask with a syringe, evacuate it again, and replace it with high-purity argon, repeating 3 times; maintain the internal argon environment, heat to 95°C, and react for 12 hours;

[0060] After the reaction is completed, the flask is moved into a dry ice bath to cool down, anhydrous N,N-dimethylformamide (DMF) is added to the reaction liquid in the flask for dilution, and the cuprous bromide (CuBr) catalyst is removed by a neutral alumina column. The remaining liquid is precipitated in methanol and filtered, and vacuum dried. It is then dissolved in tetrahydrofuran, precipitated in methanol again and filtered, and vacuum dried. The operation is repeated 3 times for purification to obtain a block polymer copolymer AbB, named PHEMA-b-PNIPAM, which is a thermosensitive microcapsule wall material;

[0061] PHEMA-b-PNIPAM was tested and its Mn (GPC) was measured to be 11.2k, Mw = 14.8k, and PDI = 1.32.

[0062] Example 5

[0063] A method for preparing a temperature-sensitive microcapsule wall material comprises the following steps:

[0064] (1) 104.15 g of styrene (St) was added to 23 g of anisole to dissolve, the reaction apparatus was sealed and stirred, evacuated, and replaced with high-purity argon gas, repeated 3 times, then 3.59 g of dried cuprous bromide (CuBr) powder and 5.03 g of N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) were added, evacuated again, replaced with high-purity argon gas, repeated 3 times, and stirred for 30 min to react; while maintaining the internal argon environment, 4.23 g of (1-bromoethyl)benzene was injected into the reaction system with a syringe, the temperature was raised to 105° C., and the reaction was carried out for 2.5 h;

[0065] After the reaction is completed, the reaction device is moved into a dry ice bath to cool down, the reaction liquid is precipitated in methanol, filtered, and vacuum dried, then dissolved in tetrahydrofuran, precipitated in methanol again, filtered, and vacuum dried, and the operation is repeated 3 times for purification to obtain a macromolecular initiator A-Br, named PSt-Br;

[0066] PSt-Br was detected and its Mn (GPC) was measured to be 3.6k, Mw = 4.3k, and PDI = 1.19.

[0067] (2) Add 18 g PSt-Br, 7.17 g cuprous bromide (CuBr), and 169.74 g N-isopropylacrylamide (NIPAM) into a flask, seal it, evacuate it, and replace it with high-purity argon gas, repeating 3 times; then inject 180 g anhydrous N,N-dimethylformamide (DMF) into the flask with a syringe, stir to dissolve, and then inject 10.07 g N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA) into the flask with a syringe, evacuate it again, and replace it with high-purity argon gas, repeating 3 times; maintain the internal argon environment, heat to 95°C, and react for 16 hours;

[0068] After the reaction is completed, the flask is moved into a dry ice bath to cool down, anhydrous N,N-dimethylformamide (DMF) is added to the reaction liquid in the flask for dilution, and the cuprous bromide (CuBr) catalyst is removed by a neutral alumina column. The remaining liquid is precipitated in methanol and filtered, and vacuum dried. It is then dissolved in tetrahydrofuran, precipitated in methanol again and filtered, and vacuum dried. The operation is repeated 3 times for purification to obtain a block polymer copolymer AbB, named PSt-b-PNIPAM, which is a thermosensitive microcapsule wall material;

[0069] PSt-b-PNIPAM was tested and its Mn (GPC) was measured to be 17.2k, Mw = 21.3k, and PDI = 1.24.

[0070] Comparative Example 1

[0071] The difference between this embodiment and Example 1 is that in step (2), N-isopropylacrylamide (NIPAM) is replaced by acrylic acid (AA), and the remaining operations are the same to obtain a non-temperature-sensitive block polymer copolymer AbB, named PSt-b-PAA;

[0072] PSt-Br was tested and its Mn (GPC) was found to be 4.1k, Mw = 4.7k, and PDI = 1.15; PSt-b-PAA was tested and its Mn (GPC) was found to be 8.7k, Mw = 10.4k, and PDI = 1.20.

[0073] Comparative Example 2

[0074] Styrene (St) and N-isopropylacrylamide (NIPAM) were used as reaction monomers in a molar ratio of 1:1, azobisisobutyronitrile was used as an initiator, and its mass accounted for 2% of the total mass of the monomers. Tetrahydrofuran was used as a solvent. The above raw materials were mixed, heated to 65°C, and reacted for 8 hours under nitrogen.

[0075] After the reaction is completed, the reaction liquid is diluted and dissolved with tetrahydrofuran, and then dropped into toluene for precipitation. A white solid precipitate can be obtained by suction filtration. The dissolution and precipitation operations are repeated for 3 times to obtain a white solid. The obtained white solid is placed in a vacuum drying oven at 40°C and dried until the mass remains unchanged to obtain a temperature-sensitive non-block polymer copolymer AbB, named PSt-co-PNIPAM;

[0076] PSt-co-PNIPAM was tested and its Mn (GPC) was measured to be 9.6k, Mw = 14.3k, and PDI = 1.49.

[0077] In order to more intuitively compare the preparation process parameters of the temperature-sensitive microcapsule wall materials, non-temperature-sensitive block polymer copolymers, and temperature-sensitive non-block polymer copolymers of Examples 1-5 and Comparative Examples 1-2, the following Table 1 is formed.

[0078] Table 1 Preparation process parameters of Examples 1-5 and Comparative Examples 1-2

[0079]

[0080]

[0081] The temperature-sensitive microcapsule wall material prepared by the preparation method of Examples 1-5 is a block polymer copolymer, which is prepared from monomer A and monomer B by atom transfer radical polymerization to form an AbB structure, wherein monomer A is a hydrophobic monomer with a polymerizable double bond at the terminal group, and monomer B is a temperature-sensitive monomer.

[0082] (II) Application of temperature-sensitive microcapsule wall materials

[0083] Example 6

[0084] An application of a temperature-sensitive microcapsule wall material, the temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule, the temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material, and the preparation method comprises the following steps:

[0085] (1) at room temperature, dissolving 1 part by weight of the block polymer copolymer PSt-b-PNIPAM prepared in Example 1 and 3 parts by weight of mosquito repellent (IR3535) in 15 parts by weight of acetone to obtain a mixed solution;

[0086] (2) in an ice water bath, using an electric stirrer at a stirring speed of 1600 rpm, the mixed solution was added dropwise at a rate of 0.08 mL / min to 450 parts by mass of deionized water to obtain a mixed system;

[0087] Keep the mixture in an ice-water bath and use a high-speed homogenizer to shear and disperse the mixed system, wherein the speed of the high-speed homogenizer is 10000 r / min and the shearing time is 30 min to obtain an emulsion;

[0088] The emulsion was spray dried, wherein the feed rate of the spray drying was 4 mL / min, the air inlet temperature was 200° C., and the air outlet temperature was 90° C., to obtain temperature-controlled sustained-release microcapsules, which were named temperature-controlled sustained-release anti-mosquito microcapsules.

[0089] Example 7

[0090] An application of a temperature-sensitive microcapsule wall material, the temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule, the temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material, and the preparation method comprises the following steps:

[0091] (1) at room temperature, dissolving 1 part by mass of the block polymer copolymer PMMA-b-PNIPAM prepared in Example 2 and 5 parts by mass of rose essential oil in 10 parts by mass of acetone to obtain a mixed solution;

[0092] (2) In an ice water bath, using an electric stirrer at a stirring speed of 1500 rpm, the mixed solution was added dropwise to 200 parts by mass of deionized water at a rate of 0.10 mL / min to obtain a mixed system;

[0093] Keep the mixture in an ice-water bath and use a high-speed homogenizer to shear and disperse the mixed system, wherein the speed of the high-speed homogenizer is 8000 r / min and the shearing time is 40 min to obtain an emulsion;

[0094] The emulsion was spray dried, wherein the feed rate of the spray drying was 3 mL / min, the air inlet temperature was 190° C., and the air outlet temperature was 95° C., to obtain temperature-controlled sustained-release microcapsules, which were named temperature-controlled sustained-release aromatic microcapsules.

[0095] Example 8

[0096] An application of a temperature-sensitive microcapsule wall material, the temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule, the temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material, and the preparation method comprises the following steps:

[0097] (1) dissolving 1 part by mass of the block polymer copolymer PEMA-b-PNIPAM prepared in Example 3 and 2 parts by mass of vitamin A in 20 parts by mass of acetone at room temperature to obtain a mixed solution;

[0098] (2) In an ice water bath, using an electric stirrer at a stirring speed of 2000 rpm, the mixed solution was added dropwise at a rate of 0.10 mL / min to 150 parts by mass of deionized water to obtain a mixed system;

[0099] Keeping the mixture in an ice-water bath, a high-speed homogenizer was used to shear and disperse the mixed system, wherein the speed of the high-speed homogenizer was 12000 r / min, and the shearing time was 30 min, to obtain an emulsion;

[0100] The emulsion was spray dried, wherein the feed rate of the spray drying was 5 mL / min, the air inlet temperature was 200° C., and the air outlet temperature was 100° C., to obtain temperature-controlled sustained-release microcapsules, which were named temperature-controlled sustained-release vitamin A microcapsules.

[0101] Example 9

[0102] An application of a temperature-sensitive microcapsule wall material, the temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule, the temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material, and the preparation method comprises the following steps:

[0103] (1) dissolving 1 part by mass of the block polymer copolymer PHEMA-b-PNIPAM prepared in Example 4 and 0.2 parts by mass of ginsenoside Rg3 in 3 parts by mass of acetone at room temperature to obtain a mixed solution;

[0104] (2) In an ice water bath, using an electric stirrer at a stirring speed of 3000 rpm, the mixed solution was added dropwise to 400 parts by mass of deionized water at a rate of 0.20 mL / min to obtain a mixed system;

[0105] Keep the mixture in an ice-water bath and use a high-speed homogenizer to shear and disperse the mixed system, wherein the speed of the high-speed homogenizer is 10000 r / min and the shear time is 60 min to obtain an emulsion;

[0106] The emulsion was spray dried, wherein the feed rate of the spray drying was 3 mL / min, the air inlet temperature was 200° C., and the air outlet temperature was 95° C., to obtain temperature-controlled sustained-release microcapsules, which were named temperature-controlled sustained-release ginsenoside microcapsules.

[0107] Example 10

[0108] An application of a temperature-sensitive microcapsule wall material, the temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule, the temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material, and the preparation method comprises the following steps:

[0109] (1) dissolving 1 part by mass of the block polymer copolymer PSt-b-PNIPAM prepared in Example 5 and 0.1 part by mass of squalane collagen in 2 parts by mass of acetone at room temperature to obtain a mixed solution;

[0110] (2) In an ice water bath, using an electric stirrer at a stirring speed of 500 rpm, the mixed solution was added dropwise to 200 parts by mass of deionized water at a rate of 0.02 mL / min to obtain a mixed system;

[0111] Keep the mixture in an ice-water bath and use a high-speed homogenizer to shear and disperse the mixed system, wherein the speed of the high-speed homogenizer is 8000 r / min and the shearing time is 10 min to obtain an emulsion;

[0112] The emulsion was spray dried, wherein the feed rate of the spray drying was 1 mL / min, the air inlet temperature was 180° C., and the air outlet temperature was 80° C., to obtain temperature-controlled sustained-release microcapsules, which were named temperature-controlled sustained-release squalane collagen microcapsules.

[0113] Comparative Example 3

[0114] The difference between this embodiment and Example 6 is that in step (1), the block polymer copolymer PSt-b-PNIPAM prepared in Example 1 is replaced by the non-temperature-sensitive block polymer copolymer PSt-b-PAA prepared in Comparative Example 1, and the other steps are the same to obtain non-temperature-controlled sustained-release microcapsules, which are named non-temperature-controlled sustained-release anti-mosquito microcapsules.

[0115] Comparative Example 4

[0116] The difference between this embodiment and Example 6 is that in step (1), the block polymer copolymer PSt-b-PNIPAM prepared in Example 1 is replaced by the temperature-sensitive non-block polymer copolymer PSt-co-PNIPAM prepared in Comparative Example 2, and the other steps are the same to obtain temperature-controlled sustained-release microcapsules, which are named non-block temperature-controlled sustained-release anti-mosquito microcapsules.

[0117] In order to more intuitively compare the preparation process parameters of the temperature-controlled sustained-release microcapsules and non-temperature-controlled sustained-release microcapsules of Examples 6-10 and Comparative Examples 3-4, the following Table 2 is formed.

[0118] Table 2 Preparation process parameters of Examples 6-10 and Comparative Examples 3-4

[0119]

[0120]

[0121] In order to verify the effect of the present invention, the temperature-controlled sustained-release microcapsules and non-temperature-controlled sustained-release microcapsules of Examples 6-10 and Comparative Examples 3-4 were tested to measure the release amount of the functional core material at different temperatures. The specific process is as follows:

[0122] The temperature-sensitive microcapsules and non-temperature-sensitive microcapsules of Examples 6-10 and Comparative Examples 3-4 were added to ultrapure water at 25°C and 35°C, respectively, at a concentration of 10 g / L, and ultrasonically dispersed for 20 minutes; while keeping the system temperature and ultrasonic state unchanged, tetrahydrofuran at the same temperature and a mass ratio of 50% of the mass of the ultrapure water in the system was added, and ultrasonication was continued for 5 minutes; filtered with a 0.22 μm tetrafluoroethylene syringe filter, 1 mL of the filtrate was placed in a centrifuge tube, and freeze-dried to remove the solvent; 1 g of anhydrous tetrahydrofuran containing quantitative triethylamine was added to dissolve it, and the concentration of the functional core material was detected and calculated using high performance liquid chromatography (HPLC), and the release rate of the functional core material at different temperatures was compared. The results are shown in Table 3.

[0123] Table 3 Release amount of functional core materials of temperature-controlled sustained-release microcapsules and non-temperature-controlled sustained-release microcapsules of Examples 6-10 and Comparative Examples 3-4 at different temperatures

[0124] Microcapsules 25℃ Dissolution concentration (ppm) 35℃ Dissolution concentration (ppm) Example 6 Temperature-controlled slow-release anti-mosquito microcapsules 13 128 Example 7 Temperature controlled slow release aroma microcapsules 22 195 Example 8 Temperature-controlled sustained-release vitamin A microcapsules 17 276 Example 9 Temperature-controlled sustained-release ginsenoside microcapsules 11 163 Example 10 Temperature-controlled sustained-release squalane collagen microcapsules 7 336 Comparative Example 3 Non-temperature controlled slow-release anti-mosquito microcapsules 15 21 Comparative Example 4 Non-blocked temperature-controlled slow-release anti-mosquito microcapsules 12 56

[0125] From Table 3, we can see that

[0126] It can be seen from Comparative Example 3 that the release rate of the functional core material of the non-temperature-controlled sustained-release microcapsules prepared in Comparative Example 3 is not significantly different under the conditions of 25°C and 35°C.

[0127] It can be seen from Comparative Example 4 that the release rate of the functional core material of the non-blocked temperature-controlled sustained-release microcapsules prepared in Comparative Example 4 at 35°C is significantly higher than that at 25°C, which indicates that the introduction of the temperature-sensitive monomer NIPAM into the microcapsule wall material can accelerate the release rate of the functional core material as the external temperature increases.

[0128] Comparing Examples 6-10 and Comparative Examples 3-4, it can be seen that the release rate of the functional core material of the temperature-controlled sustained-release microcapsules prepared in Examples 6-10 at 35°C is much higher than that at 25°C, and the release rate of the functional core material at 35°C is much higher than that of Examples 3-4, which shows that the thermosensitive block polymer copolymer prepared in Examples 1-5 as the microcapsule wall material can improve the release rate of the functional core material to a greater extent in an environment above the critical solution temperature of the temperature-sensitive monomer NIPAM, while in an environment below the critical solution temperature of the temperature-sensitive monomer NIPAM, the functional core material maintains a lower release rate. This is because the block structure of the thermosensitive wall material makes the distribution of the temperature-sensitive monomer NIPAM more concentrated, and when the temperature changes, the thermosensitive wall material exhibits a stronger phase change, thereby showing a more obvious temperature sensitivity.

[0129] The temperature-sensitive monomer NIPAM has different water solubility above and below the critical solution temperature (about 32°C). When the temperature is lower than the critical solution temperature, the amide groups in the NIPAM molecules interact with water molecules through hydrogen bonds, so that NIPAM has good solubility in water. At this time, NIPAM exhibits hydrophilicity; as the temperature increases, the entropy effect of the isopropyl side chain in the NIPAM molecule gradually increases, making the hydrophobic interaction more significant. When the temperature reaches the critical solution temperature, the hydrophobic interaction exceeds the hydrogen bond interaction. At this time, NIPAM exhibits hydrophobicity; utilizing this temperature-sensitive property of NIPAM, the present invention uses NIPAM as monomer B to prepare temperature-sensitive microcapsule wall materials, thereby realizing flexible release of the functional core material inside the microcapsule at a desired temperature.

[0130] The temperature-controlled sustained-release microcapsules prepared by the present invention can efficiently release the functional core material when used in an environment exceeding 32°C, while the release rate of the functional core material is low when stored in a normal room temperature environment. Therefore, the temperature-controlled sustained-release microcapsules prepared by the present invention can be applied to functional clothing, functional beauty products or other products for human body contact, such as mosquito-proof clothing, aromatic clothing, functional facial mask materials, etc., and have good functionality when used, while the release amount of the functional core material is small when not in contact with the human body, thereby extending the use time of the microcapsules.

[0131] It should be noted that the functional core materials in Examples 6-10 and Comparative Examples 3-4 can be selected according to different product requirements, and can be aromatic essential oils, mosquito repellent components, vitamins, drugs, or other functional materials except aromatic essential oils, mosquito repellent components, vitamins, and drugs. When preparing microcapsules, different processes can be used to prepare water-in-oil or oil-in-water microcapsules according to the properties of the functional core materials.

[0132] The present invention provides a temperature-sensitive microcapsule wall material and a preparation method thereof. A hydrophobic monomer with a polymerizable double bond at the end group is used as monomer A, and a temperature-sensitive monomer is used as monomer B. Monomer A and monomer B are prepared into an AbB structure through atom transfer free radical polymerization to obtain a block polymer copolymer AbB, which is the temperature-sensitive microcapsule wall material. The present invention also provides an application of the temperature-sensitive microcapsule wall material for preparing temperature-controlled sustained-release microcapsules. The block polymer copolymer AbB has good temperature response sensitivity and has a good temperature-controlled sustained-release effect on a functional core material inside the microcapsule as a wall material.

[0133] Compared with the prior art, (1) the present invention uses temperature-sensitive monomer N-isopropylacrylamide (NIPAM) as monomer B, and through the method of atom transfer radical polymerization (ATRP), NIPAM forms a homopolymer at one end of the polymer, and the temperature-sensitive monomers aggregate together, thereby improving the temperature response sensitivity of the block polymer copolymer AbB; when it is used as a microcapsule wall material, when the critical solution temperature of NIPAM is reached, the NIPAM molecules aggregate, and the microcapsule wall shrinks to form microchannels, so that the internal functional core material is efficiently released at the expected temperature, ensuring better functional effects; and when the expected use temperature is not reached, the functional core material is released slowly, effectively reducing the loss of functional components and extending the action time of the microcapsule; in addition, the block polymer copolymer AbB has a narrow molecular weight distribution and good macromolecular chain structure consistency. When stimulated by external temperature changes, the response consistency is high, the response is more efficient, and the effect is more obvious. (2) The present invention uses a hydrophobic monomer with a polymerizable double bond at the end group as monomer A, which can play the role of a skeleton when polymerized with monomer B to form a wall material through ATRP, maintaining the overall shape of the microcapsule; when the critical solution temperature of NIPAM is reached, the NIPAM molecules aggregate, and the microcapsule wall shrinks to form microchannels, and the functional core material inside is efficiently precipitated. At this time, the homopolymer formed by monomer A supports the microcapsule wall, avoids the overall collapse of the microcapsule, and improves the stability of the microcapsule. The process of the present invention is simple, the block polymer copolymer AbB has good temperature response sensitivity, and it has good temperature control and sustained release effect as a wall material. The prepared microcapsules can be applied to functional clothing for human contact, functional beauty products or other products, and have a wide range of applications.

[0134] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A temperature-sensitive microcapsule wall material, characterized in that: The wall material of the thermosensitive microcapsule is a block polymer copolymer, which is prepared into an AbB structure by atom transfer radical polymerization of monomer A and monomer B, wherein monomer A is a hydrophobic monomer with a polymerizable double bond at the end group, and monomer B is a temperature-sensitive monomer.

2. The temperature-sensitive microcapsule wall material according to claim 1, characterized in that: The monomer A includes any one of styrene, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate, and the monomer B includes N-isopropylacrylamide.

3. A method for preparing a temperature-sensitive microcapsule wall material according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) adding monomer A to anisole to dissolve it, then adding cuprous bromide and a ligand, stirring to react, then adding an initiator, heating and stirring to react, and post-treating to obtain A-Br; (2) A-Br, cuprous bromide, and monomer B are mixed, and then anhydrous N,N-dimethylformamide is added and stirred to dissolve, and then a ligand is added, and the temperature is raised and stirred to react, and post-processed to obtain a block polymer copolymer AbB, which is a thermosensitive microcapsule wall material.

4. The method for preparing the temperature-sensitive microcapsule wall material according to claim 3, characterized in that: In step (1), the mass ratio of monomer A to anisole is 4-5:1, the molar ratio of cuprous bromide to monomer A is 1%-2.5%:1, the ligand includes any one of N,N,N',N',N"-pentamethyldiethylenetriamine and 2,2'-bipyridine, the molar ratio of the ligand to cuprous bromide is 1:1, the initiator includes any one of (1-bromoethyl)benzene and ethyl α-bromopropionate, and the molar ratio of the initiator to cuprous bromide is 0.9-1:

1.

5. The method for preparing the temperature-sensitive microcapsule wall material according to claim 3, characterized in that: In step (1), the temperature is raised to 100-110° C. and the reaction is carried out for 0.5-3 h.

6. The method for preparing the temperature-sensitive microcapsule wall material according to claim 3, characterized in that: In step (2), the molar ratio of A-Br, CuBr and monomer B is 1:5-10:50-300, the mass ratio of A-Br to anhydrous N,N-dimethylformamide is 1:5-10, the ligand includes any one of N,N,N',N',N"-pentamethyldiethylenetriamine and 2,2'-bipyridine, and the molar ratio of the ligand to cuprous bromide is 1:

1.

7. The method for preparing the temperature-sensitive microcapsule wall material according to claim 3, characterized in that: In step (2), the temperature is raised to 85-95° C. and the reaction is carried out for 12-24 hours.

8. An application of the temperature-sensitive microcapsule wall material according to any one of claims 1 to 2, characterized in that: The temperature-sensitive microcapsule wall material is used to prepare a temperature-controlled sustained-release microcapsule. The temperature-controlled sustained-release microcapsule comprises the temperature-sensitive microcapsule wall material and a functional core material. The preparation method comprises the following steps: (1) dissolving the block polymer copolymer AbB and the functional core material in acetone at room temperature to obtain a mixed solution; (2) In an ice-water bath, the mixed solution is added dropwise into deionized water under stirring to obtain a mixed system; while maintaining the ice-water bath, the mixed system is shear-dispersed to obtain an emulsion; and the emulsion is spray-dried to obtain a temperature-controlled sustained-release microcapsule.

9. The use of the temperature-sensitive microcapsule wall material according to claim 8, characterized in that: In step (1), the mass ratio of the functional core material, the block polymer copolymer AbB, and acetone is 1:0.1-10:1-20.

10. The use of the temperature-sensitive microcapsule wall material according to claim 8, characterized in that: In step (2), the mass ratio of the mixed solution to deionized water is 1:5-100, and the dropping speed of the mixed solution is 0.02-0.2 mL / min.

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