THE STRUCTURE OF GRAFTED POLYSTYRENE LAYERS IN A RANGE OF MATRIX POLYMERS

We have used neutron reflectivity to measure concentration profiles of brushes of grafted chains in the melt. A method has been developed fo r permanently grafting end-functionalized polymers to a silicon substr ate. By changing the matrix polymer surrounding the brush, we have inv estigated how the conformation of the brush depends upon the interacti on between the matrix and brush polymers. We have observed strong stre tching of the blush chains when the matrix and brush interact favorabl y, and collapse of the brush onto the substrate when they are immiscib le. Comparisons have been made with theoretical predictions for the he ight and width of the brush, and experimental profiles have been compa red with numerical self-consistent field theory.