of 28
Supplementary Materials for
Flexible biomimetic block copolymer composite for temperature and
long-wave infrared sensing
Tae Hyun Kim
et al.
Corresponding author: Yeong Suk Choi, yeongsuk.choi@samsung.com; Chiara Daraio, daraio@caltech.edu
Sci. Adv.
9
, eade0423 (2023)
DOI: 10.1126/sciadv.ade0423
The PDF file includes:
Figs. S1 to S10
Tables S1 to S7
Legend for movie S1
References
Other Supplementary Material for this manuscript includes the following:
Movie S1
Fig. S1.
Synthesis procedure of the ABA type block copolymers.
(
A
) ABA type block copolymers
are prepared via a reversible addition-fragmentation chain
transfer (RAFT) polymerization
method. (
B
)
Increasing the rotation speed during sample vortex,
the polymer solution became opaque. This change in opacity relative to the m
ixer speed is a typical
behavior found in emulsion systems through Ostwald Ripening, indicating that the synthesized
polymer exists in colloidal states in ethanol. The particle size
in the transparent (left, 1920 rpm)
and opaque solution (right, 3200 rpm) is 97 ± 29 nm and 491 ± 151 nm respectively.
Fig. S2. Polymer characterization using GPC and NMR.
(
A
) GPC traces of
bis
[p(
t
-BA-
r
-HEA)
10
] trithiocarbonate (macro-CTA) and
(
B
)
p[(
t
-BA
5
-
r
-
HEA
5
)-
b
-(
n
-BA)
100
-
b
-(
t
-BA
5
-
r
-HEA
5
)]
r
(deprotected copolymer).
The weight average molecular
weight (
M
w
) and number average molecular weight (
M
n
) of the
final deprotected block copolymer
are high and
comparable to that of pectin
, but with a very narrow
molecular weight distribution
(dispersity
=
M
w
/
M
n
). Because of this narrow
dispersity,
the molecular weight distribution effect
can be neglected while
comprehending
the thermal sensing
properties
and the mechanical
performance of the
block copolymer.
(
C
)
1
H NMR spectrum
of p[(
t
-BA
5
-
r
-HEA
5
)-
b
-(
n
-BA)
100
-
b
-
(
t
-BA
5
-
r
-HEA
5
)]
r
dissolved in CD
2
Cl
2
, prior to
deprotection of
tert-
butyl group.
(
D
)
1
H NMR
spectrum
of p[(AA
5
-
r
-HEA
5
)-
b
-(
n
-BA)
100
-
b
-(AA
5
-
r
-HEA
5
)]
r
dissolved in CD
2
Cl
2
, after
deprotection of
tert
-butyl group. The disappearance of the peak at
1.45 ppm indicates complete
removal of
tert-
butyl group, resulting in free acid.
Fig. S3.
ATR-FTIR spectra of the block copolymer and CaCl
2
dissolved in
ethanol, and the
block copolymer-metal ion complex.
Prior to observing the
in-situ
film formation behavior of the block copolymer-metal ion complex,
the ATR-FTIR spectra of each
component
is measured for control
and plotted
with respect to
drying time: (
A
) the
block copolymer
and (
B
)
CaCl
2
. In both cases, ethanol evaporates with less
than 10 minutes. After this solvent removal, water molecules are absorbed on the metal ions,
whereas no water absorption is observed in the
block copolymer.
ATR-FTIR spectra of
the
composite mixture of block copolymer
with (
C
) 50 %,
(
D
) 25
%, and (
E
) 10
% concentration of
CaCl
2
(
Table S7
) plotted with
respect to drying time.
In the beginning, characteristic peaks of the
solvent, ethanol, appear dominantly on the spectrum; O
-H stretching (3314 cm
-
1
), CH stretching
(2972 cm
-
1
- 2878 cm
-
1
), and C-O stretching (1087 cm
-
1
and 1045 cm
-
1
), respectively. However,
after 5 minutes, the peaks near the O
-H stretching region broaden due to water absorption (3678
cm
-
1
- 3011 cm
-
1
) and peaks initially assigned to the CH stretchin
g and C-O stretching disappear.
Ethanol evaporation and water absorption occur very fast due to the relative hydrophobicity of
polymer. Meanwhile new peaks also emerge; H
2
O bending (1636 cm
-
1
); CH
3
stretching of
n-
BA
(2958 cm
-
1
), CH stretching of AA
(2934 cm
-
1
), CH
2
stretching of HEA (2873 cm
-
1
); C=O stretching
of
n-
BA (1730 cm
-
1
), AA (1723 cm
-
1
), HEA (1719 cm
-
1
); C-O stretching of
n-
BA and HEA (1065
cm
-
1
and 1160 cm
-
1
). The arising new peaks correspond to the ABA block copolymer. The unique
H
2
O bending peak at 1636 cm
-
1
from the ATR-FTIR spectra after 1 hour elucidates
that the
intensities around 3678 cm
-
1
- 3011 cm
-
1
are due to water molecules absorbed
on CaCl
2
, confirming
complete removal of ethanol.
Fig. S4.
TGA-FTIR spectra of water, ethanol, the
block copolymer
casted film, and CaCl
2
powder.
TGA-FTIR spectra
of (
A
)
water and (
B
)
ethanol plotted over time to distinguish
the gas-phase
materials diffused from TGA.
The gas-phase FTIR spectra of water shows
discrete peaks in the
temperature range of 30 °C
- 250 °C. Ethanol exhibits
a strong alkyl stretching (3056 cm
-
1
- 2746
cm
-
1
) and OH vibration (3747 cm
-
1
- 3574 cm
-
1
) when purged with N
2
at RT. (
C
) TGA profile and
the corresponding FTIR spectra of the non-crosslinked polymer solution previously dried
for 12
hours. A
first plateau
appears
in the temperature range of 30
°C - 210
°C, followed by
a dip in the
weight loss
at 210 °C
- 500 °C, indicating polymer degradation. A
second plateau appears
between
500 °C
- 650 °C (residue: 5.798
%). No sign of
water is detected even after
an additional 12 hours
of drying time. (
D
) TGA profile and the corresponding FTIR spectra of CaCl
2
. The first, stepwise
weight loss
is observed below
210 °C, revealing the presence of water
molecules absorbed on the
metal ions. This is further
confirmed
from the
gas phase FTIR spectra.
Later, a slow weight loss
is detected between
210 °C
- 650
°C. (
E
) TGA profiles of CaCl
2
powder exposed in
air for different
time period. The
water absorbed on
the metal ions increases with increasing time of exposure to
the atmosphere.
Fig. S5. TGA-FTIR spectra of the block copolymer-metal ion complex.
TGA profiles and corresponding gas-phase FTIR spectra of the composite film formed using the
ionically crosslinked block copolymer solution with varying amount of CaCl
2
concentration:
(
A
)
100%, (
B
)
50 %, (
C
)
25 %, and
(
D
) 10 % (
Table
S7
). The films are dried for 12 hours before
measurement.
The first weight loss appears between RT and 210 °C and represents the evaporation
of the water molecules bound to CaCl
2
, as shown in the characteristic peaks of the gas-phase FTIR
spectra measured in the first 20 minutes. The following weight loss observe
d in the temperature
range between 210 °C
- 550 °C corresponds to the degradation of the block copolymer (AA,
n
-BA,
HEA, and IPC), which is confirmed from the gas
-phase FTIR spectra observed between 25 to 55
minutes
(
46
48
). Finally, the slow weight loss detected in the range of 550 °C
- 650 °C is caused
by CaCl
2
, confirmed by the gas-phase FTIR spectra between 55 to 65 minutes.
The corresponding
temperature of these events are identified by the 1
st
derivative of the TGA
profile (red line). As the
amount of CaCl
2
is increased, the following amount of water adsorbed in the polymer matrix
increased, showing a linear relationship of R
2
= 0.987.
Fig. S6.
Schematic and fabrication process of the block copolymer temperature sensor and
the measured noise level and hysteresis curve.
(
A
)Device fabrication procedure. (
B
) Schematic (bottom) and optical image (top) of the fabricated
sensor. (
C
) Temperature variation measured in air. The sensor’s sensitivity is derived by
calculating the standard deviation of the te
mperature fluctuation measured while placing the sensor
on a constant temperature reservoir for 100 seconds. AC voltage of 300 mV used at 200 Hz for
readout. (
D
) The sensor displays negligible hysteresis in the current readout.
Fig. S7. Cyclic stability characterization of the block copolymer temperature sensor.
(
A
) Schematic of the measurement set up. (
B
) Profile of the temperature cycles applied over time
and the recorded RMS current and phase. (
C
) Current phase plotted by temperature during the
100-cycle measurement. Overlaid (
D
) RMS current (
E
) and phase recorded during 100 cycles of
continuous measurement. Inset: The current response error and phase error between each cycle.