Polarized‐light optical microscopy (POM), wide‐angle X‐ray diffraction (WAXD), and atomic‐force microscopy (AFM) are used to analyze the crystalline morphology in poly(ethylene succinate) (PESu) interacting with hydrogen‐bonding biodegradable tannin (TA). Upon interactions with TA via strong intermolecular H‐bonding capacity with PESu, the regular Maltese‐cross spherulites in PESu gradually transform to a pattern of maple leaves (10 wt.‐% TA). At 20 wt.‐% TA, the crystal patterns assume a highly dendritic seaweed shape (with the branches perpendicular to main stalks). Detailed characterization using AFM analyses showed that the minute crystal entities in the seaweed‐like dendrite crystals are flat‐on and take a multilayer diamond (lenticule) geometry approaching the shape of single crystals in PESu. The trend of variation with increasing TA is equivalent to decreasing the film thickness in the neat PESu. The diamond‐shape flat‐on crystals are packed into a terrace structure resembling a pyramid, indicating that multiple single crystals are stacked with partial overlapping. The strong H‐bonding interaction between TA and PESu, assisted by a confined thickness, induces a single‐crystal packing, which is equivalent to crystallization into discrete single crystals in dilute solutions. magnified image

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Two isomeric polyesters, poly(1,6-hexamethylene adipate) (PHA) and poly(e-caprolactone) (PCL), were each blended with amorphous poly(vinyl methyl ether) (PVME) and investigated and compared in the crystalline and amorphous phases. The amorphous phase, T g , and crystalline morphology of the PVME/PHA blend were compared with those of classical PVME/PCL. Both blend systems exhibit a similar peculiar asymmetry with positive deviation in T g-composition relationships, and both are similarly miscible, with the PVME/PHA blend exhibiting v 12 ¼À0.21; for PVME/PCL, v 12 ¼À0.20. These values indicate that both blends are similarly miscible but have only quite weak interactions in the amorphous phase. Neat PHA shows a regime-I to-II transition, but neat PCL exhibits a regime-II to-III transition. On blending with PVME (at 20 wt%), both PVME/PCL and PVME/PHA blends undergo changes in crystallization temperature (T c). Dendritic spherulites in the high-T c (46 1C or above)crystallized PVME/PHA blend assume a straight-stalk pattern (chrysanthemum flower pestles or banana stems). In contrast to the similarities in amorphous-phase miscibility, the crystalline phases of these two blends differ significantly. When crystallized at high T c (46 1C or above), the PVME/PCL (20/80) blend assumes a fluffy feather-like dendritic pattern, which is dramatically different from the straight-stalk dendrites in the PVME/PHA (20/80) blend.