Chemical polymerization of a 3,4-ethylenedioxythiophene derivative bearing a sulfonate group (EDOT-S) is reported. The polymer, PEDOT-S, is fully water-soluble and has been produced by polymerizing EDOT-S in water, using Na2S2O8 and a catalytic amount of FeCl3. Elemental analysis and XPS measurements indicate that PEDOT-S is a material with a substantial degree of self-doping, but also contains free sulfate ions as charge-balancing counterions of the oxidized polymer. Apart from self-doping PEDOT-S, the side chains enable full water solubility of the material; DLS studies show an average cluster size of only 2 nm. Importantly, the solvation properties of the PEDOT-S are reflected in spin-coated films, which show a surface roughness of 1.2 nm and good conductivity (12 S/cm) in ambient conditions. The electro-optical properties of this material are shown with cyclic voltammetry and spectroelectrochemical experiment reveals an electrochromic contrast (∼48% at λmax = 606 nm).

Fiber-based opto-electronic components such as light-emitting diodes (LEDs), [ 1 , 2 ] solar cells, [3][4][5] electrochromic pixels [ 6 ] and transistors [7][8][9][10][11][12] attract increasing attention for their alternative, nonplanar device architectures, which readily permit integration into 'smart' fabrics. Furthermore, devices such as transistors facilitate advanced patterning schemes of electronic circuitry through judicious weaving. [9][10][11][12] In particular conjugated polymers are suited as the (semi)conductor since they either inherently possess the required mechanical toughness or can be processed together with suitable structural polymers-including both, natural and synthetic macromolecules [ 13 , 14 ] -and thus permit the manufacture of fl exible artifacts such as tapes and fi bers. Without doubt, one of the most alluring textile materials is silk from the silkworm Bombyx mori with its delicate texture and brilliant luster. Besides, once thoroughly degummed Bombyx mori silk offers a high degree of biocompatibility, [ 15 ] which is an indispensable characteristic in particular for electronic devices that are intended to operate in a biological environment. As a result, the design of optical, [ 16 , 17 ] electrical [ 18 , 19 ] and electronic [ 20 ] components on silk-based templates has been the subject of much recent research. However, all examples have -so far-been limited to devices that comprised inorganic metal/semiconductor thin-fi lm structures on 'silk fi lms' that were produced from dissolved silk proteins. Clearly, although attractive due to their biodegradability (cf. Ref. 19 and 20) such architectures fail to benefi t from the extraordinary mechanical properties of pristine silk fi bers [ 21 , 22 ] and cannot be woven into fabrics. In a previous report, we have demonstrated that conjugated polyelectrolytescompounds that are uniquely suited to functionalize polypeptide structures [23][24][25][26] -permit facile staining of recombinant spider silk as well as natural Bombyx mori silk. [ 13 ] Depending on the choice of conjugated polyelectrolyte this approach enabled us to produce electrically conductive or photoluminescent fi bers. Here, we explore by which means such conducting silk fi bers can be incorporated as the structural as well as active component into electrochemical transistors (ECTs) that employ an electrolyte mixture composed of imidazolium-based ionic liquids as the electrochemical medium. ECTs offer unique possibilities for the realization of fi ber-based electronic circuits because of their relative insensitivity to the precise device geometry. [ 11 ] Ultimately, we anticipate that such components will permit fully integrated woven logic based on silk fi bers.We elected to work with silk fi bers from the silkworm Bombyx mori because of their availability and widespread use in textile manufacturing. Discrete degummed silk fi bers and threads thereof were obtained from Aurora Silk (Portland, Oregon, USA) and were used as received. As the conjugated polyelectrolyte we c...

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Proteins offer an almost infinite number of functions and geometries for building nanostructures. Here we have focused on amyloid fibrillar proteins as a nanowire template and shown that these fibrils can be coated with the highly conducting polymer alkoxysulfonate PEDOT through molecular self-assembly in water. Transmission electron microscopy and atomic force microscopy show that the coated fibers have a diameter around 15 nm and a length/thickness aspect ratio >1:1000 . We have further shown that networks of the conducting nanowires are electrically and electrochemically active by constructing fully functional electrochemical transistors with nanowire networks, operating at low voltages between 0 and 0.5 V.

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