Magnetic and optical studies on polyvinylpyrrolidone thin films doped with rare earth metal salts

Abstract

A casting technique was used to prepare new nanocomposite thin films of pure and GdCl 3 -or HoCl 3 -doped polyvinylpyrrolidone (PVP). Transmission electron microscopy (TEM) was used to study the particle size and dispersibility in the investigated nanocomposites. Magnetic measurements, using a vibrating sample magnetometer (VSM), were carried out at room temperature and applied magnetic fields up to 10 kO e . The appearance of hysteresis loops with small values of saturation flux density (B s ), remanent flux density (B r ), squareness ratio (SQR) and coercive field (H c ), along with permeability (l) values relatively higher than 1, may be taken, as a matter of experimentation, to consider the investigated composites as soft magnet materials. In this study, PVP-HoCl 3 films showed slightly better magnetic properties compared with PVP-GdCl 3 films. A comparative analysis of infrared (IR) and ultraviolet-visible spectra of the parent components and their composites indicated the effective role of dopant nature and concentration in morphological and microstructural changes occurring in the PVP matrix. Optical constants, such as the energy gap (E g ) and the Urbach tail (E e ), were determined and discussed in terms of a model based on the electronic transition between localized states in the band structure.

Tri-functionality of Fe3O4-embedded carbon microparticles in microalgae harvesting

“…The spectrum of raw PVP was very similar to that reported in the literature (Fig. S2(d)) [48,49]. As would be expected in a polymeric structure, a remarkable carbonyl stretch (m C@O) of the pyrrolidone ring was observed at 1663 cm À1 , in addition to the CH 2 symmetric (ms C-H) and CH 2 asymmetric stretch (mas C-H) in the chain and ring at 2922 and 2957 cm À1 , CH 2 scissor and C-H bend at around 1370-1495 cm À1 , C-N stretch and CH 2 wagging at around 1290 cm À1 , and NAC@O bend at 573 and 650 cm À1 .…”

Fabrication and Evaluation of Nanostructured Herbal Oil/Hydroxypropyl-β-Cyclodextrin/Polyvinylpyrrolidone Mats for Denture Stomatitis Prevention and Treatment

“…4. The spectrum of PVP presented peaks at 3452.2 , 2926.5, 1663.4, 1415.7, and 1290.1 cm −1 that were attributed to N-H, CH 2 , C=O, C-N stretching vibration, and C-H bending, respectively (29). The peaks at 3423.7, 2915.4, 1167.8, and 1083.7 of the HPβCD spectrum corresponded to O-H, C-H, C-H, and C-O stretching vibrations, respectively (30).…”

Synthesis, characterization, and antimicrobial properties of novel double layer nanocomposite electrospun fibers for wound dressing applications

“…The additional band characteristics of PVP appear at 1,647 cm -1 , which accounts for the carbonyl (C=O) stretching affected by hydrogen bond formation with water molecules. 40 The additional band characteristics of chlorhexidine appear at 1,492 cm -1 , which is related to the chlorophenol groups of chlorhexidine. 41 The spectrum of PVA/chitosan/AgNPs/PEO/chlorhexidine ( Figure 5F) shows the characteristic absorption bands for pure PVA, pure chitosan, and the additional absorption bands characteristic of PEO and of chlorhexidine.…”