The combination of a tannin and an iron rich source to produce a dark, insoluble complex is a wide-spread ancient technique to dye textiles. The Bogolan dyeing is the traditional technique of colouring cloths, deeply rooted in Mali and existing since the 13th Century. Bogolan is also known as Bogolanfini, “bogo” means “mud”, “lan” means “with”, and “fini” means “cloth”. The necessary materials for this process are textile, plants extract and clay[1]. Traditionally, the textile is first impregnated with a solution prepared from the leaves of N’galama trees (Anogeissus leiocarpa), rich in tannins. The pattern is then applied using the clay paste (mud), rich in iron. The reaction between the impregnated hydrolysable tannins and the clay pastes results in a dark brown or black colour[2]. The cost-effective method entirely based on natural products results in a dyed cloth that retains its dark colour for a long time (decades and even centuries)[3].

Inspired by the Bogolanfini technique, we have reported how nanocellulose films can be functionalized and patterned by surface-bound clusters of multivalent metal ions with hydrolysable tannins[4]. Gallic acid adsorbs and forms clusters onto the surface of the nanocellulose and is subsequently transformed into dark, surface-bound nanoparticles when reacted with iron ions. We used micro-contact printing to create patterns with nanoscopic features of multivalent metal ion- hydrolysable tannin complexes on nanocellulose films[4]. The colour of the patterns could be controlled by the metal ion and the colour of patterned tannic acid- iron ion complexes could be tuned by pH. This work is an example of how the understanding of the chemistry of a historically and culturally important dyeing technique can be used as an inspiration for the development of a novel and versatile patterning technique, primarily based on organic materials derived from trees and abundant metal ions.

References:

[1] J. B. Donne, Man 1973, 8, 104–107.

[2] M. V. . Limaye, Z. Bacsik, C. Schütz, A. Dembelé;, M. Pléa;, L. Andersson;, G. Salazar-Alvarez, L. Bergström, Text. Res. J. 2012, 82, 1888–1896.

[3] P. Blanchart, A. Dembelé, C. Dembelé, M. Pléa, L. Bergström, R. Granet, V. Sol, V. Gloaguen, M. Degot, P. Krausz, Appl. Clay Sci. 2010, 50, 455–460.

[4] M. V Limaye, C. Schutz, K. Kriechbaum, J. Wohlert, Z. Bacsik, M. Wohlert, W. Xia, M. Plea, C. Dembele, G. Salazar-alvarez, et al., Nanoscale 2019, DOI 10.1039/C9NR04142G.