Mobility of polymer chains confined at a free surface - art. no. 206101

Dynamic secondary ion mass spectrometry was used to investigate the chain m obility of polystyrene (MW ranging from 4.3 to 957 kg/mol) at the free surf ace. The data show that the diffusion coefficient was reduced relative to t he bulk value within a distance, d less than or equal to 4R(g), from the su rface and scaled as 1/N-2.5 at fixed d. These results are in excellent agre ement with self-consistent field calculations of the surface segmental dist ribution and provide the first direct confirmation of various theoretical m odels that predict asymmetric segmental fluctuation which arises from surfa ce induced orientation of polymer chains.