Modulating the mechanical properties of poly(diol citrates) via the incorporation of a second type of crosslink network

Novel citric acid-based polyesters were synthesized by condensation of citric acid, 1,8-octanediol, and unsaturated monomers such as glycerol 1,3-diglycerolate diacrylate and bis(hydroxypropylfumarate). Under the synthesis conditions used, the crosslinked elastomeric network exhibited a wide range of mechanical properties. The mechanical properties of acrylated elastomers ranged from 7.4 to 75.9 MPa for Young's modulus, 2.8 to 15.7 MPa for ultimate tensile stress, and 86 to 133% for elongation at break. The mechanical properties of fumarate-containing elastomers ranged from 16.4 to 38.3 MPa for Young's modulus, 5.5 to 10.2 MPa for ultimate tensile stress, and 218 to 260% for elongation at break, which depended on the content of 1-vinyl-2-pyrrolidinone. Addition of a secondary crosslink network is a viable method to increase the range of mechanical properties of citric acid-based biodegradable elastomers. The glass transition temperature (T_g) of the elastomers is between -12.7 and -1.6°C, confirming that all the elastomers are in a rubbery state at room temperature.