Research on the Innovative Polymeric Types of Photo-stabilizers via Photo-Fries’ Rearrangement
林 木 獅
Dr. Mu-Shih Lin
|關鍵字:||高分子型光安定劑;Photo-Fries’重排反應;鄰羥基苯酮;聚丙烯酸酯;環氧樹脂;芳香族聚醯胺酯;芳香族聚酯;IPN 聚合物;Photo-stabilizer;Photo Fries rearrangement;o-hydroxybenzophenone;Polyacrylate;Epoxy;Aromatic Polesteramide;Aromatic Polyester;IPN|
Long term out-door uses of polymers are very common. Therefore, the weatherability of polymers becomes an important consideration. Photostabilization of polymers can be achieved by different means. These include screen of ultraviolet light, deactivation of excited states, addition of radical scavengers, and uv absorbers. Use of uv absorbers to dissipate the photo energy and convert it into a harmless heat, and therefore, to retard the adverse effect of irradiation is widely applied in polymer technology. However, most commercial uv absorbers are low molecular weight derivatives of o-hydroxybenzophenone. When these low molecular weight uv absorbers are incorporated into polymers, many drawbacks occur quite often, such as leaching problem during long term out-door application and evaporation problem during thermal processing. Furthermore, when these uv absorbers are incorporated into polymer in large quantities, drawback of mechanical properties are often observed. In order to avoid these drawbacks, we are interested in innovative high molecular weight polymeric types of photostabilizers. In a kinetic and mechanism study of photo-fries’ rearrangement for poly(phenyl acrylate) (PPA) and poly(p-methylphenyl acrylate) (PMPA), both acrylic polymers underwent photo-fries’ rearrangement, leading to the production of o-hydroxybenzophenone moiety at the pendant group in different rate constants, and both were expected to be inherent photostabilizers, with PMPA a better one (chapter 1). Both PPA and PMPA were then used to protect thermoplastics against photodegradation and their protection to PET was confirmed (chapter 2). The same idea also applied to thermosetting polymers. Thus, an interpenetrating polymer networks (IPN) based on epoxy and bisphenol-A diacrylate was proved to produce o-hydroxybenzophenone moiety when this material was under uv irradiated. And its photostabilization of IPN materials was successfully achieved (chapter 3). This application also extended to the IPN material of epoxy and methacrylated epoxy, and was again proved successful (chapter 4). Considering a similar photo-fries’ rearrangement, aromatic polyester, random and alternating copolyesters, and random and alternating copolyester-amides were investigated under accelerated uv irradiation, o-hydroxybenzophenone moiety could be found at the main chain of these polymers, with poly(bisphenol-A terephthalate) possessing the highest rate constant of photo-fries’ reaction (chapter 5). Confirmation of the photostabilization capability for these polymeric type phtostabilizers by blending each one with PET were performed by kinetic studies (chapter 6). In conclusions, innovative polymeric types of photostabilizers via photo-fries’ rearrangement has been successfully developed in this research.
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