Thermodynamic Interactions in Organometallic Block Copolymers:  Poly(styrene-<i>b</i><i>lock</i>-ferrocenyldimethylsilane)

Abstract

The thermodynamic interactions in anionically synthesized poly(styrene- block -ferrocenyldimethylsilane) (SF) copolymers were examined using birefringence, small-angle X-ray and neutron scattering (SAXS and SANS). We show that birefringence detection of the order−disorder transition is possible in colored samples provided the wavelength of the incident beam is in the tail of the absorption spectrum. The location of the order−disorder transition was confirmed by SAXS. The temperature dependence of the Flory−Huggins parameter, χ, of SF copolymers, determined by SAXS, is similar in magnitude to that between polystyrene and polyisoprene chains. We find that χ is independent of block copolymer composition (within experimental error). We also demonstrate that the neutron scattering length densities of styrene and ferrocenyldimethylsilane moieties are identical due to a surprising cancellation of factors related to density and atomic composition.