Periodic Fractal-Growth Branching to Nano-Structured Grating Aggregation in Phthalic Acid

Tzu Yu Chen, Eamor M. Woo, Selvaraj Nagarajan

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16 Citations (Scopus)


Small-molecule phthalic acid (PA), confined in micrometer thin films, was crystallized in the presence of strongly interacting tannic acid (TA) to investigate crystal assembly and correlation between banded patterns and branching structures. Several compositions of the mixture of ethanol/water solutions and evaporation temperatures were also manipulated to investigate the kinetic effects on the morphology of PA crystals. With increasing evaporation rate, the morphology of PA crystals systematically changes from circular-banded spherulites to highly ordered grating-banded patterns. A unique periodic fractal-branch pattern with contrasted birefringent bands exists at intermediate evaporation rate, and this unique grating architecture has never been found in other banded crystals. Crystal assembly of these three periodic morphologies was analyzed by utilizing atomic-force microscopy (AFM) and scanning electron microscopy (SEM) to reveal the mechanisms of formation of hierarchical structures of PA. The detailed growth mechanisms of the novel fractal-branching assembly into circular- or grating-banded patterns are analyzed in this work.

Original languageEnglish
Article number4062
JournalScientific reports
Issue number1
Publication statusPublished - 2020 Dec 1

All Science Journal Classification (ASJC) codes

  • General


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