Supporting Information

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1 Supporting Information Enhanced X-band Electromagnetic Interference Shielding Performance of Layer-structured Fabric-supported Polyaniline/Cobalt-Nickel Coatings Hang Zhao, Lei Hou, Siyi Bi, Yinxiang Lu Department of Materials science, Fudan University, Shanghai , China *Corresponding author. Tel. & fax: ; address: S-1

2 S1. The effects of repeatedly folding on properties of the proposed EMI shielding fabric Generally, flexibility and foldability account for a considerable proportion in designing and evaluating the EMI shielding fabrics. For layer-structured shielding fabrics, repeated enfoldment may result in delamination or structural change of coatings, and thus affect the electric and magnetic properties and the EMI shielding performance. The repeatedly folding was performed on a FPC flexing cyclic tester (LX-5646A Lixin instrumental equipment Co., Ltd, Dongguan, China). As shown in Figure S1, the fabric specimen was loaded between a pair of holders with stress of 6 MPa, and then the below holder rotated repeatedly right and left with an angle of 135 degrees to complete a folding cycle. After cycle folding (Figure S2), inevitably slight delamination of alloy coating was observed on the fabric surface, which will certainly affect the properties of the proposed PANI/Co-Ni coated fabric. The effects of repeatedly folding on electric and magnetic properties and the EMI shielding performance are shown in Figure S3. The surface resistivity increased from the as-plated value to 1.47 Ω/sq, which was about % increment compared to the value prior to folding (Figure S3 (a)). The increase of resistivity was attributed to the generation of alloy cracks (as shown in Figure S2 (below)). Accompanied by the generation of cracks, some loose Co-Ni NPs detached from the fabric surface, which directly caused the decline of magnetic properties (Figure S3 (b)). At present, there is no standard document related to evaluation methodology of EMI shielding fabric after bending. Considering the 2D surface of shielding fabric, we designed a folding methodology, namely 5 creases per centimeter. It can be seen from the Figure S3 (c), although there is volatility, the maximal EMI SE showed a downward trend. The maximal EMI SE at folding cycles was 37.7 db, which is still S-2

3 suitable for commercial application. Overall, the proposed fabric-supported PANI/Co-Ni composites maintained good conductivity, satisfactory magnetic and EMI shielding performances after multi-folding. Figure S1 Experiment setup for repeatedly folding. S-3

4 Figure S2 Digital images (above), SEM photographs (below) and optical micrographs (inset) of PANI-3/Co-Ni-30-coated fabric before and after bonding (10000 cycles). Figure S3 Surface resistivity (a), saturation magnetization (b) and maximal EMI SE (c) of PANI-3/Co-Ni-30-coated fabric versus number of folding cycles. S2. Synthesis of fabric-supported Co-Ni composites The fabrication of fabric-supported Co-Ni composites was performed in consecutive stages, including mercerization, Co (0) activation and Co-Ni coating deposition followed by rinsing and drying. In the pre-treatment stage, all pristine fabrics were mercerized in 20 g/l of NaOH solution under 90 C for 30 min to remove lignin, hemicellulose, wax and oils, and then rinsed with acetic acid and DI water until the ph value reached neutral. Prior to the two-step activation, Co 2+ cations solution and KBH 4 solution were respectively prepared according to our previous work. Surface activation procedure was carried out by immersing the mercerized fabrics into the Co 2+ aqueous solution at RT for 10 min. Thereafter, the Co 2+ -adsorbed fabrics were washed with DI water, and then immersed into 0.1 mol/l of KBH 4 solution at RT for 5 min. The Co (0) activated fabrics were rinsed thoroughly with DI water to protect the following plating bath from being contaminated. Electroless Co-Ni deposition procedure was carried out immediately after Co (0) activation. The electrolesss bath composition was cobalt sulfate heptahydrate (14 g/l), nickel sulfate hexahydrate (14 g/l), sodium hypophosphite (20 S-4

5 g/l), KNa-tartrate (140 g/l) and ammonium sulfate (65 g/l). The Co (0) activated fabrics were immersed into the bath solution under constant temperature of 75 C for min (three levels). Upon removal from the plating bath, the fabric samples were rinsed with DI water, and placed in the oven at 50 C for 30 min to facilitate surface drying. Finally, the fabric-supported Co-Ni composites plated with different time were obtained. Figure S4 XPS wide-scan spectrum of PANI/Co-Ni-30 coated fabric. S-5

6 Figure S5 XRD pattern for fabric-supported Co-Ni-30 composites. Figure S6 Schematic images of the Scotch -tape test for (a) PANI/Co-Ni-30-coated and (b) Co-Ni-30-coated fabrics. S-6

7 Figure S7 Frequency dependence of total EMI SE of PANI-3-coated, Co-Ni-60-coated and PANI/Co-Ni-60-coated fabrics. Figure S8 Frequency dependence of total EMI SE of PANI-3-coated, Co-Ni-90-coated and PANI/Co-Ni-90-coated fabrics. S-7

8 Table S1 Weight, loading and surface resistance (Rs) of the fabric samples in each step. Sample pristine fabric mercerized fabric fabric-supported PANI fabric-supported PANI-3/Co-Ni n=1 n=2 n=3 t=30 min t=60 min t=90 min weight (mg cm -2 ) loading (mg cm -2 ) Rs (Ω/sq) S-8

9 Table S2 XPS atomic ratio (%) of fabric samples (Errors in detemination±1%). Sample-(%) C1s O1s N1s Cl2p3 S2p3 Co2p C/O pristine PANI-1-coated PANI-2-coated PANI-3-coated Co 2+ -captured Co (0)-activated S-9

10 Table S3 Comparison of the anti-corrosion properties of different metal-coated materials. Substrate Metalic coating Electrolyte Icorro (A cm -2 ) Ecorro (mv) Refs. Fabric-supported PANI Co-Ni 3.5 wt% NaCl This work Carbon steel Cu P 3.5 wt.% NaCl [S1] PET film Cu-Co-P 3.5 wt.% NaCl [S2] Ni-P 3.5 wt.% NaCl Polyester fabric Cu-Ni 3.5 wt.% NaCl [S3] Ni-P/Cu-Ni 3.5 wt.% NaCl Tencel fabric Co-Ni-P (Co 0 activation) 3.5 wt.% NaCl Co-Ni-P (Ni 0 activation) 3.5 wt.% NaCl [S4] S-10

11 Table S4 Classification of electromagnetic shielding textiles [S5] Type Grade SE 1 (db) Classification ES 2 (%) AAAAA SE >60 Excellent ES > % AAAA 60 SE > 50 Very good % ES >99.999% Class I 3 Professional use AAA 50 SE >40 Good % ES >99.99% AA 40 SE >30 Moderate 99.99% ES >99.9% A 30 SE > 20 Fair 99.9% ES >99.0% AAAAA SE >30 Excellent ES>99.9% AAAA 30 SE > 20 Very good 99.9% ES >99.0% Class II 4 General use AAA 20 SE >10 Good 99.0% ES >90% AA 10 SE >7 Moderate 90% ES >80% A 7 SE >5 Fair 80% ES >70% 1 : SE= Shielding Effectiveness (db); 2 : ES= Percentage of Electromagnetic Shielding (%); 3 : medical equipment, quarantine material, professional security uniform for electronic manufacturer, electronic kit, or other new applications; 4 : casual wear, office uniform, maternity dress, apron, consumptive electronic products, and communication related products, or other new applications. S-11

12 REFERENCES (S1) Faraji, S.; Rahim, A. A.; Mohamed, N.; Sipaut, C. S.; Raja, B. Corrosion Resistance of Electroless Cu-P and Cu-P-SiC Composite Coatings in 3.5% NaCl. Arabian J. Chem. 2013, 6 (4), (S2) Hou, L.; Bi. S. Y.; Zhao, H.; Xu, Y. M.; Mu, Y. H.; Lu, Y. X. Electroless Plating Cu-Co-P Polyalloy on UV/ozonolysis Irradiated Polyethylene Terephthalate Film and Its Corrosion Resistance. Appl. Surf. Sci. 2017, 403, (S3) Jiang, S. X.; Guo, R. H., Electromagnetic Shielding and Corrosion Resistance of Electroless Ni P/Cu Ni Multilayer Plated Polyester Fabric. Surf. Coat. Technol. 2011, 205 (17), (S4) Bi, S. Y.; Zhao, H.; Hou, L.; Lu, Y. X. Comparative Study of Electroless Co-Ni-P Plating on Tencel Fabric by Co 0 -based and Ni 0 -based Activation for Electromagnetic Interference Shielding. Appl. Surf. Sci. 2017, 419, (S5) Committee for Conformity Assessment of Accreditation and Certification on Functional and Technical Textiles. Specified Requirements of Electromagnetic Shielding Textiles. Document no. FTTS-FA-03. Published: 1 September 2003; Revised: 3 March Taipei/Taiwan. S-12