Review of research progress on smart polymer materials Li Qingshan1>2, Zhang Qincang2, Xie Lei2, Li Baifeng3 (1. School of Materials Science and Engineering, Donghua University, Shanghai 200051, China; 2. School of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar, Heilongjiang 161006, China ;3. School of Information Science and Electrical Engineering, Qiqihar University, Qiqihaer 161006, Heilongjiang, China; 3.) The progress of research on polymer materials, smart fabrics, smart polymer films and smart polymer composites, etc., and its prospects for development.
As early as the 1970s, Tanaka had found a smart polymer phenomenon, that is, when the polyacrylamide gel was cooled, the gel gradually became turbid from transparent to opaque, and when heated, it turned transparent. : In the 1980s, there emerged smart polymer materials used to make polymer sensors, separation membranes, and artificial organs. In the 1990s, smart polymer materials entered a period of rapid development. After entering the 21st century, smart polymer materials are moving toward the direction of smart polymers.
1 Types and Applications of Smart Polymer Materials Smart polymer materials can sense the slight changes in the external environment and stimuli, and the corresponding self-regulations such as expansion and contraction occur. Its application range is very wide, such as for sensors, actuators, displays, optical communications, drug carriers, size selection separators, biocatalysis, biotechnology, smart catalysts, smart fabrics, smart dimming materials, intelligent adhesives and artificial muscles, etc. field. The general classification method and application of smart polymer materials are shown in Table 1.
-19; Revision date: 2003 Synthetic Rubber Industry 2 Advances in research of smart polymer materials 2.1 Smart polymer gels Polymer gels refer to systems consisting of a three-dimensional polymer network and solvents. The network cross-linked structure makes them insoluble. Maintain a certain shape, because the gel structure contains a solvent-soluble group, so that it can be swollen by the solvent to reach equilibrium volume. Such polymer gels can produce reversible, non-continuous volume changes as environmental conditions change. Swelling and shrinking cycles of polymer gels make them applicable to chemical valves, adsorptive separations, sensors, and memory materials; the power provided by the cycle can be used to design "chemical engines"; the controllability of meshes is applicable to smart drug release systems. . The stimuli responsiveness of a polymer gel includes physical stimuli (such as heat, light, electric fields, magnetic fields, force fields, electron beams, and X-rays) responsiveness and chemical stimuli (such as pH, chemical, and biological substances) responsiveness. With the development of intelligent polymer materials, the development of "hybrid" intelligent polymer materials with multiple response functions has become an important development direction in this field. For example, Liu Feng et al. synthesized carboxyl groups with different pH-sensitive and temperature-sensitive hydrogels poly(/V-isopropylacrylamide-acrylic acid) and poly(dimethylsiloxane)-isopropylacrylamide- Acrylic acid) allows the papain enzyme adsorbed in the hydrogel to complete the controlled release of the drug itself as the environment in the organism changes. The methacrylamide-/V,/V-dimethylaminoethyl ester hydrogel synthesized by ultraviolet radiation method has good transparency and appropriate elasticity, and also has obvious temperature at 40*C and pH value of 3. And pH sensitivity; The chlorophyllin was copolymerized into poly(/V-isopropylacrylamide) to obtain a hydrogel with dual function of photosensitivity and temperature sensitivity.
2.2 Shape memory polymer materials Shape memory polymer materials are a type of new type of smart polymer materials manufactured by using the principle of memory effect after radiation or cross-linking of crystalline or semi-crystalline polymer materials. The shape memory process can be simply described as follows: The initial shape of a product is a secondary deformation, a deformation, a deformation, and a recovery. The pros and cons of its performance can be evaluated by indicators such as shape recovery rate and deformation. In the medical field, the shape memory resin can replace the traditional plaster stretch, and the shape-memory polymer material with biodegradability can be used as a medical combination suturing device, hemostatic forceps, and the like. In aviation, shape memory polymers are used as vibration control materials for wings. Using shape memory intelligence of polymer materials, heat shrinkable tubes and heat shrinkable films can be prepared. In recent years, China has successively developed heat-shrinkable products in the fields of petrochemicals, communications and optical cables, etc., as well as natural gas and municipal engineering water supply and other pipe joints welding joints and elbows. Polyfluoroethylene propylene resin heat shrinkable tube is a new type of heat shrinkable material with strong mechanical strength, can be used at -260~205°C for a long time, and maintains the excellent electrical properties of the original polyfluoroethylene propylene resin Chemical and corrosion resistance w. Using dimethyl terephthalate, isophthalic acid, and ethylene glycol as raw materials, batch copolymerization can be used to synthesize copolyester chips for heat-shrinkable films, using a biaxial stretching process. The new packaging film heat shrinkable biaxially stretched copolyester film can be used as a precision electronic component and cable coating material. At present, the research and development of shape-memory polyurethane, polynorbornene, and polystyrene have attractive development prospects.
2.3 Smart Fabrics Dagai combines polyethylene glycol with various fibers (such as cotton, polyester, or polyamide/polyurethane) blends to make it thermally compatible and reversibly shrinkable. The so-called thermal adaptability is to give the material a thermal memory property. When the temperature rises, the fiber absorbs heat, and when the temperature decreases, the fiber releases heat. This thermal memory property results from the hydrogen bonding interaction between the adjacent polyol's helix structure bonded to the fiber. As the temperature rises, the hydrogen bonds dissociate, the system tends to be in an unordered state, and the coil relaxation process absorbs heat. When the ambient temperature decreases, the hydrogen bonds make the system into an ordered state, and the coils are compressed and emit heat. This heat-adaptive fabric can be used in clothing and insulation systems, including biomedical products for body temperature regulation and burn treatment, and crop freeze protection systems.
Another function of this type of fabric is reversible shrinkage, ie wet shrinkage, return to the original size when dry, wet shrinkage up to 35%, can be used in sensing/execution systems, micro-engines and biomedical pressure and compression devices, such as A pressure bandage, which contracts in the blood, acts as a hemostatic effect on the pressure generated on the wound, and the pressure is relieved when the bandage is dry.
At present, the combination of molecular nanotechnology and computers, detectors, micron or nanometer machines has further increased the level of intelligence in fabrics. Automatic cleaning of fabrics and automatically repaired fabrics have attracted more attention.
2.4 Intelligent polymer membranes In the field of intelligent research, selective penetration, selective adsorption, and separation are the most common methods. The intelligentization of polymer membranes is achieved through changes in the composition, structure and morphology of the membrane. The smart polymer film currently researched is mainly used as a "chemical valve." Research on smart polymer membranes has focused on sensitive gel membranes, sensitive graft membranes, and liquid crystal membranes. Films made of high-molecular gels can achieve reversible deformation and can also withstand certain static pressures. Currently reported are polymethacrylic acid / polyethylene glycol, polyvinyl alcohol / polyacrylic acid blends and so on. Polymer grafted membranes can be prepared by surface grafting and grafting within the membrane pores, and Li Qingshan et al. Research progress on smart polymer materials. 267. The mechanism of action is basically the same. The pore size change of the membrane is based on the interaction between the solute molecules and the polymer chains grafted onto the membrane. Changes in the graft chain configuration change the pore size, and the graft chain regulates membrane permeability like a valve. Current reports in this regard include the grafting of polyacrylamide and polyvinylidene fluoride, and the grafting of polyethylene glycol and polymethacrylate. Liquid crystal polymers can exhibit liquid crystal properties such as the thermotropic branched-chain liquid crystal polymer poly(p-acetylaminobenzophenone) having chemical valve characteristics under alternating current and 0*c conditions.
At present, the scope of application of polymer membranes with chemical valve functions is still relatively narrow and still depends on the continuous development of new materials.
2.5 Intelligent polymer composites The application of smart polymer materials in the fields of industry, construction, aviation and medicine is becoming more and more widespread. Most of the composite materials are used as sensor elements. The new smart composite material has self-healing, self-strain, and other functions. In the field of aviation, the United States Research Institute is developing a "smart skin" made of composite material attached to the casing to replace the tail and flaps necessary for taking off, turning, and landing. These "smart skins" can change shape according to the instructions of pilots and aircraft computers, and play the same role as aircraft tails and flaps. In the field of construction, the self-diagnosis, self-regulation, and self-repairing functions of composite materials can be used to quickly detect environmental temperature and humidity and replace temperature control circuits and protection circuits. The use of an oxide film having an electrochromic effect and a photomemory effect to prepare an automatic dimming window material can both reduce the air conditioning load and save energy, and has been widely used in the field of smart building window glass. Intelligent multi-functional automatic alarm and intelligent infrared camera with polymer film with thermoelectric effect and thermal memory effect replace the complex detection circuit. The use of optical fibers with optical effects to produce fiber optic concrete parts, when the structural members exceed the allowable width cracks, the light path is cut off and automatically alarm, can replace the complex detection circuit.
3 Concluding remarks At present, there are deficiencies in the research and development of smart polymer materials in China, and there are still considerable gaps compared to the world's advanced level, affecting China's information, aerospace, aviation, energy, construction materials, navigation, shipping, military The development of many other sectors has sometimes become a key factor restricting the development of certain sectors. Foreign smart polymer materials are in the research and development stage, and all developed countries pay considerable attention to them. Therefore, the 21st century intelligent polymer materials will be more widely used to guide the development of materials science.