Effect of Molecular Architecture on the Conformational Relaxation for Interfacial Polymer Chains*

Conformational relaxation processes of polymer chains trapped in a metastable state in close proximity to a solid interface can strongly affect the physical properties of polymer nanocomposites. Using sum-frequency generation spectroscopy, we here report the thermal annealing effect on chain conformations of polystyrene (PS) with different molecular architecture near at the quartz interface. Relaxation dynamics for PS chains strongly adsorbed at the outermost substrate interface and those located next to the adsorbed layer were characterized. PS chains exhibited much slower relaxation dynamics with a star-shaped architecture than with a linear one. This finding is in consistent with a scenario that the entropic interaction with the solid surface is stronger for a star-shaped macromolecule than for a linear one.