Adsorption of polybutadienes with polar group terminations on the solid surface II. Molecular weight dependence

Abstract

Adsorption of polybutadienes and polybutadienes terminated with a polar group, such as 1,1-bis ( p- N, N′ diethylaminophenyl)methanol, onto a silica surface from carbon tetrachloride solution has been investigated by using FT-IR spectroscopy. Both normal and terminated polybutadienes have a narrow molecular weight distribution, i.e. M w/ M n < 1.1. Adsorbed amount, the fraction θ of the silanol groups occupied by polymers, and the fraction p of butadiene units attached directly to the silica surface were measured and compared with those for fractionated polymers, which have some polydispersities, to clarify a polydispersity effect on polymer adsorption. It was found that the polydispersity effect strongly influences the adsorption of normal polybutadiene rather than that for terminated polybutadiene. In particular, the plateau adsorbed amount of fractionated normal polybutadiene is ∼20% larger than that of homodisperse polybutadiene for a similar molecular weight. Terminated polybutadienes have a plateau adsorbed amount 2–2.5 times larger than that for normal polybutadienes. The large difference in adsorbed amount between terminated and normal polybutadienes could be interpreted by considering the preferential adsorption of the terminal polar functional group over the double-bond groups in polybutadiene chains onto the silanol groups of a silica surface.