Influence of PVAc/PVA Hydrolysis on Additive Surface Activity

Area of Science:

• Polymer Science
• Materials Chemistry
• Surface Science

Background:

• Understanding how polymer matrix properties influence small molecule surface behavior is crucial for material design.
• Hydrophobicity of polymer matrices plays a significant role in the surface activity and compatibility of additives.

Purpose of the Study:

• To establish design rules for predicting the influence of polymer matrices on small molecule surface properties.
• To investigate the dependence of additive surface behavior on polymer matrix hydrophobicity and degree of hydrolysis.

Main Methods:

• Systematic modification of polyvinyl acetate (PVAc) to polyvinyl alcohol (PVA) via controlled hydrolysis to alter matrix hydrophobicity.
• Analysis of the surface behavior of model additives (sorbitol, octanoic acid, sodium dodecyl sulfate) in matrices with varying degrees of hydrolysis (DH).

Main Results:

• Sorbitol surface segregation decreased with increasing DH, transitioning from surface blooming in PVAc to plasticization in PVA.
• Octanoic acid (OA) increased PVAc wettability due to high compatibility and reorientation, presenting a hydrophilic surface.
• Sodium dodecyl sulfate (SDS) formed wetting layers across a wide DH range, showing optimal compatibility at intermediate DH.

Conclusions:

• Additive surface segregation is complex, influenced by hydrophobicity, compatibility, surface energy, and component mobility.
• The degree of hydrolysis (DH) is a key parameter for tuning additive behavior and surface properties in polymer matrices.