JPH0686865B2 - Mechanochemical element - Google Patents

Description

TECHNICAL FIELD The present invention is capable of reversibly expanding and contracting due to changes in acidity and salt concentration in solution, changes in light, heat, and electric field, and robots, artificial legs, artificial hands, and artificial hearts. , Mechanochemical elements that can be used as a power source for chemical engines, switches, sensors, presses, jacks, etc.

Conventional technology The mechanochemical reaction that can directly convert chemical energy into mechanical energy is characterized by its small size, light weight, high efficiency, flexibility, noiselessness, etc. It is considered to be promising, and research and development have become active recently. At present, collagen, which is an organic polymer or a biological substance, has been the subject of research, and its expansion and contraction with respect to inputs such as acidity, salt concentration, electric field, light, and heat have been investigated. Among these, the organic insoluble gel made of a polymer material has a high response speed and a large expansion / contraction rate. For example, polymethacrylic acid (PMAA)
The gel, which is partially polymerized with polyvinyl alcohol (PVA) and made insoluble, has a stretching ratio of 20-35 depending on the change in acidity.
%, Response time is several minutes, and tensile strength is about 1000 times its own weight. As a means for obtaining the change in the acidity, there is a method by electrolysis of water. Furthermore, a method of utilizing an electrochemical reaction without gas generation is also possible.

Further, as a device for constructing a shape-like mechanochemical element that enhances the characteristics such as the contraction rate and response time, there is already a laminated artificial muscle in which contracting layers and non-contracting layers are alternately stacked.
This is because the layers are alternately stacked to have a long shape in the thickness direction of the layers, so that when the contraction layer contracts, the thin layer is integrated with the non-contraction layers on both sides in the longitudinal and lateral (plane) directions. It is based on the principle that it is difficult to contract and thus the volume reduction of the contraction layer effectively manifests itself as a reduction in the thickness of this layer, so that the length of the artificial muscle is effectively shortened. This summary is introduced in "Mechanical Polymers", Kyoritsu Publishing Co. (1974) P.577.

Problems to be Solved by the Invention As a problem of this laminated artificial muscle, in addition to being complicated to manufacture, it is necessary that all the non-shrinkable layer and the shrinkable layer are completely joined together. , Its certainty and reliability will cause problems. It is difficult to solve these problems over a long operating period of the artificial muscle.

Means for Solving Problems As a means for solving these problems, it is insoluble in a container that can expand and contract in the length direction but is difficult to expand and contract in the thickness direction, such as a bellows or a bellows-like container. The container is filled with molecules, and a large number of fine holes are provided on the surface of the container so that water can freely pass therethrough, so that water can enter and exit when expanding and contracting.

Action With such a configuration, when inflating due to a change in acidity, for example, the insoluble polymer first expands in volume, but the expansion is suppressed by the container in the thickness direction, so in the length direction of the element. It will expand effectively.

Practical Example FIG. 1 shows a schematic cross-sectional view of a mechanochemical element that expands and contracts depending on the change in acidity of the solution. First, 16 cm ³ of a mixture of a 3% aqueous solution of polymethacrylic acid (molecular weight: about 8000) and a 3% aqueous solution of polyvinyl alcohol (molecular weight: about 1800) in a ratio of 1: 3 was placed in a petri dish having a diameter of 12 cm, and about 3 45 ° C
After drying with, the product was peeled from the petri dish and cut into a piece having a width of 5 mm and a length of 70 mm. The thickness was about 50 μm. Then, the mixture was kept at 115 ° C. for about 2 hours to be polymerized to make it insoluble. Eighty such films were produced, bundled, and then immersed in water to swell. Then, it was immersed in a 0.05 N hydrochloric acid aqueous solution for about 5 minutes to shrink it. As shown in FIG. 1, the insoluble polymer gel 2 prepared as described above was inserted into a bellows-shaped container 1 having a length of 7 cm and a diameter of 5 mm to fill it. Then, the bellows-shaped container 1 and the insoluble polymer gel 2 were mechanically fixed at both ends so that the contraction and expansion of the gel could expand and contract the bellows-shaped container 1. The pitch of the wavy irregularities of the bellows about 2 mm, a depth is about 1.5 mm, the pores of φ0.2mm throughout provided with 1mm spacing water and H ^+, OH ^- ions, such that the polymer gel Easy to spread inside. 3 is a liquid, and 0.05N hydrochloric acid and 0.05N sodium hydroxide liquid are alternately introduced from the outside of the device through a liquid inlet 4 provided in an outer container 6 containing SBR as a main component, and a liquid outlet 5
Release from. FIG. 2 shows changes in the expansion coefficient of the mechanochemical element during the flow of each liquid. Curve A in the figure is the result obtained in this example. A swelling of about 30% occurred while flowing sodium hydroxide for 3 minutes, and then when switching to hydrochloric acid, it contracted to the original length in 3 minutes. Curve B shows the result of the same mechanochemical element except that a bellows-shaped container having the same dimensions was used instead of the bellows-shaped container of the above-mentioned embodiment. The reason why the expansion rate is reduced by several% as compared with the curve A is considered that a large amount of force is consumed by the expansion and contraction of this container. Φ0.2mm as an example of other shape containers
When using a container in which springs made of steel wire, ball rings, and pipes and sliced pieces of square hollow tubes are lined up at intervals of about 3 mm and integrated with elastic SBR,
Performances that were all between curve A and curve B were obtained.

For comparison, a curve C shows a result in the case of an element having the same configuration as that of the above-mentioned embodiment except that the above-mentioned bellows-like container is not used. From this result, it became clear that the element according to the present invention exhibits a coefficient of expansion approximately twice that of the conventional example and a fast response.

The above examples are the results when the acidity of the solution is changed by alternately inserting hydrochloric acid and sodium hydroxide solution, but the acidity change due to the electrolysis of water or the electrode reaction,
In addition, various changes such as changes in salt concentration due to collagen, changes in acetone / water composition of acrylamide gels, changes in electric field, temperature changes in gels made from polymetal acrylic acid and polyethylene glycol, and ultraviolet irradiation of polyacrylates In the case of expansion and contraction, a similar effect was produced.
In order to make it portable, for example, when using an electrochemical reaction (Hg / HgO, Hg / Hg (OH) ₂ , Pd / Pd (OH) ₂ and Pt / PtO, etc.) with electric input, both electrodes should be used. If the outer container is provided inside both ends of the container and is covered with an airtight film that is expandable and contractible, and preferably expandable and contractible in the thickness direction, the same effect can be obtained in this case as well.

INDUSTRIAL APPLICABILITY According to the present invention, an insoluble polymer that reversibly expands in response to an acidity of a container, a change in salt concentration, an input of light, heat, and an electric field is stretchable in the length direction. At the same time, the volume change of the insoluble polymer is achieved by filling the container with a large number of pores that prevent expansion and shrinkage in the thickness direction, and through which insoluble polymer does not pass but water can pass. It can be effectively used as expansion and contraction in the length direction of the, and a highly efficient mechanochemical element can be realized.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a mechanochemical element in one embodiment of the present invention, and FIG. 2 is a graph showing the performance of the mechanochemical element of the present invention. 1 ... Bellows container with pores, 4, 5 ... Liquid inlet / outlet,
2 ... Insoluble polymer, 6 ... Outer container, 3 ... Liquid.

Claims (7)

[Claims] 1. An insoluble polymer that expands and contracts reversibly in response to changes in the acidity and salt concentration of a solution and inputs such as light, heat and electric field, and is expandable and contractable in the longitudinal direction.
Mechanochemical element characterized by being configured to suppress expansion and contraction in the thickness direction, and filled in an inner container that has a porous surface that allows water to pass through but not through insoluble polymers. . 2. An expandable and airtight outer container is provided outside the inner container, filled with an electrolyte solution between the two, and electrodes are provided at both ends of the outer container so that a solution can be supplied by direct current electrical input. The mechanochemical element according to claim 1, which expands and contracts due to a change in acidity. 3. The mechanochemical element according to claim 1, wherein the inner container is filled with the insoluble polymer when the insoluble polymer contracts. 4. The mechanochemical element according to claim 1, wherein a bellows or bellows structure is used as the inner container. 5. The mechanochemical element according to claim 1, wherein a container integrated with a spring is used as the inner container. 6. The inner container is a container in which a large number of rings such as a ball-ring ring, a pipe, and a sliced piece of a rectangular hollow tube are arranged side by side and are integrated into one body. The mechanochemical element according to claim 1. 7. The mechanochemical element according to claim 2, wherein an outer container is used which is expandable and contractible not only in the length direction but also in the thickness direction.