Positron annihilation lifetime study of polyvinylpyrrolidone for nanoparticle-stabilizing pharmaceuticals

AIP Conference Proceedings

Bujňáková

et al. 2018

Atomic-deficient void structure is studied in nanocomposites prepared by mechanochemical milling of glassy g-As2Se3 in a water solution of polyvinylpyrrolidone (PVP) employing positron annihilation lifetime spectroscopy. Formalism of Ps-to-positron trapping conversion known as x3-x2-CDA (coupling decomposition algorithm) is applied to identify free-volume defects in the pelletized g-As2Se3/PVP nanocomposite in respect to dry-milled g-As2Se3 one. Under wet-milling, the inter-nanoparticle Ps-decaying sites in preferential PVP environment replace free-volume positron traps (in dry-milled g-As2Se3) with defect-specific lifetime of 0.352 ns, corresponding to di-/tri-atomic vacancies in gAs -Se.

Section: Resultsmentioning

confidence: 79%

Section: Pal Spectra Recordingmentioning

confidence: 99%

Free-volume structure of glass-As2Se3/PVP nanocomposites prepared by mechanochemical milling

AIP Conference Proceedings

Bujňáková

et al. 2018

“…As a consequence, the average lifetime τ av. in this composite grows to 0.386 ns, while the τ 3 lifetime drops to 1.891 ns, tending toward Ps‐related lifetime in pure PVP (τ 3 = 1.867 ns) . Hence, the Ps‐decaying occurs rather in PVP environment than in g‐As‐Se matrix, this process being nearly three‐times enhanced in respect to f v = 0.83% (Table ).…”

Section: Resultsmentioning

confidence: 85%

Free‐volume structure of polyvinylpyrrolidone‐capped glassy As₂Se₃ nanocomposites prepared by mechanical milling

Polymer Engineering & Sci

Bujňáková

et al. 2019

The method of positron annihilation lifetime (PAL) spectroscopy was first employed to study atomic‐deficient free‐volume structure of nanocomposites prepared by high‐energy mechanical milling of glassy g‐As2Se3 in water solution of polyvinylpyrrolidone (PVP). The formalism of x3‐x2‐CDA (coupling decomposition algorithm) describing conversion of bound positron‐electron (positronium Ps) states into positron traps was applied to identify free‐volume elements in pelletized PVP‐capped g‐As2Se3 nanocomposite in respect to parent dry‐milled g‐As2Se3. Under wet milling, the internanoparticle Ps‐decaying sites in preferential PVP environment were shown to replace free‐volume positron traps in dry‐milled g‐As2Se3 with defect‐specific positron lifetime of 0.352 ns, corresponding to diatomic/triatomic vacancies in g‐As‐Se matrix. POLYM. ENG. SCI., 59:2438–2442, 2019. © 2019 Society of Plastics Engineers

“…. To clarify the nature of NP‐related void evolution in As 4 S 4 ‐PVP nanocomposites, the PAL data for REA1,2,3 were also treated within x3‐x2‐coupling decomposition algorithm in respect to x3‐component fitting parameters of reference PVP , the results being presented in Table .…”

Section: Resultsmentioning

confidence: 99%

“…Nanoparticles (NPs) sizes in dried pellets were close to ones proper to as‐prepared suspensions (100–200 nm in a diameter ). In a similar manner, the pelletized samples of pure PVP were prepared to be used as reference in further research .…”

Section: Methodsmentioning

confidence: 99%

PVP‐stabilized arsenic sulfide As₄S₄ nanocomposites probed with positron annihilation lifetime spectroscopy

Polymer Engineering & Sci

et al. 2017

Self Cite

Atomic‐deficient nanostructurization in composites based on arsenic sulfide As4S4 polymorphs, such as (1) β‐As4S4, (2) realgar α‐As4S4, and (3) mixture of realgar, pararealgar, and intermediate χ‐phase subjected to high‐energy mechanochemical milling in polyvinylpyrrolidone (PVP) solution, are studied exploring the method of positron annihilation lifetime spectroscopy. Positron lifetime spectra reconstructed from unconstrained x3‐term fitting procedure testify in a favor of mixed positron‐positronium trapping in the studied composites. Modified x3‐x2‐coupling decomposition algorithm is applied to parameterize expected annihilation channels in As4S4‐PVP nanocomposites in respect to PVP matrix. Interfacial free‐volume voids between nanoparticles composed of arsenic sulfide crystallites embedded in PVP environment are defined as most favorable positron trapping sites, loosely packed in respect to variety of crystallographic polymorphs used for milling. POLYM. ENG. SCI., 57:502–505, 2017. © 2017 Society of Plastics Engineers