Study on glass transition and physical aging of polystyrene nanowires by differential scanning calorimetry

Wei, WanChu; Feng, Shuo; Zhou, Qing; Liang, Huaqing; Long, Yun-Ze; Wu, Qing; Gao, Haiyang; Liang, Guodong; Zhu, Fangming

doi:10.1007/s10965-017-1199-2

Cited by 8 publications

(9 citation statements)

References 118 publications

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“…For freestanding polymer membranes, the physical aging rates of polysulfone, − polyimide, − poly(phenylene oxide), , polynorbornene, and PS increased with decreasing film thickness. Similar phenomena were also found in aqueous suspensions of PS nanoparticles or nanowires . These results were explained based on free volume diffusion models: with a reduction of the film thickness, free volume can escape much more easily, leading to an aged structure within shorter timescales.…”

Section: Introductionsupporting

confidence: 68%

“…Although the origin of these differences is not yet totally clear, attractive polymer–substrate interactions seem to significantly reduce the rate of structural relaxation, while excess free volume induces a higher physical aging rate, probably because of an enhanced diffusion of free volume holes toward the interfaces. We remark, however, that opposite to such intuitive trends, in the case of PS confined in silica-capped nanoparticles or AAO nanowires, physical aging proceeded as in bulk, which is confusing and therefore requires further discussion.…”

Section: Introductionmentioning

confidence: 79%

“…Although PS has been largely studied in thin films, the literature on the aging of PS in nanopores cannot reply to the previous questions. A preliminary study by Wei et al 57 has indicated a ∼3 K increase in T g , which seems at odds with other studies, 3,5 and no quantitative investigation of physical aging has been carried out.…”

Section: Introductionmentioning

confidence: 81%

“…Similar phenomena were also found in aqueous suspensions of PS nanoparticles 50 or nanowires. 57 These results were explained based on free volume diffusion models: 58 with a reduction of the film thickness, free volume can escape much more easily, leading to an aged structure within shorter timescales. For supported polymer films 49,59,60 and nanocomposites, 61,62 physical aging slows down or accelerates depending on the polymer and the substrate.…”

Section: Introductionmentioning

confidence: 99%

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Physical Aging of Polystyrene Confined in Anodic Aluminum Oxide Nanopores

Wang

Zhang

et al. 2023

Langmuir

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We investigated the glassy dynamics of polystyrene (PS) confined in anodic aluminum oxide (AAO) nanopores by differential scanning calorimetry. Based on the outcome of our experiments, we show that the cooling rate applied to process the 2D confined PS melt has a significant impact on both the glass transition and the structural relaxation in the glassy state. A single glass transition temperature (T g) is observed in quenched samples, while slow-cooled PS chains show two T gs corresponding to a core–shell structure. The former phenomenon resembles what is observed in freestanding structures, while the latter is imputed to the adsorption of PS onto AAO walls. A more complex picture was drawn for physical aging. In the case of quenched samples, we observed a non-monotonic trend of the apparent aging rate that in 400 nm pores, reaches a value almost twice as larger than what is measured in bulk and decreases upon further confinement in smaller nanopores. For slow-cooled samples, by adequately varying the aging conditions, we were able to control the equilibration kinetics and either separate the two aging processes or induce an intermediate aging regime. We propose a possible explanation of these findings in terms of distribution in free volume and the presence of different aging mechanisms.

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Section: Introductionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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Physical Aging of Polystyrene Confined in Anodic Aluminum Oxide Nanopores

Wang

Zhang

et al. 2023

Langmuir

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“…DSC is a valuable and reliable method to determine possible interactions that may occur during the formation of films. With it, evidence can be derived from the appearance, alteration or disappearance of energy peaks or changes in enthalpy (ΔH) [16]. In the DSC analysis, 6 mg from samples of isolated films were placed in a Shimadzu calorimeter (DSC-50) using an aluminum sample holder in an atmosphere with nitrogen flow at 20 mL min −1 .…”

Section: Methodsmentioning

confidence: 99%

α-Gluco-oligosaccharide in the research and development of a polymeric material for modified drug delivery

Oliveira

Bunhak

Santos

et al. 2019

Heliyon

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This research aimed to analyse the influence of the incorporation of α-gluco-oligosaccharide (GOS-α) in the formation of isolated films of different combinations of polymethyl by applying physicochemical analyses such as Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). Polymer films were prepared by evaporation associating Eudragit® RS30D with α-GOS. FTIR results confirmed the incorporation of α-GOS. The intermolecular interaction involving carbonyl and hydroxyl groups of Eudragit® with α-GOS was not detected. By TG and DSC, it was possible to detect that there were no changes in the thermal properties between the proposed combinations and the standard film. Upon SEM analysis, the appearance of pores for the association 90:10 was evidenced. Possibly, these pores act as output ports for the drug. These results sharpen the perspective of applying this material to the coating of pharmaceutical formulations of modified drug delivery.

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Physical Aging of Polymers

Cangialosi

2018

Encyclopedia of Polymer Science and Technology

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This article provides an overview of the most important aspects of physical aging of polymers. First, we briefly introduce basic concepts of the glass transition, that is, the way a nonequilibrium glass is formed. Subsequently, after presenting the way physical aging can be monitored, we describe the main well‐established signatures of physical aging, that is, its nonexponential and nonlinear nature. The next part of the article is dedicated to recent advancements in the physical aging of bulk polymers. In this context, recent experimental activity is discussed, where the existence of multiple mechanisms for equilibrium recovery is presented. In addition, important aspects of physical aging in polymers altered by geometrical confinement are scrutinized in light of the past 20 years efforts aiming to understand glass dynamics in such conditions. It is shown how confined polymers weakly interacting with the confining medium exhibit accelerated physical aging. Importantly, such acceleration was found to be decoupled from the molecular mobility of the glass. Finally, we briefly discuss how recent advancements in physical aging of polymers in bulk and under geometrical confinement should foster experimental efforts to unveil important basic aspects of the glass transition, such as the existence of the so‐called “ideal glass.”

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Study on glass transition and physical aging of polystyrene nanowires by differential scanning calorimetry

Cited by 8 publications

References 118 publications

Physical Aging of Polystyrene Confined in Anodic Aluminum Oxide Nanopores

Physical Aging of Polystyrene Confined in Anodic Aluminum Oxide Nanopores

α-Gluco-oligosaccharide in the research and development of a polymeric material for modified drug delivery

Physical Aging of Polymers

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