Star poly(lactide-co-glycolide) and poly(ε-caprolactone) polyurethanes with shape memory properties for biomedical applications

[Display omitted] •Mechanical properties of poly(ester-urethane) are modulated by addition of star PLGA.•Low amounts of 4- or 6-arms PLGA improve the shape-memory properties.•Flexural strength is decreased by addition of low amounts of star PLGA for better surgical handling.•Linear degradation profiles are obtained when mixing star and linear PLGA in poly(ester-urethane) Shape memory polyurethane (SMPU) have the capacity to alter and regain their form in reaction to a stimulus (eg. temperature, pH) and have been investigated in biomedical applications. In this work, the shape memory properties of poly(ester-urethane)s (PEU) are studied as a function of the functionality of the poly(lactide-co-glycolide) (PLGA) and poly(e-caprolactone) (PCL) pre-polymers. Two distinct series of PEU are synthesized by reaction between linear and star-shaped PLGA polyols initiated by pentaerythritol (4-arms PLGA) or dipentaerythritol (6-arms PLGA) with PCL di-isocyanate prepolymers. The different PEUs exhibit thermally actuated shape memory properties and tunable mechanical properties with Young’s moduli reaching up to 96 MPa and elongation at break reaching 930 %. The integration of low amounts of PLGA star within the PEU structure increases the material’s shape memory properties, enhancing both fixity (from 45 % to 96 %) and recovery ratios (from 88 % to 92 %). Further exploration into potential applications led to the formulation of porous foams via the solvent casting/particles leaching (SC/PL) process. These foams exhibited high porosity ranging from 74 % to 83 % with pore sizes spanning from 100 to 300 µm. Their mechanical properties are close to the human meniscus with Young’s modulus ranging from 0.13 MPa to 0.53 MPa. Moreover, integration of PLGA star within the PEU scaffold decreases the flexural strength that is an important parameter for potential mini-invasive surgery.