Synthesis, physical properties and photodegradation of functional poly(butylene succinate) covalently linking UV stabilizing moieties in molecular chains

Functional biodegradable poly(butylene succinate) (PBS) covalently linking different amounts of anti-UV moieties in the polymer chains were synthesized from succinic acid (SA), 1,4-butanediol (BDO) and 2-hydro-4-(2,3-epoxypropoxy) benzophenone (HEPBP) via a two-step esterification and melt polycondensation process. The 1 H NMR and UV–vis spectra confirm the chemical structure and that the UV absorbing groups were preserved during polycondensation. The crystallization process is enhanced while the melting temperature hardly changes. The introduction of HEPBP does not affect the thermal stability and the crystal structure of PBS. In the accelerated aging test, all the samples underwent photo degradation but the incorporation of HEPBP delayed the degradation process, which is verified by the results of molecular weight and surface morphology changes. Higher HEPBP content leads to lower degradation rate and better UV protection effect. Furthermore, better resistance property to solvent extraction is achieved in the functional PBS. Trace amount of HEPBP migrated from PBS matrix while most of the UV absorber was extracted out in UV absorber/PBS mixture. As a result, the covalently linking UV stabilizing structure HEPBP not only delays the photo degradation of PBS but also endows functional PBS with excellent resistance when exposed to solvent, which is important for PBS application in long term use.