Friction-directed self-assembly of Janus lithographic microgels into anisotropic 2D structures.

Yadu Nath Vakkipurath Kodakkadan, Charlie Maslen, Petr Cigler, František Štěpánek, Ivan Rehor

Journal of materials chemistry. B 2021 Jun 16

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We present a method for creating ordered 2D structures with material anisotropy from self-assembling micro-sized hydrogel particles (microgels). Microgel platelets of polygonal shapes (hexagon, square, and rhombus), obtained by a continuous scalable lithographic process, are suspended in an aqueous environment and sediment on an inclined plane. As a consequence of gravitational pull, they slide over the plane. Each half of the microgel is composed of a different type of hydrogel [poly(N-isopropylacrylamide) (PNIPAM), and poly(ethylene glycol) diacrylate (PEGDA), respectively] which exhibit different frictional coefficients when sheared over a substrate. Hence the microgels self-orientate as they slide, and the side with the lower frictional coefficient positions in the direction of sliding. The self-oriented microgels concentrate at the bottom of the tilted plane. Here they form densely packed structures with translational as well as orientational order.

Citation

Yadu Nath Vakkipurath Kodakkadan, Charlie Maslen, Petr Cigler, František Štěpánek, Ivan Rehor. Friction-directed self-assembly of Janus lithographic microgels into anisotropic 2D structures. Journal of materials chemistry. B. 2021 Jun 16;9(23):4718-4725