Study of morphology and mechanical properties of polystyrene–polybutadiene blends with nanometre resolution using AFM and force–distance curves

•Characterization of a polymer blend with Tapping Mode and force–distance curves.•Measurement of the elastic moduli of the blend components.•Characterization of the surface energies of the blend components.•Study of the aging process of polybutadiene.•Optimization of the lateral resolution of force–volume measurements up to 6 nm.

Thin polybutadiene/polystyrene blend films were deposited on glass substrates by spin-coating. The two polymers were chosen, as they are immiscible and differ strongly in their mechanical properties. The blend was characterized with Tapping Mode and force–distance curves. Several advantages of force–distance curves measurements compared to Tapping Mode are shown, most of all the capability of yielding quantitative information about several properties, such as Young’s modulus and adhesion. Also the aging behaviour of the blend exposed to air could be observed, in particular the increase of the Young’s modulus due to cross-linking and dewetting processes. Additionally, the sample was used to improve the resolution of force–distance curves up to 6 nm, which is to date the best resolution achieved with force–distance curves. Such an improvement resolves the major disadvantage of force–distance curves, compared to other scanning mode, i.e. its inferior resolution.

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