Controllable self-rolling of polyurethane/SiO₂ film with differential density

Titelangaben

Zhang, Yaoming ; Ionov, Leonid:
Controllable self-rolling of polyurethane/SiO₂ film with differential density.
In: European Polymer Journal. Bd. 119 (2019) . - S. 32-36.
ISSN 1873-1945
DOI: https://doi.org/10.1016/j.eurpolymj.2019.07.004

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Abstract

In this paper we report a new kind of self-rolling polyurethane (PU) film with the vertical gradient structure – top solid PU layer and bottom PU/SiO2 hybrid layer. The differential swelling properties of these two layers allow the film to exhibit reversible shape transformation upon exposure to different solvents and their mixtures. We investigated correlation between shapes (tube/scroll/spiral) formed upon self-rolling and the size/shape of the films, fraction of silica particles, the aspect ratio of the film, and the external solvents. We have also found that Timoshenko bilayer model allows prediction of rolling behavior basing on properties of each layer. The reversible self-rolling behavior of the bilayer films with differential structure is expected to allow development of new actuator in the near future.