Non-migrating multifunctional macromolecular antioxidants based on hyperbranched polyglycerol for thermooxidative and photooxidative stabilization of polyolefins

• Multifunctional macromolecular phenolic antioxidants (HbPG-AoxAc) based on hyperbranched polyglycerol (HbPG) were synthesized. • Effective thermo- and photooxidative stabilization of LDPE and PP matrices by the HbPG-AoxAc macrostabilizers was observed. • Negligible leaching of the HbPG-AoxAc macromolecular additives was confirmed by hexane extraction tests. • Demonstrated potential for low-migration stabilization in advanced polyolefin applications. Multifunctional macromolecular antioxidants represent environmentally advantageous alternatives to conventional low molecular mass stabilizers for improving the long-term stability of polyolefins, such as polyethylene (PE) and polypropylene (PP), while minimizing additive migration in the surrounding environment. Hyperbranched macromolecules are especially promising for such purposes, due to their high number of functionalities, ease of production and limited migration. In this study, two hyperbranched polyglycerol (HbPG)-based antioxidants (HbPG-AoxAc) with different molar masses were synthesized by covalent attachment of sterically hindered phenolic units via esterification of the hydroxyl groups of HbPG. These macromolecular stabilizers were characterized by GPC, 1 H NMR and UV-Vis spectroscopies, confirming high antioxidant functionality and well-defined composition. Their performance in thermooxidative and photooxidative stabilization of LDPE and PP was systematically explored and compared with conventional low molecular mass stabilizers using chemiluminescence, oxidative induction time (OIT) determined by DSC, UV-Vis and FTIR spectroscopies. The obtained results indicate that the synthesized HbPG-AoxAc macromolecular antioxidants provide significant stabilization against both thermooxidative and photo-induced degradation in the polyolefin matrices, particularly in PP, and exhibit comparable efficiency to Irganox® 1010 and Irganox® HP-136, while outperforming the secondary antioxidant Irgafos® 168. Importantly, hexane extraction tests revealed negligible leaching of the macromolecular antioxidants, in sharp contrast to the extensive migration and loss observed for the low molecular mass reference additives. These findings confirm the potential of the HbPG-based macromolecular antioxidants as effective, low-migration additives for advanced and environmentally friendly polyolefin applications.