Polydimethylsiloxane (PDMS) has been widely used in microfluidic devices, flexible electronics, template replication and medical engineering due to its excellent flexibility, transparency, fluidity and biocompatibility. In recent years, due to the advantages of free design, rapid manufacturing and high-precision mold free forming, the research of 3D printing PDMS has attracted much attention and developed rapidly.
Wang Xiaolong, team of Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, has recently developed a general two-step photothermal curing method to achieve 3D printing of high-precision PDMS structural parts. As shown in Figure 1, the researchers used sylgard 184 silicone rubber, for example, can be cured by adding a certain amount of copolymers (m-pdms) of methylacetoxypropylmethylsiloxane and dimethylsiloxane (not more than 20%) to its precursor solution; then, the UV assisted direct writing 3D printer is used to achieve high-precision curing of m-pdms while printing during ink extrusion Finally, the printed samples were heat cured and cross-linked at 120oc to achieve high-performance PDMS structure.
Figure: UV curing assisted direct writing 3D printing PDMS schematic diagram and mechanical properties, molding accuracy and application display of the printed parts
The results show that the wire rod formed by UV curable direct writing has excellent self-supporting property, can form a long-span structure with a minimum size of less than 100 μ m, and can be stacked layer by layer to form printing pieces such as hollow cylinder, lattice and honeycomb structure. Moreover, the PDMS printing pieces have excellent mechanical properties after thermal crosslinking, and their breaking strength and elongation at break are 3.8, respectively 6 MPa and 123%, better than the reported 3D printing PDMS. The method can be applied to the construction of micro liquid devices and other fields. More importantly, this two-step photothermal curing method has good universality. It can realize 3D printing of other silicone rubber materials, including human silica gel, mold silica gel, potting glue and so on. Therefore, it has application potential in biomedical, flexible electronics, soft robot and other fields.
The above work was recently published online in macromolecular rapid communication (DOI: 10.1002 / Marc. 202000064), and relevant research was supported by National Natural Science Foundation of China, key scientific research projects of Chinese Academy of Sciences and "light of the west" talent training program.
Source: Lanzhou Institute of Chemical Physics