Synthesis of Reactive Polyesters Possessing Phenol Pendant Groups Through Selective Ketene/Hydroxyl Addition...

Reactive polymers are attractive precursors for the synthesis of functional polymers and the preparation of crosslinked polymers. This work reports an effective approach for the synthesis of reactive polyesters with pendant phenol groups employing a newly synthesized Meldrum's acid derivative (MAHP) as the monomer through a selective ketene/hydroxyl addition reaction. The MAHP-based polyester (P-MAHP) shows an inherent viscosity of 0.123 dL g^-1 (measured in 1-methyl-2-pyrrolidinone), a glass transition temperature (T_g) of 30°C (measured with a differential scanning calorimeter), and a thermal stability of about 240°C. P-MAHP, like phenolic novolac (PN), is utilized as a crosslinking agent for epoxy compounds. In dynamic mechanical analysis, the P-MAHP-crosslinked epoxy resin (ER_P-MAHP) exhibits a T_g of 102°C (lower than the value of 155°C founded with the PN-crosslinked analogue (ER_PN)) and a storage modulus of 2.37 GPa (higher than the value of 1.85 GPa found with ER_PN). Moreover, based on the dynamic ester bonds, ER_P-MAHP possesses associactive covalent adaptable networks exhibiting stress relaxation and physical recycling features. The results demonstrate a significant progress on polymer chemistry and synthesis of polymeric materials.