Chemical modification of Hyflon® AD copolymer end groups by means of physical and chemical treatments. A joint spectroscopic and quantum chemical investigation

•Chemical modifications occurring in a class of amorphous fluorinated polymers have been investigated.•The adopted experimental tool is Vibrational Spectroscopy.•Quantum chemical calculations allowed to rationalize experimental data.•The joint experimental and theoretical approach shed light on the physico-chemical phenomena occurring.

In this paper is presented a study on the effects of physical treatments, namely electron beam irradiation or fluorination, on a perfluoropolymer copolymer of tetrafluoroethylene with 2,2,4-trifluoro-5-trifluoromethoxy-1,3-dioxole (Hyflon® AD copolymer). The analysis has been carried out by means of IR spectroscopy and quantum chemical modeling based on density functional theory; this combined experimental/theoretical approach has proven effective for the interpretation of previously unassigned IR bands, which are associated to functional groups generated by polymer degradation and chain scission. We performed a systematic screening of chemical groups and structures compatible with degradation pathways that are possible from the chemical point of view: the chemical mechanisms and the correlation with the spectroscopic experimental data (both frequency and intensity) provide guidelines in understanding the phenomena. Moreover, the spectroscopic experimental/theoretical and chemical approaches allowed us to identify some chemical structures responsible for the unassigned IR bands in the CO stretching frequency region above 1800 cm−1, which is typical for carbonyl groups in fluorinated systems.

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