Application of Intelligent Thermo-Polyurethane in Infiltrating Materials

An intelligent thermal polymer is a polymer material that can respond to changes in outside temperature in a predetermined manner. That is, changes in outside temperature cause a predetermined response of the microstructure of the polymer, so that the specific macroscopic properties of the polymer follow. Corresponding changes have taken place. It is a kind of smart material. Smart thermal polymer is a kind of polyurethane material, and its intelligent heat-sensitive performance is shown in the following: when the external temperature changes, its moisture permeability also changes accordingly, like human skin, it can be adjusted with the change of external temperature and humidity. . In particular, through the molecular design, the temperature range in which the air permeability is changed can be controlled within the room temperature range, which further expands the application of intelligent heat-sensitive polyurethane in the fields of textile, medicine, and environmental protection.
Research and development of smart thermo-urethanes In 1992, Horii et al. applied for a patent in Japan and claimed to have invented a polyurethane polymer with a glass transition temperature of 0 to 60°C, made into a film for textiles, and in glass. The transition temperature section regulates evaporation of body sweat to the outside by adjusting the amount of moisture permeability. This is the first public report on smart thermo-urethanes found so far.
In 1993, one of the inventors, Mitshim Heavy Industries (MHI) Hayashi, published an article on Journal of coated Fabrics, introducing the microstructure of some highly water-permeable polyurethane materials, and tested the moisture permeability of the material, resulting in a temperature of 10 to 40°C. In the temperature range, the moisture permeability of the material increases nearly 3 times with temperature. The author's explanation is that when the temperature rises to the glass transition temperature, the sharp increase in the micro-Brown motion of the molecular chain leads to a sharp increase in the free volume, thereby providing more ways for water vapor to pass through, resulting in the penetration of the polyurethane material. The amount of moisture increases rapidly; when the temperature drops below Tg, the molecular chain's micro-Brownian motion slows and the amount of thawing of the material decreases. Therefore, the intelligent characteristics of the moisture permeability of the material change with changes in the outside temperature are imparted.
In 1998, Diaple Corporation, a company founded by MHI in New York, announced the development of smart fabrics for outdoor apparel. The fabric is composed of a very thin non-porous polymer film, and the molecular chain of the polymer is tightly arranged at a low temperature, which can prevent the outward transfer of water vapor and heat in the human body, thereby achieving the effect of keeping warm; when the temperature rises When the molecular weight reaches a predetermined range, the movement of the molecular chain suddenly increases, resulting in a sharp increase in the volume of free radicals, thereby providing more opportunities for the excretion of water vapor and heat in the human body. This helps prevent the occurrence of micro-environment in clothing. Comfortable and sticky feel.
In March 2001, the U.S. military’s soldiers and biochemical laboratories announced the design of a land and sea amphibious garment. In water, the garment can isolate the water from contact with the skin and keep the body wet. Once out of the water, the special microstructure of the garment changes the sweat in time. This is yet another application report for smart thermo-urethanes.
However, things are always changing. In August 2002, Dr. Hu Jinlian from the Department of Textiles and Clothing of the Hong Kong Polytechnic University, Dr. Hu Jinlian’s research group found that the moisture permeability of the fabric does not change within the Tg range. On the contrary, when we calculated the moisture permeability according to ASTM E96-00, the application company calculated the effect on the moisture permeability by increasing the vapor pressure with increasing temperature, it was found that the moisture permeability of the fabric slightly decreased with increasing temperature. the trend of.
Immediately afterwards, in October 2002, Dr. Gibson of the US Army Soldier System Center reported the same conclusion as ours at the American Fiber Society. Test results He believes that the moisture permeability of a variety of fabrics, including Diaplex fabrics, Gore-tex fabrics, did not change specifically with changes in humidity.
However, research on smart thermo-urethanes does not end here. From October to December of 2002, after extensive cooperation, Dr. Hu Jinlian's research team redesigned the molecular structure of polyurethane materials according to the principle of free volume, and synthesized a new type of polyurethane material. After testing, it has been found that the material has the characteristics of intelligent thermal That is, its moisture permeability has undergone a special change in the humidity of the design humidity section. The moisture permeability increases by 3 to 5 times with the temperature in the temperature range of 10 to 40°C.
Application Prospects of Smart Thermosensitive Polyurethane Materials In fact, Mitsubishi Heavy Industries and the U.S. military provide us with a very good application idea. Smart thermo-urethanes will have a wide range of applications in the textile field. The use of this intelligent thermal polyurethane to produce a smart waterproof and moisture permeable fabric can not only make the wearer more adaptable to various outdoor environments, but also can reduce defects such as micropore blocking due to micropores during use.
In addition, the free volume of the material at room temperature has been tested to be in the range of 4.95-5.75A, which should have greater application in the fields of medicine, separation/filtration industry and environmental protection. For example, in the field of medicine, it can be used as a smart drug coating to achieve targeted release of drugs. That is to say, the temperature of the affected part in the body is generally higher than that of other normal parts. At normal temperature, the rate of penetrating from the coating film is very low. When entering the affected area, the elevated temperature will cause the medicine to be coated from the coating film. The apparent increase in the rate of internal wear allows most drugs to enter the affected area directly. This will help improve drug efficacy and prevent drugs from adversely affecting other parts of the body. In the field of separation/filtration, smart polyurethane film should also have a large number of applications.

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