SURFACE CONCENTRATION OF CHAIN-ENDS IN POLYSTYRENE DETERMINED BY STATIC SECONDARY-ION MASS-SPECTROSCOPY

Diblock and triblock copolymers of hydrogenous and deuterated styrene are synthesized to investigate chain-end segregation by static seconda ry ion mass spectroscopy. Films of the diblocks on silicon wafers show no significant chain-end segregation. In contrast, the triblocks show marked chain-end segregation on silicon wafers with or without the na tive oxide. Triblocks of isotopic structure D-H-D and H-D-H both showe d end-group segregation, suggesting that the surface free energy diffe rences between C-D and C-H are not the dominant factor.