Study on the glass transition dynamics and crystallization kinetics of molecular liquid, dimethyl phthalate, confined in Anodized Aluminum Oxide (AAO) nanopores with Atomic Layer Deposition (ALD) coatings

Chat, Katarzyna; Tu, Wenkang; Unni, Aparna Beena; Geppert‐Rybczyńska, Monika; Adrjanowicz, Karolina

doi:10.1016/j.molliq.2020.113296

Cited by 8 publications

(13 citation statements)

References 91 publications

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“…The difference in the scale of molecular movements between these two layers implies two glass transition events. In the dielectric data, the interfacial layer’s glass transition temperature is typically signified as a deviation in the temperature dependence of the relaxation time from the bulk behavior. − ,,,− Moreover, numerous experimental reports show that the value of the glass transition temperature of the interfacial layers determined in this case is consistent with the T g_interface defined based on the calorimetric data. ,,,, …”

Section: Resultsmentioning

confidence: 54%

“…This phenomenon has been previously discussed in the literature. 2,4,42,43,49,52,56 Table 2 shows temperatures at which we observed the departure of the τ α (T) from the bulk dependence for PMPS 2.5 k confined in AAO nanopores with different pore sizes (20, 60, 100, 200 nm). Based on the literature findings, we can use these values to estimate vitrification temperatures of the interfacial layer as determined typically from the calorimetric studies.…”

Section: ■ Results and Discussionmentioning

confidence: 91%

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The Impact of the Molecular Weight on the Nonequilibrium Glass Transition Dynamics of Poly(Phenylmethyl Siloxane) in Cylindrical Nanopores

Chat

Adrjanowicz

2020

J. Phys. Chem. C

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Changes in the glass transition dynamics caused by nanoconfinement reveal pronounced out-of-equilibrium features. Therefore, the confinement effects weaken with time. Using dielectric spectroscopy, we have investigated the impact of molecular weight on the equilibration kinetics of the studied polymer embedded within anodic aluminum oxide nanoporous templates. For our research, we have used poly(phenylmethyl siloxane) (PMPS) with low (M w = 2530 g/mol) and high (M w = 27,800 g/mol) molecular weight. We have found that the observed faster dynamics of the nanopore-confined systems weakens with time, and ultimately it is possible to regain the bulk-like mobility. The equilibration time increases by reducing the pore size and lowering the annealing temperature much below the glass transition temperature of the interfacial layer, T g_interface. The experimental data analysis has also revealed that the molecular weight of the nanopore-confined polymer influences the recovery of the bulk segmental relaxation time, τα. Low-molecular-weight PMPS rearrange and reach denser packing of the polymer chains with greater ease than the high-molecular-weight one. Finally, we have also demonstrated that the molecular weight affects the relationship between the time constant characterizing the equilibration kinetics and the characteristic time of viscous flow in cylindrical channels of nanometer size.

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Section: Resultsmentioning

confidence: 54%

Section: ■ Results and Discussionmentioning

confidence: 91%

The Impact of the Molecular Weight on the Nonequilibrium Glass Transition Dynamics of Poly(Phenylmethyl Siloxane) in Cylindrical Nanopores

Chat

Adrjanowicz

2020

J. Phys. Chem. C

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“…This can be done according to the procedure described elsewhere . In previous works, we have demonstrated that the alumina template oneself and incomplete filling of the nanopores (filling degree ∼90%) do not affect the position of the α-peak and spectral shape for embedded glass-forming liquids and polymers (it only shifts ε″ toward higher values depending on the porosity). , However, in our case, the degree of filling of the nanochannels with the tested polymer wasat least for those AAO membranes with larger pore sizesmuch beyond that. Therefore, the dielectric data were corrected accordingly, and it was observed that there are no changes in the position of the α-relaxation peak compared with the bulk.…”

Section: Methodsmentioning

confidence: 63%

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

Winkler

Unni

et al. 2021

J. Phys. Chem. B

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Geometric nanoconfinement, in one and two dimensions, has a fundamental influence on the segmental dynamics of polymer glass-formers and can be markedly different from that observed in the bulk state. In this work, with the use of dielectric spectroscopy, we have investigated the glass transition behavior of poly(2-vinylpyridine) (P2VP) confined within alumina nanopores and prepared as a thin film supported on a silicon substrate. P2VP is known to exhibit strong, attractive interactions with confining surfaces due to the ability to form hydrogen bonds. Obtained results show no changes in the temperature evolution of the α-relaxation time in nanopores down to 20 nm size and 24 nm thin film. There is also no evidence of an out-of-equilibrium behavior observed for other glass-forming systems confined at the nanoscale. Nevertheless, in both cases, the confinement effect is seen as a substantial broadening of the α-relaxation time distribution. We discussed the results in terms of the importance of the interfacial energy between the polymer and various substrates, the sensitivity of the glass-transition temperature to density fluctuations, and the density scaling concept.

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“…Therefore, ALD alumina coatings are free of defects . Chat et al have shown that for the molecular liquid dimethyl phthalate, confined in alumina nanopores with different ALD coatings, changes in the hydrophilicity/hydrophobicity of the surface do not affect significantly the molecular dynamics and the value of glass transition temperatures for both interfacial and core layers as compared to the native nanopores . On the other hand, modification of the hydrophilic–hydrophobic character of the pores can be used to control the crystallization tendency.…”

Section: Introductionmentioning

confidence: 99%

Glass Transition Dynamics of Poly(phenylmethylsiloxane) Confined within Alumina Nanopores with Different Atomic Layer Deposition (ALD) Coatings

et al. 2022

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Dielectric spectroscopy (DS) and differential scanning calorimetry (DSC) were employed to study the effect of changes in the surface conditions on the segmental dynamics of poly(phenylmethylsiloxane) confined in alumina nanopores (AAO). The inner surface of the pores was modified by using the atomic layer deposition technique. Coated membranes include 5 nm thick layers of hafnium oxide, titanium oxide, and silicon oxide, exhibiting different wetting properties. Modification of the surface conditions dramatically affects the interfacial interactions between the polymer and confining surface. The interfacial energy calculations indicate a decrease of γSL value from 18.7 mN/m in SiO2-coated to 0.5 mN/m in HfO2-coated nanopores. The results of the dielectric relaxation study demonstrate that the segmental relaxation time of confined PMPS 2.5k depends on the thermal treatment protocol and the hydrophilic/hydrophobic character of the pore walls. From calorimetric measurements, we found that the two glass transitions events are still observed, even in the absence of strong interfacial interactions. Values of both T gs do not depend strongly on the chemical nature of the surface. In this way, changes in the glass-transition behavior of the tested polymer confined in ALD-coated nanopores cannot be rationalized in terms of the polymer/substrate interfacial energy. Eliminating strongly adhered surfaces does not eliminate the puzzling two-T gs effect seen in cylindrical nanopores.

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Study on the glass transition dynamics and crystallization kinetics of molecular liquid, dimethyl phthalate, confined in Anodized Aluminum Oxide (AAO) nanopores with Atomic Layer Deposition (ALD) coatings

Cited by 8 publications

References 91 publications

The Impact of the Molecular Weight on the Nonequilibrium Glass Transition Dynamics of Poly(Phenylmethyl Siloxane) in Cylindrical Nanopores

The Impact of the Molecular Weight on the Nonequilibrium Glass Transition Dynamics of Poly(Phenylmethyl Siloxane) in Cylindrical Nanopores

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

Glass Transition Dynamics of Poly(phenylmethylsiloxane) Confined within Alumina Nanopores with Different Atomic Layer Deposition (ALD) Coatings

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