Modulate Light-Tunable Acid-Sensitivity of a Bio-Inspired
Polymer Simply by Adjusting the Position of a Single Methoxy
Substituent
Zhilin Liu †,‡, Yufang Tang ‡, Nan Li ‡, Lican Lu ‡, Junjie Deng †, and Yuanli Cai*,†,‡
Supplementary Information
1
Visible light activating RAFT polymerization of EMpMSD monomer at 25 oC. The monomer
conversions were assessed according to Equation S1, where I4.92–5.05 is the integral of proton signal at δ
= 4.92-5.05 ppm (OCHO in cyclic acetal linkages of PEMpMSD polymer and EMpMSD monomer),
I5.56 is the integral of proton signal at δ = 5.56 ppm (one proton of CH2=CCH3 of EMpMSD monomer).
Conversion 
1H
I 4.925.05  I 5.56
I 4.925.05
(S1)
NMR evidence for effect of the position of methoxy substituent on the light-triggered Z-
isomerization. The degrees of Z-isomerization of PEMpMSD were assessed according to Equation S2,
where I5.58 is the integral of Z-type p-CH3OC6H4CH=CH signal at δ=5.58 ppm, I6.00 is the integral of Etype p-CH3OC6H4CH=CH signal at δ=6.00 ppm.
Degree of Z -isomerization =
1H
I 5.58
I 5.58  I 6.00
(S2)
NMR evidence for effect of the position of methoxy substituent on light-tunable acid-
sensitivity. The overall degree of hydrolysis of cyclic acetal linkages in PEMpMSD was assessed
according to Equation S3, where [I4.8-5.3]0 is the integral ratio of OCHO signal at δ = 4.8-5.3 ppm to the
signals of protons a, g, h and i of initial PEMpMSD, and [I4.8-5.3]t is the integral ratio of OCHO signal to
the total integral of proton signals of a, g, h and i of EMpMSD units without hydrolysis plus proton
signals of k, j and l of hydrolyzed units (see Figure 10).
Overall Degree of Hydrolysis =
[ I 4.85.3 ]0  [ I 4.85.3 ]t
[ I 4.85.3 ]0
(S3)
Furthermore, the degree of hydrolysis of cyclic acetal linkages adjacent to either E- or Z-type
chromophores was separately assessed according to Equation S4 or Equation S5, where [I6.04]0 or [I5.57]0
is the initial integral ratio of the E-type CH=CHC6H4OCH3 signal at δ=6.04 ppm or the Z-type
CH=CHC6H4OCH3 signal at δ=5.57 ppm to that of signals of protons a, g, h and i at δ = 3.3-4.4 ppm;
[I6.04]t or [I5.57]t is the integral ratio of the E-type CH=CHC6H4OCH3 signal to the total integral of
signals of protons a, g, h and i (without hydrolysis) and k, j and l (hydrolyzed) at δ = 3.3-4.4 ppm at
predetermined intervals (see Figure 10).
2
Degree of Hydrolysis (E -type) =
[ I 6.04 ]0 -[ I 6.04 ]t
[ I 6.04 ]0
Degrees of Hydrolysis (Z -type) =
(a)
a
b
c
O
b
c
[ I 5.57 ]0 -[ I 5.57 ]t
[ I 5.57 ]0
g,h k l
O
OH
e f
(b)
O
g,h i
c, CHCl3
d
j
(S4)
(S5)
d
e
c
g
f
b
O
O
h
O
i,j m
a
a
j
8
e
7
6
Figure S1.
l
i,j k
a
CHCl3
c b
d
n
OH
f
k
g h
i
2
h
e db,f g
l
5
4
3
Chemical Shift (ppm)
1H
l
1
0
8
7
6
m i
j
5
4
3
2
Chemical Shift (ppm)
nk
1
0
NMR spectra of the CDCl3 solutions of (a) 5-ethyl-5-hydroxymethyl-2-(p-
methoxystyryl)-[1,3]dioxane
(EHpMSD)
and
(b)
5-ethyl-5-hydroxymethyl-2-(o-methoxystyryl)-
[1,3]dioxane (EHoMSD).
3
15% conversion
13% conversion
31% conversion
30% conversion
47% conversion
48% conversion
61% conversion
61% conversion
69% conversion
(a)
7
8
9
10
(b)
11
12
13
14
15
16
7
8
9
Elution Time (min)
10
11
12
13
14
15
16
Elution Time (min)
16% conversion
34% conversion
52% conversion
62% conversion
70% conversion
(c)
7
8
9
10
11
12
13
14
15
16
Elution Time (min)
Figure S2. The evolution of GPC traces of PEMpMSD synthesized via RAFT polymerization of 5ethyl-5-methacryloyloxymethyl-2-(p-methoxystyryl)-[1,3]dioxane (EMpMSD) using 2-cyanoprop-2yl(4-fluoro)dithiobenzoate (CPFDB) chain transfer agent and (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO) photo-initiator at the feed molar ratios of [PEMpMSD]0:[CPFDB]0:
[TPO]0=50:1:0.2 (a), 150:1:0.2 (b), 200:1:0.2 (c) in 35 wt% THF upon irradiated with the mild visible
light at I420 nm=150 W cm-2 at 25 °C.
4
After UV radiation For 12 h
Initial PEMSD sample
(a)
7
8
9
10
11
12
13
14
15
16
Elution Time (min)
After UV radiation for 12 h
Initial PEMpMSD sample
After UV radiation for 12 h
Initial PEMoMSD sample
(b)
7
8
9
(c)
10
11
12
13
Elution Time (min)
14
15
16
7
8
9
10
11
12
13
14
15
16
Elution Time (min)
Figure S3. The GPC trace evolution of (a) PEMSD, (b) PEMpMSD or (c) PEMoMSD after irradiated
with full-wave UV light at I365 nm = 600 μW cm-2 in argon gas atmosphere at 25 °C for 12 h.
5
0.8
Hydrolysis Product: o-Methoxyphenylacrylaldehyde
Absorbance
0.6
(a)
0.4
[E]:[Z]=100:0
0.2
0.0
240
270
300 330 360
Wavelength (nm)
390
420
450
0.5
Hydrolysis Product: o-Methoxyphenylacrylaldehyde
Absorbance
0.4
(b)
0.3
0.2
[E]:[Z]=38:62
0.1
0.0
240
270
300
330
360
390
Wavelength (nm)
420
450
Figure S4. The evolution of UV-vis spectra of 1,4-dioxane solutions of PEMoMSD at different ratios of
[E]:[Z] under the hydrolyzing conditions: added 0.25 g of 0.98 mol L-1 hydrochloric acid in 50 mL of
12.0 mg L-1 PEMoMSD solutions, and stirred at 25 °C. (a) PEMoMSD at [E]:[Z]= 100:0 (from bottom
to up): 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 150, 180, 210, 240, 270, 300 min; (b)
PEMoMSD at [E]:[Z]=38:62 (from bottom to top): 0, 60, 120, 240, 360, 480, 600, 720, 900, 1080, 1260,
1440, 1620, 1800 min.
6
1.2
Hydrolysis Product: Cinnamaldehyde
Absorbance
1.0
(a)
0.8
0.6
0.4
0.2
[E]:[Z]=100:0
0.0
240
270
300 330 360 390
Wavelength (nm)
420
450
0.6
Absorbance
Hydrolysis Product: Cinnamaldehyde
0.4
(b)
0.2
[E]/[Z]=40:60
0.0
240
270
300 330 360 390
Wavelength (nm)
420
450
Figure S5. The evolution of UV-vis spectra of 1,4-dioxane solutions of PEMSD at different cinnamyl
ratios of [E]:[Z] under the hydrolyzing conditions: added 0.25 g of 0.98 mol L-1 hydrochloric acid in 50
mL of 12.0 mg L-1 PEMSD solutions, and stirred at 25 °C. (a) PEMSD at [E]:[Z]=100:0 (from bottom to
up): 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 420, 480, 540, 600, 660, 720 min; (b)
PEMSD at [E]:[Z]=40:60 (from bottom to top): 0, 60, 120, 240, 360, 480, 600, 720, 900, 1080, 1260,
1440, 1620, 1800 min.
7
1.2
(a)
Absorbance
1.0
0.8
0.6
0.4
0.2
y   0.01  0.1894 x
0.0
0
1
2
3
4
-1
Concentration (mg L )
6
0.5
1.2
(b)
(c)
0.4
Absorbance
1.0
Absorbance
5
0.8
0.6
0.3
0.2
0.4
0.1
0.2
y  0.00149  0.071173 x
y   0.0134  0.18061 x
0.0
0.0
0
1
2
3
4
-1
Concentration (mg L )
5
6
0
1
2
3
4
5
6
-1
Concentration (mg L )
Figure S6. The standard curves of (a) cinnamaldehyde (λmax=284 nm), (b) p-methoxyphenylacrylaldehyde (λmax=315 nm) and (c) o-methoxyphenylacrylaldehyde (λmax=329 nm).
The degrees of hydrolysis of these polymers were calculated by Equation S6, where A0 or AT is the
absorbance at λmax in the initial stage or at the predetermined intervals; a or b is the intercept or slope
value of the corresponding standard curve (y = a + bx); C is the concentration of theoretical completely
hydrolyzed products of the aldehyde compounds.
Degree of Hydrolysis =
( AT  A0 )  a
bC
(S6)
8
p
D3O+/acetone-d6
O OO O
g
g
e,f
d
Od O O O
(E) c' (Z)
c
b
b
+
O O
i
h
h
OH OH
25 oC
e,f
k
CHO
m
(E)
n
a
a
a,m,n
h
p
[E]:[Z]=100:0
b,k
f
H2O
e
b,k
p
421 min
173 min
173 min
81 min
81 min
a
0 min
9
8
b
c
d
7
6
5
Chemical Shift (ppm)
g e
f
36 min
0 min
4
c
504 min
421 min
35 min
10
d
f,h
[E]:[Z]=40:60
i
g
c
504 min
(b)
a,m,n
}
}
(a)
3
10
9
a
b
c
c' d
c'
d
8
7
6
5
Chemical Shift (ppm)
g
e,i
H2O
g e
4
f
3
Figure S7. The evolution of 1H NMR spectrum of PEMSD at [E]:[Z]=100:0 (a) or 40:60 (b) under the
hydrolyzing conditions: added 13 mg of 0.25 mol L-1 deuterated hydrochloric acid in 1.0 mL of 6.0 mg
mL-1 polymer solution in acetone-d6 at 25 °C.
9