Modified polyvinyl alcohol (PVA) refers to polyvinyl alcohol that has undergone chemical or physical modifications to alter its properties, making it suitable for specific applications. PVA is a synthetic polymer that is water-soluble and has excellent film-forming and adhesive properties. By modifying its chemical structure or physical properties, researchers and engineers can tailor PVA to meet the requirements of various industries and applications.

Some common modifications of polyvinyl alcohol include:

1. Crosslinking: Crosslinking involves creating chemical bonds between PVA polymer chains, resulting in improved mechanical strength and stability. This modification is particularly useful for applications that require water resistance, such as coatings, adhesives, and packaging materials.

2. Hydrophobic Modification: PVA is inherently water-soluble, but hydrophobic modification can be introduced to make it less water-sensitive and more suitable for applications in humid or wet environments. This modification can be useful for applications like coatings, films, and textiles.

3. Chemical Grafting: Chemical groups can be grafted onto PVA chains to introduce new functionalities. For example, adding reactive groups can allow PVA to bond with other materials more effectively, improving adhesion in various applications.

4. Blending: PVA can be blended with other polymers to combine their properties and create materials with a broader range of characteristics. Blending PVA with other polymers can enhance properties such as strength, flexibility, and thermal stability.

5. Functionalization: Functional groups can be attached to PVA to make it responsive to external stimuli such as temperature, pH, or light. These modifications enable PVA to be used in applications like controlled drug release, sensors, and smart materials.

6. Improved Mechanical Properties: Modifications can be made to enhance PVA's mechanical properties, such as tensile strength, elongation, and toughness. This is crucial for applications where the material will experience mechanical stresses, such as in textiles and films.

7. Biodegradable Modifications: PVA can be modified to be more biodegradable, making it a suitable choice for environmentally friendly applications such as biodegradable packaging materials.

8. Electrospinning: PVA can be electrospun into ultrafine fibers, which can find applications in areas such as tissue engineering, filtration, and wound dressings.