Temperature and Thickness Dependence of the Time Scale of Crystallization of Polymers under 1D Confinement

Wang, Binghua; Mathew, Allen; Napolitano, Simone

doi:10.1021/acsmacrolett.1c00123

Cited by 7 publications

(6 citation statements)

References 45 publications

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“…Based on the classical nucleation theory, the crystallization rate is due to both a nucleation barrier and a diffusion term that takes into account the molecular mobility. 68 As we verified that the annealing conditions do not affect molecular mobility, we conclude that the annealing time at 110 °C affects the nucleation barrier. Samples annealed for 5 min show lower cold crystallization temperatures and, hence, lower nucleation barriers, hinting at the presence of molecular aggregates, which facilitate the formation of ordered structures.…”

Section: ■ Results and Discussionsupporting

confidence: 65%

“…Lower cold crystallization temperatures are, consequently, a manifestation of higher crystallization rates. Based on the classical nucleation theory, the crystallization rate is due to both a nucleation barrier and a diffusion term that takes into account the molecular mobility . As we verified that the annealing conditions do not affect molecular mobility, we conclude that the annealing time at 110 °C affects the nucleation barrier.…”

Section: Resultssupporting

confidence: 51%

“…The cold crystallization temperature is an operational parameter expressed at a constant heating rate, as in our experiments, the ability of a system to crystallize upon heating. 68 Lower cold crystallization temperatures are, consequently, a manifestation of higher crystallization rates.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Memory Effect and Crystallization of (R, S)-2-Chloromandelic Acid Glass

Liu

Song

et al. 2021

J. Phys. Chem. B

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Chloromandelic acid, which can crystallize in racemic crystals (forms α and β) or a conglomerate (form γ), has been studied for its glass-forming behavior. Below the glass transition temperature, samples of the title compound crack into pieces. Correlation plots of DSC results have been used to investigate what determines the cracking and its occurrence temperature. We found that the latter is influenced by the polymorph from which the melt state has been obtained, showing that a certain memory of the previous crystalline phase persists in the undercooled melt. Moreover, this residual structure could be eliminated by elongating the annealing period or increasing the annealing temperature. Investigation using broadband dielectric spectroscopy confirmed such a memory effect. Finally, we studied the role of cracking in the control of the crystallization. In contrast with previous literature on other glass-forming molecular systems, we verified that the crystallization upon reheating is not impacted by the occurrence of cracks in the glassy state. This observation challenges the current views on polymorphic crystallization from organic glasses.

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Section: ■ Results and Discussionsupporting

confidence: 65%

Section: Resultssupporting

confidence: 51%

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Memory Effect and Crystallization of (R, S)-2-Chloromandelic Acid Glass

Liu

Song

et al. 2021

J. Phys. Chem. B

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“…Prediction of the crystallization rates has been challenging. For polymers under 1D confinement (thin films), an analytical model was proposed to estimate the time scale for crystallization, by assuming the crystallization rate can be expressed by a product of the probabilities involving nucleation and chain diffusion …”

Section: Features Of Confined Crystallizationmentioning

confidence: 99%

Confined Crystallization of Polymers within Nanopores

2021

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Metrics & MoreArticle RecommendationsCONSPECTUS: Crystallization of polymeric materials under nanoscopic confinement is highly relevant for nanotechnology applications. When a polymer is confined within rigid nanoporous anodic aluminum oxide (AAO) templates, the crystallization behavior experiences dramatic changes as the pore size is reduced, including nucleation mechanism, crystal orientation, crystallization kinetics, and polymorphic transition, etc. As an experimental prerequisite, exhaustive cleaning procedures after infiltrations of polymers in AAO pores must be performed to ensure producing an ensemble of isolated polymer-filled nanopores. Layers of residual polymers on the AAO surface percolate nanopores and lead to the so-called "fractionated crystallization", i.e., multiple crystallization peaks during cooling.Because the density of isolated nanopores in a typical AAO template exceeds the density of heterogeneities in bulk polymers, the majority of nanopores will be heterogeneity-free. This means that the nucleation will proceed by surface or homogeneous nucleation. As a consequence, a very large supercooling is necessary for crystallization, and its kinetics is reduced to a first-order process that is dominated by nucleation. Self-nucleation is a powerful method to exponentially increase nucleation density. However, when the diameter of the nanopores is lower than a critical value, confinement prevents the possibility to self-nucleate the material.Because of the anisotropic nature of AAO pores, polymer crystals inside AAO also exhibit anisotropy, which is determined by thermodynamic stability and kinetic selection rules. For low molecular weight poly(ethylene oxide) (PEO) with extended chain crystals, the orientation of polymer crystals changes from the "chain perpendicular to" to the "chain parallel to" the AAO pore axis, when the diameter of AAO decreases to the contour length of the PEO, indicating the effect of thermodynamic stability. When the thermodynamic requirement is satisfied, the orientation is determined by kinetics including crystal growth direction, nucleation, and crystal growth rate. An orientation diagram has been established for the PEO/AAO system, considering the cooling condition and pore size.The interfacial polymer layer has different physical properties as compared to the bulk. In poly(L-lactic acid), the relationship between the segmental mobility of the interfacial layer and crystallization rate is established. For the investigation of polymorphic transition of poly(butane-1), the results indicate that a 12 nm interfacial layer hinders the transition of Form II to Form I. Block and random copolymers have also been infiltrated into AAO nanopores, and their crystallization behavior is analogously affected as pore size is reduced.

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“…Supported polymer films exhibit physical properties that significantly deviate from bulk polymers, such as glass transition temperature, [1][2][3][4][5][6][7] physical aging, 7-14 crystallization, 7,[15][16][17][18][19][20] and diffusion, [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] because of confinement-induced alterations in the conformation and mobility of polymer chains near interfaces and free surfaces. The effects of confinement on the physical properties and dynamics of polymer films, as well as the underlying reasons, have been the focus of much scientific and technological research, owing to their potential applications in microelectronics, sensors, membranes, and coatings.…”

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confidence: 99%

Swelling of star polymer thin films exposed to supercritical carbon dioxide

Caglayan,

Satija,

Uhrig

et al. 2023

Journal of Polymer Science

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Impact of polymer chain architecture on the swelling of supported single‐layer polymer thin films with thicknesses below 80 nm in the presence of supercritical CO2 (scCO2) is investigated using in‐situ neutron reflectivity (NR) and ex‐situ x‐ray reflectivity (XR). 4‐arm star and 8‐arm star deuterated polystyrene (dPS) having similar total molecular weights are used. NR results revealed that the magnitude of the swelling for star polymers increases proportionally with decreasing dry film thicknesses similar to linear polymers. For film thicknesses above 5Rg, architectural differences have no impact on the swelling behavior. However, below 5Rg as the branching increases from linear to 4‐arm star and to 8‐arm star, swelling decreases due to the presence of a relatively thicker adsorbed layer formed by more branched architectures. Ex‐situ XR measurements verified that star architectures swell less than linear architecture and provided new information about the vitrification of the films through rapid quenching and its relation to the amount of CO2 retention.

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Temperature and Thickness Dependence of the Time Scale of Crystallization of Polymers under 1D Confinement

Cited by 7 publications

References 45 publications

Memory Effect and Crystallization of (R, S)-2-Chloromandelic Acid Glass

Memory Effect and Crystallization of (R, S)-2-Chloromandelic Acid Glass

Confined Crystallization of Polymers within Nanopores

Swelling of star polymer thin films exposed to supercritical carbon dioxide

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