Surface patterning techniques of gels have shown promising applications in various fields, such as cell guidance and differentiation, biological screening, smart robots and controlled adhesion. However, due to the high-water content and flexibility of gels, performing the surface patterning of gels with high precision remains a great challenge. 

Based on the hydrophilic/hydrophobic interactions at the solid-liquid interface and emulsion interfacial polymerization, Prof. WANG Shutao’s team from the Technical Institute of Physics and Chemistry (TIPC) of the Chinese Academy and Sciences (CAS) proposed a general wetting-enabled-transfer (WET) strategy. With the help of WET strategy precise patterning of organogels and hydrogels on organohydrogel surfaces is enabled. 

This study, published in Advanced Materials, showed the high universality of the WET strategy. Firstly, surface patterning of organohydrogels with tunable sizes from microscale to macroscale on either flat or curved surface can be achieved. Moreover, the WET strategy can be applicable to different kinds of hydrogel and organogel monomers, such as electropositive AM, electroneutral 2-hydroxyethyl acrylate (HEA), electronegative acrylic acid (AA) and so on. 

By optimizing the experimental parameters, including species of gel monomers, size of the emulsion droplets, and substrate wettability, the WET strategy realized a high resolution of several microns. And it was comparable to the result that completed by photolithography.

In this work, researchers also conducted a pattern-transfer experiment using the surface-patterned organohydrogels as a soft printing template to demonstrate the feasibility of application. Intact and robust pattern transfer to single-phase hydrogel surface is designed, while such task is quite difficult to achieve with current transfer printing techniques. 

“This WET strategy opens up new possibilities for the design and fabrication of new-generation surface-patterned soft materials. In the future, some functional molecules or nanocomponents can be introduced into the system to endow these surface-patterned soft materials with new features. We believe that our strategy may evoke great interest in many promising fields, such as flexible electronics, oil/water collection, anti-counterfeiting and neuron network construction,” said Prof. WANG. 

This work is supported by the National Key R&D Program, the International Partnership Program of CAS and the Natural Science Foundation of Jilin Province.