The use of organic polymers for electronic functions is mainly motivated by the low-end applications, where low cost rather than advanced performance is a driving force. Materials and processing methods must allow for cheap production. Printing of electronics using inkjets or classical printing methods has considerable potential to deliver this. Another technology that has been around for millennia is weaving using fibres. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles. Standard polymer field-effect transistors require well defined insulator thickness and high voltage, so they have limited suitability for electronic textiles. Here we report a novel approach through the construction of wire electrochemical transistor (WECT) devices, and show that textile monofilaments with 10-100 mum diameters can be coated with continuous thin films of the conducting polythiophene poly(3,4-ethylenedioxythiophene), and used to create micro-scale WECTs on single fibres. We also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibres.

It is challenging to obtain high-quality dispersions of single-wall nanotubes (SWNTs) in composite matrix materials, in order to reach the full potential of mechanical and electronic properties. The most widely used matrix materials are polymers, and the route to achieving high quality dispersions of SWNT is mainly chemical functionalization of the SWNT. This leads to increased cost, a loss of strength and lower conductivity. In addition full potential of colloidal self-assembly cannot be fully exploited in a polymer matrix. This may limit the possibilities for assembly of highly ordered structural nanocomposites. Here we show that nanofibrillated cellulose (NFC) can act as an excellent aqueous dispersion agent for as-prepared SWNTs, making possible low-cost exfoliation and purification of SWNTs with dispersion limits exceeding 40 wt %. The NFC:SWNT dispersion may also offer a cheap and sustainable alternative for molecular self-assembly of advanced composites. We demonstrate semitransparent conductive films, aerogels and anisotropic microscale fibers with nanoscale composite structure. The NFC:SWNT nanopaper shows increased strength at 3 wt % SWNT, reaching a modulus of 13.3 GPa, and a strength of 307 MPa. The anisotropic microfiber composites have maximum conductivities above 200 S cm(-1) and current densities reaching 1400 A cm(-2).

Structural electrode materials that integrate high mechanical strength and high electrochemical performances are attractive as they are indispensable for building lightweight, flexible electronics. [1][2][3] These materials should be able to withstand extreme mechanical stress and deformations while maintaining high charge storage properties, and thereby decrease the electrochemically inactive weight and volume for packaging of devices, especially in limited spaces. [1] Most conventional electrode materials, however, fail to meet both requirements. [4] Some of reported strategies involved using carbon fiber-reinforced composites [5,6] or graphene-based materials [1] as structural electrodes to deliver mechanical strength. These materials, however, fall short on the electrochemi cal energy storage capacitance. Alternatively, metal oxides [7] or conducting polymers [8] can be incorporated to boost the capacitance of the graphene-based materials. The problem is the weak interactions between different components, which results in low mecha nical stability of the final composites. [7,9] Therefore, there is a crucial need for the development of new-generation structural energy storage nanocomposites, which monolithically integrate excellent mechanical properties, high electronic and ionic conductivities, and high charge storage capabilities. A balance should also exist between these properties without substantially sacrificing one property over the other. [1] The family of two-dimensional (2D) metal carbides and nitrides, collectively known as MXene, are interesting materials for building high-performance supercapacitors. [10][11][12][13][14][15][16] MXenes have a general formula of M n+1 X n T x , where M is an early transition metal such as Ti, X is carbon or nitrogen, and T x indicates the presence of different functional groups (O, OH, and F) on the surface of metal layers, a result of aqueous exfoliation synthesis of MXenes. [10,17,18] Ti 3 C 2 T x MXene has been widely reported as a high-performance electrode material either in its pristine form or in hybrids with other guest materials such as poly(vinyl alcohol) (PVA), [18] polypyrrole, [19,20] and polyaniline, [21] as well as in hybridization with other carbon materials such as graphene, [22] carbon nanotubes, [23][24][25] and carbon nanofibers. [26] Most of the MXene hybrid nanocomposites, however, have only shown improvement in either capacitance or mechanical properties while sacrificing one property over the other, and they lack the required mechanical integrityThe family of two-dimensional (2D) metal carbides and nitrides, known as MXenes, are among the most promising electrode materials for supercapacitors thanks to their high metal-like electrical conductivity and surface-functional-group-enabled pseudocapacitance. A major drawback of these materials is, however, the low mechanical strength, which prevents their applications in lightweight, flexible electronics. A strategy of assembling freestanding and mechanically robust MXene (Ti 3 C 2 T x ) nanoco...