Confined Crystallization of Polyethylene Oxide in Nanolayer Assemblies

Wang, Haopeng; Keum, Jong K.; Hiltner, A.; Baer, E.; Freeman, Benny D.; Różański, Artur; Gałęski, Andrzej

doi:10.1126/science.1164601

Cited by 341 publications

(314 citation statements)

References 22 publications

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“…, gas permeability 10 and crystallization kinetics 11,12 can differ substantially from their bulk values. Unexpectedly, deviations from bulk behaviour are also sensitive to the annealing conditions used during sample preparation.…”

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confidence: 99%

The lifetime of the deviations from bulk behaviour in polymers confined at the nanoscale

2011

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monitoring the impact of annealing on the dynamic glass transition of nanometres-thick polymer layers provides new insights into the mechanisms behind the tremendous changes in the performance of macromolecular materials in close proximity to an interface. Here we present results revealing a correlation between deviations from bulk behaviour, manifesting in changes to the glass transition temperature, the reduction of dielectric strength and the growth of an irreversibly adsorbed layer (Guiselin brushes). The non-universal behaviour of polymers under confinement could be explained in terms of a dimensionless number given by the ratio between the timescale of adsorption and the annealing time. In particular, in the case of slow adsorption kinetics, such as for polystyrene on aluminium, deviations from bulk behaviour correspond to metastable states with an extremely long lifetime.

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confidence: 99%

The lifetime of the deviations from bulk behaviour in polymers confined at the nanoscale

2011

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“…Todo esto permite, a su vez, reducir el espesor y peso de los materiales utilizados manteniendo, o mejorando, sus propiedades. También permite el desarrollo de barreras poliméricas más flexibles, más resistentes y de mayor transparencia óptica con diversas aplicaciones (Wang et al, 2009), así como el desarrollo de recubrimientos que repelen la suciedad, mediante el uso de superficies hidrófobas formadas por nanopirámides de cera que repelen el agua (Uriarte y Bald, 2008). Además, también se están desarrollando nanosensores biodegradables para controlar la temperatura y humedad y así hacer un seguimiento durante el transporte y almacenamiento de los alimentos envasados.…”

Section: Materiales En Contacto Con Alimentosunclassified

Polymeric Nanoparticle-Based Insecticides: A Controlled Release Purpose for Agrochemicals

Perlatti¹,

Bergo²,

Silva³

et al. 2013

Insecticides - Development of Safer and More Effective Technologies

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RESUMENLa nanotecnología es una ciencia multidisciplinar que está teniendo un gran auge en la actualidad, ya que proporciona productos con nuevas propiedades fisicoquímicas muy atractivas para multitud de aplicaciones. En la industria agroalimentaria, la nanotecnología brinda grandes oportunidades para la obtención de productos y aplicaciones innovadoras para la agricultura y la ganadería, el tratamiento de las aguas y la producción, elaboración, conservación y envasado de los alimentos. Para ello, se utilizan una gran diversidad de nanomateriales, que van desde metales y óxidos de metales inorgánicos a nanomateriales orgánicos que llevan ingredientes bioactivos. Esta revisión muestra una visión global de las actuales y futuras aplicaciones de la nanotecnología en la industria agroalimentaria. Los aditivos alimentarios y los materiales en contacto con los alimentos son actualmente las principales aplicaciones, mientras que se espera que en un futuro sean en el campo de los nanoencapsulados y de los nanocompuestos, en aplicaciones como nuevos alimentos, aditivos, biocidas, pesticidas y materiales en contacto con alimentos.

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“…The mechanism of bulk polymer crystallization still remains a debated topic (24), and the presence of a free surface adds further complexity to this issue (25). The free surface potentially affects nucleation (26), chain configuration and mobility (27), and local and segmental dynamics (28) leading to significantly different crystallization kinetics and morphologies than are found in the bulk (29,30).Poly(ethylene terephthalate) (PET) is an excellent model system for understanding the surface properties of semicrystalline films in both the amorphous and semicrystalline states. Thin films of PET can be prepared in the amorphous phase at room temperature by spin coating onto solid substrates.…”

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Comparative surface dynamics of amorphous and semicrystalline polymer films

Becker

Brown

Killelea

et al. 2010

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

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The surface dynamics of amorphous and semicrystalline polymer films have been measured using helium atom scattering. Timeof-flight data were collected to resolve the elastic and inelastic scattering components in the diffuse scattering of neutral helium atoms from the surface of a thin poly(ethylene terephthalate) film. Debye-Waller attenuation was observed for both the amorphous and semicrystalline phases of the polymer by recording the decay of elastically scattered helium atoms with increasing surface temperature. Thermal attenuation measurements in the specular scattering geometry yielded perpendicular mean-square displacements of 2.7 • 10 −4 Å 2 K −1 and 3.1 • 10 −4 Å 2 K −1 for the amorphous and semicrystalline surfaces, respectively. The semicrystalline surface was consistently ∼15% softer than the amorphous across a variety of perpendicular momentum transfers. The Debye-Waller factors were also measured at off-specular angles to characterize the parallel mean-square displacements, which were found to increase by an order of magnitude over the perpendicular mean-square displacements for both surfaces. In contrast to the perpendicular motion, the semicrystalline state was ∼25% stiffer than the amorphous phase in the surface plane. These results were uniquely accessed through low-energy neutral helium atom scattering due to the highly surface-sensitive and nonperturbative nature of these interactions. The goal of tailoring the chemical and physical properties of complex advanced materials requires an improved understanding of interfacial dynamics, information that is obtainable through atomic beam scattering methods.atomic beam scattering | gas-surface Interactions | dynamics of polymer interfaces | polymer surfaces A tom scattering has been used to quantify key surface dynamical properties of systems of increasing complexity. Early work focused on understanding the gas-surface interaction and surface structure and dynamics of ionic (1, 2), metallic (3), and semiconductor (4) surfaces. Building on the pioneering work performed on single-crystal surfaces, further molecular beam investigations examined systems of greater structural complexity including surface defects (5), stepped surfaces (6), and adsorbates on surfaces (7,8). The success of these forays into disordered and complex systems, bolstered by advances in scattering theory (9-11), led to the study of soft organic interfaces such as liquids (12, 13), self-assembled monolayers (SAMs) (14-17), and, most recently, thin polymer films (18)(19)(20). In this work, we present the successful extension of helium atom scattering, a uniquely surface-sensitive probe, to determining the changes in local surface vibrational dynamics due to crystallization of a thin polymer film.Interfaces of thin molecular films have recently received significant attention to uncover the surface structure and properties as well as the interface's ultimate effect on bulk material properties. In particular, polymer films present a complex, macromolecular interface of importance in f...

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Confined Crystallization of Polyethylene Oxide in Nanolayer Assemblies

Cited by 341 publications

References 22 publications

The lifetime of the deviations from bulk behaviour in polymers confined at the nanoscale

The lifetime of the deviations from bulk behaviour in polymers confined at the nanoscale

Polymeric Nanoparticle-Based Insecticides: A Controlled Release Purpose for Agrochemicals

Comparative surface dynamics of amorphous and semicrystalline polymer films

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