CN-116814074-B - Low poisson ratio autonomous control intelligent window composite material film and preparation method thereof

CN116814074BCN 116814074 BCN116814074 BCN 116814074BCN-116814074-B

Abstract

The invention discloses an intelligent window composite film with low poisson ratio and autonomous regulation, which comprises a flexible matrix, transparency regulation particles distributed in the flexible matrix and a plurality of strip-shaped shape memory polymers, wherein the shape memory polymers are long and have a bending structure. The composite film has higher tensile property, can effectively reduce shrinkage perpendicular to the acting direction of load caused by poisson effect, further effectively improves the use effect of a mechanical intelligent window, and simultaneously gives consideration to excellent photo-induced autonomous regulation and control effect.

Inventors

WANG KAIQIANG
CHEN BO
LIU WEIWEI
GE DENGTENG
YANG LILI
CHEN MINGZHE
WANG XING
WU YONGJUN

Assignees

中建三局集团有限公司
东华大学

Dates

Publication Date: 20260508
Application Date: 20230119

Claims (8)

1. The low poisson ratio autonomous control intelligent window composite material film is characterized by comprising a flexible matrix, transparency control particles and a plurality of strip-shaped memory polymers, wherein the transparency control particles and the strip-shaped memory polymers are distributed in the flexible matrix; The transparency regulating particles are silicon dioxide nano particles, polystyrene nano particles, silicon dioxide coated iron oxide nano microspheres or ferric oxide nano particles; The shape memory polymer is prepared by compounding an ethylene-vinyl acetate copolymer and silver nanowires as main raw materials, and comprises the following specific preparation steps: Dispersing ethylene-vinyl acetate copolymer, initiator, cross-linking agent and silver nano wire ethanol dispersion in organic solvent I in proportion, stirring under oil bath condition, standing the obtained homogeneous solution overnight, naturally forming film, and oven drying; heating a mold coated with a release agent, placing the obtained dried product in the mold, performing hot press molding, and cooling to obtain a curved strip-shaped structure; placing the obtained bent strip-shaped structure on a heat table for ultraviolet crosslinking to obtain a shape memory polymer with the bent strip-shaped structure; The shape memory polymer is subjected to surface treatment, which comprises the specific steps of adding the obtained shape memory polymer into an organosilane coupling agent solution, carrying out dipping treatment and drying; the mass ratio of the ethylene-vinyl acetate copolymer to the initiator to the cross-linking agent to the silver nanowire ethanol dispersion to the organic solvent is 1 (0.02-0.03): (0.04-0.06): (0.04-0.08): (0.8-1); the total length of the shape memory polymer is the length corresponding to the stretch deformation of the composite material film reaching 25-35%.
2. The low poisson ratio autonomous control intelligent window composite material film according to claim 1, wherein the mass ratio of the ethylene-vinyl acetate copolymer to the silver nanowires is 100 (0.4-0.8).
3. The low poisson ratio autonomous control intelligent window composite material film according to claim 2, wherein the molecular weight of the ethylene-vinyl acetate copolymer is 1800-2200, the diameter of the silver nanowire is 40-60 nm, and the length of the silver nanowire is 10-15 μm.
4. The low poisson's ratio autonomous control smart window composite film of claim 1, wherein the transparency-controlling particles are distributed on a surface layer of the flexible substrate.
5. The low poisson's ratio autonomous control smart window composite film of claim 1, wherein the flexible substrate is polydimethylsiloxane or silica gel.
6. The low poisson ratio autonomous control intelligent window composite film according to claim 1, wherein the transparency-controlling particles have a particle size of 200 to 300nm.
7. The method for preparing the low poisson ratio autonomous control intelligent window composite material film according to any one of claims 1 to 6, which is characterized by comprising the following steps: 1) Preparing a shape memory polymer; Dispersing ethylene-vinyl acetate copolymer, initiator, cross-linking agent and silver nano wire ethanol dispersion in organic solvent I in proportion, stirring under oil bath condition, standing the obtained homogeneous solution overnight, naturally forming film, and oven drying; heating a mold coated with a release agent, placing the obtained dried product in the mold, performing hot press molding, and cooling to obtain a curved strip-shaped structure; placing the obtained strip-shaped structure on a heat table for ultraviolet crosslinking to obtain a shape memory polymer with a bent strip-shaped structure; 2) Surface treatment of shape memory polymers; Adding the obtained shape memory polymer into an organosilane coupling agent solution, carrying out dipping treatment and drying; 3) Preparing a composite film; Dispersing the transparency regulating particles in an organic solvent II, and carrying out ultrasonic stirring to obtain uniformly dispersed transparency regulating particle dispersion liquid; Preparing a liquid flexible matrix, then adopting a step-by-step pouring process, namely firstly performing primary pouring on a substrate sprayed with transparency regulating particles, wherein the pouring amount is 40-60% of the total amount of the liquid flexible matrix, performing vacuum defoamation, standing at room temperature, then placing a plurality of step 2) shape memory polymer strip structures on the surface at intervals, performing secondary pouring by using the residual liquid flexible matrix, performing vacuum defoamation and solidification, and finally stripping the substrate to obtain the low Poisson ratio autonomous regulating intelligent window composite material film.
8. The preparation method of the ultraviolet crosslinking agent according to claim 7, wherein ultraviolet light intensity is 1800-2000 mw/cm 2 , illumination time is 30-60 s, and the film is 10-18 cm away from the light source.

Description

Low poisson ratio autonomous control intelligent window composite material film and preparation method thereof Technical Field The invention belongs to the technical field of intelligent windows, and particularly relates to an autonomous control intelligent window composite material film with low poisson ratio and a preparation method thereof. Background The intelligent window can change the transmittance of the intelligent window according to external stimulus (light, electricity, force and the like) and adjust the flux of sunlight radiation entering a building, thereby adjusting the room temperature. The force-induced intelligent window is usually made of mechanical responsive materials, is a novel intelligent window with various performances regulated by simple mechanical strain, and has the advantages of simple structure, low cost, quick response time and the like. Patent CN111522151a discloses a highly sensitive mechanical control intelligent window film, and the highly sensitive control intelligent window film adopting a double-layer composite structure can achieve 50% transparent change when the strain is 40%. Patent CN110646870a discloses a film with adjustable light transmittance, which is pre-stretched for a plurality of times and the surface of the film is treated to prepare an intelligent window film which can show multiple light transmittance changes after stretching. The literature 'force-induced color change regulation and anti-counterfeiting application of transparent photonic crystal films' utilizes SiO 2 colloid particles to construct a three-dimensional protein Dan Guangzi crystal array, and an elastic film embedded in a Polydimethylsiloxane (PDMS) elastomer can change color after being stressed. However, the conventional mechanical intelligent window generally has the problems that the force-induced intelligent window mainly depends on the internal structure of the intelligent window film or other factors to change the transparency of the window when the intelligent window film is stressed, but the intelligent window film can deform beyond some expected effects after being stressed, for example, the intelligent window film can shrink transversely when being stretched longitudinally, and the side edges of the film are separated from the edges of the window, so that local gaps are formed in the intelligent window, and the use effect of the intelligent window is further affected. The main reason for the problem is that poisson's ratio effect of the material (elongation (or shortening) deformation of the material in the load direction and, at the same time, shortening (or lengthening) deformation in the direction perpendicular to the load) occurs, and therefore, further development of a composite film having high elasticity and low poisson's ratio is urgently required. Currently, a method for reducing poisson's ratio is to add a three-dimensional paper folding structure (such as a honeycomb structure, a foam structure and the like) inside a material, for example, literature' mechanical design and analysis of a negative poisson's ratio smart soft super structure' is to develop a flexible soft material based on the paper folding honeycomb structure, the material has a negative poisson's ratio effect when stretched, literature "Mechanical Metamaterials Foams with Tunable Negative Poisson's Ratio for Enhanced Energy Absorption and Damage Resistance" realizes the negative poisson's ratio by using a three-dimensional net structure, and patent CN216715096a discloses a three-node auxetic open pore structure with the negative poisson's ratio, and realizes the negative poisson's ratio effect by adding a triangular hole structure on a film. However, the existing low poisson ratio improvement means are realized by opening holes or adding a large-area three-dimensional structure, the intelligent window film needs to have higher transmittance, the structures such as holes can influence the transparency of the film and the overall performance of the composite film, and the like, and the internal addition of the large-area complex three-dimensional structure is essentially realized by the three-dimensional characteristic of the structure to reduce the poisson ratio of the overall structure, so that the internal operation is generally complicated, and the overall transparency of the material is reduced. In addition, the intelligent window manufactured by the method still needs to be adjusted by means of other detection modes through manual or other electric control modes, and automatic adjustment cannot be achieved automatically according to the change of light rays. Disclosure of Invention The invention aims to solve the problems and the defects of the prior art, provides a force-induced regulating intelligent window film with low Poisson ratio, which can keep higher stretching performance during stretching, reduce shrinkage perpendicular to the acting direction of a load caused by Poisson effect, further e