Regulation of the Interface Compatibility of the 3D-Printing Interpenetration Networks Toward Reduced Structure Anisotropy and Enhanced Performances

Digital light processing three-dimensional (DLP 3D) printing, as a promising manufacturing technology with the capability of fabricating 3D objects with complex shapes, typically develops inconsistent material properties due to the stair-stepping effect caused by weak layer-interface compatibility. Here, we report the regulation of the interface compatibility of the 3D-printing resin with versatile photocuring characteristics and the subsequent mechanical, thermal, and dielectric performances by introducing the interpenetration network (IPN). The preparation procedures, interface structure, flexural and tensile strength, modulus, and dielectric performances of the IPN are presented. The greater penetration depth in 3D printing and the subsequently thermocured epoxy network passing through the printing interface synergistically enhance the interface compatibility of 3D-printing samples, with an unobvious printing texture on the surface of the 3D-printing objects. The mechanical performances of the IPN demonstrate little anisotropy, with a bending strength twice as much as the photosensitive resin. Dynamic mechanical analysis of the IPN indicates that the storage modulus increases by 70% at room temperature and the glass transition temperature (Tg) increases by 57%. The dielectric performance of the IPN demonstrates a 36% decrease in dielectric constant and a 28.4% increase in breakdown strength. Molecular dynamics studies have shown that the IPN takes on higher nonbonded energies and hydrogen bonds than the photosensitive resin, indicating a stronger bonding force between molecular chains, thus leading to better physical properties. These results illustrate the effectiveness of the IPN toward enhanced 3D-printing interlayer compatibility for excellent mechanical, thermal, and electrical performances.