Novel morphology of polyethylene crystals created upon melt crystallization of spin-coated film

We demonstrate a strikingly novel morphology of high-density polyethylene (HDPE) crystal obtained upon melt crystallization of spin-coated thin film. This crystal gives windmill-like morphology which contains a number of petals. A detailed inspection on this morphology reveals that each petal is actually composed of terrace-stacked PE lamellae, in which the polymer chains within crystallographic a-c planes adopt ∼45° tilting around b-axis. The surrounding domains associated with a petal of the windmill composed of twisted lamellar overgrowths with an identical orientation of their long axis, which is the crystallographic b-axis shared by the petal and its corresponding twisted lamellar overgrowths. The parameters involving molecular structure of the materials, preparation history of the specimen, and subsequent crystallization conditions which possibly influence the formation of this novel morphology have been subsequently discussed. The acquisition of the new morphology of polyethylene crystal should be linked to the special thermodynamic history and large-scale uniformity of the thin film prepared via hot spin-coating method.