Wetting, ordering, and fluctuation phenomena in thin polymer films.

摘要

The behavior of a polymer chain at polymer-polymer melt interfaces, polymer-solid interfaces and solution surfaces is the focus of this thesis. The main technique used to do all these experiments are x-ray and neutron scattering and atomic force microscope. In chapter 1, the interface width of immiscible polymer were measured. The results were compared with the theoretical prediction. Also the x-ray and neutron reflectivity calculation were reviewed in this chapter. In chapter 2, the chain ends distribution at the polymer/air and polymer/polymer interfaces were measured. The results show there are no chain end enhancement near a boundary within our experiment resolution.;The block copolymer has been long of interested of their ordered morphologies due to phase separation. In chapter 3, we studied surface induced ordering of asymmetric (f = 0.24) tri-block copolymer. We found the microdomain orienting parallel to the surface. When the film thickness is not equal to the integral number of domain spacing, the excess material will pull out forming islands. The island has the same height as domain spacing and the time and temperature dependent of island is also discussed.;In chapter 4, surface fluctuation of polymer solution is studied by diffuse x-ray scattering. We have calculated the static structure factor S(k) and equal time height-height correlation function C(R) for surface hydrodynamic modes based on a coupled two-fluid model where the polymer response is taken to be that of a Maxwell viscoelastic material. We obtain the leading correction term to the capillary-wave result for C(R) dependent on the solution shear modulus ;In chapter 5, we studied wetting properties of liquid polymer thin films which would normally wet native oxide covered Si surfaces, were observed to dewet the surface when the film thickness became less than the polymer radius of gyration. The results are shown to be consistent with an expression for the spreading parameter that incorporates a stretching free energy term for the polymer chains.