阅读说明：本技术 一种双层高分子基电响应形状记忆材料及其制备方法 (Double-layer polymer-based electric response shape memory material and preparation method thereof ) 是由 郑宇� 杨丽华 郭少云 于 2019-12-02 设计创作，主要内容包括：本发明公开了一种双层高分子基电响应形状记忆材料及其制备方法,该材料是由作为固定相的热塑性高分子弹性体和作为可逆相的结晶或无定型高分子材料层叠热压制得的双层复合物,其中一相物料掺杂导电粒子或两相物料同时掺杂导电粒子。当施加电压刺激时,导电粒子产生的电热效应使材料温度升高,可逆相高分子材料分子链被解冻,进而实现电响应形状回复。本发明提供的制备方法所制得的高分子基电形状记忆材料可以通过调节电压大小,导电粒子种类、含量及分布方式,固定相与可逆相层厚比等方式实现形状回复速度和形状回复率的灵活调控；所需原料均为市售,生产成本低；制备方法工艺简单,生产效率高并可以连续批量生产。(The invention discloses a double-layer polymer-based electric response shape memory material and a preparation method thereof, wherein the material is a double-layer compound prepared by laminating and hot-pressing a thermoplastic polymer elastomer serving as a stationary phase and a crystalline or amorphous polymer material serving as a reversible phase, wherein one phase of the material is doped with conductive particles or two phases of the material are simultaneously doped with conductive particles. When voltage stimulation is applied, the electric heating effect generated by the conductive particles enables the temperature of the material to rise, the molecular chain of the reversible phase polymer material is unfrozen, and then the electric response shape recovery is realized. The polymer-based electric shape memory material prepared by the preparation method can realize flexible regulation and control of shape recovery speed and shape recovery rate by regulating voltage, types, contents and distribution modes of conductive particles, layer thickness ratio of a stationary phase and a reversible phase and the like; the required raw materials are all sold in the market, and the production cost is low; the preparation method has simple process and high production efficiency and can realize continuous batch production.)

1. A double-layer polymer-based electric response shape memory material and a preparation method thereof are characterized in that the electric response shape memory material is a double-layer compound prepared by laminating and hot-pressing the following polymer-based stationary phase materials and polymer-based reversible phase materials, wherein one phase material is doped with conductive particles or two phase materials are simultaneously doped with conductive particles:

(1) the electric response shape memory refers to a special function that the material can obtain a temporary shape by setting a thermomechanical deformation condition, and then the temporary shape is recovered to an initial shape under the action of electric stimulation, and evaluation indexes comprise shape recovery speed and shape recovery rate;

(2) the polymer-based stationary phase material is a thermoplastic polymer elastomer with rubber resilience at room temperature;

(3) the polymer-based reversible phase material is a thermoplastic polymer material with obvious melting or glass transition in the temperature rising process;

(4) the conductive particles are functional fillers which have excellent conductivity and can be efficiently dispersed in a polymer material.

2. The double-layer polymer-based electrical response shape memory material and the preparation method thereof according to claim 1, wherein the polymer-based stationary phase material is a thermoplastic polymer elastomer, such as polyurethane thermoplastic elastomer, polyester thermoplastic elastomer, styrene thermoplastic elastomer, polyacrylate thermoplastic elastomer, polyolefin thermoplastic elastomer, polyamide thermoplastic elastomer, etc.

3. The two-layer polymer-based electrical response shape memory material and the preparation method thereof according to claim 1, wherein the polymer-based reversible phase material is a polymer material with significant melting transition or glass transition, such as polycaprolactone, polyethylene oxide, polylactic acid, polyglycolide, polyvinylidene fluoride, polyvinyl chloride, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyphenylene oxide, polyamide, polyester, polycarbonate, polyvinyl alcohol, polyethylene glycol, ethylene glycol-caprolactone copolymer, polylactic acid-glycolic acid copolymer, or cellulose derivative.

4. The bilayer polymer-based electrical response shape memory material and the preparation method thereof as claimed in claim 1, wherein the polymer-based reversible phase material has a higher modulus at room temperature than the polymer-based stationary phase material, thereby achieving the fixation of temporary shape when cooling to room temperature after the completion of the thermal mechanical deformation; when voltage stimulation is applied, the generated electrothermal effect enables the polymer-based reversible phase material to be heated to the melting temperature or the glass transition temperature of the polymer-based reversible phase material, and then the recovery of the initial shape is started.

5. The double-layer polymer-based electric response shape memory material and the preparation method thereof according to claim 1, wherein the conductive particles are one or more compounds of metal, carbon black, carbon nanotubes, graphene, carbon fibers and modifications thereof, and the filling mass fraction of the conductive particles is 1-10%.

6. The double-layer polymer-based electric response shape memory material and the preparation method thereof according to claim 1, wherein the shape recovery speed of the electric response shape memory material is adjusted by changing the magnitude of the applied voltage.

7. The double-layer polymer-based electric response shape memory material and the preparation method thereof according to claim 1, wherein when an external voltage is constant, the shape recovery speed of the electric response shape memory material is regulated and controlled by designing a conductive network in the material, and the method can be used for changing the type, the addition amount or the distribution mode of conductive particles and changing the layer thickness ratio of the polymer-based stationary phase material and the polymer-based reversible phase material, wherein the change range of the layer thickness ratio is 1: 9-9: 1.

8. The double-layer polymer-based electric response shape memory material and the preparation method thereof according to claim 1, wherein the shape recovery rate of the electric response shape memory material is regulated and controlled by designing a shape memory network in the material, and the method can be that the polymer-based stationary phase materials with different block ratios, polymerization degrees and hardness degrees are selected, the types, the addition amounts and the distribution modes of conductive particles are changed, other organic or inorganic functional fillers are additionally added, or the layer thickness ratio of the polymer-based stationary phase materials and the polymer-based reversible phase materials is changed, and the change range of the layer thickness ratio is 1: 9-9: 1.

Technical Field

The invention relates to the field of polymer-based functional materials and processing and manufacturing thereof, in particular to a double-layer polymer-based electric response shape memory material and a preparation method thereof.

Background

The shape memory polymer material refers to a kind of intelligent material that can adjust its own state parameters under the stimulation of external environment change (such as light, heat, electricity, magnetism, water, etc.) and return to the initial state from a temporary set shape, wherein the most widely studied is the thermal response shape memory polymer material. Thermally responsive shape memory polymeric materials typically exhibit a distinct thermal/phase transition that can be based on providing a shape memory switching temperature: when the material is heated to a temperature higher than the switching temperature and the temperature is reduced to room temperature after the temporary shape is constructed by applying external force, the deformed molecular chains are frozen, and the temporary shape is fixed; and raising the temperature to the switching temperature again, thawing the molecular chains to generate entropy elastic recovery, and driving the material to realize the initial shape recovery. However, the thermal response shape memory polymer material can only respond to thermal stimulation, and in some special environments such as human body and space, a temperature field meeting the requirement cannot be built, so the application range is limited.

The electric response shape memory polymer material is a conductive compound prepared by doping conductive particles in the thermal response shape memory polymer material, can generate joule heat to heat the material to a temperature higher than a switching temperature under the stimulation of an electric field so as to realize the electric response shape recovery, and is widely applied to high-end fields of micro-sensing, intelligent driving, biomedical, aerospace and the like. According to joule's law, the amount of heat generated by the conductive compound per unit time at a certain voltage is proportional to its electrical conductivity. Therefore, optimizing the dispersion of the conductive particles and efficiently constructing the conductive network are the keys for obtaining the fast response and high recovery performance of the electric response shape memory polymer material. However, the dispersion of the conductive particles depends on the interaction between the particles and the matrix, and is also influenced by a plurality of factors such as the component ratio of the composite system, the interfacial tension, the molding processing conditions and the like, and the traditional thermoplastic processing method has difficulty in realizing the controllable distribution of the conductive particles. Therefore, a simple and feasible conductive particle dispersion control method is provided, and an innovative construction idea for developing a high-performance electric response shape memory polymer material has important research value and practical significance for promoting the development of the field of intelligent materials.

Disclosure of Invention

The invention provides a double-layer polymer-based electric response shape memory material and a preparation method thereof, aiming at the technical problems that the conventional polymer-based electric response shape memory material is poor in morphological structure design flexibility, difficult to control the dispersion of conductive particles, single in conductive property regulation mode, small in shape memory performance variable range and the like. The polymer composite material with a double-layer structure and an easily-adjusted electric response shape memory property is obtained by taking commercial polymer materials and conductive particles as raw materials and adopting a simple laminating hot-pressing process. The preparation process does not need organic solvent, the process is simple and efficient, the cost is low, the industrial continuous production is easy to realize, and the obtained novel material has excellent performance, wide adjustable range and huge application prospect.

The double-layer polymer-based electric response shape memory material provided by the invention uses a thermoplastic polymer elastomer and another polymer material which is in a glass state or a crystalline state at room temperature, and after one of the two materials is doped with a conductive filler or both of the two materials are doped with conductive particles, a composite with two materials in a layered and continuous distribution is prepared by laminating and hot pressing. The thermoplastic elastomer layer in the material has rubber resiliency, acting as a stationary phase; another crystalline or amorphous polymeric material can undergo a phase or thermal (crystallo-melt or glassy-rubbery) transition at a specific temperature, thereby freezing or thawing the temporary shape, acting as a reversible phase.

Specifically, the invention provides a double-layer polymer-based electric response shape memory material and a preparation method thereof, and the electric response shape memory material is a double-layer compound prepared by laminating and hot-pressing the following polymer-based stationary phase materials and polymer-based reversible phase materials, wherein one phase material is doped with conductive particles or two phase materials are simultaneously doped with conductive particles:

(1) the electric response shape memory refers to a special function that the material can obtain a temporary shape by setting a thermomechanical deformation condition, and then the temporary shape is recovered to an initial shape under the action of electric stimulation, and evaluation indexes comprise shape recovery speed and shape recovery rate;

(2) the polymer-based stationary phase material is a polymer thermoplastic elastomer with rubber resilience at room temperature;

(3) the polymer-based reversible phase material is a thermoplastic polymer material with obvious melting or glass transition in the temperature rising process;

(4) the conductive particles are functional fillers which have excellent conductivity and can be efficiently dispersed in a polymer material.

In the invention, the polymer-based stationary phase material is a thermoplastic polymer elastomer, such as a polyurethane thermoplastic elastomer, a polyester thermoplastic elastomer, a styrene thermoplastic elastomer, a polyacrylate thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polyamide thermoplastic elastomer and the like.

In the invention, the high polymer-based reversible phase material is a high polymer material with obvious melt transition or glass transition, such as polycaprolactone, polyethylene oxide, polylactic acid, polyglycolide, polyvinylidene fluoride, polyvinyl chloride, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyphenylene oxide, polyamide, polyester, polycarbonate, polyvinyl alcohol, polyethylene glycol, ethylene glycol-caprolactone copolymer, polylactic acid-glycolic acid copolymer, cellulose derivative and the like.

According to the invention, the modulus of the high-molecular-base reversible phase material at room temperature is higher than that of the high-molecular-base stationary phase material, so that the temporary shape is fixed when the material is cooled to room temperature after the thermal mechanical deformation is finished; when voltage stimulation is applied, the generated electrothermal effect enables the polymer-based reversible phase material to be heated to the melting temperature or the glass transition temperature of the polymer-based reversible phase material, and then the recovery of the initial shape is started.

In the invention, the conductive particles are one or more of metal, carbon black, carbon nanotubes, graphene, carbon fibers and modified substances thereof, and the filling mass fraction of the conductive particles is 1-10%.

In the present invention, the shape recovery speed of the electrically responsive shape memory material is controlled by changing the magnitude of the applied voltage.

In the invention, when an external voltage is applied for a certain time, the shape recovery speed of the electric response shape memory material is regulated and controlled by designing a conductive network in the material, and the method can be to change the type, the addition amount and the distribution mode of conductive particles or change the layer thickness ratio of the polymer-based stationary phase material and the polymer-based reversible phase material, wherein the change range of the layer thickness ratio is 1: 9-9: 1.

In the invention, the shape recovery rate of the electric response shape memory material is regulated and controlled by designing a shape memory network in the material, and the method can be to select the polymer-based stationary phase materials with different block ratios, polymerization degrees and hardness degrees, change the types, addition amounts and distribution modes of conductive particles, additionally add other organic or inorganic functional fillers, or change the layer thickness ratio of the polymer-based stationary phase materials and the polymer-based reversible phase materials, wherein the change range of the layer thickness ratio is 1: 9-9: 1.

The invention detects the electric response shape recovery performance of the prepared double-layer polymer-based electric response shape memory material by the following test method:

heating a rectangular sample strip of 40mm x 20mm in an oven to a temperature 10 ℃ above the switching temperature at room temperature, keeping the temperature for 3 minutes, bending the sample into a U shape, immediately placing the U-shaped sample in a room temperature environment of 25 ℃ and keeping the external force for 3 minutes to fix the temporary shape, and recording the measured bending angle as theta₀. And applying a certain voltage to the U-shaped sample, triggering the shape recovery process, and recording the recovery time as t to represent the shape recovery speed. Recording the recovery angle as theta_rElectric response shape memory recovery rate = (theta)_r/θ₀)·100%。

The invention has the following advantages:

1. the raw materials required by the invention are all commercially available, a simple laminating hot-press molding process is adopted, an organic solvent is not required, the operation is simple and convenient, the environment is friendly, the cost is low, the efficiency is high, the continuous production is easy, and the method is suitable for popularization and application.

2. The double-layer polymer-based electric response shape memory material prepared by the invention always keeps the complete phase continuous layered structure of each material, is not influenced by the change of the material component ratio in a receptor system, can adjust the thickness ratio of two phase layers in a wide range of 1:9 to 9:1, and further flexibly regulates and controls the morphological structure and the electric response shape memory performance of the material.

3. Compared with the electric response shape memory material prepared by the traditional blending composite method, the double-layer polymer-based electric response shape memory material prepared by the invention has higher shape recovery rate and faster shape recovery speed.

4. The prepared double-layer polymer-based electric response shape memory material can adjust the electric conductivity by changing the type, content and distribution mode of the conductive filler, so as to control the electric response shape memory performance of the material; the electric response shape memory performance of the material can also be directly controlled by changing the applied voltage.

Therefore, the double-layer polymer-based electric response shape memory material prepared by the preparation method provided by the invention has excellent performance and is easy to adjust; the required raw materials are all sold in the market, the formula is adjustable, and the production cost is low; the preparation method has simple process and high production efficiency, can realize continuous batch production, and has wide industrialization and market application prospects.

Drawings

The invention is further described below with reference to the accompanying drawings.

FIG. 1 is a schematic flow chart of the preparation of the double-layer polymer-based electro-responsive shape memory material according to the present invention.

FIG. 2 is a polarized light microscope photograph of the thermoplastic polyurethane elastomer/polycaprolactone two-layer composite material prepared by the invention, wherein the thermoplastic polyurethane elastomer/polycaprolactone two-layer composite material has different conductive particle distribution modes and a layer thickness ratio of 1: 1.

FIG. 3 shows the shape memory recovery process of the double-layer composite prepared by the invention, wherein the layer thickness ratio of the polycaprolactone doped with 5wt% of carbon nanotubes to the pure thermoplastic polyurethane elastomer is 1:1, under the condition that the applied voltage is 20V.

Detailed description of the invention

It is to be noted that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention, and that the skilled person in the art may make modifications and adaptations of the present invention in view of the above disclosure.