Instability-Driven Branching of Lamellar Crystals in Polyethylene Spherulites

Toda, Akihiko; Taguchi, Ken; Kajioka, Hiroshi

doi:10.1021/ma800994g

Cited by 55 publications

(54 citation statements)

References 40 publications

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“…The intrinsic surface stresses on mesoporous frameworks result in independent growth of each branched finger 44,45 . The observed nanofingers arise from pore migrations with crystal lattice rearrangement in the small domain sizes, which is considered to be the most important extrinsic factor for the formation of branching nanofinger arrays.…”

Section: Fig 5 the Proposed Growth Model (A)mentioning

confidence: 99%

Branched Artificial Nanofinger Arrays by Mesoporous Interfacial Atomic Rearrangement

et al. 2015

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The direct production of branched semiconductor arrays with highly ordered orientation has proven to be a considerable challenge over the last two decades. Here we report a mesoporous interfacial atomic rearrangement (MIAR) method to directly produce highly crystalline, finger-like branched iron oxide nanoarrays from the mesoporous nanopyramids. This method has excellent versatility and flexibility for heteroatom doping of metallic elements, including Sn, Bi, Mn, Fe, Co, Ni, Cu, Zn, and W, in which the mesoporous nanopyramids first absorb guest-doping molecules into the mesoporous channels and then convert the mesoporous pyramids into branching artificial nanofingers. The crystalline structure can provide more optoelectronic active sites of the nanofingers by interfacial atomic rearrangements of doping molecules and mesopore channels at the porous solid-solid interface. As a proof-of-concept, the Sn-doped Fe2O3 artificial nanofingers (ANFs) exhibit a high photocurrent density of ∼1.26 mA/cm(2), ∼5.25-fold of the pristine mesoporous Fe2O3 nanopyramid arrays. Furthermore, with surface chemical functionalization, the Sn-doped ANF biointerfaces allow nanomolar level recognition of metabolism-related biomolecules (∼5 nm for glutathione). This MIAR method suggests a new growth means of branched mesostructures, with enhanced optoelectronic applications.

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Section: Fig 5 the Proposed Growth Model (A)mentioning

confidence: 99%

Branched Artificial Nanofinger Arrays by Mesoporous Interfacial Atomic Rearrangement

et al. 2015

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“…The cause of different branching behaviors in the two films could be related to the different pressure gradients and stress fields between the branching and non-crystalline region induced by crystallization [24,33]. Since the crystalline region has a higher density and thus a smaller specific volume, its volume shrinks when crystallizing, and induces a pressure gradient causing a flow of surrounding material to compensate the volume shrinkage.…”

Section: Crystalline Morphologymentioning

confidence: 99%

Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Hsu

Yao

2011

ASME 2011 International Manufacturing Science and Engineering Conference, Volume 1

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Poly(L-lactic acid) (PLLA) has been shown to have potential medical usage such as in drug delivery because it can degrade into bioabsorbable products in physiological environments, and its degradation is affected by crystallinity. In this paper, the effect of film formation method and annealing on the crystallinity of PLLA are investigated. The films are made through solvent casting and spin coating methods, and subsequent annealing is conducted. The resulting crystalline morphology, structure, conformation, and intermolecular interaction are examined using optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It is observed that solvent casting produces category 1 spherulites while annealed spin coated films leads to spherulites of category 2. Distinct lamellar structures and intermolecular interactions in the two kinds of films have been shown. The results enable better understanding of the crystallinity in PLLA, which is essential for its drug delivery application. INTRODUCTIONThere is a significant interest in use of biodegradable polymers due to their biocompatibility and biodegradability. Poly lactic acid (PLA) is a biodegradable polymer and can be obtained from renewable sources such as corn starch. It has a wide range of applications, such as in food packaging and tissue engineering. PLA is also of interest in drug delivery application because it can degrade into bioabsorbable products in physiological environments. Its degradation mainly comes from the cleavage of its ester groups, and is sensitive to chemical hydrolysis. In polymeric drug delivery system, drugs are encapsulated in polymer. As the polymer degrades, the drugs are released, and the release rate is determined by the polymer degradation rate. Crystallinity of polymer is a factor affecting the degradation rate. A good review on the effect of crystallinity on degradation and drug release can be found in [1]. In general, less crystallinity accelerates degradation and drug release rate. To create polymeric drug delivery system, drug molecules are dispersed or dissolved in the polymeric solution, formed through melting the polymer or dissolving it in a solvent. During the process the polymer may crystallize. The crystal structure also influences the degradation rate. Tsuji and Ikada [2] studied the hydrolysis of PLA films and proposed that it begins in the amorphous region between the crystalline lamellae, followed by the disorientation of the lamellae and disappearance of the spherulitic structure.

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“…[99,165,167,267,[274][275][276] Allgemein ist noch keine Theorie der Organisation verwundener Lamellen in Sphärolithen verfügbar. Aus Beobachtungen an Poly(l-milchsäure), [120] Poly(ethylen), [124,125] Poly(R-3-hydroxybutyrat) [148] und Poly(vinylidenfluorid) [166] sowie aus unseren eigenen Beobachtungen an Mannit und Tetraphenylblei (Abbildung 1 f) ist bekannt, dass gut organisierte gebänderte Muster nur bei kleinen Verwindungsperioden entstehen. Starke Verwindung scheint alle anderen Inhomogenitäten zu unterdrücken.…”

Section: Morphologie Von Individuenunclassified

“…[220] und + [219] ), Oxalsäure-Dihydrat, H 2 C 2 O 4 ·2 H 2 O, Einkristalle (&), [219] Kaliumdichromat, K 2 Cr 2 O 7 , Einkristalle [248] und offene Sphärolithe [32] (N), d-Mannit-Sphärolithe mit 15 Gew.-% Polyvinylpyrrolidon (^), [105] Hippursäure-Einkristalle (* [8,9] und c), [7] (1,4-Bis[2-(pyren-1-yl)vinyl]-2,5-dimethylbenzol)-IBr 2 , (BPE-DMB)IBr 2 , einkristalline Bänder (&), [198] zwei Typen von Selen-Sphäroli-then (! ), [116,117] Polyethylen-Sphärolithe, PE, 32 kDa (Fünfecke) [125] und Poly(R)-3-hydroxybutyrat-Sphärolithe, PHB (~). [148] Die Werte von n sind Exponenten der Anpassung an P = const h n .…”

Section: Enantiopolare Wachstumsrichtungenunclassified

“…Felder kçnnen Kräfte an einem wachsenden Kristall erzeugen, die eine Verwindung verursachen. [313] Es wurde angenommen, dass dieser Mechanismus allgemein Verwindung in Kaliumdichromat, [32,205] Orthoborsäure, [30,32] Kaliumsulfat, [308] d-und l-Asparaginsäure, [30,31] Hippursäure, [7] Polyethylen, [124,125] Poly(vinylidenfluorid) [166] und Polymerlamellen induziert. [7,314] Starke Temperaturgradienten sind bei vielen Kristallen, die nahe am Schmelzpunkt wachsen, [14,27] und bei Metalllamellen, die während der eutektischen Kristallisation entstehen, [212][213][214] [6] Mannit [105] ).…”

Section: Felderunclassified

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Wachstumsinduziertes Biegen und Verwinden von Einkristallen

et al. 2014

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Kristalle von verschiedenen Stoffen, z. B. von Elementen, Mineralien, einfachen Salzen, organischen Molekülkristallen und hochmolekularen Polymeren, können die Translationsfernordnung aufgeben, indem sie sich während des Wachstums verwinden und verbiegen. Diese Erscheinungen wurden bei Kristallen im Größenbereich von Nano‐ bis Zentimetern beobachtet. Wir analysieren, wie und warum viele Materialien solche oft drastischen nichtkristallographischen Verzerrungen wählen und betonen dabei die Kristallchemie, die zu Spannungen an Oberflächen von Kristalliten oder innerhalb des Volumens führt.

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Instability-Driven Branching of Lamellar Crystals in Polyethylene Spherulites

Cited by 55 publications

References 40 publications

Branched Artificial Nanofinger Arrays by Mesoporous Interfacial Atomic Rearrangement

Branched Artificial Nanofinger Arrays by Mesoporous Interfacial Atomic Rearrangement

Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Wachstumsinduziertes Biegen und Verwinden von Einkristallen

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