Laboratory preparation of polyvinyl alcohol hydrogel

1, PVA choose a low degree of alcoholysis, such as 1788, 2488 dissolved in cold water, warmed to 75 degrees to accelerate and all dissolved, according to the PVA mass fraction of 0.5%-1% to add aqueous boric acid or sodium tetraborate, aqueous solution, rapid stirring is a hydrogel.

2, freeze-drying method, the aqueous solution of PVA for repeated low-temperature freezing - freezing - freezing - freezing, after 3 or 4 cycles of PVA in the case of physical changes in temperature on the formation of a solid hydrogel

Polyvinyl alcohol: organic compounds, white flakes, flocculent or powdered solid, odorless. Soluble in water (above 95℃), slightly soluble in dimethyl sulfoxide, insoluble in gasoline, kerosene, vegetable oil.

Extended information:

Polyvinyl alcohol characteristics:

1, physical properties are affected by the chemical structure, alcoholysis, polymerization degree.

2, polyvinyl alcohol molecules in the existence of two chemical structures, namely, 1,3 and 1,2 glycol structure, but the main structure is the 1,3 glycol structure, that is, "head-tail" structure. The degree of polymerization of polyvinyl alcohol is divided into ultra-high degree of polymerization (molecular weight of 250,000 to 300,000), high degree of polymerization (molecular weight of 170,000 to 220,000), medium degree of polymerization (molecular weight of 120,000 to 150,000), and low degree of polymerization [2.5 to 35,000].

3, emulsion stabilizer for polyvinyl acetate emulsion polymerization. Used in the manufacture of water-soluble adhesives. Used as a modifier for starch adhesive. Also used in the preparation of photographic adhesive and benzene solvent resistant sealant. Also used as mold release agent, dispersant, etc.. Store in a cool and dry warehouse. It is moisture-proof and fire-proof.

Baidu Encyclopedia-Polyvinyl Alcohol