Morphology of Free‐Volume Holes in Amorphous Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Consolati, G.; Quasso, F.

doi:10.1002/9780470600160.ch10

Cited by 9 publications

(7 citation statements)

References 54 publications

(52 reference statements)

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“…Such energies correspond to mean implantation depth values x̅ between 27 and 1.4 × 10 3 nm, as indicated by the relation In this relation, ρ is the cellulose density (1.5 g cm –3 ) and E is the positron implantation energy (keV). In the following, we will only discuss the information obtained by the o-Ps annihilation process because the τ 3 value permits to evaluate the average size of the voids where o-Ps annihilates, while the intensity I 3 of the o-Ps annihilation signal is proportional to the cavity number density. , Figure shows the values of these parameters, as a function of the positron implantation depths. We can see that both the long-lived τ 3 component and the I 3 signal are constant and maintain average values of 1.37 ± 0.02 ns and 17.7 ± 0.3%, respectively.…”

Section: Resultssupporting

confidence: 93%

Cellulose Nanofibrils Films: Molecular Diffusion through Elongated Sub-Nano Cavities

et al. 2017

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We have studied the kinetics of gas transport through films made of self-assembled cellulose nanofibrils (CNF) by a timeresolved mass spectroscopy technique. Few micrometers thick films deposited on polylactic acid (PLA) substrates act as impermeable barriers for CO 2 , O 2 , and N 2 and reduce the 2 H 2 (deuterium) and He permeation flux by a factor of ∼10 3 with respect to the uncoated substrate. Penetrant transport is controlled by the solution-diffusion mechanism and the coating acts as a diffusive barrier. 2 H 2 and He diffusivity values are in the 10 −10 and 10 −9 cm 2 s −1 range, respectively, and their migration occurs by thermally activated process with 39 ± 1 and 33 ± 2 kJ mol −1 activation energy. Positron annihilation lifetime spectroscopy analysis indicates that the diffusive path between the packed nanofibrils consists of elongated cavities with cross-sectional size ∼ 0.31 nm. Results evidence that the selective transport of the small size penetrants is due to sieving effects and that small penetrant transport occurs in configurational diffusion regime.

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Section: Resultssupporting

confidence: 93%

Cellulose Nanofibrils Films: Molecular Diffusion through Elongated Sub-Nano Cavities

et al. 2017

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“…We have to note that the relation (1) in the high temperature range, where s o-Ps with increasing temperature changes slowly and reaches liquid plateau region, gives slightly different values of intermolecular free volume sizes compared to other physical methods. 34 The bubble effect at the positronium formation 26,35,36 is one of the possible explanations for these differences in the liquid state with low viscosity. Ps creates a bubble in its surrounding and does not reect the actual intermolecular space.…”

Section: Palsmentioning

confidence: 99%

Microstructural free volume and dynamics of cryoprotective DMSO–water mixtures at low DMSO concentration

et al. 2019

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“…The temperature dependence of the annihilation parameters can be used to obtain additional information on the material properties, such as transition temperatures (phase and dynamic transitions). Combining PALS with other techniques, e.g., dilatometry [ 35 ], the shape of the pores or the anisotropy of their extensibility can also be obtained [ 36 ].…”

Section: Introductionmentioning

confidence: 99%

UV-Cured Green Polymers for Biosensorics: Correlation of Operational Parameters of Highly Sensitive Biosensors with Nano-Volumes and Adsorption Properties

et al. 2022

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The investigated polymeric matrixes consisted of epoxidized linseed oil (ELO), acrylated epoxidized soybean oil (AESO), trimethylolpropane triglycidyl ether (RD1), vanillin dimethacrylate (VDM), triarylsulfonium hexafluorophosphate salts (PI), and 2,2-dimethoxy-2-phenylacetophenone (DMPA). Linseed oil-based (ELO/PI, ELO/10RD1/PI) and soybean oil-based (AESO/VDM, AESO/VDM/DMPA) polymers were obtained by cationic and radical photopolymerization reactions, respectively. In order to improve the cross-linking density of the resulting polymers, 10 mol.% of RD1 was used as a reactive diluent in the cationic photopolymerization of ELO. In parallel, VDM was used as a plasticizer in AESO radical photopolymerization reactions. Positron annihilation lifetime spectroscopy (PALS) was used to characterize vegetable oil-based UV-cured polymers regarding their structural stability in a wide range of temperatures (120–320 K) and humidity. The polymers were used as laccase immobilization matrixes for the construction of amperometric biosensors. A direct dependence of the main operational parameters of the biosensors and microscopical characteristics of polymer matrixes (mostly on the size of free volumes and water content) was established. The biosensors are intended for the detection of trace water pollution with xenobiotics, carcinogenic substances with a very negative impact on human health. These findings will allow better predictions for novel polymers as immobilization matrixes for biosensing or biotechnology applications.

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Morphology of Free‐Volume Holes in Amorphous Polymers by Means of Positron Annihilation Lifetime Spectroscopy

Cited by 9 publications

References 54 publications

Cellulose Nanofibrils Films: Molecular Diffusion through Elongated Sub-Nano Cavities

Cellulose Nanofibrils Films: Molecular Diffusion through Elongated Sub-Nano Cavities

Microstructural free volume and dynamics of cryoprotective DMSO–water mixtures at low DMSO concentration

UV-Cured Green Polymers for Biosensorics: Correlation of Operational Parameters of Highly Sensitive Biosensors with Nano-Volumes and Adsorption Properties

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