Dendritic Morphology Composed of Stacked Single Crystals in Poly(ethylene succinate) Melt-Crystallized with Poly(<i>p</i>-vinyl phenol)

Ni’mah, Hikmatun; Woo, Eamor M.

doi:10.1021/cg401413f

Cited by 21 publications

(17 citation statements)

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“…In the blue-color quadrants (horizontal quadrants), lamellae are slanted (bent) at 60°; in the orange-color quadrants, bending is similarly at a 60° angle. The 60°-angle of bending is in line with the branching angles in PLLA or poly(ethylene succinate) (PESu) single-crystal packing, as revealed in recent studies [ 37 , 38 ], although the dendritic spherulites are not composed as single crystals, but polycrystalline bundles. The main stalks mostly have lamellar orientation in the radial direction, with branches curving counterclockwise at a 60–90° angle to the main stalks.…”

Section: Resultssupporting

confidence: 75%

Lamellae Assembly in Dendritic Spherulites of Poly(l-lactic Acid) Crystallized with Poly(p-Vinyl Phenol)

et al. 2018

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Lamellar assembly with fractal-patterned growth into dendritic and ringed spherulites of crystallized poly(l-lactic acid) (PLLA), of two molecular weight (MW) grades and crystallized at (temperature of crystallization) Tc = 120 and 130 °C, respectively, are evaluated using optical and atomic-force microscopies. The results of surface-relief patterns in correlation with interior microscopy analyses in this work strongly indicate that the observed birefringence changes in PLLA polymer dendritic or ringed spherulites (from blue to orange, or to optical extinction) need not be definitely associated with the continuous helix twisting of lamellae; they can be caused by sudden and discontinuous lamellae branching at intersected angles with respect to the original main lamellae, as proven in the case of dendritic and zig-zag rough-ringed spherulites. Intersection angles between the main stalks and branches tend to be governed by polymer crystal lattices; for PLLA, the orthorhombic lattice (α-form) usually gives a 60° angle of branching and hexagonal growth. The branching lamellae then further bend to convex or concave shapes and finally make a 60–90° angle with respect to the main stalks. Such mechanisms are proven to exist in the straight dendritic/striped high-molecular weight (HMW)-PLLA spherulites (Tc = 120 °C); similar mechanisms also work in circularly ringed (Tc = 130 °C) HMW-PLLA spherulites.

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Section: Resultssupporting

confidence: 75%

Lamellae Assembly in Dendritic Spherulites of Poly(l-lactic Acid) Crystallized with Poly(p-Vinyl Phenol)

et al. 2018

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“…Such a morphology can be compared to that of the singlecrystal-like crystals observed in poly(ethylene succinate) (PESu) diluted with interacting amorphous polymers. A recent study in our lab 18 has reported that the polymer single crystals may grow to form a crystal pattern that resembles the shape of its single crystal. In that study, lozenge-shaped single crystals of poly(ethylene succinate) (PESu), when blended with poly(p-vinyl phenol) (PVPh) and melt-crystallized into thin films, grew and stacked to form a dendritic morphology.…”

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confidence: 97%

A novel hexagonal crystal with a hexagonal star-shaped central core in poly(l-lactide) (PLLA) induced by an ionic liquid

Ni’mah

Woo

2014

CrystEngComm

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“…Many inorganic compounds and metal salts have been reported to form highly symmetric branching structures under appropriate conditions 8-10 . Besides, semi-crystalline polymers diluted with another strongly-interacting amorphous polymer were also found to have the ability to form well-defined dendritic patterns [11][12][13][14][15] . Tannic acid (TA), with multi-phenol groups, has been reported to have a strong interaction with some semi-crystalline polymers with carbonyl groups and further induce diversified morphologies [11][12][13] .…”

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confidence: 99%

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

Chen

Woo

2020

Sci Rep

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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 fractalbranch 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.Cooling of a matter in liquid state causes it to crystallize into either 2D or 3D ordered states. The crystallization process may occur in sequential steps to gradually increase the degree of order while in the meantime the hierarchical aggregation structures may diversify in patterns and vary significantly in increasingly higher-order morphologies. Crystallization of atoms or molecular compounds into ordered states has been a complex yet fascinating phenomenon that has attracted extensive scientific studies from classical to modern times, to cite just a few recent examples 1-3 . Self-assembly of organic or inorganic compounds, of either small-molecules or polymers, has been interesting and intriguing, yet complex issues, in soft matters either synthetic or natural. Fractal patterns are widely seen in hierarchical structural assemblies in natural materials. Khire and Yadavalli, et al. 4 by using high-resolution atomic-force microscopy (AFM), investigated the fractal self-assembly of silk protein sericin [a protein by Bombyx mori (silkworms) in producing silk], and observed the fractal structure of the silk protein's self-assembly, where they proposed that the protein globules may be thought to act as seeds for the subsequent attachment of protein molecules and the formation of the fractal architectures. Guo et al. 5 studied the relationship between the fractal-ladder viscoelastic behavior of bio-fibers with fractal ladder hyper-cell structures. Snowflakes or aggregates of self-similar snow/ice single crystals are well known to be an excellent example of fractal patterns in nature. Yang, et al. 6 proposed the fractal growth kinematics of snow-flakes with many self-similar multilevel small structures. Crystalline morphology is governed by the cooperation of the driving force of crystallization and the transport of atom, ions, molecules, and heat. 7 When the growth condition is relatively...

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Dendritic Morphology Composed of Stacked Single Crystals in Poly(ethylene succinate) Melt-Crystallized with Poly(p-vinyl phenol)

Cited by 21 publications

References 50 publications

Lamellae Assembly in Dendritic Spherulites of Poly(l-lactic Acid) Crystallized with Poly(p-Vinyl Phenol)

Lamellae Assembly in Dendritic Spherulites of Poly(l-lactic Acid) Crystallized with Poly(p-Vinyl Phenol)

A novel hexagonal crystal with a hexagonal star-shaped central core in poly(l-lactide) (PLLA) induced by an ionic liquid

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

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