Segregation study of a BAB triblock copolymer at the A/B homopolymer interface

The segregation of a poly[(2-vinylpyridine)-b-styrene-d 8 -b-(2-vinylpyridine)] triblock copolymer (PVP-dPS-PVP) to a planar interface between the homopolymers PS and PVP is determined by forward recoil spectrometry (FRES). Compared to a diblock copolymer of dPS-PVP with the same mole fraction of PVP (∼0.15) and total degree of polymerization (∼500), we find that the triblock copolymer interfacial excess z i * at saturation is roughly half that of the diblock copolymer. Self-consistent mean field theory produces a segregation isotherm in fair agreement with the experimental results for the triblock copolymer using the same value of the Flory parameter χ deduced for the diblock copolymer