3D Printing of Superhydrophobic Objects with Bulk Nanostructure

Abstract

The rapid development of 3D printing (or additive manufacturing) technologies demands new materials with novel properties and functionalities. Superhydrophobic materials, owing to their ultralow water adhesion, self‐cleaning, anti‐biofouling, or superoleophilic properties are useful for myriad applications involving liquids. However, the majority of the methods for making superhydrophobic surfaces have been based on surface functionalization and coatings, which are challenging to apply to 3D objects. Additionally, these coatings are vulnerable to abrasion due to low mechanical stability and limited thickness. Here, a new materials concept and methodology for 3D printing of superhydrophobic macroscopic objects with bulk nanostructure and almost unlimited geometrical freedom is presented. The method is based on a specific ink composed of hydrophobic (meth)acrylate monomers and porogen solvents, which undergoes phase separation upon photopolymerization to generate inherently nanoporous and superhydrophobic structures. Using a desktop Digital Light Processing printer, superhydrophobic 3D objects with complex shapes are demonstrated, with ultralow and uniform water adhesion measured with scanning droplet adhesion microscopy. It is shown that the 3D‐printed objects, owing to their nanoporous structure throughout the entire volume, preserve their superhydrophobicity upon wear damage. Finally, a superhydrophobic 3D‐printed gas‐permeable and water‐repellent microfluidic device and a hierarchically structured 3D‐printed super‐oil‐absorbent are demonstrated.

Nano- to macro-scale control of 3D printed materials via polymerization induced microphase separation

“…The alternative to hardware-driven strategies are chemically controlled strategies for nano- and microscale structuration. Systems which use this strategy typically rely on phase separation between thermodynamically incompatible components to drive the formation of discrete nano- and microscale domains throughout the 3D printed material 14 – 18 . These chemical approaches are very noteworthy as they can produce nanostructured materials using inexpensive and highly accessible equipment and at higher throughputs.…”

“…In this case, the resulting 3D printed bottlebrush elastomers exhibited near-perfect recoverability well beyond the yield strain, however, the macroscopic material resolution was low due to the use of DIW 3D printing. Other groups 15 , 16 , 18 have applied polymerization induced phase separation (PIPS) 19 , 20 to photoinduced 3D printing to fabricate materials with micro-/nanoscale internal structures. The use of photoinduced techniques provides more highly resolved geometrical structures, however, the employed phase separation processes in these works resulted in limited control over nanostructuration.…”

Superhydrophobic SLA 3D printed materials modified with nanoparticles biomimicking the hierarchical structure of a rice leaf

“…Hierarchical superhydrophobic surfaces can be manufactured using either physical modification (for instance by plasma and molding processes) [ 19 , 20 ], or hydrophobic coatings (for instance by spin-coating, aerosol, and electrochemical deposition) [ 21 , 22 ]. Apart from those processes, 3D printing has been gaining interest in the last years since it allows for the creation of objects with many possibilities in terms of precision, sizes, shapes, mechanical and surface properties, including from delicate prototypes to robust engineering products.…”

Atomic Layer Deposition Reinforcement of Methylcellulose Nanowire Forests

“…[ 16 ] More recently, phase separation methods have been employed to create 3D printed structures that are fully superhydrophobic; however, this approach dictates both the surface and bulk properties, limiting potential applications. [ 17 ]…”

“…[16] More recently, phase separation methods have been employed to create 3D printed structures that are fully superhydrophobic; however, this approach dictates both the surface and bulk properties, limiting potential applications. [17] In this work, we introduced electrospray deposition (ESD) as an inexpensive method for obtaining superhydrophobic surfaces via the spraying of a fibril gel former, methylcellulose (MC) in water:ethanol blends. We have reported in a previous study that in ESD the gelation process of MC can be enhanced by shear forces and surface charge, allowing it to electrospin on a dropby-drop basis to create forests of 3D individual nanowires.…”