The hottest new achievement of Wuhan University wa

2022-08-24
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Wuhan University's new achievement - dissolving cellulose at low temperature in water system

using urea, sodium hydroxide and water as solvents, precooling to -12 ℃, put the extremely insoluble cellulose into it, and it turns into mucus in two minutes. The natural polymer, which stubbornly brings confidence to extruder Enterprises, is thus "conquered". By developing this "magical and simple" water solvent system, the research team led by Zhang Lina, a professor of the school of chemistry of Wuhan University, opened the door to the cellulose material industry for basic research of Cellulose Science, and won the highest award in the field of cellulose and renewable resource materials in the world

Professor Zhang Lina

the new theory and technology of "green" solvent low-temperature dissolution created by them is a major breakthrough in the field of renewable resources and materials, and a mythical story from laboratory basic research to industrial experiment. This mixed aqueous solution composed of alkali and urea is non-volatile, non-toxic, non polluting to the environment, and it has low cost and fast dissolution. This solvent has great potential in cellulose technology. This is the international evaluation of Zhang Lina and her team

Zhang Lina, who has been committed to the scientific basis and Application Research of natural polymer materials in biomass resources, led her team to break through the traditional method of heating and dissolving with organic solvents, and put forward a "green" method and new concept of low-temperature dissolving polymers in water system, transforming agricultural wastes such as cotton lint, bagasse, shrimp shell, crab shell into new materials with practical value. In this way, waste can be transformed into comfortable fabrics, degradable films, daily necessities and biomedical materials. Compared with traditional dissolution technology, where is the "green" of cellulose low-temperature dissolution theory? How big is the impact on the textile industry? In this regard, this newspaper conducted an exclusive interview with Professor Zhang Lina

-12 ℃ the fastest dissolution rate in 2 minutes

"at present, the viscose method used in the production of rayon and cellophane in China requires a large amount of carbon disulfide, which has caused serious pollution to the environment. We have invented a new cellulose solvent -7% sodium hydroxide (NaOH)/12% urea aqueous solution. When the solvent is cooled to -12 ℃, it can quickly dissolve cellulose (its molecular weight is 1.2 × Below 105), the dissolution time is only 2 minutes, reaching the fastest dissolution rate in the history of cellulose. We studied the dissolution process and low-temperature dissolution mechanism of cellulose by variable temperature FT-IR spectroscopy, dynamic and static light scattering (LLS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and 15n- and 13C-NMR. " Zhang Lina said

they proved by experiments that NaOH hydrate is easy to form hydrogen bonds with cellulose and directly connect to the cellulose molecular chain, forming a wormlike inclusion complex with urea as the main body to enclose cellulose NaOH guest. This kind of complex formed by self-assembly between macromolecules and solvents driven by hydrogen bonds is sensitive to highly stable states at low temperatures. It is concluded that the dissolution of cellulose at low temperature is caused by the dynamic self-assembly between small solvent molecules (sodium hydroxide, urea, water) and cellulose macromolecules, which not only broadens the theory of polymer dissolution, but also puts forward a new concept of low temperature dissolution. In the water system, low-temperature dissolution does not volatilize any chemical substances, so this is a clean production process

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