Gecko-inspired hierarchically rough surface used as a reprintable paper

Abstract

While paper continues to remain one of the most widely used materials for writing and printing, and while its demand continues to grow, the environmental cost of using paper is rather huge. Paper is made by extracting the cellulose fibres from wood, and to meet the demand for it, large numbers of trees are felled. Making paper requires huge quantity of water, energy, and also toxic chemicals. In fact, paper is considered the 3rd largest industrial polluter of air, water, and soil. Yet a viable alternative to paper doesn't exist. Inspired by the inherent ability of many natural surfaces to keep themselves clean, we have made a reprintable paper which can be used over 50 cycles. It is prepared by casting crosslinkable silicone on a porous template, leading to hierarchical random surface features having dimensions ranging from tens of nano-meter to hundreds of micrometers. On this surface, ink particles of wide-ranging sizes and surface chemical characteristics adhere via intermolecular interactions. However, unlike conventional papers, in which particles get mechanically trapped inside the porous network of the cellulose fibres, here the ink particles remain accessible for cleaning via gentle scrubbing with a rough surface, soaked with a suitable liquid. Thus, this paper continues to remain both cleanable and printable.

Keywords

• Hierarchical roughness
• Particle adhesion
• Particle removal
• Reprintable paper