Heterogeneous and Aging Dynamics in Single and Stacked Thin Polymer Films

Fukao, Koji; Terasawa, Takehide; Nakamura, Kenji; Tahara, Daisuke

doi:10.1007/12_2012_172

Cited by 8 publications

(4 citation statements)

References 80 publications

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“…For example, the glass transition temperature T g of these films shows changes by 10–50 K, − which may translate to changes in the relaxation time by several orders of magnitude. In fact, experiments − yield a broad distribution of relaxation times in spin-coated polymer films, suggesting temporal and spatial variations in polymer dynamics and, possibly, differences in local structures. Can we relate these intriguing observations with processing-induced changes in properties?…”

Section: Key Experimental Observationsmentioning

confidence: 99%

Processing Pathways Decide Polymer Properties at the Molecular Level

et al. 2019

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Conditions of rapid processing often drive polymers to adopt nonequilibrium molecular conformations, which, in turn, can give rise to structural, dynamical, and mechanical properties that are significantly different from those in thermodynamic equilibrium. However, despite the possibility to control the desired nonequilibrium properties of polymers, a rigorous microscopic understanding of the processing–property relations is currently lacking. In an attempt to stimulate progress along this topical direction, we focus here on three prototypical and apparently different cases: spin-coated polymer films, rapidly drawn polymer fibers, and sheared polymer melts. Inspired by the presence of common observations in the chosen cases, we search for order parameters as, for example, topological correlations and heterogeneities, which may allow characterizing the processing-induced behavior of polymers. We highlight that such approaches, necessitating concerted efforts from theory, simulations, and experiments, can provide a profound understanding leading to predictable and tunable properties of polymers.

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Section: Key Experimental Observationsmentioning

confidence: 99%

Processing Pathways Decide Polymer Properties at the Molecular Level

et al. 2019

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“…It has been observed that the acceleration of physical aging, occurring in thin freestanding films and in stacked films, in terms of the time required to reach equilibrium, associated the depression of the glass transition temperature [30]. Furthermore Fukao et al [38,72] have shown that the rate of physical aging in stacked films could evolve from thin film like to bulk like with interlayer diffusion. In the multilayer system investigated in the present study, it is interesting to observe that the constraints generate an increase of the glass transition, in contrast to the behavior of stacked films.…”

Section: Influence Of the Constraint Nature On The Physical Aging Kinmentioning

confidence: 99%

Reduced physical aging rates of polylactide in polystyrene/polylactide multilayer films from fast scanning calorimetry

Monnier

Nassar

Domenek

et al. 2018

Polymer

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The physical aging behavior of amorphous polylactide constrained against polystyrene in layers of 300 nm, thanks to the layeremultiplying coeextrusion process, was investigated by fastescanning calorimetry (FSC). By cooling down the sample from the liquid state to the glassy one at very fast scanning rates, it was possible to investigate the structural relaxation of the polymer glass at high temperatures for which the time needed to reach the equilibrium was shortened. Therefore it was possible to perform the study of physical aging in experimental conditions providing an expanded view of the structural relaxation for short aging times. Taking benefit of this property, it was highlighted that the aging kinetics of polylactide occurred significantly slower in the multilayer film, in comparison with a bulk amorphous film. The process of recovery in the multilayer system was found to occur at similar rates, or even slower, than in a threeelayer film in which polylactide reached its maximum extent of crystallinity. This was attributed to mobility hindrance that might be inherent to the extrusion conditions or associated with the presence of capped interfaces with polystyrene.

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“…The TFC membrane comprising 50-nm-thick Teflon AF1600 film shows slightly lower selectivity than the others with thicker films. Thinner films are widely reported to have more flexible polymer chains (which may be indicated by lower T g ) [58,59], leading to weaker size sieving ability and lower selectivity. The TFC membranes comprising 100 nm, 175 nm and 375 nm selective layers seem to have very similar selectivity, especialy after 100 hr aging.…”

Section: Effect Of Physical Aging and Film Thickness On Gas Selectivimentioning

confidence: 99%

Physical aging of glassy perfluoropolymers in thin film composite membranes. Part I. Gas transport properties

Yavari

Lin

2017

Journal of Membrane Science

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Physical aging of thin film glassy polymers continuously decreases gas permeability, presenting a great challenge in designing membrane systems for long-term gas separation. Most studies on the effect of physical aging on membrane applications use freestanding thin films, which are often annealed above the polymer glass transition temperature (T g) before gas permeability is determined. However, industrial membranes are often thin film composites (TFCs) comprising the thin film on top of porous polymeric supports, and they may not be annealed above the T g. The objective of this study is to investigate the effect of physical aging of the selective layer on gas permeance and selectivity of TFC membranes to establish industrial relevance. Two-layer TFC membranes consisting of perfluoropolymers (including Teflon ® AF1600 and Hyflon ® AD) at various film thicknesses (50-400 nm) on polyethersulfone porous support were prepared and determined for permeances of CH 4 , N 2 , H 2 and CO 2 at 35 o C for over 1000 hr. Gas permeances decrease with time, and the decrease is more significant for larger penetrants and for membranes with thinner selective layers. For example, CH 4 permeance decreases by 54% and 27% after aging for about 1400 hr in TFC membranes comprising 50-nmand 370-nm-thick Teflon AF1600, respectively. The decrease of gas permeances over time in these TFC membranes is compared with that of freestanding films. This study is one of only a few to present the results of physical aging in industrial TFC membranes and to provide useful insights for practical membrane applications.

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Heterogeneous and Aging Dynamics in Single and Stacked Thin Polymer Films

Cited by 8 publications

References 80 publications

Processing Pathways Decide Polymer Properties at the Molecular Level

Processing Pathways Decide Polymer Properties at the Molecular Level

Reduced physical aging rates of polylactide in polystyrene/polylactide multilayer films from fast scanning calorimetry

Physical aging of glassy perfluoropolymers in thin film composite membranes. Part I. Gas transport properties

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