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We present a study of homogeneous nucleation in polymer crystallization. Crystal nucleation is observed within discrete droplets of poly(ethylene oxide) that are formed by the dewetting of a thin film. The samples provide an ensemble of impurity-free droplets, with length scales that can easily be measured. Droplet crystallization is found in two distinct temperature regimes corresponding to homogeneous and heterogeneous nucleation. Here we focus on homogeneous nucleation and show that the nucleation rate scales with the volume of the crystallizable domain, indicating that we are observing homogeneous nucleation in the bulk of the droplets. In addition, the dependence of the nucleation rate on temperature is consistent with classical nucleation theory.

We present a study of homogeneous and heterogeneous nucleation in polymer crystallisation. In bulk samples the crystallization is typically dominated by nucleation from defects (heterogeneous nucleation), and consequently studies must rely on sample preparation to minimize this effect. We present a study of nucleation within discrete droplets of poly(ethylene oxide) that are formed by the dewetting of a thin film on an unfavourable substrate. The samples provide an ensemble of impurity-free droplets, with length scales that can easily be measured. We show that the data for heterogeneous and homogeneous nucleation is qualitatively different, and that the data mirrors the fundamental differences in the underlying mechanisms for the two nucleation processes. The experiments presented here provide a simple method that can be used to study heterogeneous and homogeneous nucleation in great detail.