CN114409942A

CN114409942A - Preparation method of shape memory super-lubricating microtube and application of shape memory super-lubricating microtube in aspect of intelligent liquid drop transportation

Info

Publication number: CN114409942A
Application number: CN202210044880.7A
Authority: CN
Inventors: 成中军; 来华; 王瑞洁; 张东杰; 刘宇艳
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2022-04-29
Anticipated expiration: 2042-01-14
Also published as: CN114409942B

Abstract

A preparation method of a shape memory super-lubrication microtube and application thereof in intelligent liquid drop transportation belong to the technical field of intelligent transportation. The invention modifies PDMS and SiO by template shaping₂And preparing an asymmetric shape memory super-wetting lubricating tube by lubricating oil filling technology and the like. Based on excellent liquid drop transport capacity, the controllable transportation of liquid drops to and from and segmented controllable transportation can be realized, and the gravity resistance self-operation can be carried out on a slope with the gradient of 20 degreesAnd (5) transporting. In addition, the asymmetric shape memory super-wetting lubricating tube can also be used as a novel micro-reactor to perform liquid drop reaction. The asymmetric shape memory super-wetting lubrication tube has huge potential in liquid microfluid equipment and application.

Description

Preparation method of shape memory super-lubricating microtube and application of shape memory super-lubricating microtube in aspect of intelligent liquid drop transportation

Technical Field

The invention belongs to the technical field of intelligent transportation, and particularly relates to a preparation method of a shape memory super-lubrication micro-tube and application of the shape memory super-lubrication micro-tube in intelligent liquid drop transportation.

Background

From the viewpoint of scientific research and practical application, controlling liquid transportation plays an important role in liquid reaction, analysis or basic research of biology, physics and chemistry. However, most of the current research on liquid transportation focuses on one-dimensional fiber or two-dimensional planar open systems, and compared to open systems, liquid transportation in closed tube systems has many advantages, such as low susceptibility to external pollution and damage, and low volatility.

At present, the transport of liquids in tubes is less studied and is usually carried out under the action of external fields such as heat, light, magnetism, etc. For example, a magnetic hose drive such as that recently manufactured by Jiang et al can introduce liquid to a desired location by asymmetrically deforming a magnetic tube by a force between an applied magnetic field and the tube. Yu et al reported a strategy for manipulating liquids by photo-induced asymmetric deformation of liquid crystal polymer tubular actuators. Although these are excellent liquid driving methods, they can only be generated by the action of external field at any moment, and the liquid can not be transported spontaneously, which brings various inconveniences to the application in real life. Despite the wide application of shape memory polymers in aerospace, optical chips, biomedicine, controlled droplet storage and bouncing, and other fields in recent years, no research on self-transportation of liquids in pipes has been reported.

Disclosure of Invention

The invention aims to solve the problems that the existing liquid driving mode usually needs to be assisted by the action of an external field and liquid cannot be transported spontaneously, and provides a preparation method of a shape memory super-lubricating microtube and application thereof in the aspect of intelligent liquid drop transportation.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of a shape memory super-lubrication microtube specifically comprises the following steps:

the method comprises the following steps: preparing a shape memory circular tube by template forming;

step two: from PDMS/SiO₂The mixture of (a) modifies the inner wall of the tube;

step three: and pouring lubricating oil into the tube after solidification to prepare the shape memory super-infiltration lubricating tube.

Further, the method specifically comprises the following steps:

the method comprises the following steps: using PI tubes as templates, shape memory epoxy prepolymers E44 and D230 were then placed in a 2: 1, mixing and pouring the mixture into a gap between two PI pipes, and then placing the mixture into an oven to be cured for 1 hour and 3 hours at 100 ℃ and 130 ℃ respectively to finish the preparation of the shape memory circular pipe;

step two: dispersing PDMS prepolymer and hydrophobic silicon oxide nano particles in a hexane solvent, injecting the PDMS prepolymer and the hydrophobic silicon oxide nano particles from one section of a shape memory tube, flowing out from the other end of the shape memory tube after the PDMS prepolymer and the hydrophobic silicon oxide nano particles are fully filled, and finally curing the shape memory tube in an oven at 80 ℃ for 2 hours to finish the modification of the inner wall of the tube;

step three: and (3) filling the interior of the pipe treated in the step two with silicone oil as lubricating oil, then standing the pipe for 20 minutes, and draining the redundant lubricating oil to finish the preparation of the whole pipeline.

Further, the shape memory super-lubrication microtubule can realize self-transportation of acid, alkali, salt and organic solvent.

Further, in the first step, the outer diameter of the circular shape memory tube is 2-5mm, the wall thickness is 0.5-2.0mm, and specifically, the wall thickness needs to be specifically adjusted according to the outer diameter.

Further, in the first step, the outer diameter of the circular shape memory tube is 3mm, and the wall thickness is 0.6 mm.

Further, in the second step, the mass ratio of the PDMS prepolymer, the hydrophobic silica, and the hexane is 12: 5: 18.

the application of the shape memory super-lubricating microtube prepared in the aspect of intelligent liquid drop transportation is as follows: by applying external force, the shape memory material changes the permanent shape when the temperature is higher than Tg, and memorizes the temporary shape after cooling, and the form gradient of the tube generates asymmetric Laplace force for driving liquid to move, thereby realizing intelligent transportation of liquid drops.

Further, the pipe diameter of the deformed shape memory super-lubrication micro-pipe is 0.6 mm.

Furthermore, the transportation speed can be regulated and controlled by adjusting the deformation included angle of the pipe.

Compared with the prior art, the invention has the beneficial effects that: the invention is inspired by nature and combines the characteristics of two organisms, namely the lubricating inner surface of pitcher plant and the asymmetric structure of beast beak. The shape memory super-lubricating microtube can realize self-transportation of various liquids such as acid, alkali, salt, organic solvent and the like, and the transportation speed of part of the liquid in the tube can even reach 1.5 cm/s. Based on the performance of the shape memory material, the liquid drop can be transported to and fro in the pipe, transported in sections and transported against gravity on a slope with the gradient of 20 degrees by reshaping the shape of the pipe. In addition, the shape memory super-lubrication microtube can also be used as a novel liquid drop reaction device. The excellent liquid self-transportation performance and controllability of the shape memory super-lubrication microtube make the shape memory super-lubrication microtube have great potential in the fields of microfluidic chips, biochemical microreactors and the like.

Drawings

FIG. 1 is an optical photograph of a bird's beak;

FIG. 2 is an optical photograph of nepenthes;

FIG. 3 is a photograph of a water droplet sliding on a lubricated surface of the inner wall of a pipe;

FIG. 4 is a photograph of a sliding of a droplet of ethylene glycol on a lubricated surface of the inner wall of a tube;

FIG. 5 is an SEM of the tube in its initial state;

FIG. 6 is an SEM image of the temporary state after the tube is deformed by extrusion;

FIG. 7 is an SEM image after the tube shape is recovered;

FIG. 8 is a schematic view of an asymmetric tube shape;

FIG. 9 is a photo shot of an optical shot of a water droplet self-transporting in an asymmetric tube;

FIG. 10 is a photograph of the self-transport process of different droplets in an asymmetric pipe;

FIG. 11 is a graph of the velocity of a water droplet traveling through a tube as a function of the included angle of deformation of the tube;

FIG. 12 is a schematic view of the reciprocal self-movement of droplets in a conduit;

FIG. 13 is a schematic view of the stepwise controlled transport of droplets in a tube;

FIG. 14 is a schematic illustration of antigravity transport of droplets in a pipe.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings, but not limited thereto, and any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.

Shape memory materials (SMPs) are capable of changing their permanent shape from an external force at temperatures above Tg and remembering temporary shapes after cooling. The invention is inspired by two organisms, namely a beagle with a shape gradient form (figure 1) and pitcher plant with a smooth inner surface (figure 2), and an asymmetric shape memory super-lubricating microtubule is designed. The shape gradient of the pipe can generate asymmetric Laplace force for driving the liquid to move, and the lubricated inner surface can eliminate the pinning of liquid drops on the pipe wall and reduce the hysteresis force of the liquid drop movement, so that the liquid drops can easily move in a self-conveying mode in the pipe.

The invention modifies PDMS/SiO through mold shaping₂The shape memory super-lubricating tube is prepared by processes of filling lubricating oil and the like. Because the lubricated surface can eliminate the liquid drop pinning, and the asymmetric shape can generate the liquid drop driving force, the self-transportation of various liquid drops such as acid, alkali, salt, organic liquid drops and the like in the pipe is realized, and the driving mechanism is theoretically explained. Based on the shape memory effect of the material, the deformation degree of the tube can be controlled, and further the regulation and control of the liquid drop transportation speed are realized. In addition, by endowing the shape memory super-wetting lubricating pipe with asymmetric deformation in sections, the transportation position can be accurately controlledAnd to achieve anti-gravity transport and microfluidic reactions. Based on excellent liquid drop self-transportation performance and controllability of transported liquid drops, the shape memory super-wetting lubrication tube has great potential in the fields of microfluidic chips, biochemical microreactors and the like, and meanwhile, the concept can be expanded to other responsive shape memory materials with optical, thermal and electric responses.

Example 1:

the method comprises the following steps: using PI tubes as templates, shape memory epoxy prepolymers E44 and D230 were then placed in a 2: 1, mixing and pouring the mixture into a gap between two PI pipes, and then placing the mixture into an oven to be cured for 1 hour and 3 hours at 100 ℃ and 130 ℃ respectively to finish the preparation of the shape memory circular pipe; FIG. 5 shows an electron micrograph of an SMP tube before deformation, the tube having an inner diameter of 3mm and a wall thickness of 0.6 mm. In the experiment, the pipe diameter and the pipe wall can be adjusted by changing the specification of the preparation die. FIG. 6 shows an SEM image of an SMP tube flattened to 0.6mm diameter after being deformed by external forces at a temperature above the glass transition temperature (Tg) of the material and then cooled to room temperature. When the tube is further heated, as shown in fig. 7, the shape of the nozzle is completely restored to the original circular shape, and the size is also restored to the original value. These results indicate that the prepared super-lubricated pipeline has a good shape memory function.

Step two: dispersing PDMS prepolymer and hydrophobic silicon oxide nano particles in a hexane solvent, injecting the PDMS prepolymer and the hydrophobic silicon oxide nano particles from one section of a shape memory tube, flowing out from the other end of the shape memory tube after the PDMS prepolymer and the hydrophobic silicon oxide nano particles are fully filled, and finally curing the shape memory tube in an oven at 80 ℃ for 2 hours to finish the modification of the inner wall of the tube; the mass ratio of the PDMS prepolymer to the hydrophobic silicon oxide to the hexane is 12: 5: 18.

step three: and (3) filling the interior of the pipe treated in the step two with silicone oil as lubricating oil, then standing the pipe for 20 minutes, and draining the redundant lubricating oil to finish the preparation of the whole pipeline. After the lubricating oil is injected, the inner wall of the pipe has super-lubricating performance. A tube was cut with scissors and the sliding angle of water and organic solvent on the surface was tested as shown in fig. 3 and 4, and both water droplets and organic solvent such as ethylene glycol were very easy to slide on the surface with very low sliding angle. The effect of the lubricating surface can successfully overcome the problem of transport resistance, and the possibility of self-transport of liquid drops in the super-wetting lubricating pipe is ensured.

Step four: by applying external force, the shape memory material changes the permanent shape when the temperature is higher than Tg, and memorizes the temporary shape after cooling, and the form gradient of the tube generates asymmetric Laplace force for driving liquid to move, thereby realizing intelligent transportation of liquid drops.

Asymmetric deformation of the tube is critical for self-transport of the liquid. Initially, the shape memory super-wetting lubrication tube is in an initial round tube shape, when the temperature is raised to be higher than Tg and an asymmetric force is applied, the round tube is asymmetrically deformed, and after the round tube is cooled to room temperature and pressure is removed, the shape memory super-wetting lubrication tube can memorize the asymmetric deformation (fig. 8). In such asymmetric morphology tubes, water droplets can move in the tube in a self-transporting manner, from the small deformation end to the large deformation end (fig. 9). In addition to pure water, a variety of other organic solvents and acidic, basic and aqueous salt solutions can also achieve similar self-transport (fig. 10), exhibiting excellent versatility.

The self-transport speed of the droplets may also be controllable. The invention can realize the regulation and control of the transportation speed by regulating the deformation included angle of the pipe based on the shape memory effect. As shown in fig. 11, the larger the deformation angle, the faster the liquid moves in the tube.

Based on the shape memory property of the material, the liquid can not only be directionally transported by self in the tube, but also can be shaped to move the liquid drop to the opposite direction by reforming. As shown in fig. 12, the droplets move in the form-memory super-wetting lubrication tube in a self-driven manner, and after moving to the other end, the form-memory super-wetting lubrication tube is heated in sections, and after the side without droplets is heated to Tg, the tube is reshaped by applying pressure, so that the original section with smaller deformation is changed into a section with larger deformation, and after cooling to room temperature, the shape is temporarily memorized. The part with the droplets is then heated to Tg to return it to a permanent tubular shape. At this time, the water drops will move to the other side because they are in the unbalanced state again. The self-transportation mode of the liquid drops capable of being transported back and forth cannot be completed by the prior self-transportation because the chemical components or the geometrical composition of the prior self-transportation material are fixed. Thus, there is only a single permanent liquid transport path.

The shape memory super-wetting lubrication pipe can also realize the accurate control of the droplet transportation position, and the pipe can be endowed with any morphological structure at Tg based on the excellent shape memory performance of the material, thereby providing the possibility for accurately controlling the droplet position. Firstly, under Tg, the shape memory super-wetting lubricating tube is subjected to sectional asymmetric deformation and is divided into four sections (figure 13). Injecting water drops into the section with smaller deformation of the first section, stopping the water drops from the first section to the middle of the second section when the water drops are driven by self, wherein the water drops are in a stress balance state, locally heating the first section part to restore the first section part to an initial tubular shape, and returning the water drops to a stress unbalance state and continuously moving forwards because the second section is in an asymmetric deformation state. From the transport local heating cycle in this way, the droplets can be transported in pulses to any desired location. In the field, the intelligent control of the movement position of the liquid is realized for the first time by self-transport liquid drops in a tubular system. Because the curvature gradient or chemical gradient which is relied on by the prior self-driving is limited, the shape memory super-infiltration lubricating tube can carry out self-transportation by utilizing the curvature gradient for many times based on the shape memory performance, thereby having wider application potential.

The gravity-resistant climbing motion of the liquid is an important parameter for measuring the self-transportation capacity of the liquid drops. Based on excellent liquid self-driving capability, the shape memory super-wetting lubricating pipe not only can control the transportation of liquid on a horizontal route, but also can realize self-transportation on a slope, and can intelligently control the self-transportation against gravity. As shown in FIG. 14, the shape memory tube is asymmetrically shaped in four sections. The water drops are injected into one end of the small deformation, then the first section is heated, the pipe is slowly recovered to be in a round pipe shape, the Laplace force generated by the first section is reduced, the original asymmetric deformation is kept in the second section at the time, the asymmetric structure can enable the water drops to generate asymmetric Laplace force overcoming gravity, therefore, the liquid drops are conveyed to the second section, the circulation is repeated, the conveying can be easily transferred to the next section, and therefore, the liquid can continuously climb upwards along the slope.

Claims

1. A method for preparing a shape memory super-lubrication micro-tube is characterized by comprising the following steps: the method specifically comprises the following steps:

2. The method for preparing a shape memory super-lubricated microtubule as claimed in claim 1, wherein the method comprises the following steps: the method specifically comprises the following steps:

3. The method for preparing a shape memory super-lubricated microtubule as claimed in claim 1 or 2, wherein the method comprises the following steps: the shape memory super-lubricating microtube can realize self-transportation of acid, alkali, salt and organic solvent.

4. The method for preparing a shape memory super-lubricated microtubule as claimed in claim 1 or 2, wherein the method comprises the following steps: in the first step, the outer diameter of the circular shape memory tube is 2-5mm, and the wall thickness is 0.5-2.0 mm.

5. The method for preparing a shape memory super-lubricated microtubule as claimed in claim 1 or 2, wherein the method comprises the following steps: in the first step, the outer diameter of the circular shape memory tube is 3mm, and the wall thickness is 0.6 mm.

6. The method for preparing a shape memory super-lubricated microtubule as claimed in claim 2, wherein the method comprises the following steps: in the second step, the mass ratio of the PDMS prepolymer to the hydrophobic silicon oxide to the hexane is 12: 5: 18.

7. the application of the shape memory super-lubricating microtube prepared according to any one of claims 1 to 6 in intelligent liquid drop transportation is characterized in that: the application is as follows: by applying external force, the shape memory material changes the permanent shape when the temperature is higher than Tg, and memorizes the temporary shape after cooling, and the form gradient of the tube generates asymmetric Laplace force for driving liquid to move, thereby realizing intelligent transportation of liquid drops.

8. The use of a shape memory super-lubricated microtube for intelligent transport of droplets as claimed in claim 7, wherein: the pipe diameter of the deformed shape memory super-lubrication micro-pipe is 0.6 mm.

9. The use of a shape memory super-lubricated microtube for intelligent transport of droplets as claimed in claim 7, wherein: the transport speed can be regulated and controlled by adjusting the deformation included angle of the pipe.