Direct visualisation of homogeneous and heterogeneous crystallisation in an ensemble of confined domains of poly(ethylene oxide)

Massa, Michael V.; Carvalho, Jessica L.; Dalnoki-Veress, Kari

doi:10.1140/epje/i2003-10045-3

Cited by 88 publications

(94 citation statements)

References 40 publications

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“…The melting behavior can be fitted into a sigmoidal plot where half of the crystals melt at ΔT 50% ¼ 0.1°C. Our observation of a cumulative distribution of melting resembles experiments on crystal nucleation in which samples comprised of small separate droplets were observed (24)(25)(26). In the case of melting nucleation, the crystals can be in the same droplet due to the fact that melting of one crystal does not induce melting of a nearby crystal.…”

Section: Resultssupporting

confidence: 71%

Superheating of ice crystals in antifreeze protein solutions

Celik

Graham

Mok

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

127

126

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It has been argued that for antifreeze proteins (AFPs) to stop ice crystal growth, they must irreversibly bind to the ice surface. Surface-adsorbed AFPs should also prevent ice from melting, but to date this has been demonstrated only in a qualitative manner. Here we present the first quantitative measurements of superheating of ice in AFP solutions. Superheated ice crystals were stable for hours above their equilibrium melting point, and the maximum superheating obtained was 0.44°C. When melting commenced in this superheated regime, rapid melting of the crystals from a point on the surface was observed. This increase in melting temperature was more appreciable for hyperactive AFPs compared to the AFPs with moderate antifreeze activity. For each of the AFP solutions that exhibited superheating, the enhancement of the melting temperature was far smaller than the depression of the freezing temperature. The present findings clearly show that AFPs adsorb to ice surfaces as part of their mechanism of action, and this absorption leads to protection of ice against melting as well as freezing.Gibbs-Thomson effect | ice recrystallization | irreversible binding | melting hysteresis | thermal hysteresis

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Section: Resultssupporting

confidence: 71%

Superheating of ice crystals in antifreeze protein solutions

Celik

Graham

Mok

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

127

126

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“…8,10 The transition occurs over a 5 8C range, which is expected because each domain must create its own nucleus, and this is a process that has been shown to occur stochastically. 8,28 In agreement with the findings of Röttele et al, 15 we also have observed a wide temperature range (%5 8C) over which melting occurs. This has been attributed to the fact that individual domains exist in various metastable states, having been formed under such large supercoolings.…”

Section: Resultssupporting

confidence: 92%

Ellipsometry as a probe of crystallization kinetics in thin diblock copolymer films

Carvalho

Massa

Dalnoki-Veress

2006

J Polym Sci B Polym Phys

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ABSTRACT:We present results on the use of ellipsometry as a novel probe for the crystallization kinetics in thin films of a diblock copolymer. Ellipsometry makes use of the change in polarization induced upon the reflection of light from a film-covered substrate to enable the calculation of the refractive index and thickness of the film. The information obtained with these measurements can be compared with information from differential scanning calorimetry, with the additional advantages that small sample volumes and slow cooling rates can be employed and that expansion coefficients can be determined. By studying the temperature dependence of these quantities, we are able to measure the crystallization kinetics within very small volumes ($10 À10 L) of a poly(butadiene-b-ethylene oxide) diblock copolymer. Through a comparison of two different poly (ethylene oxide) block lengths, we demonstrate a reduction in both the crystallization and melting temperatures as the domain volume is reduced.

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“…We focus on confined systems since they can provide a deep understanding of crystallization processes inside this material, because the confinement volume approaches intrinsic lengths of the phenomenon studied. 5,11 In this article, the crystallization activity energy of PCL under spatial confinement was shown much lower than that of PCL in bulk, and this provides a model to explain the phenomenon of double-melting peak for PCL. The nonisothermal crystallization kinetics of PCL in bulk and PMMA/ PCL (85/15) blend was investigated by two kinetic approaches which have been proposed to predict and analyze nonisothermal crystallization kinetics.…”

Section: Introductionmentioning

confidence: 85%

Comparison of crystallization behaviors of poly(ε‐caprolactone) in confined environment with that in bulk

Zhang²,

Yang

2007

J of Applied Polymer Sci

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ABSTRACT:The spatial confinement of poly(e-caprolactone) (PCL) in the matrix of PMMA was synthesized by in situ polymerization and characterized by WAXD and SEM. The nonisothermal crystallization behavior and the kinetics of PCL in PMMA/PCL (85/15) blend and pure PCL were investigated by means of DSC. Jeziorny and Ozawa's theoretical prediction methods were used to analyze the crystallization kinetics. The melting behavior after cooling was also studied. There was an additional interesting phenomenon of double-melting peak for pure PCL. Peaks at lower temperature shifted to lower temperature, and peaks at higher temperature did not shift with the increasing cooling rate. This behavior can be due to recrystallization. For the high-crystallization activity energy and low-crystallization rate, PCL in bulk would recrystallize during the melting process, and displayed a double-melting behavior. Under spatial confinement of the rigid PMMA, PCL had much lower crystallization activity energy and had only one melting peak.

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Direct visualisation of homogeneous and heterogeneous crystallisation in an ensemble of confined domains of poly(ethylene oxide)

Cited by 88 publications

References 40 publications

Superheating of ice crystals in antifreeze protein solutions

Superheating of ice crystals in antifreeze protein solutions

Ellipsometry as a probe of crystallization kinetics in thin diblock copolymer films

Comparison of crystallization behaviors of poly(ε‐caprolactone) in confined environment with that in bulk

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