Photodegradation-Bisphenol

It has been found that the photodegradation of several polders such as poly(vinyl chloride)(115).polyisoprene (109, 116).bisphenol A polycarbonate (117) is sensitized by peroxides. 

The results from the previous sections confirm that all the variables surveyed in this study have measurable effects on the photodegradation of bisphenol A polycarbonate. The first part of this discussion will summarize these effects. The second part will examine possible reaction pathways to the products seen in this and other works and suggest how some of the variables could affect these reactions. 

Miscellaneous.—Recent papers have reported the photodegradation of urethanes,247 the photolysis of organopoly(silanes),248 and the photodegradation of bisphenol-A-polycarbonate.249 The degradation in the last study was shown to involve chain scission, cross-linking, and the photo-Fries rearrangement. 

Photolysis of Model Compound I. The bis-n-propyl ether of bisphenol-A (I) is a colorless liquid and easily miscible in 1,4-dioxane. Figure 3 shows the GC as drawn by the computer and Table I shows the various significant peaks that appeared in the GC spectrum and their corresponding m/e ratios for all three photolysis runs at various intervals of time. The proposed photodegradation pathways are shown in Scheme 1. 

An evaluation of hydroxyl radical formation in river water and the potential for photodegradation of bisphenol A... 

Abstract—The influence of the hydroxyl radical (OH) on the photodegradation of the estrogen-like compound, bisphenol A (BPA), was examined in this study. The formation rate of OH, normalized to the vernal equinox solar noon condition of Higashi-Hiroshima (34°N) was in the range 0.70-3.25 X 10 °M s in Kurose river water. The total consumption rate constant of OH in river water ranged from 1.66 to 3.89 X 10 s . Based on the photochemical formation rate and the total consumption rate constant of OH, steady-state OH concentrations on the order of 3.33-8.35 X 10 M were determined. The reaction rate constant for OH with BPA determined by competition kinetics was found to be 1.55 X 10 ° s in water containing nitrate ions that photochemically produced OH. 

In yet other polymers, such as with bisphenol polycarbonates both photodegradation and photo-initiated oxidative reactions take place simultaneously. The direct photoreaction is a Erie s rearrangement reaction, while the oxidative reactions result in chain scission and discoloration of the polymer. The chemical pathways involved in the latter process are not well understood. 

Pickett JE. Influence of photo-Fries reaction products on the photodegradation of bisphenol-A polycarbonate. Polym Degrad Stab 2011 96 (12) 2253-2265. 

Rivaton A. Recent advances in bisphenol-A polycarbonate photodegradation. Polym Degrad Stab 1995 49 163-179. 

The photodegradation of unstabilized bisphenol A polycarbonate films is described as an autoaccelerating process initiated by formation of products arising from a formal photo-Fries reaction. Oxidation also contributes as an additional photodegradation pathway. Photosensitive polymers... 

Diepens M, Gijsman P. Photodegradation of bisphenol a polycarbonate with different... 

Epoxy resin based on bisphenol-A-epichlorhydrin 4.32) is susceptible to photodegradation when exposed to prolonged UV radiation [675 814 1174 1340, 1691, 1698, 2109]. 

Photodegradation of bisphenol-A-epichlorhydrin [1225], poly(dian carbonates) [1738] and of polycarbonate blends with polypropylene [1282] and poly(methyl methacrylate) has also been described [673, 1645]. 

Diepens, M. Photodegradation and Stability of Bisphenol A Polycarbonate in Weathering Conditions. Ph.D. thesis, Eindhoven Techincal University, Eindhoven (2009)... 

The most important polycarbonate in commercial terms is derived from 4,4 -isopropylidene-bisphenol. The photodegradation behaviour of this material has been extensively studied both in the absence and presence of air. ... 

Figure 15. Schematic outline of principal features of the nature of the excited state involved in Bisphenol A polycarbonate photodegradation.

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