Determining Preparation-Induced Differences in Local Forces Acting along Polymer Chains in Spin-Coated Films

Area of Science:

• Materials Science
• Polymer Physics
• Spectroscopy

Background:

• Understanding forces within polymer chains is crucial for material properties.
• Mechanochromophores offer a route to optically probe mechanical stress in polymers.
• Spin-coated polymer films are widely used but their internal stress distributions are complex.

Purpose of the Study:

• To utilize photoluminescence (PL) from mechanochromophores as optical force sensors.
• To investigate forces acting along polymer chains in spin-coated thin films.
• To correlate these forces with preparation conditions and macroscopic residual stresses.

Main Methods:

• Employing photoluminescence (PL) from mechanochromophores covalently linked into glassy polymer backbones.
• Analyzing shifts in PL peak positions to determine main force changes.
• Interpreting changes in PL spectral shapes to understand force distribution variations.
• Correlating PL data with spin-coating preparation parameters (p_ev).

Main Results:

• Distinct changes in PL spectra were observed based on spin-coating conditions (p_ev).
• These spectral changes reflect variations in the distribution of forces along polymer chains.
• A link was established between forces on individual polymer chains and macroscopically detected residual stresses.
• Residual stresses and individual chain forces showed different dependencies on p_ev.

Conclusions:

• Photoluminescence from mechanochromophores effectively quantifies forces within polymer chains.
• Spin-coating parameters critically influence the intra-chain force distribution.
• The relationship between microscopic chain forces and macroscopic residual stress is complex and not always linear.