Wettability and Composition of Styrene—Tetrahydrofuran Block Copolymers

Abstract

The wettability and surface morphology of cast films of styrene—tetrahydrofuran block (AB and ABA type) copolymers were studied. Contact angles (θ) of water droplets against films cast from cyclohexane solutions were measured and surface morphology of the films was also examined by OsO4 stainning electronmicroscopy. Cos θ was not a unique function of copolymer composition. The wettability of tetrahydrofuran-rich copolymers was almost equal to that of homopolystyrene, whereas styrene-rich copolymers exhibited reverse wettability. Surface composition or fraction of styrene portion was evaluated from the electron micrographs. The accumulation of styrene or tetrahydrofuran block at the surface of films was indicated, which depends upon the crystallization segregation or the surface activity caused by tetrahydrofuran block. It was found that cos θ is a function of surface composition and this shows that the wettability is the reflection of the, surface composition of the copolymers irrespective of morphologies. © 1978, The Society of Polymer Science, Japan. All rights reserved.