Dielectric Spectroscopy on Propylene Glycol∕Poly(Vinyl Pyrrolidone) Solutions: Polymer and Solvent Dynamics in Hydrogen-Bonding Systems

2008 ◽  
Author(s):  
Anna Spanoudaki ◽  
Naoki Shinyashiki ◽  
Apostolos Kyritsis ◽  
Polycarpos Pissis ◽  
Michio Tokuyama ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Propylene Glycol ◽  
Dielectric Spectroscopy ◽  
Vinyl Pyrrolidone ◽  
Solvent Dynamics ◽  
Poly Vinyl Pyrrolidone ◽  
Bonding Systems

Ultrafine Cellulose Acetate Fibers with Nanoscale Structural Features

2008 ◽  
Vol 8 (9) ◽  
pp. 4461-4469 ◽  
Author(s):  
Lifeng Zhang ◽  
You-Lo Hsieh
Keyword(s):  
Hydrogen Bonding ◽  
Cellulose Acetate ◽  
Pore Volume ◽  
Structural Features ◽  
Fiber Formation ◽  
Vinyl Pyrrolidone ◽  
Chain Entanglement ◽  
Bicomponent Fibers ◽  
Micron Size ◽  
Poly Vinyl Pyrrolidone

Nano-structural features were introduced to ultrafine cellulose acetate (CA) fibers by electrospinning of its mixtures with either poly(vinyl pyrrolidone) PVP or β-cyclodextrin (β-CD) in DMF, followed by dissolution of the added PVP or β-CD. The presence of the charge-holding PVP enabled fiber formation from CA below its entanglement chain length and improved the electrospinning efficiency to produce bicomponent fibers with wide ranging diameters from 30 to 650 nm. At up to 50% contents, the PVP in the bicomponent fibers was phase-separated from CA and, upon removal, resulting in highly angulated fiber surfaces with nanometer-size spherulites and sub-micron size ridges and grooves. Adding β-CD to CA enabled fiber formation at concentrations below the chain entanglement concentration Ce (16.5%). Hydrogen bonding between β-CD and CA, as evident by FTIR, helped to distribute β-CD as individual molecules in the CA matrix and producing more uniform and finer (130–150 nm in diameters) fibers, irrespective of their β-CD contents. Removal of β-CD from the fibers originally containing 40% β-CD, generated nanoporous fibers with 2-nm nanopores and 70% increase in specific surface and doubled pore volume.

Stability and rheological properties of nanofluids containing ZnO nanoparticles, poly(propylene glycol) and poly(vinyl pyrrolidone)

2015 ◽  
Vol 403 ◽  
pp. 136-144 ◽  
Author(s):  
Mohammed Taghi Zafarani-Moattar ◽  
Hemayat Shekaari ◽  
Rima Munes-Rast ◽  
Roghayeh Majdan-Cegincara
Keyword(s):  
Rheological Properties ◽  
Propylene Glycol ◽  
Zno Nanoparticles ◽  
Vinyl Pyrrolidone ◽  
Poly Vinyl Pyrrolidone ◽  
Poly Propylene

Solid-State Photoreversible Polymerization of n-Alkyl-Linked Bis-Thymines using Non-Covalent Polymer-Templating

2010 ◽  
Vol 63 (4) ◽  
pp. 631 ◽  
Author(s):  
Priscilla Johnston ◽  
Milton T.W. Hearn ◽  
Kei Saito
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Nucleic Acid ◽  
Green Chemistry ◽  
Vinyl Pyrrolidone ◽  
Acid Base ◽  
Polymer Templating ◽  
Nucleic Acid Base ◽  
Poly Vinyl Pyrrolidone

Procedures derived from bioinspired mechanisms are increasingly being used to create novel materials based on the principles of green chemistry. Thymine, a nucleic acid base in DNA, has the propensity to both hydrogen bond and photodimerize. Photodimerization of thymine occurs when irradiated at wavelengths of >270 nm and can be reversed by irradiation at wavelengths of <250 nm. In this investigation, n-alkyl-linked bis-thymines have been supramolecularly aligned with poly(vinyl pyrrolidone) templates by non-covalent hydrogen bonding, and photopolymerized in the solid state. Photo-depolymerization of the products was performed to complete the reversible polymerization.

scholarly journals ALD coating of centrifugally spun polymeric fibers and postannealing: case study for nanotubular TiO2 photocatalyst

2021 ◽  
Author(s):  
Martina Rihova ◽  
Oksana Yurkevich ◽  
Martin Motola ◽  
Ludek Hromadko ◽  
Zdeněk Spotz ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Atomic Layer ◽  
Vinyl Pyrrolidone ◽  
Tio2 Photocatalyst ◽  
Polymeric Fibers ◽  
Layer Deposition ◽  
Centrifugal Spinning ◽  
Poly Vinyl Pyrrolidone

This work describes the synthesis of highly photocatalytically active TiO2 tubes (TiTBs) by combining centrifugal spinning and atomic layer deposition (ALD). Poly(vinyl pyrrolidone) (PVP) fibers were first produced by centrifugal...

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