Headgroup effect on silane structures at buried polymer/silane and polymer/polymer interfaces and their relations to...

Area of Science:

• Materials Science
• Surface Chemistry
• Polymer Science

Background:

• Polymer adhesion is critical for material performance.
• Epoxy silanes are common adhesion promoters.
• Understanding interfacial molecular interactions is key to improving adhesion.

Purpose of the Study:

• To investigate the role of silane headgroups in interfacial molecular interactions.
• To elucidate the effect of methylvinylsiloxanol (MVS) on these interactions.
• To correlate molecular structures with adhesion performance at polymer interfaces.

Main Methods:

• Sum frequency generation (SFG) vibrational spectroscopy was employed to probe interfacial molecular structures.
• Three epoxy silanes with varying headgroups were studied: (3-glycidoxypropyl) trimethoxysilane (γ-GPS), (3-glycidoxypropyl) methyl-dimethoxysilane (γ-GPMS), and (3-glycidoxypropyl) dimethyl-methoxysilane (γ-GPDMS).
• Interfaces between poly(ethylene terephthalate) (PET) and silanes, with and without MVS, and with silicone were analyzed.

Main Results:

• Silane headgroups exhibited diverse interfacial segregation and ordering behaviors.
• The influence of MVS on interfacial structure was dependent on the specific silane headgroup.
• Distinct interfacial molecular structures of silane methoxy headgroups were observed at PET/silane versus PET/silicone interfaces.

Conclusions:

• Silane methoxy headgroups play a crucial role in adhesion at PET/silicone interfaces.
• MVS can alter interfacial methoxy segregation and ordering, thereby modulating adhesion strength.
• The study provides molecular-level insights into silicone-polymer adhesion mechanisms.