The study investigates the impact of bidispersity on the mechanical properties of star-polymer thin films, focusing on their toughness and impact resistance. Using molecular dynamics simulations, the researchers found that increasing the dispersity of the star polymers, particularly by varying the lengths of the arms, significantly enhances the toughness and impact resistance of the films without compromising their elastic modulus. The higher dispersity leads to less entanglement and better interpenetration, resulting in increased toughness. The findings highlight the potential of controlled dispersity as a design strategy to improve the mechanical properties of polymer composites, particularly in the context of impact-resistant materials. The study also provides insights into the molecular mechanisms underlying these improvements, such as the alignment and entanglement behavior of the polymer chains during deformation.The study investigates the impact of bidispersity on the mechanical properties of star-polymer thin films, focusing on their toughness and impact resistance. Using molecular dynamics simulations, the researchers found that increasing the dispersity of the star polymers, particularly by varying the lengths of the arms, significantly enhances the toughness and impact resistance of the films without compromising their elastic modulus. The higher dispersity leads to less entanglement and better interpenetration, resulting in increased toughness. The findings highlight the potential of controlled dispersity as a design strategy to improve the mechanical properties of polymer composites, particularly in the context of impact-resistant materials. The study also provides insights into the molecular mechanisms underlying these improvements, such as the alignment and entanglement behavior of the polymer chains during deformation.