Single-Chain Nanoparticles Break the Strength-Toughness-Processability Trilemma in Polymer Glasses

The strength-toughness trade-off in polymer glasses presents a fundamental challenge, as enhancing one property typically compromises the other. Moreover, efforts to enhance mechanical performance often lead to increased melt viscosity, which in turn hinders processability. Here, we demonstrate that incorporating single-chain nanoparticles (SCNPs) breaks this trilemma by simultaneously enhancing strength, toughness, and processability. Through a combined experimental and molecular dynamics simulation approach, we reveal that SCNPs with higher glass transition temperature than the matrix not only increase yield strength but also delay and homogenize crazing, leading to dramatically improved toughness in the glassy state. Importantly, the SCNPs reduce melt viscosity in the molten state, countering the conventional trend of viscosity increase in nanocomposites. This triple enhancement establishes a universal framework for designing high-performance polymer glasses that transcend traditional material property limitations.