Synthesis of novel acrylic liquid-crystal resin and its in-situ enhancement in light-curing 3D printing performance

Acrylic liquid-crystal resin (ALCR) was synthesized in three steps using 4-hydroxybenzoate 4-carboxylic phenyl ester as the mesocrystalline unit. The structure, heat resistance, and liquid–crystal properties of the ALCR were systematically investigated. The ALCR was used to produce new 3D printing inks, which exhibited good fluidity and rapid photopolymerization ability to meet the rheological prerequisites of 3D printing ink. Compared with commercial ink, the initial decomposition temperature increased from 304.9 to 334.3 °C, the glass transition temperature increased from 74.8 to 89.8 °C, and the storage modulus increased from 1107.6 to 2230.6 MPa for the ALCR inks. The tensile strength, elongation at break, flexural strength, impact strength, and hardness of an ink containing 20% ALCR were improved to 65.3 MPa, 17.3%, 103.9 MPa, 4.8 kJ m−2, and 77.1 HD, respectively, corresponding to 147.4%, 174.7%, 207.4%, 171.4%, and 106.6% of the values for commercial ink. These results indicate that ALCR can effectively improve the mechanical properties of 3D-printed products in-situ. This is because the liquid-crystal molecules in the product stack to form mesogenic domains. When subjected to an external force, these mesogenic domains exploit their own orientation, cross-linking, and high-strength characteristics to effectively improve the mechanical properties of the product.