Unusual Absorption and Fluorescence Properties of p-Substituted Stilbenes in Poly (vinyl alcohol) Films

1995 ◽  
Vol 50 (12) ◽  
pp. 1170-1174
Author(s):  
A. Kawski ◽  
B. Kukliński ◽  
T. Nowosielski
Keyword(s):  
Double Bond ◽  
Polyvinyl Alcohol ◽  
Vinyl Alcohol ◽  
Fluorescence Properties ◽  
Poly Vinyl Alcohol ◽  
Emission Anisotropy ◽  
Unusual Behaviour ◽  
Different Temperatures ◽  
Linear Polyenes ◽  
Linear Molecules

Abstract The behaviour of absorbance, fluorescence and emission anisotropy of linear molecules with one double bond, i.e. 4-amino-4'-nitrostilbene (ANS), 4-dimethylamino-4'-nitrostilbene (DNS) and 4,4'-diphenylstilbene (DPS), was examined in polyvinyl alcohol) (PVA) films at different temperatures (293-423 K). The unusual behaviour of absorption and fluorescence properties of the molecules in­ vestigated, similar to those of linear polyenes in PVA, was, however, less pronounced.

scholarly journals Photoselection of Luminescent Molecules in Anisotropic Media in the Case of Two-Photon Excitation. Part II. Experimental Studies of Hoechst 33342 in Stretched Polyvinyl alcohol) Films

1996 ◽  
Vol 51 (9) ◽  
pp. 1037-1041 ◽  
Author(s):  
A. Kawski ◽  
Z. Gryczyński ◽  
I. Gryczyński ◽  
J. R. Lakowicz ◽  
G. Piszczek
Keyword(s):  
Polyvinyl Alcohol ◽  
Vinyl Alcohol ◽  
Experimental Studies ◽  
Poly Vinyl Alcohol ◽  
Hoechst 33342 ◽  
Emission Anisotropy ◽  
Two Photon ◽  
Photon Excitation ◽  
Polyvinyl Alcohol Films ◽  
Two Photon Excitation

Abstract It was found by investigating dichroism and emission anisotropy in the case of one-and two-photon excitation of Hoechst 33342 [bis-benzimide,2,5'-bi-1H-benzimidazole, 2'-(4-ethoxyphenyl)-5-5(4-methyl-1-piperazinyl)] in stretched poly(vinyl alcohol) (PVA) films, that the absorption and fluorescence transition moments lie along the long molecular axis of the molecule studied. The slight deviation of the transition moment direction in fluorescence (about 8°) from that in absorption can be due to the incomplete linearity of the Hoechst molecule.

Absorption and Fluorescence Properties of p-Substituted Stilbenes in Poly (vinyl chloride) Film

1995 ◽  
Vol 50 (12) ◽  
pp. 1175-1178
Author(s):  
A. Kawski ◽  
B. Kukliński ◽  
T. Nowosielski
Keyword(s):  
Double Bond ◽  
Polyvinyl Alcohol ◽  
Fluorescence Spectra ◽  
Experimental Studies ◽  
Absorption And Fluorescence Spectra ◽  
Emission Anisotropy ◽  
Poly Vinyl Chloride ◽  
Pvc Film ◽  
Linear Molecules ◽  
Chloride Film

Abstract Experimental studies have demonstrated that the absorption and fluorescence spectra of linear molecules with one double bond, i.e. 4-amino-4'-nitrostilbene (ANS), 4-dimethylamino-4'-nitro-stilbene (DNS) and 4,4'-diphenylstilbene (DPS), contained in preheated to 393 K or nonheated polyvinyl chloride) (PVC) films are identical in shape and position, unlike those observed for ANS, DNS and DPS in polyvinyl alcohol) (PVA) films. For polar ANS and DNS molecules in PVC film a decrease in the emission anisotropy with growing wavelength of the fluorescence band was observed. This unusual behaviour of the emission anisotropy is accounted for by the overlap of two close emission bands from different luminescent centres, resulting from different microenvironments of the ANS and DNS molecules in PVC film. The emission anisotropy of nonpolar DPS molecule in PVC does not change within the fluorescence spectrum.

Photoluminescence Properties of trans–4,4'–Diamino–stilbene in Poly(vinyl alcohol) Films

1996 ◽  
Vol 51 (10-11) ◽  
pp. 1153-1156 ◽  
Author(s):  
A. Kawski ◽  
A. Kubicki ◽  
B. Kukliński ◽  
T. Nowosielski
Keyword(s):  
Vinyl Alcohol ◽  
Experimental Studies ◽  
Poly Vinyl Alcohol ◽  
Photoluminescence Properties ◽  
Emission Anisotropy ◽  
Distinct Effect ◽  
Unusual Behaviour ◽  
Nonpolar Molecule ◽  
Direct Irradiation ◽  
Fluorescence And Phosphorescence

Abstract Experimental studies have shown that the nonpolar molecule 4,4'-diamino-stilbene (DAS) in poly(vinyl alcohol) film (PVA) at 296 K, apart from fluorescence displays phosphorescence whose intensity differs only slightly from that observed at 84 K. The overlapping of fluorescence and phosphorescence bands is the reason of the unusual behaviour of the emission anisotropy in the longwave absorption and photoluminescence bands. A distinct effect of direct irradiation on the intensity of these bands was observed.

Isomerization of Diphenyl Polyenes. Part III. Absorption and Fluorescence Properties of 1,4-Diphenyl-1,3-butadiene in Poly(vinyl alcohol) Film

1992 ◽  
Vol 47 (12) ◽  
pp. 1204-1210 ◽  
Author(s):  
A. Kawski ◽  
B. Kukliński ◽  
A. Kubicki ◽  
I. Gryczyński
Keyword(s):  
Quantum Yield ◽  
Polyvinyl Alcohol ◽  
Vinyl Alcohol ◽  
Wavelength Region ◽  
Fluorescence Properties ◽  
Effect Of Temperature ◽  
Poly Vinyl Alcohol ◽  
Trans Form ◽  
Long Wavelength ◽  
Polyvinyl Alcohol Film

The effect of temperature on the absorption and fluorescence properties of 1,4-diphenyl-1,3-butadiene (DPB) in polyvinyl alcohol) film (PVA) was investigated in the range from 293 to 423 K. Upon heating above 353 K, the optical density in the long wavelength region (at 339 nm) increases five times only, whereas for 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1,8-diphenyl-1,3,5,7-octatetraene (DPO) ten and twenty times, respectively. However, the total quantum yield (ΦF = 0.68) at 293 K is greater than that for the trans-trans form (ΦF = 0.63) and decreases with growing temperature. Both this effect and broadening effect in the fluorescence band at 293 K evidence the existence of two emission centres, i.e. the trans-trans and cis-trans conformers.

scholarly journals Morphological and Thermal Properties of Poly(Vinyl Alcohol)/Layered Double Hydroxide Hybrid Nanocomposite Fibers

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
A. F. Al Naim ◽  
J. Mazher ◽  
S. S. Ibrahim
Keyword(s):  
Crystal Structure ◽  
Heat Treatment ◽  
Layered Double Hydroxide ◽  
Vinyl Alcohol ◽  
Separation Distance ◽  
Molecular Vibration ◽  
Poly Vinyl Alcohol ◽  
Rapid Weight Loss ◽  
Different Temperatures ◽  
Double Hydroxide

Nanolayered particulate of Zn-based layered double hydroxide (LDH) was prepared by a low temperature greener sol-gel method. X-ray diffraction (XRD) studies were performed on the particles annealed at different temperatures. Hexagonal crystal structure of the as-grown LDH particulates was observed. The crystal structure was modified to tetragonal structure of layered double oxide (LDO) on annealing at 250°C. Rietveld fittings showed a collapse of interlayer separation distance along the preferred orientation of the LDH particles as a result of heat treatment. Further, LDH particles were used as fillers of electrospun poly(vinyl alcohol) (PVA) fibers. Heat treatment of the polymer fibers was also performed at different temperatures, and thermal changes were studied by thermogravimetric analysis (TGA), Raman spectroscopy, and scanning electron microscopy (SEM) techniques. Improved interaction of fibers with LDH nanoparticles was observed and ascribed to LDH-related LDO phase transformation at higher temperature. Thermal mechanisms of the rapid weight loss in filled fibers were discussed in comparison to the pure PVA fiber losses. Experimental Raman frequencies of the composite fibers were compared with the calculated Raman modes of the enol and ZnO monomers. The molecular vibration frequencies were found to differ significantly due to heat treatment. Finally, the role filler in the faster and greener thermal decomposition of polymeric fibers was also discussed in the present work.

Isomerization of Diphenyl Polyenes. Part VIII. Absorption and Fluorescence Properties of l-Phenyl-4-diphenylthiophosphinyl Butadiene in Poly (vinyl alcohol) Film

1994 ◽  
Vol 49 (7-8) ◽  
pp. 824-828 ◽  
Author(s):  
A. Kawski ◽  
G. Piszczek ◽  
B. Kukliński ◽  
T. Nowosielski
Keyword(s):  
Vinyl Alcohol ◽  
Thermal Isomerization ◽  
Fluorescence Properties ◽  
Trans Configuration ◽  
Effect Of Temperature ◽  
Poly Vinyl Alcohol ◽  
Direct Irradiation

Abstract The effect of temperature (from 296 to 423 K) upon the absorption and fluorescence of l-phenyl-4-diphenylthiophosphinyl butadiene (PDPB) and of the direct irradiation on the absorbance were investigated in poly(vinyl alcohol) film. It was found that for PDPB in PVA film the transition from cis to trans configuration is only possible as a result of thermal isomerization due to the softening of PVA polymer, whereas photoisomerization results in both cis-to-trans and trans-to-cis transitions. Similar as with 1,4-diphenyl-1,3-butadiene in PVA, the luminescence is due to two, trans-trans and cis-trans, PDPB conformers.

Rheological properties of pectin, poly(vinyl alcohol) and their blends in aqueous solutions

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Katarzyna Lewandowska ◽  
Aldona Dąbrowska ◽  
Halina Kaczmarek
Keyword(s):  
Aqueous Solutions ◽  
Rheological Properties ◽  
Vinyl Alcohol ◽  
Water Soluble ◽  
Poly Vinyl Alcohol ◽  
Concentric Cylinder ◽  
Water Soluble Polymer ◽  
Flow Measurements ◽  
Result Show ◽  
Different Temperatures

AbstractThe new blends composed of natural polysaccharide - pectin and synthetic water soluble polymer - poly(vinyl alcohol) (PVA) are attractive materials due to their biocompatibility, non-toxicity and biodegradability. In this work the rheological properties of aqueous solutions of pectin (PEC), poly(vinyl alcohol) and their mixtures at various weight ratios (70/30, 50/50, 30/70) have been investigated. Flow measurements were carried out using a rotary viscometer with concentric cylinder at different temperatures (20-70 ºC) and shear rates (24- 1234 s-1). The flow parameters and energy of activation have been calculated from the flow curves and Arrhenius plots, respectively. It was found that studied polymer solutions exhibited non-Newtonian behavior, moreover, the flow properties were dependent on the blend composition. The result show that practically there was no thixotropy in studied system but some interactions between PVA and pectin in water occurred.

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