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Tobias Baeyens, Kai Rist, Yohann Catel, Sabine Rosenfeldt, Holger Schmalz, Seema Agarwal

Macromolecules 2024, https://doi.org/10.1021/acs.macromol.4c01108

The brittleness of neat (meth)acrylic resins hampers their use in additive manufacturing, an emerging method in dentistry. Here, we show that polybutadiene-block-poly(methyl methacrylate) (PB-b-PMMA) diblock copolymers are highly efficient toughening agents for methacrylic resins, resulting in a significantly enhanced fracture toughness (up to K_max = 2.2 MPa m^1/2) without compromising mechanical strength or processability. The composition and molecular weight of the diblock copolymers, their weight fraction in the resin, and the preparation method were systematically varied, revealing most efficient toughening for a diblock copolymer with 60 wt% PB and a Mn of 20 kg mol^-1 (5 wt% in resin). The formation of homogeneously dispersed worm-like micelles with a soft, resin-immiscible PB core and a resin-miscible PMMA corona was found to be essential for toughening. These results underscore the potential of diblock copolymers as highly efficient toughening agents for methacrylic resins, advancing dental material development for 3D printing applications.