Intercalation kinetics of long polymers in 2 nm confinements

The motion of confined polymers is measured experimentally between parallel , atomically smooth solid surfaces, separated by 2 nm. In particular, the k inetics of intercalation of monodispersed polystyrene in alkylammonium modi fied mica-type silicates were studied using X-ray diffraction. The kinetics of the neat polymers and their functionalized derivatives were measured as functions of molecular weight, extent of functionalization, and silicate s urface organic modification, at various temperatures. Selective corroborati ve studies were also performed using in-situ small-angle neutron scattering (SANS). The kinetic data are interpreted in terms of an effective diffusio n coefficient (D-eff) of the polymer, which undergoes a dramatic decrease w ith stronger silicate surface-polymer interaction. This interaction is vari ed by either changing the silicate surface modification or by increasing th e extent of functionalization of the polystyrene chains. Furthermore, the d iffusion coefficient exhibits an inverse dependence on chain length (N), i. e., D-eff proportional to N-1, for chains up to 900 000 molecular weight.