Altering surface fluctuations by blending tethered and untethered chains.

Area of Science:

• Polymer Physics
• Materials Science
• Surface Science

Background:

• Surface height fluctuations in thin polymer films influence properties like wetting and adhesion.
• Understanding factors controlling these dynamics is crucial for materials design.

Purpose of the Study:

• To investigate the impact of partial covalent tethering of polymer chains on surface dynamics.
• To compare the effect of partial tethering with other factors like molecular weight and entanglement.

Main Methods:

• Covalently attaching a fraction of polymer chains to a substrate in an unentangled melt.
• Measuring surface height fluctuations in partially tethered films.
• Comparing results with untethered polymer films of varying molecular weights.

Main Results:

• Partial tethering significantly increases the relaxation time of surface height fluctuations, even for thick films.
• The tethering effect is more dominant than substrate attraction, chain entanglement, or increased glass transition temperature (Tg).
• Low molecular weight tethered polymers exhibited slower dynamics than high molecular weight untethered polymers.

Conclusions:

• Partial tethering is a powerful method to control and reduce surface dynamics in polymer films.
• This technique offers a route to tailor surface properties for applications in wetting, adhesion, and tribology.