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Photoconductivity of poly(vinyl alcohol) films with Fe 3+ complexes and ESR study of their structures
Author(s) -
Sumita Osao,
Fukuda Atsuo,
Kuze Eiichi
Publication year - 1981
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1981.070260521
Subject(s) - vinyl alcohol , photoconductivity , polymer , polymer chemistry , materials science , metal , chemistry , photochemistry , organic chemistry , optoelectronics
We have studied whether photoconductivity is observed in polymer films containing the first transition metal complexes. Polymers investigated were poly(vinyl alcohol) (PVA), polyacrylamide, poly(acrylic acid), poly(vinyl pyrrolidone), and polyethylene glycol. Transition metal salts used were CrCl 3 , MnCl 2 , FeCl 3 , CoCl 2 , NiCl 2 , FeBr 3 , Fe(NO 3 ) 3 , Fe 2 (SO 4 ) 3 , and Fe(ClO 4 ) 3 . Only in the PVA–FeCl 3 film was relatively large photoconductivity due to the photoreduction of Fe 3+ observed. ESR spectra indicate that an Fe 3+ ion is chelated with two in‐plane OH residues of PVA and coordinated with three Cl − ions on the meridian. UV irradiation causes an electron transfer from Cl − to Fe 3+ . The produced chlorine atom extracts an electron from the oxygen of a neighboring OH residue. The unpaired electron thus formed can move from one oxygen to another through hydrogen bonding. In other words, the photoconductivity is due to holes produced in the network of PVA hydrogen bonding by the reduction of Fe 3+ . Finally, we have tried to explain why the photoconductivity is observed only in the PVA–FeCl 3 film.