Matrix-assisted laser desorption ionization mass spectrometry (MALDI) is an excellent method to use in detg. the structure of the mols. produced in the photo-oxidative degrdn. of nylon 6 at 60 °C in air. The MALDI spectra of photo-oxidized nylon 6 (Ny6) show the presence of over 40 compds., as compared to only 3 in the blank Ny6 sample. The extremely favorable event here is that the MALDI spectra present so many new well-resolved peaks, which provide information on the structure and end groups of the oxidn. products. The structural anal. of the photo-oxidn. products provided by the MALDI spectra allowed us to draw a detailed map of the photo-oxidn. mechanisms of Ny6 (Schemes 1-4). The presence of the majority of the oligomers listed in Table 1 had not been revealed before. Our results extend and modify the currently accepted picture for the photo-oxidn. mechanisms of Ny6. In fact, our results confirm previous insights that the hydrogen abstraction and subsequent formation of a hydroperoxide intermediate actually occur but also reveal that Norrish I and Norrish II chain-cleavage reactions play an important role in the photo-oxidn. process of Ny6. This essential feature of the process had been missed in previous studies focused on UV and IR techniques. The peculiarity of our approach consists of using a high-sensitivity and nonaveraging technique such as mass spectrometry, which allows the detection and monitoring of each new oligomers formed during the oxidn. process. This is a remarkable result, and it should be expected that future MALDI studies may have an impact on the current views of photo-oxidn. processes of other polymer systems
New Vistas in the Photo-Oxidation of Nylon 6
SCarroccio;
2003
Abstract
Matrix-assisted laser desorption ionization mass spectrometry (MALDI) is an excellent method to use in detg. the structure of the mols. produced in the photo-oxidative degrdn. of nylon 6 at 60 °C in air. The MALDI spectra of photo-oxidized nylon 6 (Ny6) show the presence of over 40 compds., as compared to only 3 in the blank Ny6 sample. The extremely favorable event here is that the MALDI spectra present so many new well-resolved peaks, which provide information on the structure and end groups of the oxidn. products. The structural anal. of the photo-oxidn. products provided by the MALDI spectra allowed us to draw a detailed map of the photo-oxidn. mechanisms of Ny6 (Schemes 1-4). The presence of the majority of the oligomers listed in Table 1 had not been revealed before. Our results extend and modify the currently accepted picture for the photo-oxidn. mechanisms of Ny6. In fact, our results confirm previous insights that the hydrogen abstraction and subsequent formation of a hydroperoxide intermediate actually occur but also reveal that Norrish I and Norrish II chain-cleavage reactions play an important role in the photo-oxidn. process of Ny6. This essential feature of the process had been missed in previous studies focused on UV and IR techniques. The peculiarity of our approach consists of using a high-sensitivity and nonaveraging technique such as mass spectrometry, which allows the detection and monitoring of each new oligomers formed during the oxidn. process. This is a remarkable result, and it should be expected that future MALDI studies may have an impact on the current views of photo-oxidn. processes of other polymer systemsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
