CN111906994B

CN111906994B - Method for manufacturing anti-icing self-removing condensed water drop surface with nano structure and application thereof

Info

Publication number: CN111906994B
Application number: CN202010486021.4A
Authority: CN
Inventors: 黄汉雄; 张宇翔
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2020-06-01
Filing date: 2020-06-01
Publication date: 2022-03-25
Anticipated expiration: 2040-06-01
Also published as: CN111906994A

Abstract

The invention discloses a method for manufacturing an anti-icing self-removing condensed water drop surface with a nano structure, which comprises the following steps: preparing a nano-structure template, and forming a nano-pore structure on the surface of the template; modifying the template; fixing the template on the surface of a cavity of an injection mold, molding a high polymer product by adopting an injection molding technology, and forming regular and orderly-arranged nano structures with high aspect ratio on the surface of the high polymer product. Also relates to the application of the manufacturing method of the anti-icing self-removing condensed water drop surface with the nanometer structure. The nano structure on the surface of the injection molding polymer product prevents infiltration of water drops, reduces the solid-liquid contact area of the surface, reduces the adhesion force between the surface and condensed water drops, reduces the heat exchange of a solid-liquid interface, does not need low surface energy modification, shows high static and dynamic super-hydrophobic characteristics, a condensed micro-water drop self-removal function and anti-icing performance on the surface of the product, has simple and easy operation process, realizes continuous, batch and low-cost manufacture, is easy to popularize and apply, and belongs to a manufacturing method of the bionic nano structure surface.

Description

Method for manufacturing anti-icing self-removing condensed water drop surface with nano structure and application thereof

Technical Field

The invention relates to a method for manufacturing a bionic nano-structure surface, in particular to a method for manufacturing a polymer product with a nano-structure on the surface so as to present anti-icing and self-removing condensed water drop performance by adopting an injection molding technology and application thereof.

Background

Water condensation and freezing on the surface are natural phenomena which can cause adverse and even serious influence on industry and daily life. Many anti-icing and de-icing methods have been developed, including mechanical, electrical heating, and liquid mixing methods. The methods realize deicing through ice breaking and ice melting, generally need special equipment, are difficult to meet the requirements of light weight and economy, and also have the problems of safety and reliability.

The polymer material is widely applied in the world nowadays, and has very important significance in researching the anti-icing performance of the surface of the polymer material. The nano structure on the surface of a natural organism is used as inspiration, and the super-hydrophobic surface with the nano structure is manufactured by adopting a template method, so that the icing time of water drops can be prolonged. However, how to manufacture a template with a proper nano structure and how to accurately copy the nano structure on the surface of the template to the surface of a high polymer material and smoothly demould the template are technical difficulties in large-scale manufacturing of the nano structure super-hydrophobic surface for anti-icing.

The surface of the cicada wing is provided with a compact and regular nano-columnar structure, the nano-columns have a certain taper, and the top of the nano-columns is round. It was found that on a cicada wing surface with nanostructures, not only do water droplets exhibit a distinct hydrophobic wetting state, but the coalescence of condensed micro-droplets can trigger a jumping behavior from the surface. Therefore, the template method is adopted to manufacture the high molecular product with the conical nano structure with the high aspect ratio on the surface, and the research on the performances of hydrophobicity, anti-icing, condensate water drop self-removal and the like on the surface of the product is of great significance.

Disclosure of Invention

In view of the problems in the prior art, the present invention aims to provide a method for manufacturing a polymer product with a nano structure on the surface so as to exhibit anti-icing and self-removing condensed water droplet properties by using an injection molding technology, and an application thereof.

In order to achieve the above object, the present invention adopts the following technical solutions.

A method for manufacturing an anti-icing self-removing condensed water droplet surface with a nano structure comprises the following steps.

(1) Preparing a nano-structure template, and forming a nano-pore structure with a high aspect ratio on the surface of the nano-structure template;

(2) modifying the nano-structure template;

(3) fixing the modified nano-structure template on the surface of a cavity of an injection mold, heating the injection mold, injecting a polymer melt into the cavity of the mold by using an injection molding machine, maintaining the pressure, cooling and shaping the melt, forming a regular and orderly arranged nano-structure on the surface of an injection molding product, opening the mold, and taking out the injection molding product.

Preferably, in the step (1), the thickness of the nanostructure template is 0.1-3 mm, the diameter of the surface nano-pores is 40-500 nm, the center distance is 50-800 nm, and the depth is 150-2500 nm.

Preferably, in step (1), the material used for preparing the nanostructure template is ultra-pure aluminum, copper alloy, stainless steel or silicon.

Preferably, in the step (1), the preparation method of the nano-pore structure on the surface of the template is anodic oxidation, photolithography, chemical etching or laser etching according to different template materials.

Preferably, in the step (2), the prepared template is placed in a prepared fluorosilane solution for modification.

Preferably, in the step (3), an injection molding machine is used to melt and plasticize the polymer material into a melt, the melt is injected into a cavity of an injection mold fixed with a template with a nano structure, the melt is filled into nano holes of the template under the action of mold filling pressure or mold compression force, and the melt is subjected to pressure maintaining, cooling and shaping to form the regular and orderly arranged nano structure on the surface of the injection molded product.

Preferably, in step (3), the nanostructures on the surface of the injection-molded polymer product are columnar, needle-shaped, filamentous or villous, and the diameters, heights and intervals of the nanostructures are all nano-scale.

Preferably, in step (3), the polymer material is polypropylene, polyethylene, polycarbonate, polystyrene, polymethyl methacrylate or polyurethane.

Preferably, the nano structure on the surface of the injection-molded polymer product can effectively prevent infiltration of water drops, the solid-liquid contact area and the energy ratio in a wetting state of the surface are obviously reduced, the adhesion force between the surface and condensed water drops is reduced, the condensed water drops can be subjected to high-efficiency self-removal action by the surface energy released by merging of the liquid drops, the surface is continuously renewed, the amount of the condensed water drops covered on the surface is obviously reduced, and the heat exchange of a solid-liquid interface is reduced, so that the surface of the injection-molded polymer product has high static and dynamic super-hydrophobic characteristics, obvious self-removal function of the condensed water drops and high anti-icing performance.

The application of the method for manufacturing the polymer product with the nano-structure on the surface by adopting the injection molding technology is used for preparing the material for preventing icing, strengthening condensation heat transfer, preventing fouling, preventing dust or collecting electrostatic energy.

In general, the present invention has the following advantages.

(1) The invention has simple and easy operation process, adopts the injection molding machine which is commonly adopted in the processing of high polymer materials, can realize continuous, batch and low-cost manufacture, is easy to popularize in the industry and has wide application prospect.

(2) The invention adopts one-step method of anodic oxidation, photoetching, chemical etching or laser etching to prepare the nano-structure template, can change the size, shape and distribution of nano-holes on the template by changing the process parameters, and can form nano-structures with different shapes and sizes on the surface of a high molecular product by changing the injection molding process parameters. In addition, the prepared nano-structure template can be repeatedly used after being modified by low surface energy.

(3) The invention is inspired by the structure and performance of the nanometer column on the surface of the cicada wing, the nanometer structure on the surface of the manufactured polymer product has high aspect ratio (namely the ratio of the height to the diameter of the nanometer structure), can effectively prevent the infiltration of water drops, obviously reduce the solid-liquid contact area of the surface, reduce the adhesive force between the surface and condensed water drops and reduce the heat exchange of a solid-liquid interface, and the surface of the injection molded polymer product is not required to be modified by low surface energy, thus showing high static and dynamic super-hydrophobic characteristics, obvious self-removing function of condensed micro water drops and high anti-icing performance.

Drawings

FIG. 1 is a schematic view of a surface nanopore structure of an aluminum template prepared by the present invention, corresponding to examples 1 to 3.

FIGS. 2a to 2c are schematic diagrams of the process of manufacturing a polymer product with a nano-structure on the surface by using an injection molding technique according to the present invention.

FIG. 3 is a scanning electron micrograph of the surface of an injection molded polypropylene (PP) article according to example 1 of the present invention.

FIG. 4 is a photograph showing the state of wetting of 4. mu.L of water droplets on the surface of an injection molded PP article of example 1 of the present invention at 25 ℃.

FIG. 5 is a photomicrograph of the surface of the injection molded PP part of example 1 of the present invention before coalescence of the condensed water droplets (left) and immediately after coalescence has disappeared from the surface (right). This is a video cut from the surface condensation process (surface temperature about 1 ℃ C. at test) with a time interval of about 40ms for the left and right 2 photographs.

FIG. 6 is a photomicrograph of the surface of the injection molded PP part of example 1 of the present invention before (top) and just after (bottom) the coalescence of condensed water droplets. This is a video cut from the surface condensation process (surface temperature about 1 ℃ C. at test) with a time interval of about 40ms for the top and bottom 2 photographs.

FIG. 7 is a photograph showing the state of wetting of 7. mu.L of water droplets on the surface of an injection molded PP article of example 1 of the present invention at-10 ℃.

FIG. 8 is a photomicrograph of the freezing process of water droplets on the surface of an injection molded PP article according to example 1 of the present invention taken from a video of the freezing process on the surface (surface temperature of-20 ℃ C. in the test).

FIG. 9 is a photomicrograph of the freezing process of water droplets on the surface of an injection molded generic PP article (which has a smooth surface) taken from a video of the freezing process of the surface (surface temperature of-20 ℃ C. when tested).

FIG. 10 is a scanning electron micrograph of the surface of an injection molded PP article according to example 2 of the present invention.

FIG. 11 is a scanning electron micrograph of the surface of an injection molded PP article according to example 3 of the present invention.

In the above figures, a — injection mold; b, local enlargement of the surface nanostructure of the injection molding polymer product; 1-a nanostructure template; 2, moving a mold; 3, fixing the mold; 4-injection molding of polymer products with nano-structures.

Detailed Description

The present invention will be described in further detail with reference to examples.

Example 1

The embodiment provides a method for manufacturing an anti-icing self-removing condensed water drop nano-structure surface, which comprises the following steps.

(1) An aluminum template is prepared by adopting an anodic oxidation method, and an inverted cone-shaped nano-pore structure is formed on the surface of the ultra-pure aluminum foil (as shown in figure 1). The thickness of the prepared aluminum template is 0.2mm, and the diameter of the top of the surface nano-hole (D)_t) Is 100nm, the bottom diameter (D)_b) 40nm, a center-to-center distance (p) of 120nm, and a depth (h) of 500 nm.

(2) And (3) placing the prepared aluminum template in a prepared fluorosilane solution for modification.

(3) Fixing the modified aluminum template on the surface of a cavity of a fixed die 3 in an injection mold A (figure 2 a); heating the injection mold A to 120 ℃, melting and Plasticizing Polypropylene (PP) into a melt by using an injection molding machine, and injecting the melt into a mold cavity formed by the movable mold 2 and the fixed mold 3 (figure 2 b); filling the melt into the nano holes of the aluminum template under the action of mold filling pressure or mold compression force at the same time; after the pressure maintaining, cooling and shaping are carried out on the melt, a tapered nano-pillar structure which is arranged in order is formed on the surface of the injection molding PP product 4 (figure 2 c); and opening the mold, and taking out the injection molding PP product 4.

FIG. 3 shows a scanning electron micrograph of the surface of the injection molded PP part 4 of the present embodiment. As can be seen, the surface of the PP product 4 presents a compact and orderly-arranged conical nano-pillar structure, and the tops of the nano-pillars are relatively sharp. The nano-pillars have an average diameter of about 38nm at the top, an average center-to-center spacing of about 90nm, and an average height of about 505 nm. The wet state energy ratio for this surface was calculated to be about 0.43.

FIG. 4 shows a photograph of a water droplet having a volume of 4. mu.L in a wet state on the surface of an injection molded PP article 4 (measured at 25 ℃). It can be seen that the contact angle of the water drop on the surface reaches 166 deg., the Cassie state is present, which indicates that the surface of the PP article 4 exhibits a distinct superhydrophobic character. The water drop impact behavior on the surface of the injection molding PP product 4 is tested and analyzed under different water drop impact speeds (0.7-1.6 m/s), surface temperatures (-10-25 ℃) and surface inclination angles (0-45 ℃), and the result shows that the impact water drops can rebound from the surface and the surface presents good water drop impact stability. The two results show that the surface of the injection moulded PP article 4 has high static and dynamic superhydrophobic properties.

Fig. 5 shows the micrographs of the surface of the injection molded PP article 4 before merging (left) and just after merging (right) of the condensed water droplets on the surface, and fig. 6 shows the micrographs of the surface of the injection molded PP article 4 before merging (top) and just after merging (bottom). This is a video of the condensation process (surface temperature about 1 ℃ C. when tested) on the surface of the injection moulded PP product 4, with a time interval of about 40ms for 2 pictures, left and right or up and down. As can be seen from FIG. 5, after the adjacent condensed water droplets on the surface of the injection molded PP product 4 grow to a certain size, they contact each other and disappear in the visual field in a very short time, and the condensed water droplets in the surrounding area are not affected, which indicates that the disappearance of the condensed water droplets is a spontaneous phenomenon of the condensed water droplets jumping off the surface without any external force. As can be seen from fig. 6, after the condensed micro water drops are merged on the surface of the injection molded PP product 4, a significant micro water drop sweeping behavior occurs without any external force, tens of even hundreds of condensed micro water drops are "swallowed" during the sweeping process, and a "dry" path is exposed on the surface. The two phenomena show that the surface of the injection molding PP product 4 has a relatively obvious self-removing function of condensed micro water drops.

FIG. 7 shows a photograph of a state where a water droplet having a volume of 7. mu.L at-10 ℃ is wetted on the surface of an injection molded PP article 4. It can be seen that at low temperatures the water droplets on the surface of the PP article 4 still exhibit hydrophobic properties. The icing test was performed on water droplets on the surfaces of the injection molded conical nanocolumnar structured PP article 4 and the injection molded ordinary PP article (the surfaces of which were smooth) at-20 ℃, and the microscopic optical photographs taken from the icing process video are shown in fig. 8 and fig. 9, respectively. Obviously, the conical nano-pillar structure on the surface of the injection molded PP product 4 obviously prolongs the icing time of water drops on the surface (23min 19s, figure 8), and is 5.4 times of the icing time on the surface of the injection molded common PP product (4min 18s, figure 9).

The high static and dynamic super-hydrophobic characteristics, the obvious self-removing function of condensed micro-water drops and the high anti-icing performance of the surface of the injection molding PP product 4 are shown because the conical nano-pillar structure on the surface of the product 4 can effectively prevent the infiltration of the water drops, the solid-liquid contact area and the energy ratio of the wetting state of the surface are obviously reduced, the adhesive force between the surface and the condensed water drops is reduced, the surface energy released by the merging of the liquid drops can enable the condensed micro-water drops to have the high-efficiency self-removing action, the surface is continuously updated, and the amount of the condensed micro-water drops covered on the surface is obviously reduced.

Example 2

This example is a method for manufacturing a nano-structured surface of an anti-icing self-removing condensed water droplet, comprising the same steps as in example 1, except that the depth (h) of the surface nano-pores of the prepared aluminum template (fig. 1) was 350 nm. FIG. 10 shows a scanning electron micrograph of the surface of the injection molded PP part 4 of the present example. As can be seen, the surface of the PP product 4 is distributed with regular and orderly arranged conical nano-pillar structures. The wet state energy ratio for this surface was calculated to be about 0.60.

And (3) testing the self-removing behavior of condensed micro water drops, the anti-icing behavior and the like on the surface of the injection-molded PP product 4.

Example 3

This example is a method for manufacturing a nano-structured surface of an anti-icing self-removing condensed water droplet, comprising the same steps as in example 1, except that the depth (h) of the surface nano-pores of the prepared aluminum template (fig. 1) was 200 nm. FIG. 11 shows a scanning electron micrograph of the surface of the injection molded PP part 4 of the present example. As can be seen, regular and orderly arranged conical nano-pillar structures are distributed on the surface of the PP product 4. The wet state energy ratio for this surface was calculated to be about 0.98.

Example 4

The present embodiment is a method for manufacturing a nano-structured surface of an anti-icing self-removing condensed water droplet, which includes the same steps as those of embodiment 1, except that the template material is copper alloy or stainless steel, and a nano-pore structure is formed on the surface of the template material by a chemical etching method.

And testing the self-removing behavior of condensed micro water drops, the anti-icing behavior and the like on the surface of the injection molding product.

Example 5

The method for manufacturing the anti-icing self-removing condensed water droplet nano-structure surface comprises the same steps as those in the embodiment 1, except that the template material is silicon, and a nano-pore structure is formed on the surface of the template material by adopting a photoetching, chemical etching or laser etching method.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A method of making an anti-icing self-removing condensate droplet surface having nanostructures, comprising the steps of:

(2) modifying the nano-structure template;

(3) fixing the modified nano-structure template on the surface of a cavity of an injection mold, heating the injection mold, injecting a high-molecular melt into the cavity of the mold by using an injection molding machine, maintaining the pressure, cooling and shaping the melt, forming a regular and orderly arranged nano-structure on the surface of an injection molding product, opening the mold, and taking out the injection molding product;

in the step (1), the thickness of the nano-structure template is 0.2mm, the diameter of the top of the surface nano-hole is 100nm, the diameter of the bottom of the surface nano-hole is 40nm, the center distance of the surface nano-hole is 120nm, and the depth of the surface nano-hole is 500 nm;

in the step (3), the nano-structure on the surface of the injection-molded polymer product is columnar, and the diameter, height and spacing of the nano-structure are all nano-scale;

in the step (3), the high polymer material is polypropylene.

2. The method of making an anti-icing self-removing condensate droplet surface having nanostructures of claim 1, wherein: in the step (1), the material for preparing the nano-structure template is ultra-pure aluminum, copper alloy, stainless steel or silicon.

3. The method of making an anti-icing self-removing condensate droplet surface having nanostructures of claim 1, wherein: in the step (1), according to different template materials, the preparation method of the template surface nano-pore structure is anodic oxidation, photoetching, chemical etching or laser etching.

4. The method of making an anti-icing self-removing condensate droplet surface having nanostructures of claim 1, wherein: in the step (2), the prepared template is placed in a prepared fluorosilane solution for modification.

5. The method of making an anti-icing self-removing condensate droplet surface having nanostructures of claim 1, wherein: in the step (3), an injection molding machine is adopted to melt and plasticize the high polymer material into a melt, the melt is injected into an injection mold cavity fixed with the nano-structure template, the melt is filled into the nano-holes of the template under the action of mold filling pressure or mold compression force at the same time, and the melt is subjected to pressure maintaining, cooling and shaping to form a regular and orderly arranged nano-structure on the surface of the injection molding product.

6. The method of making an anti-icing self-removing condensate droplet surface having nanostructures of claim 1, wherein: the nano structure on the surface of the injection-molded high-molecular product can effectively prevent infiltration of water drops, the solid-liquid contact area and the energy ratio of a wetting state of the surface are obviously reduced, the adhesion force of the surface and condensed water drops is reduced, the condensed water drops can be efficiently and automatically removed by the surface energy released by merging the liquid drops, the surface is continuously updated, the amount of the condensed water drops covered on the surface is obviously reduced, and the heat exchange of a solid-liquid interface is reduced, so that the surface of the injection-molded high-molecular product has high static and dynamic super-hydrophobic characteristics, an obvious condensed water drop self-removal function and high anti-icing performance.

7. Use of a method of manufacturing a nanostructured self-removing condensate droplet surface according to any of claims 1 to 6, characterized in that: the method is used for preparing anti-icing, condensation heat transfer enhancement, antifouling, dustproof or electrostatic energy collection materials.