Home-3D Printed Silicone Lattice Mixes Antifungal Resistance with Vibration Isolation
Researchers fromJiangnan University, a research university in Wuxi, China, and Jiangda Vibration Isolator Co., Ltd., a vibration-control manufacturer based in the same city, have developed a 3D printed silicone rubber lattice designed to resist fungal growth while absorbing vibration and repeated compression in marine environments. Reported in a study published inAdvanced Composites and Hybrid Materials, the work addresses a materials trade-off that has limited earlier approaches: surface coatings can lose antimicrobial effectiveness when worn, while higher filler loadings can improve fungal resistance but reduce the flexibility silicone rubber needs for cushioning applications.
Additive manufacturing is central to the study because it lets the authors control both composition and internal geometry. Conventional foaming methods tend to produce pores with irregular size and distribution, making performance harder to predict and optimize. Here, the team formulated a printable composite ink using silicone rubber and hexagonal boron nitride, or hBN, then deposited it through a custom gantry-type 3D printing system fitted with a 250 μm nozzle. Optical microscopy and micro-CT images showed ordered filaments, stable interlayer bonding, and preservation of the intended lattice architecture. Rheology tests also established a processing limit: inks containing more than 5 wt% hBN became too viscous for reliable extrusion, making 1–5 wt% the workable composition range. That processing window matters because it shows the balance between printability and antifungal performance was part of the design problem, not an afterthought.
Antifungal testing produced the clearest performance contrast. Under ASTM G21 conditions using five fungal species, hBN-free silicone lattices developed visible colonization after 28 days, including dark spots and dense white hyphal networks, corresponding to a fungal growth rating of 2. Lattices containing hBN inhibited growth more effectively as filler content increased. At 5 wt% hBN, fungal coverage fell below 0.8%, and the material achieved a rating of 0, meaning no observable fungal growth under the standard. Geometry also influenced performance. For a given hBN concentration, larger filament spacing increased fungal coverage, especially at lower filler loadings, because more exposed surface area made attachment easier. In a second test using carbon-rich peptone-dextrose-agar to accelerate growth, the hBN-free lattice degraded rapidly, while the 5 wt% hBN version retained its white appearance and showed no internal fungal penetration over seven days.
The paper links that fungal resistance to two measurable effects. First, hBN increased surface hydrophobicity: water contact angle rose from 106° in neat silicone rubber to 121° with 5 wt% hBN, while the lattice architecture raised it further to 124°. That more water-repellent surface reduces fungal spore penetration. Second, microscopy data indicated biochemical and physical damage at the fungus-material interface. Fluorescence imaging detected reactive oxygen species at the interface between fungi and the hBN-filled composite, but not with neat silicone rubber, while SEM images showed disrupted hyphal surfaces on the hBN material. In the authors’ interpretation, hBN contributes both a hydrophobic barrier and direct antifungal activity through oxidative stress and cell-wall damage.
Mechanical testing showed that the same lattice architecture also functioned as a cushioning structure. Compression curves contained an initial elastic region, an extended stress plateau, and a final stage of rapidly increasing stress. The authors attribute that broad plateau to elastic buckling in the ordered lattice cells, creating a near-zero-stiffness region associated with energy absorption. Finite element simulations and in situ observations supported that mechanism. Durability remained high under repeated loading: a lattice containing 5 wt% hBN with 0.6 mm filament spacing retained more than 90% of its maximum stress after 10,000 compression-release cycles at 70% strain, and post-test micro-CT analysis found no structural defects.
Vibration tests extended those results beyond compression. A sinusoidal sweep showed that introducing the lattice shifted the isolation frequency leftward compared with a solid reference, widening the effective vibration-isolation range. Random vibration tests produced direction-dependent results. Under one condition, X- and Y-direction isolation efficiencies reached 81.9% and 91.2%. Under a second condition, those values rose to 92.5% and 91.4%. One specific configuration, EL-3-0.6, delivered 30.0% and 11.3% higher efficiency than its solid counterpart under the two test conditions. Additional tests at −20 °C, at 25 °C with 80% relative humidity, and at 150 °C showed isolation efficiencies above 80% across all three directions tested. Even after fungal exposure in a carbon-rich medium, vibration-isolation performance changed only marginally over the test period.
Taken together, the results describe a 3D printed elastomer lattice that uses controlled architecture to manage a materials trade-off: adding enough functional filler to resist fungal growth without giving up the flexibility and damping needed for cushioning and vibration isolation. Rather than treating antifungal protection and mechanical performance as separate design problems, the study combines them in a single printed structure aimed at shipborne equipment and other systems exposed to humidity, temperature variation, and persistent vibration.
The study, titled “Antifungal and cushioning elastomer lattices via additive manufacturing,” was authored by Zhenyu Wang, Xinyu Song, Tao Zhang, Peng Chen, Chenxi Hua, Yu Liu, and Changli Cheng.
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Source: 3D Printing Industry
