Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is © The Royal Society of Chemistry 2017

Supporting Information

Ultrathin Nanoporous Membranes Derived from Protein-based

Nanospheres for High-performance Smart Molecular Filtration

Ting Chen, Ming Duan*, Peng Shi, Shenwen Fang

(a) (b)

Figure S1 Top view (a) and cross-sectional (b) SEM images of the

support membrane in the present study.

600 250 (a) a (b) a 500 200 y y t t i i s s n n 400 g g e e t t 150 n n i i

e e

c c 300 n n e e 100 c c s s e 200 e r r o o u u l l 50 F 100 F 0 0 280 300 320 280 300 320 Wavelength(nm) Wavelength(nm)

25000 C-C/C-H 15000 (c) (d) C-C/C=C (e) 20000 15000 C-O N-C=O C-N C-O 10000 15000 N-C s s s t t

t 10000 n n n

N-C=O u u u o o o 10000 C C C N-C=O 5000 5000 O-C=O 5000

0 0 290 288 286 284 282 290 289 288 287 286 285 284 283 282 404 402 400 398 396 Binding energy(eV) Binding energy(eV) Binding energy(eV)

30000 10000 25000 25000 (f) (g) C-O (h)

20000 20000 N-C=O O-C=O C=O C=O N-C=O N-C s s t s t t n 15000 N-C=O n

n

15000 u u

u o C-O o o C C

C 5000 10000 10000

5000 5000

534 533 532 531 530 529 536 534 532 530 528 404 402 400 398 396 Binding energy(eV) Binding energy(eV) Binding energy(eV)

Figure S2 Synchronous spectra with (a)  =60 nm and (b)

 =20 nm of silk fibroin/tannic acid mixtures containing various concentrations of

tannin acid: a control; b 0.1 mg L-1; c 0.2 mg L-1; d 0.5 mg L- 1; e 1.0 mg L-1 ; f 2.0 mg

L-1; g 3.0 mg L-1 ; h tannic acid. (c) C1s spectrum of pure silk fibroin and; (d) C1s

spectrum of the nanoporous membrane. (e) O1s and (f) N1s XPS spectra of pure silk

fibroin; (g) O1s and (h) N1s XPS spectra of the nanoporous membrane. B

New coccine Methyl orange

Metanil yellow

L-phenylalanine

Figure S3 Chemical structures and molecular sizes calculated using Materials studio

7.0 of the tested . The unit of the molecular size is angstrom (Å)

0.6 0.6 feed solution (a) feed solution (b) 0.5 feed filtrate 0.5 feed filtrate 0.4 0.4 e e c

c n n 0.3 0.3 a a b

b r r o o s s 0.2 0.2 b b A A 0.1 0.1 filtrate filtrate 0.0 0.0

400 450 500 550 600 650 700 400 450 500 550 600 650 Wavelength(nm) Wavelength(nm)

0.5 0.5 (c) (d) 0.4 feed filtrate 0.4 feed solution feed filtrate feed solution 0.3 0.3 e e c c n n a a b

b

r r 0.2 0.2 o o s s b b A A 0.1 0.1 filtrate filtrate 0.0 0.0

400 450 500 550 600 650 700 750 800 500 550 600 650 700 750 800 Wavelength(nm) Wavelength(nm)

feed solution 0.8 (e) feed filtrate

0.6 filtrate e c n a b 0.4 r o s b A 0.2

0.0 400 500 600 700 Wavelength(nm) Figure S4 UV-vis spectra of the feed solution and filtrate of (a)Rhodamoine B;

(b) Rhodamine 6G; (c)Crystal violet; (d)Methylene blue after filtrating across the nanoporous membrane; (e) UV-vis spectra of the feed solution and filtrate of

Rhodamoine B after filtrating across the support membrane. The insets were the corresponding pictures of the aqueous solution before and after filtration. The support membrane exhibited a 36.8 % rejection of Rhodamine B, indicating that the fibroin

selective layer played a dominate role in the excellent rejection performance. Table S1 (a) Surface elemental composition of pure silk fibroin and the nanoporous membrane

Surface elemental composition (%) Samples N/C O/C C N O Pure SF 62.56 17.08 20.35 0.273 0.325 membrane 64.34 6.67 29 0.104 0.451

Table S1 (b) Chemical composition of pure silk fibroin

C1s N1s O1s BE Content BE Content BE Content Species Species Species (eV) (%) (eV) (%) (eV) (%) 288.2 N–C=O 10.4 400.0 N–C=O 52 532.1 C–O 29.9 287.6 C–N 13.3 286.2 C–O 28 399.5 N–C 48 531.4 N–C=O 35.4 C–C 284.7 48.3 530.9 C=O 34.7 C–H

Table S1 (c) Chemical composition of the nanoporous membrane

C1s N1s O1s BE Content BE Content BE Content Species Species Species (eV) (%) (eV) (%) (eV) (%) 288.7 O–C=O 0.8 400.1 N–C=O 50.2 533.2 O–C=O 26.3 288.1 N–C=O 9.9 532.6 C–O 24.6 286.1 C–O 33.4 399.6 N–C 49.8 531.8 C=O 23.1 C–C 284.5 55.9 531.2 N–C=O 26 C=O