ENHANCED SEGREGATION OF A DIBLOCK COPOLYMER CAUSED BY HYDROGEN-BONDING

Utilizing forward recoil spectrometry (FRES), we have determined the s egregation isotherm which describes the interfacial excess z(i) of di block copolymers of poly(d(8)-styrene-b-2-vinylpyridine) [dPS-PVP] at the interface between the PS/PVP, PS/poly(4-vinyl phenol) [PS/PVPh], a nd PS/poly(4-vinylbenzoic acid) [PS/PVBA] as a function of phi infinit y, the volume fraction of diblock copolymer remaining in the host PS p hase after annealing the specimens to reach the equilibrium segregatio n. A remarkable increase in the saturation z(i) is observed at the PS /PVBA and the PS/PVPh interfaces as compared to that at the correspond ing PS/PVP interface. This enhanced segregation is caused by an attrac tion due to the formation of hydrogen bonds of the PVP block with PVBA and PVPh homopolymers. The segment density profile of copolymer at th e PS/PVBA interface determined by neutron reflectometry indicates that the interface is almost totally occupied by the copolymer and the cop olymer chains at the interface are highly stretched. This result sugge sts that the interface is close to the ''brush'' structure as pictured by Leibler.