Hashemi Seyyed Alireza, Ghaffarkhah Ahmadreza, Hosseini Hadi, Arjmand Mohammad
Nanomaterials and Polymer Nanocomposites Laboratory, School of Engineering, University of British Columbia, Kelowna, BC V1V 1V7, Canada.
ACS Appl Mater Interfaces. 2024 Sep 4;16(35):46923-46936. doi: 10.1021/acsami.4c09971. Epub 2024 Aug 20.
3D printing ultralightweight porous structures using direct ink writing (DIW) while maintaining their mechanical robustness is highly challenging. This difficulty is amplified when low ink concentrations are used to create complex geometries. Herein, this shortfall was addressed by interfacially jammed emulsion gels. The gel emerged from the electrostatic interaction among synergized nanomaterials (graphene oxide (GO) and cellulose nanocrystals (CNCs)) in the aqueous phase and a ligand in the oil phase. This interaction led to the jamming of the nanoparticles and the creation of stable emulsion gels. The formed interfacial assemblies were further treated by post-jamming ionic cross-linking with NaHCO, which dictated the emulsion gels' rheological characteristics, enhancing the ink's viscoelastic properties for high-resolution 3D printing. The customizable emulsion system allows control over porosity from the macro- to the micro-scale and generates complex geometries with desired compositions. By manipulating post-annealing processes and varying concentrations, it is possible to achieve aerogels that feature a remarkably low density (∼2.63 mg/cm) and adjustable mechanical robustness (elastic modulus of 0.45 MPa). Additionally, this method allows for producing aerogels with flexible or stiff characteristics as required, alongside the capability to tailor specific electromagnetic shielding effectiveness (ranging from 6791 to 19615 dB cm/g), showcasing the technique's versatility and engineerability.
使用直接墨水书写（DIW）3D打印超轻多孔结构并同时保持其机械强度极具挑战性。当使用低墨水浓度来创建复杂几何形状时，这一困难会加剧。在此，通过界面堵塞乳液凝胶解决了这一不足。该凝胶由水相中的协同纳米材料（氧化石墨烯（GO）和纤维素纳米晶体（CNC））与油相中的配体之间的静电相互作用形成。这种相互作用导致纳米颗粒的堵塞并形成稳定的乳液凝胶。通过用NaHCO进行堵塞后离子交联对形成的界面组装体进行进一步处理，这决定了乳液凝胶的流变特性，增强了墨水的粘弹性以用于高分辨率3D打印。可定制的乳液系统允许从宏观到微观尺度控制孔隙率，并生成具有所需组成的复杂几何形状。通过控制退火后工艺和改变浓度，可以实现密度极低（约2.63 mg/cm）且机械强度可调节（弹性模量为0.45 MPa）的气凝胶。此外，该方法能够根据需要生产具有柔性或刚性特性的气凝胶，同时具备定制特定电磁屏蔽效能（范围从6791到19615 dB cm/g）的能力，展示了该技术的多功能性和可工程性。
