Photochemical crosslinking of poly-(ethylene–butyl-acrylate) copolymers functionalized with anthracene moieties by reactive extrusion

• We have modified EBA copolymers with anthracene chromophores by reactive extrusion.
• Photodimerization of anthracene takes place in the solid-state upon UV irradiation.
• Photocleavage of anthracene dimers occurs partially under nitrogen.
• DMTA and mechanical properties were studied before and after UV irradiation.
• Photocrosslinking of EBA by anthracene dimerization improves mechanical properties.

Anthracene chromophores were successfully bonded onto an ethylene-co-butyl acrylate (EBA) with a content of 19% butyl ester (BA) by transesterification reaction in the molten state using dibutyl tin oxide (DBTO) as catalyst. The modified EBA with covalently attached anthracene moieties (EBA-Ant) were crosslinked by irradiation at 365 nm due to face-to-face dimerization in the solid state using films of 10 and 200 μm thickness. Also, the anthracene photodimers were cleaved in solid films by irradiating at 280 nm. The photoreactions were monitored by UV and fluorescence spectroscopic methods while the mechanical properties of the materials, initial and irradiated, were studied by Dynamic Mechanical Thermal Analysis (DMTA) coupled with measurements of tensile strength and retention of elongation at break.

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