Supplementary Material

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1 Supporting Online Material, MS #107265, W. Lu et al. 1 Supplementary Material 1. Materials and Methods Polyaniline fibers and yarns PANION textile fibers and yarns (Fig. S1) are commercially available through Santa Fe Science and Technology Corporation. Different deniers and different dopants are available depending on desired properties. The mechanical properties of the fiber are similar to those of Nylon-6, with the volume electrical conductivity ranging from 200 to 1,000 S cm -1, depending upon the desired dopant for a given application. PANION Triflate (Triflate = trifluoromethanesulfonate) fibers were used in these studies. Ionic Liquid Preparation 1-Butyl-3-methylimidazolium chloride, [BMIM][Cl], was prepared in Santa Fe according to (1). 1-methylimidazole (82g) was mixed with chlorobutane (139g) in a round bottom 1L flask. The flask was sealed with a septum, and air was evacuated from the flask using a needle and a vacuum line. The reaction was carried out at C for h. The product of the reaction phase separated from the reaction mixture, which accumulated at the bottom of the flask as a clear viscous liquid. The unreacted reagents were decanted and the hot product was washed 10 times with 200 ml aliquots of ethyl acetate. The final product, [BMIM][Cl], which solidified upon washing and cooling steps, was then dried at 70 C under dynamic vacuum for 24 h. 1-Butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ] was prepared as described by Bonhote (2) for other ionic liquids. An aqueous solution of HBF 4 (50wt%), in the

2 Supporting Online Material, MS #107265, W. Lu et al. 2 amount of 152g, was slowly added to 150 g of [BMIM][Cl] that had been previously dissolved in 500 ml of water. The produced [BMIM][BF 4 ] was extracted from the mixture with dichloromethane. The solvent was removed by vacuum distillation and [BMIM][BF 4 ] was dried at 70 C under dynamic vacuum. [BMIM][PF 6 ] was synthesized at Monish University by a metathesis reaction from [BMIM][Br] and KPF 6 in water. This procedure was a variation on the synthesis of Suarez et al. (3) who used [BMIM][Cl] and NaPF 6. Spectroscopic characterization was consistent with the published data. Measurement of Electrochemical Mechanical Actuation of PANION in [BMIM][BF 4 ] Both electrochemical and electrochemical-actuation measurements of the PANION fibers or yarn were carried out using a PGSTAT30 potentiostat purchased from Eco Chemie B.V. with an electrochemical cell consisting of the polymer fiber as the working electrode, a 1.5 mm diameter platinum wire as the counter electrode, and a 1.0 mm diameter silver wire as the quasi-reference electrode. The polymer fiber was partially immersed in the electrolytes to perform linear actuation measurements. One end of the fiber was clamped on the bottom of the electrochemical cell and a platinum plate electrically contacted the inside of this clamp. The other end of the fiber was fixed with epoxy resin onto the tip of the arm of a dual-mode lever arm system (model 300B) purchased from Aurora Scientific Inc. The upper portion of the fiber, approximately two cm in length, was in the air, and only the lower portion, approximately one cm, was immersed in the electrolyte. A small load (usually N) was applied to the polymer

3 Supporting Online Material, MS #107265, W. Lu et al. 3 fiber to keep it straight and slightly taught. Two typical mechanical actuation measurements, namely, isotonic length change and isometric force change, were performed for the polymer fibers. In isotonic measurements, a constant load was applied to the polymer fiber, and the position change of the arm of the dual-mode lever arm system corresponding to the length change of the polymer fiber upon its redox reactions was recorded. In isometric measurements, the arm position and, thus, the length of polymer fiber was maintained constant, while the force generated by the polymer fiber upon its redox reactions was recorded. Conditions of electrochemically synthesizing polymers on ITO glass electrodes used for CV Electrochemical synthesis (Fig. S4) of the polymers were carried out in a cell consisting of the ITO glass electrode (0.7cm 4.2 cm) as working electrode, a 1.5 mm diameter Pt wire as counter electrode, and a 1.0 mm diameter Ag wire as quasi-reference. Polymers were synthesized potentiodynamically by potential cycling at 50 mv/s. The polymerization solutions were 0.1 M 3, 4-ethylenedioxythiophene in [BMIM][BF 4 ] for poly(3, 4-ethylenedioxythiophene) (PEDOT), 0.1 M pyrrole in [BMIM][BF 4 ] for polypyrrole (PPy), and 0.5 M aniline and 2 M CF 3 COOH in [BMIM][BF 4 ] for polyaniline (PANI), respectively. The potential ranges and cycling numbers were 0.5 ~ 0.9 V for 20 cycles for PEDOT, 0.8 ~ 0.8 V for 12 cycles for PPy, and 0.2 ~ 1.2 V for 15 cycles for PANI, respectively.

4 Supporting Online Material, MS #107265, W. Lu et al. 4 Conditions for electrochemically synthesizing polymers on pixelated ITO glass electrodes used for the fabrication of electrochemical displays For the fabrication of a 7-pixel electrochromic display, polymers were synthesized galvanostatically (constant current) onto Scotch tape masked ITO glass electrodes at a current density of 0.5 ma/cm 2. The electrochemical cell and polymerization solutions used for the display were the same as reported above. PEDOT was electrodeposited on top of the 7 masked pixel regions that had previously been spin-coated with a thin film of polyoctylthiophene (POT) that covered each of the exposed ITO glass pixel areas ( cm 1.7 cm). The PANI was electrodeposited onto the exposed area for each (0.25 cm 1.7 cm) of the 7 ITO glass pixels. The time used to electrodeposit PEDOT and PANI at constant current was 40 seconds and 120 seconds, respectively. During the fabrication of the display, a thin film of [BMIM][BF 4 ] was sandwiched between the two polymer coated ITO electrodes to fabricate the PANI/[BMIM][BF 4 ]/PEDOT_POT numeric display. The edges of the device were sealed with epoxy. During the device operation, numeric information was sent by a signal generator through control logic to the driver which sends +/- voltage signals to drive the redox reaction at the pixel level of the display. The voltage level of each pixel can be independently controlled to address the different pixels (a-g) to display numbers (S6) between 0 and 9.

5 Supporting Online Material, MS #107265, W. Lu et al Supporting Tables Supplemental Table S1. Performance characteristics of the PPy tube with and without the Pt helix in propylene carbonate (TBAPF 6 ) electrolyte. Property Tube with Helix Tube No Helix Conductivity (S cm -1 ) 585 S/cm 170 S/cm Tensile Strength 12 MPa 23 MPa Elongation to Break 15-17% 15-19% Displacement (%) (±5V/1Hz) 1.3% 0.2% Displacement Rate (±5V/1Hz) 1.33 mm sec -1 (2.6% sec -1 ) 0.2 mm sec -1 (0.4% sec -1 ) EE% (±5V/1Hz) 40% 10%

6 Supporting Online Material, MS #107265, W. Lu et al Supporting Figures Supplemental Figure S1. SEM Images of PANION fiber (top) and yarn (bottom) employed in these studies.

7 Supporting Online Material, MS #107265, W. Lu et al. 7 Supplemental Figure S2. Construction of the novel wound inter-connect system for PPy electromechanical actuators: A) a 125 mm Pt wire; B) a 25 mm Pt wire is wrapped around A in a spriral; C) the assembly is placed in the electrolyte solution containing pyrrole monomer and electroplated for 24 hours at 245 K; D) polymer coating forms around spiral; E) central Pt wire is removed; F) two short 125 mm Pt wires are inserted into the tube at both ends to make good electrical contact and sealed with epoxy; G) final actuator configuration.

8 Supporting Online Material, MS #107265, W. Lu et al. 8 Supplemental Figure S3. The two-electrode test cell used in the PPY-PF 6 tube actuator studies. The auxiliary electrode is another conducting polymer. Note that the strain is measured by videotaping the displacement against a calibrated ruler. Spring (5g) Moving Pin Connect to Auxiliary Electrode Electrolyte 70 mm ~200 mm 20 ~ 60 mm 125 mm Connect to Working Electrode The PPy Hollow Fibre Pt Wire 9 ~ 10 mm

9 Supporting Online Material, MS #107265, W. Lu et al. 9 Supplemental Figure S4. Cyclic voltammograms of PEDOT (I, solid yellow line), PPy (ii, blue dashed-line), and PANI (iii, solid green line) coated ITO glass electrodes (0.7cm 4.2 cm) obtained in [BMIM][BF 4 ]. Scan rate: 50 mv/s. Excellent electroactivity is achieved with all three films. The PANI thin-film used for the EC window shows outstanding electrochemical stability (iii) in [BMIM][BF 4 ], where only two pairs of redox peaks corresponding to the entire redox process of LEB (faint yellow color) ES (bluegreen color) pernigraniline [PN] (deep blue color) are observed. In other electrolyte systems, especially aqueous electrolyte systems, a third middle peak related to PANI degradation by hydrolysis occurs between these two peaks after a few cycles. Current (ma) i ii iii Potential (V vs Ag/Ag + )

10 Supporting Online Material, MS #107265, W. Lu et al. 10 Supplemental Figure S5. The pixilated numeric display was constructed by: 1) patterning each of the two transparent Indium Tin Oxide (ITO) glass electrodes (ii and iii); 2) electrochemically synthesizing PEDOT from [BMIM][BF 4 ] onto POT pre-coated conductive surface (iii); 3) electrochemically synthesizing PANI from [BMIM][BF 4 ] onto conductive surface (ii); and, 4) driving a thin layer (i) of [BMIM][BF 4 ] between the two film interfaces by capillary action to form the layered sandwich structure. The edges of the device were sealed with epoxy.

11 Supporting Online Material, MS #107265, W. Lu et al. 11 Supplemental Figure S6. Numeric information is sent by the signal generator through control logic to the driver which sends +/- voltage signals to drive the redox reaction at the pixel level of the display. The voltage level of each pixel can be independently controlled to address the different pixels (a-g) to display numbers between 0 and 9.

12 Supporting Online Material, MS #107265, W. Lu et al. 12 Supplemental Figure S7. Cyclic voltammogram obtained for an individual pixel from the PANI/[BMIM][BF 4 ]/PEDOT_POT numeric display. Scan rate: 50 mv/s Current (ma) Voltage (V vs Ag/Ag + )

13 Supporting Online Material, MS #107265, W. Lu et al Supporting References and Notes 1. J.S. Wilkes, J.A. Levitsky, R.A. Wilson, C.L. Hissey, Inorg. Chem. 21, 1263 (1982). 2. P. Bonhôte, A.-P. Dias, N. Papageorgiou, K. Kalyanasundaram, M. Grätzel, Inorg. Chem. 35, 1168 (1996). 3. P. A. Z. Suarez, S. Einloft, J. E. L. Dullius, R. F. De Souza, J. Dupont, Journal de Chimie Physique et de Physico-Chimie Biologique. 95, 1626 (1998).