What is the raw photopolymerization 3D printing biomimetic functional nanocomposites made of? It turned out to be a creature from nature.
Introduction: Organisms in nature show unique survival strategies due to their special multi-scale and multi-material structures, which are not only hierarchical, but also highly flexible and have a clear division of functions.
The multi-scale or multi-layer structure allows it to exhibit excellent thermal conductivity and energy dissipation when exposed to external stimuli, and the biomaterials give it excellent mechanical, optical and hydraulic properties.
Just like the whisk-like structure on the surface has excellent superhydrophobic properties, the multi-layer structure of brick and mortar that always keeps the leaf surface clean allows it to effectively disperse energy shocks when subjected to external forces, showing excellent energy dissipation capacity.
Due to the mechanical reinforcement of the array nanofiller in the polymer, the cap tooth acts as the hardest structure in nature, making it firmly attached to the rock wall in ocean turbulence, and the microneedles on the surface of the cactus can effectively absorb moisture in the air even in arid environments.
These structures with different functions all contribute to improving the survival rate of natural organisms, hierarchical biomaterial matrices and organic as well as inorganic fillers, both essential for achieving highly functional structures, which also provide a wide range of opportunities for manufacturing the next generation of highly integrated functional structures and materials.
The cap shell is an aquatic gastropod mollusk with a flattened tapered shell that uses a special organ called the toothed tongue to obtain food from hard marine rocks, consisting of rows of mineralized teeth that exhibit the highest known mechanical strength.
More than any other naturally occurring material, this superior mechanical strength stems from biomineralization, a cyclical process that enhances the chitin protein matrix through the distribution of arranged iron oxide minerals to produce a unique layered structure.
These mineral-based microstructures, which have evolved to provide the necessary strength for cap shells to graze on rough ocean surfaces, allow them to extract nutrients from the environment without causing damage.
The structural stiffness of mature cap teeth eventually decreases due to repeated feeding, which prompts the formation of new biomineralized dental rows, naturally occurring nanocomposites that are a combination of soft proteins and arranged mineral phases.
Mainly determined by the presence of mineral nanorods, which enhance the mechanical properties of other weak biological materials, the cap teeth provide an ideal design inspiration for the fabrication of biomimetic nanocomposites with layered microstructure and excellent mechanical strength.
To reproduce the microstructure observed in Capitus teeth, an AM process called magnetic field-assisted reduction photopolymerization can be employed, as it flexibly controls the direction in which ferromagnetic nanofillers are arranged in polymer resins.
When a dynamic magnetic field is applied to the printed area, randomly distributed magnetic nanoparticles are arranged along flux lines and subsequently agglomerated to form magnetic microbeams.
The magnetic field-assisted 3D printing process is advantageous because it enables the rapid arrangement of magnetic nanofillers in any spatial orientation without the need for direct contact between magnets and nanocomposites.
Digital light projectors use microscale mask images to selectively crosslink polymer resins on the printed platform, thereby limiting the magnetic nanofillers in the structure, and this alignment and photopolymerization process is repeated continuously in a layer-by-layer manner to fabricate the desired 3D printed object.
Studies have shown that the excellent mechanical properties exhibited by Capei teeth are mainly attributed to the enhancement of the soft protein matrix by controlling the arrangement of embedded iron-based minerals.
The anisotropic mechanical strength of biomimetic layered microstructures should be controlled by managing the spatial orientation of magnetic nanofillers within polymer resins.
In order to achieve high mechanical properties, nanocomposites are prepared by uniform distribution of goethite nanoparticles in light-curing polymer resins.
When goethite nanoparticles are initially distributed in light-curing resins, they have a random spatial orientation and must be coupled to the primary photopolymerization process in order to enhance normal weak polymer materials with a controlled arrangement of nanofillers.
The biological material found in living organisms has been adapted through the process of natural selection to develop unique microstructures with enhanced physical properties.
The complex microstructure found in mantis shrimp employs a twisted plywood structure to enhance its mechanical properties and flexibility in order to withstand high impact forces using its fist-like clubs.
By observing the mechanical strength, mainly attributed to the mineral phase, this superior mechanical strength, enhanced by biomineralization of the integrated polymer matrix, alleviates the challenges associated with manufacturing technology.
In order to fabricate microstructures with highly complex geometries and excellent mechanical properties, current manufacturing methods have certain limitations that must be addressed in view of the high difficulty of achieving microstructures using arranged mineral biomaterials.
With recent advances in biomimetic additive manufacturing technology, these limitations can be mitigated by the use of 3D printing methods to tightly control the microstructure that was previously not possible with traditional manufacturing methods.
The impact on biomimetic fabrication of highly functional structures found in nature is both important and challenging, first of all, since a single material is not enough to make the structure highly functional, bioinspired polymer and nanofiller composites can effectively impart better mechanical properties, optical properties, thermal conductivity, hygroscopic deformation and superhydrophobicity to the structure.
Secondly, given that there are still some subtle differences between biomimetic and natural structures, and that these differences are decisive for performance, it is necessary to replicate natural structures at the macro and micro levels, which will play an important role in improving performance.
At the level of manufacturing methods, reduced photopolymerization provides an effective means for fabricating multi-scale complex structures, the introduction of magnetic and electric fields creates the possibility of increasing structural complexity, and nanofillers arranged spatially in specific directions bring mechanical, thermal, optical and deformation manifestations of structural anisotropy.
The intelligent bionic structure should not only originate from nature, but also return to nature to achieve the purpose of green manufacturing and sustainable development.
Conclusion: Overall, deconstructing at the material and structural level and using additive manufacturing to reproduce natural structures can effectively facilitate biomimetic design and manufacturing and open new doors to the next generation of high-performance mechanical, thermal, optical, and hydraulic structures.
