Interfacial molecular restructuring of plasticized polymers in water

Area of Science:

• Materials Science
• Surface Chemistry
• Polymer Science

Background:

• Phthalate-plasticized poly(vinyl chloride) (PVC) surfaces are unstable upon water contact due to unbound plasticizers.
• Predicting plastic/water interface interactions requires in situ investigation.

Purpose of the Study:

• To investigate the molecular surface restructuring of PVC films with and without bis 2-ethylhexyl phthalate (DEHP) plasticizer upon water contact.
• To analyze the behavior of plasticizers at the plastic/water interface and their transfer dynamics.

Main Methods:

• Sum frequency generation (SFG) vibrational spectroscopy was used to probe PVC films in situ.
• A thin-film model spectral analysis allowed differentiation of surface and interface changes.

Main Results:

• Water contact induced molecular restructuring at both the surface and the plastic/substrate interface of DEHP-plasticized PVC.
• Surface structures did not fully recover after drying.
• Small amounts of DEHP leached into water and could transfer to new surfaces.

Conclusions:

• Phthalates can transfer between surfaces via water contact within minutes.
• This research provides critical insights into the surface behavior and environmental fate of plasticizers in polymers.