First inelastic neutron scattering studies on thin free standing polymer films

Area of Science:

• Polymer Physics
• Materials Science
• Neutron Scattering

Background:

• Studies show that the glass transition temperature (T(g)) in free-standing polymer films decreases significantly as film thickness reduces below bulk values.
• Investigating the T(g) of thin polymer films is crucial for understanding material properties at the nanoscale.

Purpose of the Study:

• To prepare and analyze stacks of free-standing polystyrene films with controlled thicknesses.
• To demonstrate the applicability of inelastic neutron scattering (INS) for studying the T(g) of these thin films.

Main Methods:

• Preparation of two stacks of free-standing polystyrene films: one with 70 films (h ≈ 107 nm) and another with 140 films (h ≈ 55 nm).
• Utilizing inelastic neutron scattering (INS) on time-of-flight spectrometer IN6 and backscattering spectrometer IN16 at the Institut Laue-Langevin.
• Performing the first INS measurements on such multi-layered thin film samples.

Main Results:

• Successfully prepared multi-layered free-standing polystyrene films with thicknesses of approximately 107 nm and 55 nm.
• Demonstrated the feasibility of conducting INS experiments on these thin film stacks.
• Collected initial data on the glass transition behavior of the polymer films using INS.

Conclusions:

• Inelastic neutron scattering is a viable technique for investigating the glass transition in thin, free-standing polymer films.
• The study paves the way for future research into the size-dependent T(g) of polymers using neutron scattering.
• The feasibility demonstrated here enables further exploration of nanoscale polymer dynamics.