Low-Migration Macromolecular Benzophenones as UV Absorbers for Food Packaging Polymers

Extending the durability of polymer plastics and minimizing toxicity concerns to humans and the environment are among the essential goals toward sustainability. Continuing our efforts in this area, we report herein the design, optimized synthesis, and migration studies of macromolecular benzophenones (MBPs) using three important building blocks including poly(ethylene-co-acrylic acid), pentaerythritol, and tris(2,3-epoxypropyl)isocyanurate for sustainable food packaging applications. All MBPs are synthesized in gram scales, with the synthetic limitations being investigated. Interestingly, polymer-bound triphenyl phosphine is found to be an effective and recyclable Lewis-based catalyst for an epoxy ring opening reaction to prepare an MBP in only one step starting from 2,4-dihydroxybenzophenone. The migration profiles of MBPs are much improved in comparison with that of the small molecule BP-1 (Uvinul 3008) and on par with the Food and Drug Administration-approved macromolecular cyanoacrylate Uvinul 3030 (UVN). They also show an excellent ability to protect polystyrene from photodegradation and yellowing processes, suggesting that they may find a real-life application in the plastic industry.