Spectroscopic study on poly(methyl methacrylate) doped with metal dithizonates

Abstract

The IR and UV spectra of poly (methyl methacrylate) (PMMA) doped with metal dithizonate were investigated. Films of the doped samples were heated in air at various temperatures from 25 to 14OoC for 2 h. Other films were also exposed to UV irradiation. The doped samples were treated with iodine. The experimental results provided strong evidence that certain weak reaction occurs between the dopants and the polymer, and the rate of reaction depends on the concentration of the dopant and the nature of the metal ions. It was found that heat treatment of the doped films induces considerable changes in the intensities of their IR bands. The magnitude of these changes depends also on the concentration and the nature of the metal ion. Moreover, the results proved that exposure of the doped films to UV irradiation has no effect on their absorption spectra. Furthermore, the treatment of the doped samples with iodine causes considerable changes in their UV absorption spectra. I NTRO DUCT10 NT h e studies of photoconductivity of charge transfer complexes performed hitherto fall into two groups. On the one hand there have been studies concerned with the mechanism of fluorescence quenching and dissociation process in solutions.'s2 On the other hand, there have been investigations connected with the search for polymeric materials of relatively high photoelectric sensitivity and low dark current. These materials doped with acceptors forming charge transfer complexes are employed in the production of photosensitive films in electrophotography. The influence of the polymeric matrices on the mechanism of fluorescence quenching of the organic dyes has been investigated by a number of researchers.3-Poly (methyl methacrylate) is among the polymeric materials that have been used as matrices for the organic dyes. It has also been accepted that metal dithizonates form a n interesting class of photochromic complexes, in addition ultraviolet, visible, and infrared spectroscopic technique were used for * To whom correspondence should be addressed. the characterization of the structural properties of metal d i t h i z~n a t e s .~,~ These techniques have also been used for the investigation of the structure of T h e present study is undertaken to apply ultraviolet and infrared spectroscopic techniques for the characterization of PMMA doped with metal dithizonates. The effect of heat, exposure to ultraviolet radiation, and doping with iodine on the spectral feature of the doped polymer will be investigated. PMMA.9-12 EXPERIMENTALThe metal dithizonate complexes were prepared by the methods cited in the literat~re.~,' Solution of concentration m / L of dithizone and its metal complexes in chloroform were prepared for UV measurements using a Beckman 5260 ultraviolet spectrophotometer. The solution of PMMA in chloroform at 10% ( w / w ) was homogenized for 1 h a t 110°C. Solutions of dithizone ( 1 , 3 , 6 , and 9 m L ) a t its metal complexes were then thoroughly mixed with 25 mL of the polymer solution. For the infrared measurements thin films of...

Detection of residual acidic groups in several poly(N‐alkyl methacrylate)s using photophysical and photochemical probes

“…Additional evidence for the presence of acidic groups in poly(alkyl methacrylate)s was obtained by the solvatochromic properties of Hg(DTz) 2 . When this dye was dissolved in both PS and PMMA‐p, the visible spectrum was composed of an absorption band centered at 490 nm (isomer A) that was shifted under irradiation to 610 nm (isomer B) (Scheme ) 14–19. Nevertheless, this dye was completely bleached when it was incorporated in PMMA, PEMA, and PBMA samples, similar to that which was observed in an acidic solution.…”

“…Nile Blue A (NBA; Sigma, St. Louis, MO) was used as received. Mercury (II) dithizonate [Hg(DTz) 2 ] was prepared as described elsewhere 14–19. Spectrometric‐grade solvents (dichloromethane, acetonitrile, heptane, and ethanol) (Aldrich, Milwaukee, WI) were used after drying and distillation.…”

“…This work describes three simple spectrophotometric methods for detecting acidic impurities in poly(alkyl methacrylate)s: (1) photochromic properties of 4‐dimethylaminoazobenzene (DAB) and the influence of protonation on its anti‐syn photoisomerization reaction (Scheme )10–15; (2) photochromic properties of mercury (II) dithizonate [Hg(DTz) 2 ] (Scheme )14–19; and (3) photochromic properties of Nile Blue A (NBA) (Scheme ) 20–25. In addition, we present a quantitative spectrophotometric methodology to quantify the acidic groups in poly( n ‐alkyl methacrylate)s using the absorption spectra of Nile Blue A.…”

The effect of dye-polymer interactions on the kinetics of the isomerization of 4-dimethylaminoazobenzene and mercury dithizonate

“…[24][25][26][27] Since both ligands of the mercury dithizonate (Hg(HDZ) 2 ) participate in the isomerization reactions (Scheme 1), this reaction involves a very large change of molecular volume and demands a large free-volume to be available in the polymer matrix. [24][25][26][27][28] Further, absorption spectra of mercury dithizonate contain a strong absorption band centered at The Effect of Dye-Polymer Interactions on the Kinetics Vol. 15, No.…”

“…[24][25][26][27][28] The photochemical reaction proceeds through a rotational movement of the dithizone, involves the cleavage of the hydrogen-nitrogen-4 bond followed by a rotation around the N=C bond accompanied by the formation of a new bond between hydrogen and nitrogen-2 (Scheme 1). [24][25][26][27] Since both ligands of the mercury dithizonate (Hg(HDZ) 2 ) participate in the isomerization reactions (Scheme 1), this reaction involves a very large change of molecular volume and demands a large free-volume to be available in the polymer matrix. [24][25][26][27][28] Further, absorption spectra of mercury dithizonate contain a strong absorption band centered at The Effect of Dye-Polymer Interactions on the Kinetics Vol.…”