Wirkungsweise von stabilisatoren in polymeren unter berücksichtigung der 2‐hydroxyphenylbenzotriazole

Abstract

In the first part a survey is given on UV screeners, UV absorbers, wenchers of excited states, antioxidants and peroxide decomposers.In the second part UV absorbers,e.g. Tinuvin P (2-(2'-hydro~y-5~methylphenyl)benzotriazole, Scheme 8) are described in detail where intramolecular proton transfer occurs in the excited state (TIN(intra)). This proton transfer may be accompanied and/or followed by very fast and effective temperature dependent radiationless deactivation processes which are promoted by internal vibrations and librations of the molecule.

Non-typical fluorescence studies of excited and ground state proton and hydrogen transfer

“…Both experimental and theoretical aspects of lightinduced proton or hydrogen transfer have been reviewed many times [8,. In recent years, the research has been shifting towards practical applications of ESIPT in such areas as fluorescence sensing and imaging [50][51][52][53][54], clinical diagnostics [55], white light emitting materials [56,57], solid state emitters [58], functional polymer materials [59], polymer stabilizers [60], micro-and nanoscale lasers [61].…”

Hydroxyphenyl-s-triazines: advanced multipurpose UV-absorbers for coatings

“…[1][2][3] More than three decades ago, it became evident that hindered amine light stabilizers (HALS)-which interact with radicals 4 and retard the photooxidative degradation of polymers-are key additives for the stabilization of clearcoats. 5,6 HALS are mainly derivatives of 2,2,6,6-tetramethylpiperidine and reported to function mainly as chain-breaking antioxidants 7 and, in addition, transition metal complexing agents. 8 A variety of HALS compounds is available where the most important group is difunctional piperidine derivatives linked by diester, as shown in Fig.…”

New UV Absorber for PET Packaging: Better Protection With Less Discoloration

“…Besides their strong UV absorbance over a broad range of wavelengths, the high level of photostability of the o-hydroxybenzotriazoles is particularly noteworthy. This has been attributed to a very rapid deactivation of the photochemical excited state via an excited-state intramolecular proton transfer (ESIPT) mechanism (Figure 3) [10]. This process continuously regenerates the ground state molecule, which can then absorb another photon of incident UV light.…”