DLP Printing High-Performance Acryloyl-Functional Benzoxazine Based on Dual-Cure System

Light-based three-dimensional (3D) printing technologies are regarded as one of the most promising manufacturing methods. However, 3D printed objects based on free radical polymerization have disadvantages such as anisotropy, poor mechanical strength, and heat resistance and cannot meet the requirements of high-performance applications. This study reports a class of acryloyl-functional benzoxazine exhibiting excellent mechanical properties, heat resistance, and flame retardancy. 3-Acryloyl-3,4-dihydro-2<i>H</i>-1,3-benzoxazine (Ph-am) and bis(3-phenyl-(3-acryloyl-3,4-dihydro-2<i>H</i>-1,3)-benzoxazine) (Ba-am) have been synthesized by the Mannich reaction using acrylamide as the amine source. The acryloyl-functional benzoxazine was printed by a DLP printer. Then, the oxazine ring undergoes ring-opening polymerization under a high temperature to form a dense polymer, enabling the printed object to exhibit isotropy. The Mannich bridge and hydrogen-bond structure in polybenzoxazine enhance the mechanical properties and thermal resistance of printed objects. The glass-transition temperature (<i>T</i>_g) and tensile strength of dual-cured Ph-am reach 270 °C and 116.55 MPa, respectively. Meanwhile, after blending modification with tris(2-hydroxyethyl)-isocyanurate triacrylate, hybrid polymer networks have been formed. The tensile strength and Young's modulus of dual-cured P₈B₂T₁ reaches 130.89 MPa and 6.45 GPa, respectively. Moreover, the dual-cured P₈B₂T₁ shows good flame retardancy. This high-performance photosensitive resin has great potential in fields such as aerospace, automotive, and electronics.