Dendritic-to-faceted crystal pattern transition of ultrathin poly(ethylene oxide) films

Zhang, Guoliang; Jin, Liuxin; Ma, Zhenpeng; Zhai, Xuemei; Yang, Miao; Zheng, P.; Wang, Wei; Wegner, Gerhard

doi:10.1063/1.3037229

Cited by 20 publications

(30 citation statements)

References 33 publications

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“…33 When the solution was very dilute (0.1 wt %), dispersed droplets formed on glass substrate due to dewetting of PCL thin film. 31 The cubic shape morphology of PCL nanoparticles, however, has not been reported yet to our best knowledge. We hope that our finding might help us to understand the crystalline behaviors of PCL polymers at a more microcosmic level.…”

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confidence: 96%

Polymeric Nanocubes Spontaneously Formed from Poly(ε-caprolactone)

Wang

Chen

et al. 2012

ACS Macro Lett.

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A facile and economical approach was successfully developed to prepare polymeric nanocubes from poly(ε-caprolactone) (PCL). Nanocubes which are rarely achieved with polymer were obtained simply by a proper thermal treatment on PCL thin film on a glass slide or silicon wafer. The results of scanning electron microscopy (SEM) and atomic force microscopy (AFM) observation showed that the nanocubes were as small as ∼70 nm with high yield (up to ∼130 000 nanocubes in 1 cm 2 area). The combination of high-resolution transmission electron microscopy (HRTEM) and fast Fourier transform (FFT) demonstrated that these particles were single nanocrystals. We suggest that the formation of these nanocubes is based on a dewetting and crystallization mechanism. In addition, the size and yield of nanocubes could be controlled by the solution concentration and architecture of polymer as well as substrate. This work might not only facilitate gaining further basic knowledge about nucleation and crystalline growth mechanism of PCL but also provide a new way to fabricate nonspherical polymeric nanoparticles.

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confidence: 96%

Polymeric Nanocubes Spontaneously Formed from Poly(ε-caprolactone)

Wang

Chen

et al. 2012

ACS Macro Lett.

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“…Besides, in some organic glasses discontinuous enhancement of crystal growth is observed [12][13][14], which is associated with diffusionless crystallization [15]. Although various theories have been developed to explain the existence of diffusion-controlled and diffusionless rapid modes [14][15][16], none of them predicts a facetednonfaceted morphological transition often associated with different crystallization modes, when interpreting experiments [3]. Growth mode (i) and mode (ii) have also been observed in simple mean-field models [17], although these theories address anisotropic crystal growth in a phenomenological way.…”

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confidence: 99%

“…Faceting is also present in advanced, technologically important materials, such as ceramics [1], semiconductors [2], polymers [3], metallic nanostructures [4], colloid suspensions [5], and monolayers of various surfactant molecules [6,7]. The amazing complexity of faceted patterns has been generating considerable interest for decades.…”

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confidence: 99%

“…The amazing complexity of faceted patterns has been generating considerable interest for decades. Various crystal shapes; compact symmetric, dendritic, ramified fractal and needlelike morphologies have been investigated experimentally [1][2][3][4][5]. While robust theoretical interpretations of faceted equilibrium shapes exist, the dynamical aspects of faceted pattern formation are less understood.…”

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confidence: 99%

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Faceting and Branching in 2D Crystal Growth

2011

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Using atomic scale time-dependent density functional calculations we confirm that both diffusioncontrolled and diffusionless crystallization modes exist in simple 2D systems. We provide theoretical evidence that a faceted to nonfaceted transition is coupled to these crystallization modes, and faceting is governed by the local supersaturation at the fluid-crystalline interface. We also show that competing modes of crystallization have a major influence on mesopattern formation. Irregularly branched and porous structures are emerging at the crossover of the crystallization modes. The proposed branching mechanism differs essentially from dendritic fingering driven by diffusive instability. [6,7]. The amazing complexity of faceted patterns has been generating considerable interest for decades. Various crystal shapes; compact symmetric, dendritic, ramified fractal and needlelike morphologies have been investigated experimentally [1][2][3][4][5]. While robust theoretical interpretations of faceted equilibrium shapes exist, the dynamical aspects of faceted pattern formation are less understood. The main difficulty in establishing a theoretical description lies in the multiscale nature of faceted crystal growth, the mesoscale behavior is influenced by the local arrangement of the particles. Russel et al. [8] have identified some mesoscale characteristics of crystal growth kinetics: (i) a diffusion-controlled (or ''slow'') growth mode that may lead to diffusive instability and dendritic branching in monodisperse colloids [8,9], and (ii) a diffusionless (or ''fast'') steady growth mode, in which crystalline ordering takes place without significant density change. The existence of these modes is verified experimentally by investigating crystallization kinetics in hard-sphere suspensions [10,11]. Besides, in some organic glasses discontinuous enhancement of crystal growth is observed [12][13][14], which is associated with diffusionless crystallization [15]. Although various theories have been developed to explain the existence of diffusion-controlled and diffusionless rapid modes [14][15][16], none of them predicts a facetednonfaceted morphological transition often associated with different crystallization modes, when interpreting experiments [3]. Growth mode (i) and mode (ii) have also been observed in simple mean-field models [17], although these theories address anisotropic crystal growth in a phenomenological way. In contrast, molecular theories based on the classical density functional technique (DFT) predict not only the anisotropic bulk crystal properties, such as the crystal structure and elastic constants, but also anisotropic surface properties (e.g., surface tension [18]). A simple dynamical DFT [19], the phase-field crystal (PFC) model [20] is able to address crystallization kinetics up to the mesoscale [21]. While the phase-field crystal model represents the average of the microscopic states over a coarse graining time, it does describe crystal defects. Grain boundaries and dislocations can be observed directl...

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“…There have also been experimental studies of crystal pattern transition from dendrites through fourfold-symmetric structures to faceted crystals of ultra thin poly(ethylene oxide) films which were carried out by Zhang et al [8]. These research works on fractals were done only on laboratory experiments, theoretical modeling and experimental studies, or modeling and computer simulations.…”

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confidence: 99%

Simulation model of the fractal patterns in ionic conducting polymer films

2009

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Abstract:Normally polymer electrolyte membranes are prepared and studied for applications in electrochemical devices. In this work, polymer electrolyte membranes have been used as the media to culture fractals. In order to simulate the growth patterns and stages of the fractals, a model has been identified based on the Brownian motion theory. A computer coding has been developed for the model to simulate and visualize the fractal growth. This computer program has been successful in simulating the growth of the fractal and in calculating the fractal dimension of each of the simulated fractal patterns. The fractal dimensions of the simulated fractals are comparable with the values obtained in the original fractals observed in the polymer electrolyte membrane. This indicates that the model developed in the present work is within acceptable conformity with the original fractal. PACS

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Dendritic-to-faceted crystal pattern transition of ultrathin poly(ethylene oxide) films

Cited by 20 publications

References 33 publications

Polymeric Nanocubes Spontaneously Formed from Poly(ε-caprolactone)

Polymeric Nanocubes Spontaneously Formed from Poly(ε-caprolactone)

Faceting and Branching in 2D Crystal Growth

Simulation model of the fractal patterns in ionic conducting polymer films

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