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Graphical Abstract:

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.

A 3D graphene network was constructed in polyamide 6 (PA6) monomers through the reduction and self-assembly of graphene oxide (GO), and then PA6 nanocomposites with low graphene content were fabricated through in situ polymerization. The effects of the 3D graphene network on the structure and properties of the PA6 were systematically investigated. Results show that the 3D graphene network can significantly improve the thermal conductivity of PA6. In the case of the PA6 with only 0.25 wt % graphene, its thermal conductivity is 0.69 W/(m K), about 2.88 times of that of the pure PA6. This improvement is attributed to the more-compact thermal conductive paths of the 3D graphene network, and its stronger interfacial interaction with PA6 in this work compares with those of pre-synthesized free-standing 3D graphene networks. Moreover, the mechanical properties and water resistance of PA6 also have significantly improved with the incorporation of the 3D graphene network.

Large-scale shrinkages and holes are the two critical disadvantages of the silicone resin prepared by the sol–gel technology and cured via traditional processes. To simultaneously overcome both problems, sol–gel technology along with γ-radiation curing is developed for preparing organic–inorganic hybrids with large size and thicknesses. A hyperbranched polysiloxane (H-PMAPS) is successfully synthesized through the controlling hydrolysis of 3-methacryloxypropyltrimethoxysilane and then is subjected to nuclear magnetic resonance (Si NMR) and Fourier transform infrared (FTIR) spectra to characterize its structure. Room-temperature radiation curing followed by thermal curing out-of-the-mold at 170 °C for 3 h is suitable for curing H-PMAPS (denoted as RC-T/PMAPS). The RC-T/PMAPS hybrid exhibits a homogeneous phase with a riverlike morphology, excellent thermal resistance, and dielectric properties and is optically transparent. These attractive features of the RC-T/PMAPS hybrid suggest that the new approach proposed here is suitable for cutting-edge industries to develop high-performance organic–inorganic hybrids.