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

J Mater Chem B. 2021 Jun 16;9(23):4718-4725. doi: 10.1039/d1tb00572c.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylic Resins / chemistry
  • Friction*
  • Materials Testing
  • Microgels / chemistry*
  • Molecular Structure
  • Polyethylene Glycols / chemistry

Substances

  • Acrylic Resins
  • Microgels
  • poly(ethylene glycol)diacrylate
  • poly-N-isopropylacrylamide
  • Polyethylene Glycols