Although the direction of flow during imprint for amorphous polymers is accessible via simulations, a direct observation in the experiment is difficult. The authors address an indirect method, the detection of imprint-induced ordering in the residual layer by optical inspection of the imprint result. The method relies on imprint materials featuring optical anisotropy when existing in an ordered state, ordering being induced by the imprint process proceeding under shearing flows. Organic polymers with π-electrons along the backbone were chosen to test the approach; similar materials with regular and random chemical chain structure were compared, where only the polymer with regular chemical structure exhibits optical anisotropy after imprint, due to its semicrystalline nature. A clear correlation of the anticipated flow direction in the residual layer with optical anisotropy in transmission was possible. Beyond visualization of the direction of flow, the experiments allowed to attribute the local ordering observed in the residual layer with poly 3-hexylthiophene-2.5-diyl to a flow-induced stretching of the polymeric network occurring at the beginning of the squeeze process.

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