Invariance of lamellar thickness with crystallization temperature of polyesteramide 6NT6 crystals

Polyesteramide of the type COøCONH(CH₂)₆NHCOøCOO (CH₂)₆O]_n, conventionally referred to as PEA 6NT6, was crystallized from dilute solutions in benzyl alcohol at different temperatures. Single crystals were obtained in ellipsoidal and flat form, as revealed by electron microscopy. X-ray small- and wide-angle diffraction experiments were carried out on oriented mats of the lamellae. Invariance of long spacing with crystallization temperature in the range 72°–118°C was found. Annealing experiments revealed a quantized increase of the long spacing. The thermal behaviour of the single crystals was studied by differential scanning calorimetry and by i.r. spectroscopy. A chain-folding model based on tight folds and adjacent re-entry is proposed for this polymer.