Cu2+-loaded cellulose micro-beads applied to the direct patterning of metallic surfaces using a fast and convenient process

Abstract

In this paper, we propose both a new application for cellulose micro-beads and a new concept in colloidal lithography to directly deposit and template a metal from ions transported by the organized colloidal particles, using the colloidal particles themselves. To do so, 5 μm-sized cellulose micro-beads (CμBs) were first surface-functionalized by trimellitic anhydride to introduce carboxylate ligands before decorating them with Cu²⁺ ions by complexation of the carboxylate groups with a CuCl₂ solution. The Cu²⁺-loaded CμBs, dispersed in an aqueous phase, were organized in compact monolayer at the vicinity of a planar electrode. The release of cupric ions and subsequent copper deposition were triggered by an electric field delivered by a tension generator. 2D non-close-packing arrays of copper dots assemblies displaying hexagonal symmetry were generated below or around the micro-beads - depending on the ions concentration in the aqueous phase - leading respectively to copper dots deposited circularly or concentrated in rings. The Cu²⁺-loaded cellulose beads allowed the covering of 2 cm²-surfaces by copper patterns in less than 45 min, using an easy and cheap process.

Keywords: Arrays of copper dots clusters; Cellulose beads; Colloids; Direct lithography; Electric fields.