Dewetting of Thin Block Copolymer Films

Area of Science:

• Polymer Science
• Materials Science
• Surface Science

Background:

• Thin films of poly(oxyethylene)/poly(oxybutylene) diblock and triblock copolymers are relevant in various material applications.
• Understanding dewetting phenomena is crucial for controlling film morphology and properties.

Purpose of the Study:

• To investigate the dewetting behavior of low molecular weight poly(oxyethylene)/poly(oxybutylene) copolymer thin films on silicon substrates.
• To characterize the morphology and structure of dewetted films and understand the underlying mechanisms.

Main Methods:

• Video microscopy was employed to observe the dewetting process and film morphology.
• X-ray reflectivity was utilized to determine the thickness of the residual polymer film on the substrate.
• Optical microscopy was used to study the kinetics of hole growth during dewetting.

Main Results:

• Dewetting resulted in the formation of polygonal domains of polymer droplets, with domain sizes in the millimeter range.
• X-ray reflectivity revealed a residual polymer film less than 50 Å thick coexisting with macroscopic droplets, indicating autophobic dewetting.
• The growth velocity of holes in the polymer film was constant at a fixed temperature and showed an exponential dependence on temperature.

Conclusions:

• The study demonstrates autophobic dewetting in poly(oxyethylene)/poly(oxybutylene) copolymer thin films on silicon.
• A microscopically thin film is in equilibrium with macroscopic polymer droplets after dewetting.
• The temperature dependence of hole growth velocity follows an exponential relationship, providing insights into the dewetting kinetics.