KR102078477B1 - Shear thickening fluid with high-performance shear thickening behavior comprising polystyrene particles with polyacrylamide on their surfaces and its manufacturing method - Google Patents

Abstract

The present invention relates to a shear thickening fluid having excellent shear thickening behavior. More specifically, the present invention provides: a shear thickening fluid having excellent shear thickening behavior, which comprises polystyrene particles having polyacrylamide on surfaces thereof, thereby being able to be used in protective clothing, protective equipment, bulletproof jackets, shock absorbing materials, braking devices, control devices and the like; and a manufacturing method thereof.

Description

Shear thickening fluid with high-performance shear thickening behavior comprising polystyrene particles with polyacrylamide on their surfaces and its manufacturing method}

The present invention relates to a shear thickening fluid having excellent viscosity behavior, and in particular, it can be used in protective clothing, protective equipment, body armor, shock absorbing material, braking device and regulating device, including polyacrylamide bonded to the surface of polystyrene. The present invention relates to a shear thickening fluid having excellent roughening behavior and a method of manufacturing the same.

Shear thickening behavior is a type of concentrated suspension, non-Newtonian behavior of a fluid, and is a reversible phenomenon that causes a viscosity when shear stress or shear rate is applied to a non-viscosity fluid. It is the behavior that increases several times.

Materials exhibiting viscous behavior are inherently pliable and rapidly harden at critical points when shear stress is applied, so they are used in protective clothing, protective equipment such as gloves, shock absorbers, brakes and regulating devices.

Viscous behavior is influenced by particle parameters such as volume fraction, shape, size, size distribution and interparticle interactions. Among them, the interaction between particles can be enhanced by introducing hydrogen bonds on the particle surface into secondary bonds. In suspensions of particles with functional groups capable of hydrogen bonding at the surface, stronger viscous behavior is observed than suspensions without functional groups capable of hydrogen bonding.

In the paper 'Contribution of Surface Chemistry to the Shear Thickening of Silica Nanoparticle Suspensions.', The condensation behavior of the suspension of silica particles removed from hydroxyl groups by heat treatment of the surface was confirmed. This result indicates that the presence of hydrogen-bondable functional groups on the particle surface has a significant effect on the fluid's viscous behavior.

Shear Thickening Fluid (STF) with this viscous behavior exhibits a reversible state change from liquid phase to solid phase due to the rheological properties of which the viscosity increases rapidly when the shear stress or shear rate is increased in the suspension. As fluids, studies are being actively conducted for impregnating fibers and using them as materials for bulletproof or sword proofing.

Accordingly, 'Korean Patent Publication No. 10-2011-0114008' provides a bulletproof material using a shear thickening fluid and a kevlar suit including the same, but there is a problem in that the property of the viscosity of the shear thickening fluid is limited to the bulletproof material.

KR 10-2011-0114008

 Yang W, Wu Y, Pei X, Zhou F, Xue Q (2017) Contribution of Surface Chemistry to the Shear Thickening of Silica Nanoparticle Suspensions. Langmuir 33 (4): 1037-1042

In order to solve the above problems, an object of the present invention is to provide a shear thickening fluid having excellent consistency in behavior that can be used in protective clothing, protective equipment, body armor, shock absorbing material, braking device and control device.

In addition, an object of the present invention is to provide a method for producing a shear thickening fluid excellent in viscosity consistency behavior.

It is also an object of the present invention to provide a protective clothing, protective equipment, body armor, shock absorbing material, a braking device or a control device made of shear thickening fluid with excellent consistency.

The present invention to solve the above object,

First polystyrene derivative or silica; And

It includes; polyacrylamide (polyacrylamide) present on the surface of the second polystyrene,

The first polystyrene derivative or the silica provides a shear thickening fluid, characterized in that the polyacrylamide and hydrogen bonding.

The weight blending ratio of the first polystyrene derivative and the second polystyrene is 25-100: 1, and the weight blending ratio of the silica and the second polystyrene is 10-100: 1.

In addition, the first polystyrene derivative is poly (2-hydroxyethyl methacrylate) [PHEMA], polymethacrylic acid, and polyacrylic acid on the surface of polystyrene. Any one selected from the group consisting of a combined form.

The present invention to solve the above other object,

Forming a first polystyrene derivative;

Forming a polyacrylamide polymer with a second polystyrene; And

Suspending the derivative and the polymer in a solvent; provides a method for producing a shear thickening fluid comprising a.

The present invention to solve the above another object,

Forming a polyacrylamide polymer with a second polystyrene; And

Suspending the polymer and silica in a solvent; provides a method for producing a shear thickening fluid comprising a.

The first polystyrene derivative is composed of poly (2-hydroxyethyl methacrylate) [PHEMA], polymethacrylic acid, and polyacrylic acid on the polystyrene surface. Any one selected from the group is in combined form.

The solvent is any one selected from the group consisting of ethylene glycol, methylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol and butylene glycol.

In addition, the step of forming the derivative or the polymer consists of a surfactant-free emulsion polymerization.

The present invention to solve the above another object,

Provided are protective clothing, protective equipment, body armor, shock absorbing materials, braking devices, or regulating devices made from shear thickening fluid.

The present invention is to provide a shear thickening fluid having a good consistency behavior effect including a polyacrylamide bonded to the surface of polystyrene and a method for manufacturing the same, protective clothing, protective equipment, body armor, shock absorbing material, braking device or There is an effect that can be utilized in the development of the control device.

1 is a DLS, SEM and TEM picture of the PS-PAAm particles according to an embodiment of the present invention.
2 is a DLS, SEM and TEM picture of PS-PHEMA particles according to an embodiment of the present invention.
3 is a DLS, SEM and TEM picture of silica particles according to an embodiment of the present invention.
Figure 4a is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of PS-PHEMA particles and PS-PAAm-PS-PHEMA particles to 50%.
Figure 4b is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of PS-PHEMA particles and PS-PAAm-PS-PHEMA particles to 52%.
Figure 5a is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of silica particles and PS-PAAm-silica particles at 68%.
Figure 5b is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of silica particles and PS-PAAm-silica particles to 69%.
Figure 5c is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of silica particles and PS-PAAm-silica particles to 70%.
FIG. 6 is a diagram showing a mechanism in which viscous behavior is enhanced by binding of PS-PAAm and PS-PHEMA particles.
FIG. 7 is a diagram showing a mechanism in which the viscosity behavior is enhanced due to the combination of PS-PAAm and silica particles.

The present invention relates to a shear thickening fluid having excellent viscosity behavior, and in particular, it can be used in protective clothing, protective equipment, body armor, shock absorbing material, braking device and regulating device, including polyacrylamide bonded to the surface of polystyrene. The present invention relates to a shear thickening fluid having excellent roughening behavior and a method of manufacturing the same.

Hereinafter, the present invention will be described in more detail.

According to one aspect of the invention, the first polystyrene (polystyrene) derivative or silica (silica); And polyacrylamide present on the surface of the second polystyrene, wherein the polystyrene derivative or silica is connected to the polyacrylamide by hydrogen bonding to provide a shear thickening fluid.

Acrylamide is a material made by hydrolyzing acrylonitrile, which is a raw material for adhesives and plastics, and the polymer is used for various purposes because of its low adsorption, good water retention, and strong resistance to heat, acid, alkali, and surfactant. Separation of upper polymer such as protein or nucleic acid by electrophoresis (Polyacrylamide gel electrophoresis; PAGE) in gel, analysis of molecular weight by using granular gel It can be used for microcarrier culture or the like using one particulate gel.

Polystyrene is an amorphous polymer obtained by radical polymerization of styrene. A colorless transparent thermoplastic resin is also called styrol resin. It consists of polystyrene, a polymer of liquid styrene units produced by the reaction of ethylene and benzene, and does not erode well in chemicals. Styrene resins are the easiest to process among plastics and have a high refractive index, which can be used to make electrically insulating materials or rigid molded parts.

Hard polystyrene has a relatively low density compared to inorganic particles, and can control the rheological properties by varying the molecular structure and surface properties by controlling hardness, surface function, surface charge and size.

Silica is a chemical combination of silicon and oxygen (SiO ₂ ), which is a major component of rocks and soils, and is contained in trace amounts in natural water in ionic and colloidal states. Silica gel, dehydrated to form a gel, is an adsorbent and is also used for adsorption or recovery of hydrates, solvents. Silica particles have a large number of hydroxy groups and O-groups on the surface, so the particle dispersion is good, and the particles can interact with each other and can be used as a constituent of shear thickening fluid. In addition, the synthesis method is relatively simple and easy to purchase, so the accessibility is good.

The weight blending ratio of the first polystyrene derivative and the second polystyrene is preferably 25-100: 1.

The weight ratio of silica and second polystyrene is 10-100: 1, preferably 10: 1.

The first polystyrene derivative is composed of poly (2-hydroxyethyl methacrylate) [PHEMA], polymethacrylic acid, and polyacrylic acid on the polystyrene surface. Any one selected from the group may be in a combined form, preferably poly (2-hydroxyethyl methacrylate) [poly (2-hydroxyethyl methacrylate), PHEMA is bonded to the surface of polystyrene.

Polystyrene derivatives bound to the surface by PHEMA have a plurality of hydrogen bond acceptors (: O :) on the surface of one hydrogen bond donor (-OH), thereby forming hydrogen bonds between the polystyrene derivative particles. There will be residual receptors that do not form.

Silica also has a larger number of hydrogen bond acceptors than hydrogen bond donors, so that when a hydrogen bond is formed between silica particles, there is a residual receptor that cannot form a hydrogen bond.

Polyacrylamide has a relatively strong hydrogen bond acceptor (-N :) belonging to amines (-NH ₂ ) and abundant hydrogen bond donors. When a polymer (polystyrene with polyacrylamide, PS-PAAm) formed by binding such polyacrylamide to the surface of polystyrene is mixed with a polystyrene derivative or silica, a donor capable of binding to the remaining hydrogen bond acceptor remaining on the surface of the polystyrene derivative or silica is obtained. Can provide Therefore, the interaction between the particles can be improved to exhibit a more excellent effect of consistency behavior.

In another aspect of the invention, forming a first polystyrene derivative; Forming a polyacrylamide polymer with a second polystyrene; And suspending the derivative and the polymer in a solvent. It provides a method for producing a shear thickening fluid, comprising: a.

In another aspect of the invention, forming a second polystyrene and polyacrylamide polymer; And suspending the polymer and the silica in a solvent. It provides a method for producing a shear thickening fluid.

The first polystyrene derivative is composed of poly (2-hydroxyethyl methacrylate) [PHEMA], polymethacrylic acid, and polyacrylic acid on the polystyrene surface. Any one selected from the group may be in a combined form, preferably poly (2-hydroxyethyl methacrylate) [poly (2-hydroxyethyl methacrylate), PHEMA is bonded to the surface of polystyrene.

The solvent is any one selected from the group consisting of methylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol and butylene glycol. Preferably it may be ethylene glycol, diethylene glycol, triethylene glycol or tetraethylene glycol, more preferably ethylene glycol may be used.

Ethylene glycol is a dihydric alcohol, a colorless sticky liquid, hygroscopic and capable of dissolving inorganic compounds. Can be.

Forming the derivative or polymer used in the present invention consists of surfactant-free emulsion polymerization.

The surfactant-free emulsion polymerization method is an emulsion polymerization method that stabilizes particles by using an initiator that has a charge without using a surfactant. The low molecular weight chains formed after monomer exhaustion of high molecular weight chains formed at a high monomer concentration The particles can be formed while stabilizing. Since the surfactant-free emulsion polymerization method does not use a surfactant, the removal of the surfactant is not necessary, and the particle size may be larger than that of the general emulsion polymerization method.

In still another aspect of the present invention, there is provided a protective clothing, protective equipment, body armor, shock absorbing material, braking device or control device made of shear thickening fluid.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are provided to illustrate the present invention and the scope of the present invention is not limited by the examples. It is intended to provide a complete description of the invention and to fully convey the scope of the invention to those of ordinary skill in the art.

<Example>

Example 1 Synthesis of Polystyrene Particles Having Polyacrylamide on the Surface

Polystyrene with polyacrylamide (PS-PAAm) particles having polyacrylamide on the surface are made of acrylamide using divinylbenzene (DVB) as a crosslinking agent and potassium persulfate (KPS) as an initiator. , AAm) and styrene (ST) were synthesized through surfactant-free emulsion polymerization. To a 1000 ml round bottom flask add ST (48.16 mL, 0.42 mol), AAm (2.99 g, 0.042 mol), crosslinker (4.79 mL, 0.034 mol) and tertiary distilled water (580 mL) and spray N ₂ over 20 hours By deoxidation. After polymerization for 24 h under N ₂ , the product was obtained by centrifugation and the final product was dried in a vacuum oven at 30 ° C.

Example 2 Preparation of PS-PAAm-PS-PHEMA and PS-PAAm-Silica Shear Thickening Fluids

PS-PAAm and Polystyrene-poly (2-hydroxyethyl methacrylate), PS-PHEMA, PS-PAAm and silica were added to ethylene glycol (EG), respectively. The mixture was then suspended uniformly using a grinder. The mixture was mixed until there was no large aggregate in the suspension, and the finally prepared shear thickening fluid removed ultrasonic bubbles for 30 minutes using ultrasonic waves.

Example 3. PS-PAAm Particle Analysis-DLS, SEM and TEM

In order to analyze PS-PAAm particles, pictures were taken using dynamic light scattering (DLS), field-emission scanning electron microscope (FE-SEM), and transmission electron microscopy (TEM).

Example 4 Viscous Behavior of PS-PAAm-PS-PHEMA and PS-PAAm-Silica Shear Thickening Fluids

In order to compare the viscous behavior of PS-PAAm-PS-PHEMA and PS-PAAm-silica shear thickening fluids, the viscosity of each fluid was measured and plotted as a graph.

PS-PAAm-PS-PHEMA particles are fixed at 50 wt% and 52 wt% weight ratios of the suspension, and in both types PS-PAAm / PS-PHEMA particles of 1/25, 1/50 and 1/100, respectively The viscosity of the shear thickening fluid prepared by adding the ratio was measured according to the shear rate.

In addition, the PS-PAAm-silica particles were fixed at a weight ratio of 68 wt%, 69 wt% and 70 wt% of the suspension, and the shear prepared by adding PS-PAAm / silica at a particle ratio of 1/10 in all three types The viscosity of the thickening fluid was measured according to the shear rate.

Comparative Example 1. Synthesis of polystyrene-poly (2-hydroxyethyl methacrylate) particles

Polystyrene-poly (2-hydroxyethyl methacrylate) is named PS-PHEMA to facilitate the description on the specification.

PS-PHEMA was synthesized in the same manner as in Example 1, and silica particles (quartz, SG-SO500) were purchased and used in the experiment.

Comparative Example 2. Preparation of PS-PHEMA and Silica Particle Shear Thickening Fluid

In the same manner as in Example 2, PS-PHEMA and silica particles were added to EG and suspended to prepare a shear thickening fluid.

Comparative Example 3 PS-PHEMA and Silica Particle Analysis-DLS, SEM and TEM

In order to analyze PS-PHEMA and silica particles, pictures were taken under the same microscope as in Example 3.

Comparative Example 4 Viscosity Behavior of PS-PHEMA and Silica Shear Thickening Fluids

In order to compare the viscous behavior of PS-PHEMA and silica shear thickening fluid, the viscosity was measured and plotted according to the shear rate of each fluid.

PS-PHEMA particles were prepared at a weight ratio of 50 wt% and 52 wt% of the suspension to prepare shear thickening fluid, and the viscosity thereof was measured according to the shear rate.

In addition, the silica particles were fixed at a weight ratio of 68 wt%, 69 wt% and 70 wt% of the suspension to prepare a shear thickening fluid, and the viscosity thereof was measured according to the shear rate.

<Evaluation and Analysis>

Outcome 1.DLS, SEM and TEM photo of PS-PAAm, PS-PHEMA and silica particles

The results of confirming the DLS, SEM and TEM photographs of the PS-PAAm particles, the silica particles, and the PS-PHEMA particles are shown in FIGS. 1 to 3.

The PS-PAAm particles had a diameter of 410 nm, the PS-PHEMA particles had a diameter of about 390 nm and the silica particles had a diameter of about 530-555 nm. PS-PAAm particles and PS-PHEMA particles had a rough surface, which is characteristic of particles synthesized by emulsion polymerization without surfactant, and the silica particles had a smooth spherical shape.

Outcome 2. Viscous behavior of PS-PAAm, PS-PHEMA and silica shear thickening fluid

As an example, the viscosity according to the shear rate of the PS-PAAm-PS-PHEMA and PS-PAAm-silica shear thickening fluid was measured. As a comparative example, the viscosity according to the shear rate of the PS-PHEMA and silica shear thickening fluid was measured. 4a to 5c.

Figure 4a is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of PS-PHEMA particles and PS-PAAm-PS-PHEMA particles to 50%, Figure 4b is PS-PHEMA particles And a weight ratio of PS-PAAm-PS-PHEMA particles is fixed at 52% to show the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles.

As a result, in both cases, as the PS-PAAm content ratio was increased, the critical shear rate decreased, and the initial viscosity and the maximum viscosity were increased.

Figure 5a is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of silica particles and PS-PAAm-silica particles to 68%, Figure 5b is a silica particle and PS-PAAm-silica The weight ratio of the particles to 69%, Figure 5c is a graph showing the viscosity of the shear thickening fluid according to the content ratio of PS-PAAm particles by fixing the weight ratio of silica particles and PS-PAAm-silica particles to 70%.

As a result of Figures 4a to 5c, in each example, the higher the content of each particle, the lower the viscosity critical shear rate and the higher the maximum viscosity. PS-PAAm was not added in the shear thickening fluid to which PS-PAAm was added. It was found that the decrease in the critical shear rate and the increase in the maximum viscosity were greater than the PS-PHEMA and silica shear thickening fluids. In addition, the higher the PS-PAAm content ratio in the shear thickening fluid, the larger the decrease in the critical shear rate and the increase in the maximum viscosity.

Outcome 3. Coupling structure of PS-PAAm and PS-PHEMA and PS-PAAm and silica particles

The mechanism by which the consistency of viscous behavior is enhanced due to the combination of PS-PAAm with PS-PHEMA and silica particles is shown in FIGS.

In FIG. 6, the particle structure of the suspension (a) in which only silica particles are present at a condition lower than the critical shear rate and the suspension (b) in which PS-PAAm and silica particles are added together is confirmed. It was found that the interaction between particles became stronger.

In Figure 7 a to c is a schematic of the flow of particles in the suspension when shear stress or shear rate is applied, d and e is a suspension containing only PS-PHEMA particles and PS-PAAm and PS-PHEMA added together The particle structures in the suspension were shown respectively, and it was found that the interaction between particles was stronger when PS-PAAm was added together.

The results of FIGS. 6 to 7 mean that the rich hydrogen bond donor groups of PS-PAAm particles enhance the inter-particle interactions by interacting with the PS-PHEMA particles and the remaining hydrogen bond acceptor groups which are not hydrogen bonded to the silica particles.

Claims (10)

First polystyrene derivative or silica; And
It includes; polyacrylamide (polyacrylamide) present on the surface of the second polystyrene,
The first polystyrene derivative or the silica is characterized in that the polyacrylamide is connected to the hydrogen bond, shear thickening fluid. The method of claim 1,
A weight thickening ratio of the first polystyrene derivative and the second polystyrene is 25-100: 1, Shear thickening fluid. The method of claim 1,
The weight ratio of the silica and the second polystyrene is 10-100: 1, characterized in that the shear thickening fluid. The method of claim 1,
The first polystyrene derivative is poly (2-hydroxyethyl methacrylate) [PHEMA], polymethacrylic acid, and polyacrylic acid on the polystyrene surface. Shear thickening fluid, characterized in that any one selected from the group consisting of a combined form. Forming a first polystyrene derivative;
Forming a polyacrylamide polymer with a second polystyrene; And
And suspending the derivative and the polymer in a solvent. Forming a polyacrylamide polymer with a second polystyrene; And
Suspending the polymer and silica in a solvent; characterized in that it comprises a, shear thickening fluid production method. The method of claim 5,
The first polystyrene derivative is poly (2-hydroxyethyl methacrylate) [PHEMA], polymethacrylic acid, and polyacrylic acid on the polystyrene surface. Shear thickening fluid production method, characterized in that any one selected from the group consisting of a combined form. The method according to claim 5 or 6,
The solvent is any one selected from the group consisting of ethylene glycol, methylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol and butylene glycol, shear thickening fluid production method. The method according to claim 5 or 6,
Forming the derivative or the polymer is characterized in that consisting of surfactant-free emulsion polymerization, a method for producing a shear thickening fluid. The shock absorbing material produced by the shear thickening fluid according to any one of claims 1 to 4.

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