A renewable dynamic covalent network based on itaconic anhydride crosslinked polyglycerol: Adaptability, UV blocking and fluorescence

An adaptive dynamic covalent network with UV blocking and fluorescence is prepared by crosslinking hyper-branched polyglycerol (HPG) with itaconic anhydride (IA) via esterification. The abundant hydroxyl groups and ester linkages in the resulting polymer (HPG/IA) afford the dynamic transesterification at elevated temperatures and enable adaptive behaviors such as stress relaxation and reparability. Because the double bonds of IA are purposely reserved in the crosslinked network, the HPG/IA exhibits excellent UV blocking due to the strong UV absorption of the double bonds. HPG/IA also exhibits strong glass adherence. With a OH/anhydride ratio of 4/1, HPG/IA displays an adhesion shear strength to glass of similar to 30 kPa, which is explained by the flexible structure that ensures a good contact of the polymer film with glass and the high dielectric constant that favors accumulation of electrostatic charges. Interestingly, HPG/IA exhibits strong fluorescence (FL) under UV light, and the FL of HPG/IA exhibits strong selective quenching with respect to Fe3+. These unique properties make HPG/IA a promising functional material for UV blocking glass film and fluorescent Fe3+ sensor.