Polymer composite comprising liquid metal-magnetic particles

Abstract

Disclosed is a polymer composite comprising liquid metal-magnetic particles. The polymer composite is a mixture of elastic polymer material and liquid metal-magnetic particles.

Description

Polymer composites containing liquid metal-magnetic particles

[0001] The present invention relates to a polymer composite, and more particularly, to a polymer composite that provides real-time tactile sensation to a user by mixing liquid metal-magnetic particles into a polymer elastic material and thereby implementing a rapid transition of a soft-stiff modulus depending on an external frequency.

[0002] Virtual Reality (VR) blocks out the real world and uses computer graphics and camera technology to provide images with a variety of three-dimensional effects, similar to cyberspace. Augmented Reality (AR) is a technology that synthesizes virtual objects or information into an existing environment, making them appear as if they were in the original environment. Based on these VR and AR technologies, games, movie theaters, and simulators that allow users to experience virtual worlds have begun to compete with each other, and the market for equipment and systems that allow users to virtually experience not only sight but also three dimensions and various senses has begun to grow.

[0003] Accordingly, interest in implementing accurate and delicate screen-user tactile sensations in virtual worlds is focusing on haptic display technologies. However, conventional haptic displays mostly use a single vibration actuator, which limits the implementation of accurate, delicate, and different tactile differences in different areas within a single device substrate. To solve this problem, haptic displays are being implemented using array-based motors. However, this also has limitations in structural simplification and efficiency in terms of the direction of electronic device development, such as increased weight, increased structural thickness, and high power consumption. In addition, from a material perspective, attempts were made to adjust the ductility-stiffness modulus of polymers with temperature, but there is a limitation in that the individual characteristics of the stiffness modulus and ductility modulus cannot be accurately implemented due to the heat diffusion time in successive layers of the array.

[0004] To address this, polymer composites capable of delivering real-time tactile sensations to users by implementing rapid transitions between soft and stiff moduli are required.

[0005] The present invention provides a polymer composite capable of rapid ductility-stiffness modulus transition by external frequency application.

[0006] In addition, the present invention provides a composite film having a thickness of 10 to 100 μm based on a polymer composite.

[0007] In addition, the present invention provides a method for manufacturing liquid metal-magnetic particles by coating magnetic particles on the surface of liquid metal from which a metal oxide film has been removed.

[0008] A polymer composite according to an embodiment of the present invention may be a mixture of a polymer elastic material and liquid metal-magnetic particles.

[0009] Additionally, the polymer elastic material may be in a gel state.

[0010] Additionally, the polymer elastic material may be PBDMS or gelatin-chitosan.

[0011] In addition, the liquid metal-magnetic particles may be coated with magnetic particles on the surface of the liquid metal.

[0012] Additionally, it can have a stiffness of 1 to 100 KPa.

[0013] In addition, when a frequency of less than 10 Hz is applied from the outside, it can have a first magnitude of intensity, and when a frequency of 30 Hz or more is applied from the outside, it can have a second magnitude of intensity greater than the first magnitude.

[0014] A composite film according to an embodiment of the present invention is provided with the polymer composite and may have a thickness of 10 to 100 um.

[0015] A method for manufacturing liquid metal-magnetic particles according to an embodiment of the present invention may include a pretreatment step of removing a metal oxide film from the liquid metal; and a coating step of coating magnetic particles on the surface of the liquid metal from which the metal oxide film has been removed.

[0016] Additionally, in the above pretreatment step, a strong acid or strong base solution can be applied to the liquid metal surface.

[0017] In addition, the coating step may include introducing the liquid metal from which the metal oxide film has been removed and the magnetic particles into a homogenizer and mixing them in the homogenizer.

[0018] According to the present invention, a polymer composite can provide real-time tactile information to a user by rapidly switching between soft and stiff moduli with external frequency application.

[0019] In addition, according to the present invention, the composite film can provide a thin film of 10 to 100 μm based on a polymer composite.

[0020] In addition, according to the present invention, the method for manufacturing liquid metal-magnetic particles can manufacture liquid metal-magnetic particles by coating magnetic particles on the surface of liquid metal from which a metal oxide film has been removed.

[0021] FIG. 1 is a drawing showing a polymer composite according to an embodiment of the present invention.

[0022] FIG. 2 is a graph showing shear rate, shear stress, and viscosity according to the shear stress state of a polymer elastic material according to an embodiment of the present invention.

[0023] FIG. 3 is a graph showing Young's modulus according to frequency applied to a polymer elastic material according to an embodiment of the present invention.

[0024] Figure 4 is a graph showing the stiffness of a polymer elastic material according to an embodiment of the present invention.

[0025] FIG. 5 is a diagram showing the phase transition characteristics of PBDMS according to one embodiment of the present invention.

[0026] FIG. 6 is a diagram showing the relaxation time and transition frequency of PBDMS according to molecular weight according to one embodiment of the present invention.

[0027] FIG. 7 is a diagram showing absorption energy for frequency by molecular weight of PBDMS according to one embodiment of the present invention.

[0028] Figure 8 is a drawing showing a boundary layer according to the magnetic field strength of a polymer composite according to an embodiment of the present invention.

[0029] Figure 9 is a graph showing deformation and stress according to strength of a polymer composite according to an embodiment of the present invention.

[0030] Figure 10 is a flowchart showing a method for manufacturing a polymer composite according to an embodiment of the present invention.

[0031] FIG. 11 is a drawing showing the manufacture of a polymer composite according to an embodiment of the present invention.

[0032] A polymer composite according to an embodiment of the present invention may be a mixture of a polymer elastic material and liquid metal-magnetic particles.

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art.

[0034] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. In addition, in the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents.

[0035] Also, although terms such as first, second, and third have been used to describe various components in various embodiments of this specification, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Also, the term "and / or" has been used herein to mean including at least one of the components listed before and after.

[0036] In the specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In addition, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, and should not be construed as excluding the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. In addition, the term "connection" is used in the present specification to mean both indirectly connecting multiple components and directly connecting them.

[0037] In addition, when describing the present invention below, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0038]

[0039] FIG. 1 is a drawing showing a polymer composite according to an embodiment of the present invention.

[0040] Referring to FIG. 1, a polymer composite (10) is provided by mixing liquid metal-magnetic particles (100) into a polymer elastic material (200). Through this, a quick soft-rigid modulus transition can be realized according to an external frequency, thereby transmitting real-time tactile changes to the user. Specifically, the liquid metal-magnetic particles (100) present in the polymer composite (10) move according to the intensity of the vibration frequency adjusted by the external frequency, and accordingly, a shear force is transmitted between the periphery of the liquid metal-magnetic particles (100) and the interface of the polymer elastic material (200), thereby enabling a partial quick soft-rigid modulus transition.

[0041] The polymer composite (10) has a strength that varies depending on the frequency applied from the outside. Specifically, when a frequency lower than a preset frequency is applied, the polymer composite (10) has a ductility modulus having a first strength, and when a frequency higher than a preset frequency is applied, the polymer composite (10) has a stiffness modulus having a second strength greater than the first strength. The first strength refers to a strength that can provide a relatively soft touch based on rubber properties, and the second strength refers to a strength that can provide a relatively hard touch based on glass properties. According to an embodiment, the polymer composite may have a strength change of 1 to 100 KPa. In addition, the ductility modulus may be generated when a frequency lower than 10 Hz is applied, and the second ductility modulus may be generated when a frequency higher than 30 Hz is applied.

[0042] The polymer composite may be provided as a thin composite film having a thickness of 10 to 100 μm. The composite film may be provided as a display tactile implementation substrate capable of providing real-time tactile information to a user based on the rapid ductility-stiffness modulus transition of the polymer composite.

[0043] The liquid metal-magnetic particle (100) has a structure in which a metal oxide film of the liquid metal (110) is removed (111) and the surface of the liquid metal (110) is coated with magnetic particles (120) that are responsive to a magnetic field, so that the liquid metal-magnetic particle (100) can move even with a small external frequency. The movement of the liquid metal-magnetic particle (100) maximizes the transmission of a shear rate stimulus applied to the polymer elastic material (200) surrounding the liquid metal-magnetic particle (100). According to an embodiment, the liquid metal-magnetic particle (100) may have a diameter of several tens to several hundred μm.

[0044] Liquid metal is a metal that is liquid at room temperature, and may be selected from the group consisting of gallium (Ga), indium (In), and tin (Sn), or may be provided as an alloy composition of at least two or more thereof.

[0045] The magnetic particles are iron (Fe), nickel (Ni), cobalt (Co), and iron oxide (Fe). x O y ), nickel oxide (NiO), cobalt oxide (CoO), and a multi-component material including two or more elements selected from iron, nickel, and cobalt.

[0046] The polymer elastic material (200) is provided in a gel state, and shear thickening, in which the viscosity increases depending on the frequency, and shear thinning, in which the viscosity decreases, occur, thereby inducing a transition from ductility to stiffness modulus of the polymer composite (10). The polymer elastic material (200) is a material whose properties can change depending on an external stimulus. According to an embodiment, the polymer elastic material (200) may be provided as gelatin-chitosan or PBDMS (Polyborodimethylsiloxane). The gelatin-chitosan has dependence on molecular weight and viscosity, and thus a target modulus can be obtained by controlling the molecular weight. In addition, the PBDMS includes hydrogen bonds and BO bonds. These dynamic bonds absorb energy due to an external frequency, and based on this, the PBDMS experiences shear thickening and shear thinning. Accordingly, the modulus transition frequency can be controlled by adjusting the molecular weight of the monomer used in the synthesis of the PBDMS. Furthermore, the PBDMS can maintain vibration absorption properties for more than three months, which is longer than that of existing hydrogel damping materials, thereby demonstrating long-term durability.

[0047]

[0048] Figure 2 is a graph showing shear rate, shear stress, and viscosity according to the shear stress state of a polymer elastic material according to an embodiment of the present invention. (A) shows shear stress versus shear rate when the polymer elastic material is in a shear thickening state, (B) shows viscosity versus shear rate when the polymer elastic material is in a shear thickening state, (C) shows shear stress versus shear rate when the polymer elastic material is in a shear thinning state, and (D) shows viscosity versus shear rate when the polymer elastic material is in a shear thinning state.

[0049] Referring to FIG. 2, it can be seen that as the shear rate of the polymer elastic material (200) increases in a shear thickening state, the shear stress increases (A) and the shear stress decreases (B). On the other hand, it can be seen that as the shear rate of the polymer elastic material (200) increases in a shear thinning state, the shear stress also increases (C) and the shear stress decreases (D).

[0050]

[0051] Figure 3 is a graph showing Young's modulus according to frequency applied to a polymer elastic material according to an embodiment of the present invention. The horizontal axis represents the frequency applied to the polymer elastic material, and the vertical axis represents Young's modulus according to frequency applied to the polymer elastic material.

[0052] Referring to FIG. 3, when a low frequency of less than 10 Hz is applied to a polymer elastic material (200), the polymer elastic material (200) absorbs the corresponding frequency and implements a mechanical ductility (rubbery) modulus. On the other hand, when a high frequency (transition frequency) of 30 Hz or more is applied, it can be seen that a mechanical property transition occurs from a ductile modulus to a rigidity (glassy) modulus.

[0053]

[0054] Figure 4 is a graph showing the stiffness of a polymer elastic material according to an embodiment of the present invention. (A) shows the modulus according to frequency, and (B) shows the tangent delta according to frequency.

[0055] Referring to FIG. 4, it can be seen that the coefficient of a polymer elastic material (200) increases as the frequency increases under the condition of a Deborah number (De) of 1 and 27°C (A). On the other hand, it can be seen that the tangent delta is high only when the applied frequency is 1 (B).

[0056]

[0057] FIG. 5 is a diagram showing the phase transition characteristics of PBDMS according to an embodiment of the present invention. (A) shows the relaxed state of PBDMS, (B) shows damping and relaxing when the Deborah number (De) is less than 1, and (C) shows alignment and transmitting when the Deborah number (De) is greater than 1.

[0058] Referring to Figure 5, in (A), PBDMS can be seen in a relaxed state with molecules forming stable bonds, in (B), PBDMS can be seen in a Deborah number less than 1, energy absorption occurs, and PBDMS changes to a rigid modulus, and in (C), PBDMS can be seen in a Deborah number greater than 1, energy transmission occurs, and PBDMS changes to a soft modulus.

[0059]

[0060] Figure 6 is a diagram showing relaxation times and transition frequencies according to molecular weight of PBDMS according to an embodiment of the present invention. (A) shows the relaxation time and transition frequency according to molecular weight when PBDMS is 5, (B) shows the relaxation time and transition frequency according to molecular weight when PBDMS is 25, and (C) shows the relaxation time and transition frequency according to molecular weight when PBDMS is 100.

[0061] Referring to Figure 6, in (A), when PBDMS is 5, the molecular weight and relaxation time are the largest, and the transition frequency is the lowest. In (B), when PBDMS is 25, the molecular weight and relaxation time are lower than in (A), and the transition frequency is higher than in (A). In (C), when PBDMS is 100, the molecular weight and relaxation time are much lower than in (A), and the transition frequency is much higher than in (A).

[0062]

[0063] Figure 7 is a diagram showing absorption energy per volume according to frequency by molecular weight of PBDMS according to one embodiment of the present invention. (A) shows absorption energy per volume according to frequency when PBDMS is 5, (B) shows absorption energy per volume according to frequency when PBDMS is 25, and (C) shows absorption energy per volume according to frequency when PBDMS is 100.

[0064] Referring to Figure 7, when PBDMS is 5, it can be seen that there is a little absorption energy at low frequencies below 10 Hz, and almost no absorption energy at frequencies above 10 Hz (A), when PBDMS is 25, the absorption energy is somewhat high when the frequency is 50 Hz, but is generally below 200 (B), and when PBDMS is 100, very high absorption energy can be seen at a frequency of 100 Hz (C).

[0065]

[0066] Figure 8 is a drawing showing a boundary layer according to the magnetic field strength of a polymer composite according to an embodiment of the present invention. (A) shows a boundary layer when a low-intensity magnetic field is applied to a polymer composite, (B) shows a boundary layer when a high-intensity magnetic field is applied to the polymer composite of (A), and (C) shows a boundary layer when the roughness of the polymer composite of (B) is adjusted.

[0067] Referring to FIG. 8, in (A), a low shear rate is applied to the ductile-to-rigid modulus transition polymer matrix due to a low intensity magnetic field in the polymer composite (10), so that a small range of mechanical property transition region (A') can be observed, and in (B), by applying a high intensity magnetic field (B) to the polymer composite (10) of (A), a high shear rate is applied to the ductile-to-rigid modulus transition polymer matrix, so that a large range of mechanical property transition region (B') can be observed, and by adjusting the ropeness (C) in the polymer composite (10) in the state of (B), it can be seen that it has changed to a red mechanical property transition region (C'). Through this, the polymer composite (10) of (A') has a low overall stiffness, enabling implementation of a soft touch, and the polymer composite (10) of (B') has an increased overall stiffness, enabling implementation of a hard touch, and by controlling the ropeness of the polymer composite (10) of (B'), the mechanical property transition range can be controlled.

[0068]

[0069] Figure 9 is a graph showing strain and stress according to the strength of a polymer composite according to an embodiment of the present invention. (A) shows strain and stress when the polymer composite is rigid, (B) shows strain and stress when the polymer composite is ductile, and (C) shows strain and stress in the ductile-rigid modulus transition state of the polymer composite.

[0070] Referring to FIG. 9, it can be seen that when the polymer composite (10) is rigid, the deformation is small but it has high elasticity for small deformation (A), when the polymer composite (10) is ductile, the deformation is large but it has low elasticity (B), and when the polymer composite (10) is in a ductile-rigid modulus transition state, the deformation and elasticity are more relaxed than in (A) and (B).

[0071]

[0072] FIG. 10 is a flowchart showing a method for manufacturing a polymer composite according to an embodiment of the present invention, and FIG. 11 is a drawing showing the manufacturing of a polymer composite according to an embodiment of the present invention.

[0073] Referring to FIGS. 10 and 11, the method for manufacturing a polymer composite includes a pretreatment step (S100) and a coating step (S200).

[0074] In the pretreatment step (S100), a strong acid or strong base solution is applied to the surface of the liquid metal (110) to remove the metal oxide film of the liquid metal (110) (A). According to an embodiment, hydrochloric acid (HCl) or 1 to 3 wt% of sodium hydroxide (NaOH) may be applied to remove the metal oxide film.

[0075] In the coating step (S200), the liquid metal (111) from which the metal oxide film has been removed and the magnetic particles (120) are introduced into a homogenizer (B), and mixed in the homogenizer to coat the magnetic particles (120) on the surface of the liquid metal (110), thereby completing the liquid metal-magnetic particles (100). At this time, in order to increase the efficiency of the movement of the liquid metal-magnetic particles (100) with respect to an external magnetic field, the rotation speed and duration of the homogenizer are adjusted to mix until the size of the liquid metal-magnetic particles (100) is reduced (C). According to an embodiment, the liquid metal-magnetic particles (100) can be mixed until their diameter becomes several tens to several hundreds of μm.

[0076] And, in order to prevent agglomeration of the liquid metal-magnetic particles (100), an anti-agglomeration additive is added to fix the liquid metal-magnetic particles (100). According to an embodiment, the anti-agglomeration additive may be polyvinyl alcohol (PVA).

[0077]

[0078] While the present invention has been described in detail using preferred embodiments, the scope of the present invention is not limited to the specific embodiments described above, and should be interpreted in accordance with the appended claims. Furthermore, those skilled in the art will appreciate that numerous modifications and variations are possible without departing from the scope of the present invention.

[0079] The polymer composite according to the present invention can transmit tactile changes to the user in real time.

Claims

1. A polymer composite material mixed with polymer elastic material and liquid metal-magnetic particles.

2. In paragraph 1, The above polymer elastic material is a polymer composite in a gel state.

3. In paragraph 2, The above polymer elastic material is a polymer composite of PBDMS or gelatin-chitosan.

4. In paragraph 1, The above liquid metal-magnetic particles are a polymer composite in which magnetic particles are coated on the surface of liquid metal.

5. In paragraph 1, Polymer composite with a stiffness of 1 to 100 KPa.

6. In paragraph 5, When a frequency less than 10 Hz is applied from the outside, it has the intensity of the first magnitude, A polymer composite having a second size strength greater than the first size when a frequency of 30 Hz or more is applied from the outside.

7. A composite film provided with any one of the polymer composites of clauses 1 to 6 and having a thickness of 10 to 100 μm.

8. Pretreatment step for removing metal oxide film from liquid metal; and A method for manufacturing liquid metal-magnetic particles, comprising a coating step of coating magnetic particles on the surface of liquid metal from which the metal oxide film has been removed.

9. In paragraph 8, The above preprocessing step is, A method for producing liquid metal-magnetic particles by applying a strong acid or strong base solution to the surface of the liquid metal.

10. In paragraph 8, The above coating step is, A method for manufacturing liquid metal-magnetic particles, comprising: introducing liquid metal from which the metal oxide film has been removed and the magnetic particles into a homogenizer and mixing them in the homogenizer.

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