Supporting Information Organic Solvent-Free Fabrication of Durable and Multifunctional Superhydrophobic Paper from borne Fluorinated Cellulose Nanofiber Building Blocks Avijit Baidya a,b,c, Mohd Azhardin Ganayee a, Swathy Jakka Ravindran a, Kam (Michael) Chiu Tam d, Sarit Kumar Das c, Robin H. A. Ras b, Thalappil Pradeep a, * a DST Unit of Nanoscience, Thematic Unit of Excellence, Department of Chemistry, Indian Institute of Technology Madras, Chennai, India b Department of Applied Physics, Aalto University School of Science, Puumiehenkuja 2, 02150 Espoo, Finland c Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, India d Department of Chemical Engineering, loo Institute for Nanotechnology, University of loo, 200 University Avenue West, loo, ON, N2L 3G1, Canada * pradeep@iitm.ac.in 1
Table of contents Figure No. Description Page No. S1 AFM image (2D & 3D view) of unmodified cellulose nanofibers (coated on glass) 3 S2 Droplet pinning test: Dragged water droplet 3 S3 Vertical drop adhesion test 4 S4 Tackiness measurement 4 S5 S6 Strength of modified cellulose nanofiber composed waterproof paper SEM images of the unmodified cellulose coated surface, tilt angle 45º 5 5 S7 Hardness test 6 S8 S9 Deconvoluted XPS spectrum of C1s shows the presence of only cellulosic carbons Deconvoluted XPS spectrum of F1s (modified and unmodified CNFs) 6 7 S10 Characterization of cellulose nanofiber (CNF) 7 S11 S12 Characterization of supernatant of modified CNF dispersion Long term stability test of chemically attached FS and AS with CNF 8 8 Video No. Description Video S1 Video S2 Video S3 Video S4 Video S5 Video S6 Video S7 Video S8 Video S9 Video S10 Jet motion of water on coated glass (extent of water repellency test) Droplet dragged test (water pinning test) Vertical drop adhesion test (water pinning test) Knife scratch test Peel-off test Sand paper abrasion test with a load of 50 g Finger wiping test on abraded waterproof paper Self-cleaning property Effect of organic solvents 2
Video S11 Video S12 Integrity test: Stability of waterproof paper in water Extent of water repelling nature of waterproof paper, ink diffusion test Figure S1. AFM image (2D & 3D view) of unmodified cellulose nanofibers (coated on glass). Figure S2. Droplet pinning test: Dragged water droplet (~ 2 µl). Droplet moved back and forth 5 cm on coated surface without any sign of pinning. 3
Figure S3. Vertical drop test. Volume of water drop ~ 2 µl. 0.010 Normal force (N) 0.005 0.000-0.005-0.010 Native CNF dispersion Modified CNF dispersion 1 2 3 4 5 6 7 8 9 Gap (mm) Figure S4. Tackiness measurement. Both native and modified CNF show water-like nature. Concentrations of CNF in both the cases were the same. 4
Figure S5. Mechanical strength of modified cellulose nanofiber composed waterproof paper (without any adhesive). This is compared with the unmodified cellulose nanofiber paper. Figure S6. SEM images of the unmodified cellulose in different magnifications at a tilt of 45º. Fibrous nature of the surface is lear in the images. 5
Figure S7. The reduced Young's modulus and hardness of the modified CNF (coated on glass). The values determined at 500 µn peak load are shown in the Table. The E r and H values corresponding to 500 µn can be considered as representative bulk values obtained using equations (i) and (ii), respectively. Cellulosic C Absence of C-F bonds Intensity (a.u.) 282 285 288 291 294 Binding Energy (ev) Figure S8. Deconvoluted XPS spectrum of C1s shows the presence of only cellulosic carbons. The reduced Young's modulus and hardness of the modified CNF. 6
Intensity (a.u.) 684.5 ev ( -CF 3 ) F in modified CNF 686.9 ev (-CF 2 ) Absence of F in unmodified CNF 684 687 690 Binding Energy (ev) 680 684 688 692 Binding Energy (ev) Figure S9. Deconvoluted XPS spectrum of F1s of the modified CNF. Spectrum of the unmodified CNF is also shown. Figure S10. Characterization of the native cellulose nanofiber. (A) TEM image and (B) AFM image of the sample. 7
(A) (B) Region of interest Intensity (a.u.) - CH 2 of FS and AS AS FS Supernatant N-H (bending) AS FS Supernatant C-N (stretch) 1241 1198 1145 1121 x 5 4000 3000 2000 1000 Wavenumber (cm -1 ) 1600 1500 1400 1300 1200 1100 Wavenumber (cm -1 ) Figure S11. Characterization of the supernatant of modified CNF dispersion. (A) IR spectra of supernatant, AS, FS, and water. (B) Expanded view of marked area in A. IR spectrum of supernatant (blue) does not contain any characteristic peak of AS (black) and FS (red). It is similar to pure water (orange). Intensity (a.u.) (A) - CH 2 of FS and AS AS FS Sonicated 4000 3000 2000 1000 Wavenumber (cm -1 ) (B) N-H (bending) Region of interest AS FS Sonicated C-N (stretch) 1241 1198 1145 1121 x 5 1600 1500 1400 1300 1200 1100 Wavenumber (cm -1 ) Figure S12. Long term stability test of chemically attached FS and AS with CNF. (A) IR spectra of water after sonication, AS, FS, and water. (B) Expanded view of marked area in A. IR spectrum of water after sonication (purple) does not contain any characteristic peak of AS (black) and FS (red). It is similar to pure water (orange). Supporting videos are given separately. 8