CONCENTRATION PROFILES OF END-GRAFTED, DIBLOCK AND TRIBLOCK POLYMERS IN THE MELT - NEAR-WALL STRUCTURE AND EFFECTS OF SEGMENT-WALL INTERACTION

We report a neutron reflectivity and secondary-ion mass spectrometry s tudy of segment-density profiles of grafted polymers in a homopolymer matrix. The effect of monomer-wall interactions was investigated by gr afting to ''neutral'' or ''attractive'' interfaces. The low-density gr afting regime was studied where bulk-like screening of the excluded-vo lume interactions for grafted chains is expected to be effective. Expe riments confirm this picture of screened interactions. Current many-ch ain calculations do not appear to predict the ideal chain statistics o bserved for the neutral-wall case, nor reproduce the experimentally ob served variation of the profiles with wall interaction strength.