Relaxation spectra of polymers and phenomena of electrical and hydrophobic recovery: Interplay between bulk and surface properties of polymers

Abstract

Low‐density polyethylene, polypropylene, and polycarbonate were exposed to cold air plasma treatment. The decay of electret response, hydrophobic recovery, and mechanical relaxation of polymers were studied experimentally. The three‐exponential decay kinetic model was used for the treatment of mechanical and electret responses. The characteristic time scales of mechanical and electret responses turned out to be very close. The “longest” relaxation time, extracted from the experimental study of the hydrophobic recovery, was also close to the corresponding characteristic time spans of electret and mechanical responses. The kinetics of surface processes taking place in polymers is controlled by the mobility of their functional groups, represented by the bulk relaxation spectra. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 198–205

Protein–polymer interaction: Transfer loading at interfacial region of PES‐based membrane and BSA

“…Further, the measured specific surface charge density of PES–BSA is considered to be due to the presence of BSA on the surface of PES. This obtained value of surface charge density 2.3 μC m −2 coincides reasonably with the surface charge densities of PES surface treated with BSA, as established by other independent experimental techniques . In order to understand the effect of interfacial region and transfer loading in which locking will happen, the mentioned methods have been coordinated numerically to document the surface charge behavior over a range of solid–liquid interface, and surface density.…”

Investigation of the Impact of Cold Plasma Treatment on the Chemical Composition and Wettability of Medical Grade Polyvinylchloride

“…We established that the hydrophobic recovery following the cold plasma treatment was the slowest for the radiofrequency plasma discharge, and was most rapid for the DBD plasma treatment of PVC. The characteristic times inherent to the kinetics of the hydrophobic recovery of the plasma-treated PVC (τ ∼ = 1.0 day) supported the hypothesis that the effect was influenced by the bulk mobility of polymer chains [50]. Energy-dispersive X-ray spectroscopy of the chemical composition of the near-surface layers of the catheters indicated their oxidation, emerging from the cold air plasma treatment.…”

“…Thus, we conclude, that the process of the hydrophobic recovery hardly correlated with the oxidation of the polymer arising from the cold plasma treatment. Hydrophobic recovery is a complex relaxation process including restoring of mechanical, electrical, and surface properties of plasma-treated polymers [50]. The relatively "long" times inherent to the kinetics of the hydrophobic recovery of the plasma-treated PVC (τ ∼ = 1.0 day) hint to the assumption that the effect is constituted to a large extent by the bulk mobility of polymer chains [50].…”

“…Hydrophobic recovery is a complex relaxation process including restoring of mechanical, electrical, and surface properties of plasma-treated polymers [50]. The relatively "long" times inherent to the kinetics of the hydrophobic recovery of the plasma-treated PVC (τ ∼ = 1.0 day) hint to the assumption that the effect is constituted to a large extent by the bulk mobility of polymer chains [50]. The surface mobility of polymer chains is described by the markedly shorter characteristic times [50].…”

Influenceof Vinyl Acetate Content on the Surface Hydrophobic Recovery of Ethylene Vinyl Acetate Copolymer after Plasma Modification

“…The modified thickness is usually confined to the top several tens nanometers and would not affect the bulk properties . Generally, the polymer surface would be hydrophilic state immediately after plasma modification, but the surface would return to hydrophobic state after a few hours or days, which is called hydrophobic recovery . The hydrophobic recovery could be attributed to the diffusion of hydrophobic low molecular weight molecules or the relaxation of hydrophobic chain segments ,.…”