A shear thickening material and a method of making the same

Abstract

The present application relates to a kind of shear thickening material and its preparation method, belong to polymer material preparation technical field.The method is that small molecule dihydroxy compound and long chain dihydroxy compound are placed in vacuum oven, and vacuum drying is obtained after drying dihydroxy compound;Isocyanate, small molecule dihydroxy compound and long chain dihydroxy compound are placed in flask according to certain molar ratio, and are reacted under the condition of nitrogen protection, are stirred and mixed uniformly and are poured into polytetrafluoroethylene mould;Finally, the material prepared is placed in vacuum oven, removes bubble, is taken out after drying 8-48h at 25-75 ℃ temperature, and shear thickening material is obtained.The present application realizes the preparation of shear thickening material with semi-solid characteristics at lower temperature, overcomes the problem of existing material, and process is simple, has the potential of large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of shear thickening material and its preparation method, belong to polymer material preparation technical field. BACKGROUND

[0002] Shear thickening effect is a kind of non-Newtonian fluid behavior, generally refers to the material in normal state is flexible, when being subjected to high-speed shearing or impact, modulus or viscosity rapidly increases and has solid state characteristics phenomenon.When external force is removed, material can recover to soft state again, it is a kind of new intelligent impact-resistant material.Shear thickening material is sensitive to strain rate this characteristic can effectively absorb the energy of stamping, and can quickly adapt to the stress field of external environment.Therefore, in the innovation road of traditional hard, heavy protective material, shear thickening material is also considered to be the most potential product.Because shear thickening material has the characteristics of high-efficiency energy absorption, light weight, recoverable, has broad application prospect in soft protection and impact damping field.

[0003] The shear thickening materials currently studied mainly have two categories.One is shear thickening liquid, mainly composed of liquid polymer matrix and nano-particles.The shear thickening system is difficult to package due to its strong fluidity, and there is also the problem of easy sedimentation of nano-particles, which affects its wide use.The other is shear thickening glue, generally refers to borosiloxane polymer, its semi-solid characteristics make the material easy to package, and overcome the problem of particle sedimentation.But because its reaction process is dehydration condensation reaction, its production preparation process often needs to be carried out in high temperature environment, and it has high requirements for production equipment and complex production process. SUMMARY

[0004] The purpose of the present application is to solve the problems of existing materials, provide a kind of shear thickening material and its preparation method, which can prepare shear thickening material with semi-solid characteristics at lower temperature, overcome the problems of existing materials, and the preparation process is simple, has the potential of large-scale production.

[0005] The purpose of the present application is realized by the following technical scheme.

[0006] A preparation method of shear thickening material, comprising the following steps:

[0007] Step one, place small molecule dihydroxy compound and long chain dihydroxy compound in vacuum oven, vacuum dry for a certain time, to obtain dried dihydroxy compound.

[0008] The small molecule dihydroxy compound includes but is not limited to: triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, which can be one or a mixture of multiple;

[0009] The long-chain dihydroxy compound includes but is not limited to: polyethylene glycol (PEG), polytetramethylene glycol (PTMEG), hydroxyl-terminated polydimethylsiloxane (PDMS), which can be one or a mixture of multiple thereof;

[0010] The PEG has a molecular weight of 200-20000 g / mol, preferably, a molecular weight of 1000-4000 g / mol. The PTMEG has a molecular weight of 250-3000 g / mol, preferably, a molecular weight of 1000-2000 g / mol. The PDMS has a molecular weight of 450-20000 g / mol, preferably, a molecular weight of 1200-3600 g / mol.

[0011] The vacuum oven temperature is 100-120℃;

[0012] The vacuum drying time is 0.5-2h;

[0013] Step two, the isocyanate, small molecule dihydroxy compound, long-chain dihydroxy compound are put into a flask according to a certain molar ratio, stirred and mixed uniformly under the condition of nitrogen protection, and poured into a polytetrafluoroethylene mold.

[0014] The molar ratio of the isocyanate to the dihydroxy compound is 0.9:1-1.1:1;

[0015] The molar ratio of the small molecule dihydroxy compound to the long-chain dihydroxy compound is 0.5:1-5:1;

[0016] The reaction time is 3-20 min in the presence of the catalyst dibutyltin dilaurate (DBTDL), and the reaction time is 0.5-4h in the absence of the catalyst;

[0017] A small amount of small molecule alcohol can be added to control the polymerization degree of the prepared shear thickening material, and the addition amount is 0.1%-10% of the total mass of the reaction system, and the small molecule alcohol includes but is not limited to methanol, ethanol, etc.

[0018] The reaction temperature is 50-75℃;

[0019] The isocyanate includes but is not limited to: diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), which can be one or a mixture of multiple thereof;

[0020] Step three, the material prepared in step two is put into a vacuum oven to remove bubbles, and after drying for a certain time, the shear thickening material is obtained.

[0021] The oven temperature is 25-75℃;

[0022] The drying time is 8-48h;

[0023] Advantages

[0024] 1. The preparation method of the shear thickening material, the prepared material presents semi-solid properties, the preparation process is simple and convenient for packaging, and the problems of strong fluidity, difficulty in packaging, and easy sedimentation of nano particles of shear thickening liquid and the harsh preparation process of polysilane shear thickening glue are overcome. The shear thickening material with semi-solid properties is prepared at a lower temperature. The prepared shear thickening material also has micro-phase separation properties, and has great application potential in the fields of soft protection and impact damping.

[0025] 2. The present application can improve the problems of shear thickening materials in actual application or preparation. On the other hand, it can also expand new materials in the fields of soft protection and impact damping, and provide research ideas for the application of shear thickening materials in related fields. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the gel permeation chromatography (GPC) retention time curve of sample A;

[0027] Figure 2 is the frequency scanning curve of sample A;

[0028] Figure 3 is the GPC retention time curve of sample B;

[0029] Figure 4 is the frequency scanning curve of sample B;

[0030] Figure 5 is the two-dimensional Young's modulus distribution diagram of sample B. DETAILED DESCRIPTION

[0031] The present application is better illustrated by the following examples, but the present application is not limited to the following examples.

[0032] Example 1

[0033] Triethylene glycol, PEG were dried in vacuum oven at 120°C for 0.5h to remove water. IPDI 33.35g (0.15mol), PEG 50.0g (molecular weight 1000g / mol, 0.05mol), triethylene glycol 150.02g (0.1mol) were placed in a flask, and the oil bath temperature was set at 60°C. After stirring uniformly under nitrogen protection, one drop of DBTDL was added to the mixed solution. The reaction was continued for 10 min, and the reaction system began to become viscous. It was poured into a polytetrafluoroethylene mold, and then placed in a vacuum oven to degas, with the temperature kept at 60°C. After 30h, it was taken out and cooled to room temperature to obtain a shear thickening material, named A.

[0034] The GPC and dynamic frequency scanning curves of shear thickening material A can be seen in Figure 1 , Figure 2 From the GPC curve, it can be seen that material A is an oligomer with low molecular weight. In the dynamic frequency scanning curve, it can be seen that with the increase of frequency, the storage modulus and loss modulus of material A increase exponentially, showing obvious shear thickening effect.

[0035] Example 2

[0036] Triethylene glycol, PEG were dried in vacuum oven at 110°C for 1h to remove water. IPDI 26.68g (0.12mol), PEG 20.0g (molecular weight 1000g / mol, 0.02mol), triethylene glycol 15.02g (0.1mol) were placed in a flask, and the oil bath temperature was set at 60°C. After stirring for 40 min under nitrogen protection, the reaction system became viscous. After adding 1ml of ethanol and stirring for 0.5h, it was poured into a polytetrafluoroethylene mold, and then placed in a vacuum oven to degas, with the temperature kept at 60°C. After 12h, it was taken out to obtain a shear thickening material, named B.

[0037] The GPC and dynamic frequency scanning curves of shear thickening material B can be seen in Figure 3 , Figure 4 It can be seen from the figure that material B is also an oligomer with low molecular weight and has shear thickening properties. The two-dimensional Young's modulus distribution of material B can be seen in Figure 5 It can be seen that material B has a microphase-separated structure and has obvious soft and hard interface regions. At the same time, the shear thickening material with small molecule ethanol has good storage stability.

[0038] Example 3

[0039] Pentaglycol, PTMEG was dried in vacuum oven at 110 °C for 1 h to remove moisture. HMDI 26.24 g (0.1 mol), PTMEG 50.0 g (molecular weight 1000 g / mol, 0.05 mol), pentaglycol 11.91 g (0.05 mol) were weighed into a flask and the oil bath temperature was set to 65 °C. After stirring uniformly under nitrogen, one drop of DBTDL was added to the mixture. The reaction was continued for 5 min and the reaction system began to become viscous. It was poured into a Teflon mold, and then placed in a vacuum oven to remove bubbles, and the temperature was kept at 50 °C for 16 h, then removed and cooled to room temperature to obtain a shear thickening material, named C.

[0040] Example 4

[0041] Triglycol, PDMS was dried in vacuum oven at 110 °C for 1 h to remove moisture. IPDI 22.23 g (0.10 mol), PDMS 60.0 g (molecular weight 1200 g / mol, 0.05 mol), triglycol 7.51 g (0.05 mol) were weighed into a flask and the oil bath temperature was set to 60 °C. After stirring uniformly under nitrogen, one drop of DBTDL was added to the mixture. The reaction was continued for 5 min and the reaction system began to become viscous. It was poured into a Teflon mold, and then placed in a vacuum oven to remove bubbles, and the temperature was kept at 60 °C for 12 h, then removed and cooled to room temperature to obtain a shear thickening material, named D.

[0042] Example 5

[0043] Triglycol, tetraglycol, PEG was dried in vacuum oven at 110 °C for 1 h to remove moisture. IPDI 22.23 g (0.10 mol), PEG 50.0 g (molecular weight 1000 g / mol, 0.05 mol), triglycol 3.75 g (0.025 mol), tetraglycol 4.86 g (0.025 mol) were weighed into a flask and the oil bath temperature was set to 65 °C. After stirring uniformly under nitrogen, one drop of DBTDL was added to the mixture. The reaction was continued for 10 min and the reaction system began to become viscous. It was poured into a Teflon mold, and then placed in a vacuum oven to remove bubbles, and the temperature was kept at 60 °C for 24 h, then removed and cooled to room temperature to obtain a shear thickening material, named E.

[0044] Example 6

[0045] The tetraglycol, PEG was placed in a vacuum oven at 120°C for 0.5h to dry and remove moisture. HDI 15.14g (0.09mol), PEG 50.0g (molecular weight 1000g / mol, 0.05mol), tetraglycol 9.71g (0.05mol) were weighed into a flask and the oil bath temperature was set to 60°C. After stirring uniformly under nitrogen protection, one drop of DBTDL was added to the mixed solution. The reaction was continued for 6min, and the reaction system began to become viscous. It was poured into a polytetrafluoroethylene mold, and then placed in a vacuum oven to degas, and the temperature was kept at 60°C. After 16h, it was taken out and cooled to room temperature to obtain a shear thickening material, named F.

[0046] Example 7

[0047] The tetraglycol, PEG was placed in a vacuum oven at 120°C for 0.5h to dry and remove moisture. HDI 15.14g (0.09mol), PEG 50.0g (molecular weight 1000g / mol, 0.05mol), tetraglycol 9.71g (0.05mol) were weighed into a flask and the oil bath temperature was set to 60°C. After stirring uniformly under nitrogen protection, one drop of DBTDL was added to the mixed solution. The reaction was continued for 6min, and the reaction system began to become viscous. It was poured into a polytetrafluoroethylene mold, and then placed in a vacuum oven to degas, and the temperature was kept at 60°C. After 16h, it was taken out and cooled to room temperature to obtain a shear thickening material, named F.

[0048] Example 8

[0049] The PEG in Example 2 was changed to PDMS (molecular weight 1200g / mol), and the corresponding PDMS mass was 39.6g, and the rest remained unchanged, to obtain a shear thickening material, named H.

[0050] Example 9

[0051] The tetraglycol in Example 4 was changed to hexaglycol, and the corresponding hexaglycol mass was 14.12g, and the rest remained unchanged, to obtain a shear thickening material, named I.

[0052] The above specific description further describes the purpose, technical solution and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A shear-thickening material and its preparation method, characterized in that... Includes the following steps: Step 1: Place the small molecule dihydroxy compound and the long-chain dihydroxy compound in a vacuum oven and dry them under vacuum to obtain the dried dihydroxy compound; Step 2: Isocyanate, small-molecule dihydroxy compound, and long-chain dihydroxy compound are placed in a flask at a specific molar ratio and reacted. Under nitrogen protection, the mixture is stirred until homogeneous and then poured into a polytetrafluoroethylene mold. The molar ratio of isocyanate to dihydroxy compound is: The molar ratio of the small molecule dihydroxy compound to the long-chain dihydroxy compound is 0.5:1 to 5:

1. Step 3: Place the material obtained in Step 2 into a vacuum oven to remove air bubbles, and dry it at 25-75℃ for 8-48 hours to obtain the shear thickening material. The small molecule dihydroxy compound in step one is one or a mixture of more than one of triethylene glycol, tetraethylene glycol, pentaethylene glycol, and hexaethylene glycol; the long-chain dihydroxy compound in step one includes one or a mixture of more than one of polyethylene glycol (PEG), polytetrahydrofuran (PTMEG), and hydroxyl-terminated polydimethylsiloxane (PDMS); the isocyanate in step two includes one or a mixture of more than one of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), and dicyclohexylmethane diisocyanate (HMDI).

2. The method as described in claim 1, characterized in that: The vacuum drying in step one is as follows: drying at 100-120℃ for 0.5-2 hours.

3. The method as described in claim 1, characterized in that: The reaction described in step two is carried out in the presence of the catalyst dibutyltin dilaurate (DBTDL) for a reaction time of 3 to 20 minutes, or in the absence of a catalyst for a reaction time of 0.5 to 4 hours; the reaction temperature is 50 to 75°C.

4. The method as described in claim 1 or 3, characterized in that: In step two, a small amount of small molecule alcohol is added during the reaction to control the degree of polymerization of the prepared shear thickening material; the amount added is 0.1% to 10% of the total mass of the reaction system, and the small molecule alcohol is methanol or ethanol.

5. The method as described in claim 1, characterized in that: The PEG has a molecular weight of 200-20000 g / mol; the PTMEG has a molecular weight of 250-3000 g / mol; and the PDMS has a molecular weight of 450-20000 g / mol.

6. The method as described in claim 5, characterized in that: The PEG has a molecular weight of 1000-4000 g / mol; the PTMEG has a molecular weight of 1000-2000 g / mol; and the PDMS has a molecular weight of 1200-3600 g / mol.

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