Glassy dynamics in thin films of polystyrene

Area of Science:

• Materials Science
• Polymer Physics
• Condensed Matter Physics

Background:

• Glassy dynamics in polymers are crucial for material properties.
• Thin film behavior can differ significantly from bulk materials.
• Understanding aging effects is key to predicting polymer performance.

Purpose of the Study:

• To investigate the glassy dynamics of atactic polystyrene thin films.
• To correlate changes in electric capacitance with volume and dielectric permittivity during aging.
• To examine memory and rejuvenation effects in thin polymer films.

Main Methods:

• Complex electric capacitance measurements.
• Dielectric relaxation spectroscopy.
• Isothermal aging of atactic polystyrene thin films.

Main Results:

• The real part of electric capacitance increased with aging time, linked to volume changes (film thickness).
• The imaginary part of electric capacitance decreased with aging time, associated with dielectric permittivity changes.
• Dielectric permittivity exhibited memory and rejuvenation effects, similar to poly(methyl methacrylate) films.
• Volume changes showed a less pronounced rejuvenation effect compared to dielectric permittivity.

Conclusions:

• Aging in atactic polystyrene thin films is primarily governed by changes in dielectric permittivity.
• Dielectric permittivity displays memory and rejuvenation, critical for understanding thin film polymer behavior.
• Volume relaxation dynamics differ from dielectric relaxation dynamics in these systems.