MALDI Investigation of Photooxidation in Aliphatic Polyesters:  Poly(butylene succinate)

Abstract

Matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS) has been found to be an excellent method to determine the structure of the molecules produced in the photooxidative degradation of poly(butylene succinate) (PBSu) at 60 °C in air. Over 20 compounds are present in the MALDI spectrum of the oxidized sample, as compared to only 4 in the original PBSu sample. The MALDI spectra present many new well-resolved peaks, which provide information on the structure and end groups of the oxidation products. The MALDI peaks correspond to sodiated ions of oxidized oligomers, and they have been assigned to polymer chains containing succinic and malonic acid, butyl ester, ethyl ester, and butyl formate end groups. These oligomers had not been revealed before. The mechanisms accounting for the formation of photooxidation products of PBSu involve the operation of several reactions: (i) oxidation of hydroxyl end groups; (ii) α-H abstraction decomposition; (iii) Norrish I photocleavage. Our results establish the photooxidation mechanisms of PBSu. The novelty of our approach consists of using a nonaveraging technique, such as mass spectrometry, which allows the detection of individual compounds formed during the oxidation process. This is a remarkable result, and it should be expected that future MALDI studies might have an impact on the current views on photooxidation processes of other polymer systems.

Effects of ZnO quantum dots on the photostability of acrylate photopolymers used as recording materials

“…This corroborates the fact that 2EEEA units were responsible for the instability on PETTA/2EEEA film. This source of instability had already been recognized in several systems containing ether groups [49,[51][52][53]. …”

“…Their formation was explained by chain scission reactions (Norrish I cleavage and ester elimination reactions) that took place both on PETTA and 2EEEA units [49,50]. In the 1300-600 cm -1 domain, new absorption bands developed and they were assigned amongst others, to C-O-C bond vibrations (Fig.…”

Photostability of acrylate photopolymers used as components in recording materials

“…They also clearly evidenced the formation of carbon dioxide trapped in the polymer matrix. According to the literature [35,47], Norrish I cleavage and ester elimination reactions (chain scission reactions) accounted for the formation of this gas. To get more information about the photochemical aging of the polymer, photo-IR experiments were performed.…”

“…In situ infrared spectra not only confirm the release of CO 2 but also show the presence of carbon monoxide. This latter resulted from chain scission reactions as in the case of carbon dioxide [35,47].…”

“…These latter species could further undergo b scission, cage reaction or hydrogen abstraction reaction and would cause the chemical modifications of the polymer matrix. Besides, MALDI analysis performed on poly(butylene succinate) highlighted that, upon irradiation, this polymer undergoes oxidation of the hydroxyl end groups, a-hydrogen abstraction and Norrish I cleavage reactions [35].…”