The morphology of nascent poly (p-oxybenzoate/2,6-oxynaph-thoate) copolymers of 3/1, 1/1, and 1/3 mole ratio composition, prepared by bulk solution and confined thin film melt and solution polymerization (CTFMP, CTFSP), is described. While the bulk solution polymerization (at 300°C in heat transfer fluids) yields only spherical aggregates of smaller spheres, both CTFMP and CTFSP yield lamellar crystals suitable for electron diffraction (ED);hk0patterns are obtained resembling those from the homopolymers. Shearing of the solution-polymerized material permits obtaining ED fiber patterns; as expected nonperiodic c-axis reflections are obtained, the 002 spacing corresponding to that observed by x ray for the same compositions. The effect of annealing nearTk-misexamined using differential scanning calorimetry (DSC) and ED. In thicker CTFMP films a superlattice structure is observed. It is apparently composed of ribbons on edge, of uniform width and thickness, with step changes in the width and, in some cases, a periodic structure (in phase from ribbon to adjacent ribbon) along their length. The periodicities in the three directions are on the order of 1000 Å. Limited evidence suggests they grow from a basal lamella, with the molecules normal to the substrate and parallel to the width of the ribbon.