Abstract
Changes in the glass transition dynamics caused by the nanoconfinement reveal pronounced out-of-equilibrium features. Therefore, the confinement effects weaken with time. Using the Dielectric Spect...
Highlights
The properties of soft matter confined at the nanoscale often differ significantly from the behavior observed for the macroscopic samples.[1−19] In recent years, numerous studies have shown that the various deviations from the bulk behavior in a confined geometry are manifestations of the nonequilibrium phenomena.[20−29] it has been found that prolonged annealing at temperatures above the glass transition temperature reduces or even eliminates the effects caused by the nanoconfinement.[20,24,26−30]
It has been found that the enhanced segmental motion in the polymer thin films of poly(4chlorostyrene) is the nonequilibrium phenomenon.[21−24] prolonged annealing can reduce changes in the glass transition temperature and the dielectric strength caused by confinement.[25−27,31−34] It has been suggested that the time needed to recover the bulk properties depends on the molecular weight of the polymer system as well as the type of interaction with the substrate.[22−26] Literature results have demonstrated that the equilibration phenomena observed in thin films are associated with an increase in irreversible chain adsorption on the supporting substrate
To investigate the equilibration kinetics of phenomena of poly(phenylmethyl siloxane) (PMPS) 2.5 k confined in anodic aluminum oxide (AAO) nanopores, we have carried out dielectric measurements, which involved prolonged annealing experiments at various temperatures located below the glass transition temperature of the interfacial layer
Summary
The properties of soft matter confined at the nanoscale often differ significantly from the behavior observed for the macroscopic samples.[1−19] In recent years, numerous studies have shown that the various deviations from the bulk behavior in a confined geometry are manifestations of the nonequilibrium phenomena.[20−29] it has been found that prolonged annealing at temperatures above the glass transition temperature reduces or even eliminates the effects caused by the nanoconfinement.[20,24,26−30]In the case of one-dimensional (1D) geometrical nanoconfinement, it has been observed that the many macroscopic properties can be recovered with time.[20−24] Literature data show that the faster dynamics observed for thin films of poly(methyl methacrylate) and poly(vinyl acetate) slows down during prolonged annealing.[20]. Apart from thin films, nanopore-confined systems can exhibit out-of-equilibrium features.[28,29,35−37] Numerous studies show that in the presence of two-dimensional (2D) nanoconfinement, the glass transition dynamics depends strongly on the sample’s thermal history This includes changes in the relaxation time and the glass transition temperature.[2,28,29,35−37] the bulk properties can be recovered with time, as reported for thin polymer films.[28,29] Importantly, in the case of confinement realized by cylindrical nanopores, the effects of annealing on glass transition dynamics are visible only in a Received: August 1, 2020 Revised: September 10, 2020 Published: September 11, 2020. Understanding how the glass transition dynamics in the macro- and nanoscale is related can provide much better possibilities for nanomaterial applications in materials sciences and various cross-disciplinary research fields
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