MOE Key Laboratory of Macromolecular Synthesis and Functionalization, and Key Laboratory ofAdsorption and Separation Materials & Technologies of Zhejiang Province, Department of PolymerScience and Engineering, Zhejiang University, Hangzhou 310027, China.

*Corresponding author：E-mail: 11529019@zju.edu.cn (Xi. Yang)

Supporting Information

Controllable Interfacial Polymerization for Nanofiltration

Membrane Performance Improvement by the Polyphenol

Interlayer

Xi Yang*

MOE Key Laboratory of Macromolecular Synthesis and Functionalization, and Key

Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province,

Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027,

China.

S2

Figure S1. UV-vis spectra of the PEI/TA assembly in solutions at different pH values.

Photograph courtesy of ‘Xi Yang’. Copyright 2019.

Figure S2. Zeta potential of the surface of nascent PSf substrate, PSf substrate with a

PEI coating and PEI/TA-modified substrate, respectively.

0.0

0.5

1.0

1.5

pH = 3

Abs

orba

nce a

.u.

Wavelength nm500450400350

pH = 12

300

pH = 7.5

-60

-40

-20

0

20

40

60

PEI/TA-modified

substrate

PSf with

PEI coating

Zeta

pot

entia

l m

V

Nascent PSf

substrate

S3

Figure S3. PEI/TA deposition degree (wt%) on the nascent PSf substrate increasing

with (a) different TA concentrations when PEI is fixed at 2 mg/mL, and the add-up

total immersion time is 6 minutes and with (b) different total immersion time when

the reactant concentration is fixed at PEI = 2 mg/mL and TA= 4 mg/mL.

Figure S4. FESEM images of the surface morphologies of (a-d) PEI/TA-modified

substrate surface, when PEI concentration is fixed at 2 mg/mL and the TA

concentration of 1, 2, 3 and 5 mg/mL (with the add-up total immersion time is fixed at

6 minutes).

TA = 1 mg/mL TA = 2 mg/mL

TA = 3 mg/mL TA = 5 mg/mL

1 2 3 4 5

2

4

6

8

10

Depo

sitio

n de

gree

wt%

TA concentration mgmL

(a)

2 4 6 8 10

2

4

6

8

10

Depo

sitio

n de

gree

wt%

Total assembly time min

(b)

S4

Figure S5. Surface (a-b) and cross-sectional (c-d) FESEM images of the nascent PSf

substrate and the PEI/TA-modified substrate, at the optimal PEI/TA assemble

condition of reactant concentration of PEI = 2 mg/mL, TA = 4 mg/mL and the add-up

total immersion time is 6 minutes.

Figure S6. WCA exhibits hydrophilicity of the nascent PSf substrate, and

PEI/TA-modified substrate (assembled at different pH values).

Nascent PSfsurface

PEI/TA-modifiedcross-section

Nascent PSfcross-section

PEI/TA-modifiedsurface

Original Acid Neutral Base

20

40

60

80

Wat

er c

onta

ct a

ngle

S5

Figure S7. The cross-sectional FESEM images of NF membranes fabricated on (a)

the nascent PSf substrate and (b) PEI/TA-modified substrate, and exhibiting the

reduced polyamide layer thickness from 134 ± 6 nm of PSf NF to 82 ± 5 nm of

PEI/TA-PSf NF.

Figure S8. AFM images showing the topographies of (a-b) the nascent PSf substrate

and PEI/TA-modified substrate (c-d) the PSf NF and PEI/TA-PSf NF, respectively.

Nascent PSf PEI/TA-modified

S6

Table S1. AFM measurement and analyses of surface roughness of the nascent PSf

substrate, PEI/TA-modified substrate, PSf NF and PEI/TA-PSf NF, respectively.

Sample Rq (nm) Ra (nm) Rmax (nm)

Nascent PSf substrate 4.58 3.57 22.4

PEI/TA-modified substrate 6.90 5.41 68.2

PSf NF 38.4 29.7 264

PEI/TA-PSf NF 22.7 18.5 127

Figure S9. (a) OCA experimental digital photographs showing the hexane solution

spreading behavior as a function of spreading time, with the hexane solution

spreading on the nascent PSf substrate and PEI/TA-modified substrate, respectively

and (b) interfacial polymerization process, with the reactive monomers (diamine in

the aqueous phase and acyl chloride in the organic phase, respectively).

S7

Figure S10. The aqueous/organic interfacial tensions of (a) water-hexane (b)

PIP-hexane and (c) water-acyl chloride, respectively (interfacial tensions were

measured by the pendant drop method).

Table S2. Surface free energy of nascent PSf substrate and PEI/TA-modified substrate,

respectively.

Sample Test liquidCA

(deg.)

IFT

(mN/m)

Disp./

LWPolar

Surface free

energy (mN/m)

PSf substrateWater 60 72.8 29.1 43.7

41.6Diiodo-Methane 25 50.8 50.8 0

PEI/TA-modified

substrate

Water 25 72.8 29.1 43.771.6

Diiodo-Methane 29 50.8 50.8 0

S8

Figure S11. Three-dimensionally in-situ FT-IR spectra of the absorbance vs.

interfacial polymerization reaction time, which taking place on the (a) nascent PSf

substrate and (b) PEI/TA-modified substrate, respectively.

Figure S12. (a) In-situ FT-IR absorbance height and (b) the converted polyamide

layer thickness calculated, which is according to the characteristic C=O absorbance

band at 1640 cm-1, with the interfacial polymerization of the PSf NF and the

PEI/TA-PSf NF, respectively. First-order derivative of (c) absorbance height and (d)

the converted polyamide layer thickness of the PSf NF and the PEI/TA-PSf NF, as a

function of interfacial polymerization reaction time, respectively.

0 50 100 150 200 250 300

0.0

0.1

0.2

0.3 PSf NF PEI/TA-PSf NF

Hei

ght

Reaction time s

(a)

0 50 100 150 200 250 3000.000

0.001

0.002

0.003

0.004

0.005

PSf NF PEI/TA-PSf NF

Reaction time s

dH/d

t s-1

(c)

0 50 100 150 200 250 300

0

25

50

75

100

125

150 PSf NF PEI/TA-PSf NF

Thic

knes

s (n

m)

Reaction time (s)

(b)

0 50 100 150 200 250 3000.0

0.5

1.0

1.5

2.0

2.5

3.0

PSf NF PEI/TA-PSf NF

dT/d

t (nm

/s)

Reaction time (s)

(d)

S9

Table S3. Linear fitting parameters for the first-order derivative of absorbance height

as a function of interfacial polymerization reaction time of the PSf NF and the

PEI/TA-PSf NF, respectively.

Table S4. Linear fitting parameters for the first-order derivative of peak area and

polyamide layer thickness as a function of interfacial polymerization reaction time of

the PSf NF and the PEI/TA-PSf NF, respectively.

Linear fitting parametersAbsorbance height

PSf NF PEI/TA-PSf NF

Slope k (s-2) -8.15×10-6 -1.14×10-6

Intercept b (s-1) 3.54×10-3 9.24×10-4

R2 0.9900 0.9982

Linear fitting

parameters

Peak area Polyamide layer thickness (nm)

PSf NF PEI/TA-PSf NF PSf NF PEI/TA-PSf NF

Slope k -1.83×10-3 (s-2) -3.84×10-4 (s-2) -4.69×10-3 (nm·s-2) -3.28×10-4 (nm·s-2)

Intercept b 2.07 (s-1) 0.75 (s-1) 2.06 (nm·s-1) 0.54 (nm·s-1)

R2 0.9996 0.9993 0.9994 0.9904

S10

Figure S13. (a) FT-IR/ATR and (b) XPS spectra of the nascent PSf substrate, the

PEI/TA-modified substrate, the PSf NF, and PEI/TA-PSf NF, respectively

Table S5. XPS analyses of elemental composition, O/N ratio and calculated

cross-linking degree of the substrates and fabricated polyamide membrane surfaces.

Sample C 1s (%) O 1s (%) N 1s (%) S 2p (%) O/N ratioCross-linking

degree (%)

Nascent PSf substrate 75.68 20.08 2.56 1.68 7.84 /

PEI/TA-modified substrate 70.35 23.21 5.50 0.94 4.22 /

PSf NF 70.47 17.08 12.20 0.25 1.40 50

PEI/TA-PSf NF 70.07 16.20 13.50 0.23 1.20 73

1800 1600 1400 1200 1000 800

PEI/TA-PSf NF

PSf NF

PEI/TA-modified substrate

Nascent PSf substrate

Wavenumber cm-1)

(a)

600 500 400 300 200 100

PEI/TA-PSf NF

PSf NF

PEI/TA-modified substrate

Binding Energy (eV)

Nascent PSf substrate(b) S 2p

N 1s

S 2s

C 1sO 1s

S11

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Nor

mal

ized

sal

t rej

ectio

n

Acid

Nor

mal

ized

wat

er fl

ux

Normalized water flux Normalized salt rejection

Base

Figure S14. pH stability of PEI/TA-PSf NF membrane of normalized flux and salt

rejection, before and after acidic and alkaline treatments.

Figure S15. The stress-strain curves of the PSf NF and the PEI/TA-PSf NF,

respectively.

0 50 100 150 2000

5

10

15

2 PEITA-PSf NF

Stre

ss (M

Pa)

Strain (%)

21

1 PSf NF

S12

Figure S16. The fitting straight standard line of the UV-vis absorbance vs. the

FITC-PIP concentration at the maximum UV-vis absorption peak at 495 nm.

Figure S17. UV-vis spectra of the FITC-PIP diffusion from the aqueous phase into the

hexane phase (without trimesoyl chloride), through the nascent PSf substrate and

PEI/TA-modified substrate, respectively (at the diffusion time of 60 s).

200 300 400 500

0.00

0.05

0.10

0.15

PEITA-modified substrate

Wavelength nm

Abs

orba

nce a

.u.

Nascent PSf substrate

0.0 0.2 0.4 0.6

0.0

0.5

1.0

1.5

Abs

orba

nce a

.u.

y=2.53x+0.03

R2=0.9988

Concentration mg/mL