Morphology of polymer crystals grown from solutions epitaxially on alkali halides

초록

Polyethylene (PE), polyoxymethylene (POM), and poly(3-oxotrimethylene) (POK) were epitaxially crystallized from respective solutions onto the (001) face of alkali halides, and the morphologies of resultant crystals were studied by transmission electron microscopy (TEM). Rodlike crystals of each polymer were oriented in some crystallographic directions of the substrate surface. Bright-field and dark-field observations and selected-area electron diffraction experiments revealed that the rodlike crystals are edge-on lamellae. The thickness of the crystalline core in the edge-on lamella was found to be about 60% of the corresponding lamellar thickness. It was concluded that each of the folded-chain single crystals of the polymers under consideration consists of a crystalline core and a certain but somewhat less-ordered surface layer, containing folds, on each side of the core. This structure model could be visualized, at molecular level resolution, by high-resolution TEM of the POK edge-on lamellae.

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