Strong and Tough Polylactide via Branched Rigid-Flexible Hybrid Segments

Polylactide (PLA), as a biodegradable polymer, holds great promise in biomedicine, packaging, and sustainable materials. However, inherent brittleness and low fracture toughness limit its practical applications. To address the strength–toughness trade-off, we designed and prepared a high-molecular weight (Mη > 260 kDa) branched block copolymer, branched polyethylene glycol-polylactide (B-PELA). This architecture was constructed by using a branched polyester as a macroinitiator for the ring-opening polymerization of l-lactide, successfully integrating rigid PLA and flexible polyethylene glycol (PEG) segments. Specifically, the long-chain branched physical network significantly enhances chain entanglements to retain structural integrity for high strength. Concurrently, the branched PEG nodes act as topological anchors to efficiently dissipate strain energy and guide extensive plastic deformation. The synergy enables B-PELA to achieve high tensile strength (64.4 MPa), high elongation at break (52%), and superior toughness (30.6 MJ·m–3). Furthermore, B-PELA exhibits excellent biocompatibility and hemocompatibility. Therefore, this work provides a novel strategy for constructing high-performance PLA, enabling its potential application in bioimplants.