The effect of chain interpenetration on an ordering process in the early stage of polymer crystal nucleation

Polymer ◽  
2006 ◽  
Vol 47 (14) ◽  
pp. 5213-5219 ◽  
Author(s):  
Zhuqing Zhang ◽  
Xiaozhen Yang
Keyword(s):  
Early Stage ◽  
Crystal Nucleation ◽  
Polymer Crystal

scholarly journals Polymer Nucleation under High-Driving Force, Long-Chain Conditions: Heat Release and the Separation of Timescales

2018 ◽  
Author(s):  
Kyle Hall ◽  
Simona Percec ◽  
Michael Klein
Keyword(s):  
Conformational Changes ◽  
Driving Forces ◽  
Early Stage ◽  
Polymer Crystallization ◽  
Crystal Nucleation ◽  
Crystal Formation ◽  
Polymer Crystal ◽  
Dynamics Simulations ◽  
New Research ◽  
Chain Level

<p>This study reveals two important features of polymer crystal formation at high-driving forces in entangled polymer melts based on molecular dynamics simulations of polyethylene, a prototypical polymer. First, in contrast to existing literature on small-molecule crystallization, it is demonstrated that the heat released during polymer crystallization does not appreciably influence molecular-level structural details of early-stage, crystalline clusters (i.e., polymer crystal nuclei). Second, it is revealed that early-stage polymer crystallization (i.e., crystal nucleation) can occur without substantial chain-level relaxation and conformational changes, which is consistent with previous experimental work and yet in contrast to many previous computational studies. Given the conditions used to process polyethylene, the separation of timescales associated with crystallization and chain-level processes is anticipated to be of substantial importance to processing strategies. This study thus provides insights that highlight new research directions for understanding polymer crystallization under industrially-relevant conditions while also providing guidance as to how this work can be undertaken.</p>

scholarly journals Monodisperse Polymer Melts Crystallize via Structurally Polydisperse Nanoscale Clusters: Insights from Polyethylene

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 447 ◽  
Author(s):  
Kyle Wm. Hall ◽  
Timothy W. Sirk ◽  
Simona Percec ◽  
Michael L. Klein ◽  
Wataru Shinoda
Keyword(s):  
Large Scale ◽  
Polymer Melts ◽  
Polymeric Materials ◽  
Crystalline Polymer ◽  
Crystal Nucleation ◽  
Stem Length ◽  
Polymer Crystal ◽  
Polyethylene Melts ◽  
Nanoscale Clusters ◽  
Entangled Polymer Melts

This study demonstrates that monodisperse entangled polymer melts crystallize via the formation of nanoscale nascent polymer crystals (i.e., nuclei) that exhibit substantial variability in terms of their constituent crystalline polymer chain segments (stems). More specifically, large-scale coarse-grain molecular simulations are used to quantify the evolution of stem length distributions and their properties during the formation of polymer nuclei in supercooled prototypical polyethylene melts. Stems can adopt a range of lengths within an individual nucleus (e.g., ∼1–10 nm) while two nuclei of comparable size can have markedly different stem distributions. As such, the attainment of chemically monodisperse polymer specimens is not sufficient to achieve physical uniformity and consistency. Furthermore, stem length distributions and their evolution indicate that polymer crystal nucleation (i.e., the initial emergence of a nascent crystal) is phenomenologically distinct from crystal growth. These results highlight that the tailoring of polymeric materials requires strategies for controlling polymer crystal nucleation and growth at the nanoscale.

scholarly journals Reversible disorder-order transitions in atomic crystal nucleation

Science ◽  
2021 ◽  
Vol 371 (6528) ◽  
pp. 498-503
Author(s):  
Sungho Jeon ◽  
Taeyeong Heo ◽  
Sang-Yeon Hwang ◽  
Jim Ciston ◽  
Karen C. Bustillo ◽  
...  
Keyword(s):  
Early Stage ◽  
Nucleation Theory ◽  
Crystal Nucleation ◽  
Classical Nucleation Theory ◽  
Gold Nanocrystals ◽  
Size Dependent ◽  
In Situ Electron Microscopy ◽  
Nucleation Mechanisms ◽  
Structural Fluctuations

Nucleation in atomic crystallization remains poorly understood, despite advances in classical nucleation theory. The nucleation process has been described to involve a nonclassical mechanism that includes a spontaneous transition from disordered to crystalline states, but a detailed understanding of dynamics requires further investigation. In situ electron microscopy of heterogeneous nucleation of individual gold nanocrystals with millisecond temporal resolution shows that the early stage of atomic crystallization proceeds through dynamic structural fluctuations between disordered and crystalline states, rather than through a single irreversible transition. Our experimental and theoretical analyses support the idea that structural fluctuations originate from size-dependent thermodynamic stability of the two states in atomic clusters. These findings, based on dynamics in a real atomic system, reshape and improve our understanding of nucleation mechanisms in atomic crystallization.

Polymer Nucleation under High-Driving Force, Long-Chain Conditions: Heat Release and the Separation of Timescales

2019 ◽  
Author(s):  
Kyle Hall ◽  
Simona Percec ◽  
Michael Klein
Keyword(s):  
Driving Force ◽  
Polymer Melts ◽  
Early Stage ◽  
Polymer Crystallization ◽  
Crystal Nucleation ◽  
Crystal Formation ◽  
Local Structures ◽  
Entangled Polymer ◽  
Entangled Polymer Melts ◽  
Chain Level

This study reveals important features of polymer crystal formation at high-driving forces in entangled polymer melts based on simulations of polyethylene. First and in contrast to small-molecule crystallization, the heat released during polymer crystallization does not appreciably influence structural details of early-stage, crystalline clusters (crystal nuclei). Second, early-stage polymer crystallization (crystal nucleation) can occur without substantial chain-level relaxation and conformational changes. This study's results indicate that local structures and environments guide crystal nucleation in entangled polymer melts under high-driving force conditions. Given that such conditions are often used to process polyethylene, local structures and the separation of timescales associated with crystallization and chain-level processes are anticipated to be of substantial importance to processing strategies. This study highlights new research directions for understanding polymer crystallization.

scholarly journals On the question of two-step nucleation in protein crystallization

2015 ◽  
Vol 179 ◽  
pp. 41-58 ◽  
Author(s):  
Andrea Sauter ◽  
Felix Roosen-Runge ◽  
Fajun Zhang ◽  
Gudrun Lotze ◽  
Artem Feoktystov ◽  
...  
Keyword(s):  
Real Time ◽  
Intermediate Phase ◽  
Early Stage ◽  
Protein Crystallization ◽  
Structural Evolution ◽  
Equation Model ◽  
Nucleation Mechanism ◽  
Crystal Nucleation ◽  
Time Study ◽  
Nucleation Kinetics

We report a real-time study on protein crystallization in the presence of multivalent salts using small angle X-ray scattering (SAXS) and optical microscopy, focusing particularly on the nucleation mechanism as well as on the role of the metastable intermediate phase (MIP). Using bovine beta-lactoglobulin as a model system in the presence of the divalent salt CdCl2, we have monitored the early stage of crystallization kinetics which demonstrates a two-step nucleation mechanism: protein aggregates form a MIP, which is followed by the nucleation of crystals within the MIP. Here we focus on characterizing and tuning the structure of the MIP using salt and the related effects on the two-step nucleation kinetics. The results suggest that increasing the salt concentration near the transition zonepseudo-c** enhances the energy barrier for both MIPs and crystal nucleation, leading to slow growth. The structural evolution of the MIP and its effect on subsequent nucleation is discussed based on the growth kinetics. The observed kinetics can be well described, using a rate-equation model based on a clear physical two-step picture. This real-time study not only provides evidence for a two-step nucleation process for protein crystallization, but also elucidates the role and the structural signature of the MIPs in the nonclassical process of protein crystallization.

scholarly journals Nonclassical Nucleation—Role of Metastable Intermediate Phase in Crystal Nucleation: An Editorial Prefix

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 174
Author(s):  
Fajun Zhang ◽  
José A. Gavira ◽  
Geun Woo Lee ◽  
Dirk Zahn
Keyword(s):  
Intermediate Phase ◽  
Solid Phase ◽  
Early Stage ◽  
Order Parameters ◽  
Nucleation Theory ◽  
Crystal Nucleation ◽  
Classical Nucleation Theory ◽  
Supersaturated Solution ◽  
Liquid Phases

Classical nucleation theory (CNT), which was established about 90 years ago, represents the most commonly used theory in describing nucleation processes. For a fluid-to-solid phase transition, CNT states that the solutes in a supersaturated solution reversibly form small clusters. Once a cluster reaches its critical size, it becomes thermodynamically stable and is favored for further growth. One of the most important assumptions of CNT is that the nucleation process is described by one reaction coordinate and all order parameters proceed simultaneously. Recent studies in experiments, computer simulations, and theory have revealed nonclassical features in the early stage of nucleation. In particular, the decoupling of order parameters involved during a fluid-to-solid transition leads to the so-called two-step nucleation mechanism, in which a metastable intermediate phase (MIP) exists in parallel to the initial supersaturated solution and the final crystals. These MIPs can be high-density liquid phases, mesoscopic clusters, or preordered states. In this Special Issue, we focus on the role of the various MIPs in the early stage of crystal nucleation of organic materials, metals and alloys, aqueous solutions, minerals, colloids, and proteins, and thus on various scenarios of nonclassical pathways of crystallization.

scholarly journals Magma chambers versus mush zones: constraining the architecture of sub-volcanic plumbing systems from microstructural analysis of crystalline enclaves

2019 ◽  
Vol 377 (2139) ◽  
pp. 20180006 ◽  
Author(s):  
Marian B. Holness ◽  
Michael J. Stock ◽  
Dennis Geist
Keyword(s):  
Early Stage ◽  
Microstructural Analysis ◽  
Crystal Nucleation ◽  
Microstructural Development ◽  
Crystal Mush ◽  
Magma Chambers ◽  
Reservoir Architecture ◽  
Plumbing Systems ◽  
Robust Evidence

There are clear microstructural differences between mafic plutonic rocks that formed in a dynamic liquid-rich environment, in which crystals can be moved and re-arranged by magmatic currents, and those in which crystal nucleation and growth are essentially in situ and static. Crystalline enclaves, derived from deep crustal mushy zones and erupted in many volcanic settings, afford a unique opportunity to use the understanding of microstructural development, established from the study of intrusive plutons, to place constraints on the architecture of sub-volcanic systems. Here, we review the relevant microstructural literature, before applying these techniques to interrogate the crystallization environments of enclaves from the Kameni Islands of Santorini and Rábida Volcano in the Galápagos. Crystals in samples of deep-sourced material from both case studies preserve evidence of at least some time spent in a liquid-rich environment. The Kameni enclaves appear to record an early stage of crystallization during which crystals were free to move, with the bulk of crystallization occurring in a static, mushy environment. By contrast, the Rábida enclaves were sourced from an environment in which hydrodynamic sorting and re-arrangement by magmatic currents were common, consistent with a liquid-rich magma chamber. While presently active volcanoes are thought to be underlain by extensive regions rich in crystal mush, these examples preserve robust evidence for the presence of liquid-rich magma chambers in the geological record. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics'.

Polymer Nucleation under High-Driving Force, Long-Chain Conditions: Heat Release and the Separation of Timescales

2019 ◽  
Author(s):  
Kyle Hall ◽  
Simona Percec ◽  
Michael Klein
Keyword(s):  
Driving Force ◽  
Polymer Melts ◽  
Early Stage ◽  
Polymer Crystallization ◽  
Crystal Nucleation ◽  
Crystal Formation ◽  
Local Structures ◽  
Entangled Polymer ◽  
Entangled Polymer Melts ◽  
Chain Level

This study reveals important features of polymer crystal formation at high-driving forces in entangled polymer melts based on simulations of polyethylene. First and in contrast to small-molecule crystallization, the heat released during polymer crystallization does not appreciably influence structural details of early-stage, crystalline clusters (crystal nuclei). Second, early-stage polymer crystallization (crystal nucleation) can occur without substantial chain-level relaxation and conformational changes. This study's results indicate that local structures and environments guide crystal nucleation in entangled polymer melts under high-driving force conditions. Given that such conditions are often used to process polyethylene, local structures and the separation of timescales associated with crystallization and chain-level processes are anticipated to be of substantial importance to processing strategies. This study highlights new research directions for understanding polymer crystallization.

scholarly journals Property Decoupling across the Embryonic Nucleus–Melt Interface during Polymer Crystal Nucleation

2020 ◽  
Vol 124 (23) ◽  
pp. 4793-4804
Author(s):  
Kyle Wm. Hall ◽  
Simona Percec ◽  
Wataru Shinoda ◽  
Michael L. Klein
Keyword(s):  
Crystal Nucleation ◽  
Polymer Crystal

Examining Protein Crystallization Using Scanning Electron Microscopy

2012 ◽  
Vol 19 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Kathryn Gomery ◽  
Elaine C. Humphrey ◽  
Rodney Herring
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Crystal Growth ◽  
Early Stage ◽  
Protein Crystallization ◽  
Crystal Nucleation ◽  
Protein Crystal ◽  
Microscopy Imaging ◽  
Protein Crystal Growth ◽  
Scanning Electron

AbstractElucidation of protein structure using X-ray crystallography relies on the quality of the crystal. Crystals suffer from many different types of disorder, some of which occur during crystal nucleation and early crystal growth. To date, there are few studies surrounding the quality and nucleation of protein crystals partly due to difficulties surrounding viewing biological samples at high resolution. Recent research has led our current understanding of nucleation to be a two-step mechanism involving the formation of nuclei from dense liquid clusters; it is still unclear whether nuclei first start as amorphous aggregate or as crystalline lattices. Our research examines this mechanism through the use of electron microscopy. Using scanning electron microscopy imaging of the protein crystal growth process, a stacking, spiraling manner of growth is observed. The tops of the pyramid-like tetragonal protein crystal structures measure ~0.2 μm across and contain ~125,000 lysozyme units. This noncrystalline area experiences strain due to growth of the protein crystal. Our work shows that it is possible to view detailed early stage protein crystal growth using a wet scanning electron microscopy technique, thereby overcoming the problem of viewing liquids in a vacuum.

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