A current challenge in polymer chemistry is the bottom-up synthesis of textile structures in which one-dimensional fibres are interwoven to form a two-dimensional sheet. Now, Wang et al. report a self-standing textile made of polymer fibres about 200 nm long.
Wang et al. first make a template layered structure comprising planar metal–organic frameworks of square arrays with copper(I) atoms at the vertices and organic linkers with a central benzene ring at the edges. The benzene rings are also shared by two other groups pointing towards the centre of the squares and ending with a reactive alkyne moiety. The structure alternates these layers with sacrificial ones being analogously constructed — the only difference being that the alkynes are replaced by inert methyls.
To create the interwoven fibres, Wang et al. link adjacent alkynes by an oxidative acetylene coupling reaction. Steric arguments dictate that, out of the four alkynes pointing towards the inside of the square, only those attached to parallel linkers can react with each other, and no reaction between moieties from different layers can occur. Once one reaction has taken place, the second one between the unreacted pair of alkynes can only occur either above or below the plane of the already-coupled alkynes. Extending this chemistry to the entire framework creates randomly interwoven polymeric fibres. Finally, the copper atoms and the sacrificial layer are easily removed to isolate a self-standing textile.