PVA molecular structure
PVA, chemically known as polyvinyl alcohol, has numerous hydroxyl groups (-OH) on its molecular chain, which form its "functional core." These hydroxyl groups can form hydrogen bonds, resulting in a tough film after drying. Simultaneously, the hydroxyl groups are highly hydrophilic, allowing PVA to dissolve in water at specific temperatures-a property known as "dry film formation and wet dissolution."
Performance Character
PVA is primarily differentiated by adjusting its degree of polymerization and degree of alcoholysis to meet performance requirements in various applications:
• High degree of alcoholysis PVA (98%-99%): While less water-soluble, it exhibits high strength and good barrier properties, making it suitable for packaging films, fibers, and other products.
• Low degree of alcoholysis PVA (87%-89%): Easily soluble in cold water, with slightly weaker film-forming properties, it is suitable for use as a carrier in cosmetics and as a water-soluble adhesive.
Furthermore, PVA possesses advantages such as being non-toxic, biocompatible, and biodegradable, playing a significant role in the medical and environmental protection fields
Comparison of water solubility and film strength of PVA with different degrees of alcoholysis
Preparation process
PVA monomers are unstable and cannot be directly polymerized. Industrially, an indirect route of "polyvinyl acetate (PVAc) polymerization → alcoholysis reaction → post-treatment" is usually adopted.
Application
Consuming goods sector
Cosmetics and Daily Chemicals:
PVA in facial mask sheets efficiently absorbs essence and slowly releases nutrients when in contact with the skin; PVA film-forming agents added to shampoos and conditioners form a protective film on the hair surface, improving smoothness; PVA anti-redeposition agents in laundry detergents prevent dirt from re-adhering to clothing.
Packaging Materials: Water-soluble PVA packaging films are widely used for small-dose encapsulation of pesticides and detergents, eliminating the need for unpacking and effectively preventing residual contamination; PVA coatings in food packaging enhance barrier properties and extend food shelf life.
medical field
Pharmaceutical formulations:
As an auxiliary material for capsule shells, PVA can improve the dissolution rate of capsules, ensuring precise drug release in the body; at the same time, it can be used to make sustained-release drug carriers for long-term drug delivery.
Medical consumables: Water-soluble wound dressings can protect wounds, absorb exudate, prevent adhesion to wounds, and reduce patient suffering.
Emerging fields
3D Printing: Low-polymerization-degree PVA is a good support material for 3D printing, and it can be easily removed by washing with water after printing.
Electronic Materials: PVA-modified electrolyte membranes can improve the ion conduction efficiency of batteries, providing support for the development of flexible electronic devices
