Supporting Information - For Review Only - Not for Publication
S1
Improving Brush Polymer Infrared
1-D Photonic Crystals via Line
ar Polymer Additives
Supporting Information
Robert J. Macfarlane, Bongkeun Kim, Byeongdu Lee, Raymond A. We
itekamp, Christopher M.
Bates, Siu Fung Lee, Alice B. Chang, Kris T. Delaney, Glenn Fre
derickson, Harry A. Atwater,
Robert H. Grubbs
Materials:
Unless otherwise noted, all solvents and reagents were purchase
d from VWR or Sigma-Aldrich.
The ruthenium-based metathesis catalyst was obtained from Mater
ia Inc. and stored in a drybox
prior to use, and the RuO
4
SEM staining agent was obtained from Polysciences, Inc and sto
red at
4
º
C. The ruthenium metathesis catalyst ((H
2
IMes)(pyr)
2
(Cl)
2
RuCHPh) and PLA macromonomer
initiator (N-(hydroxy
ethanyl)-cis-5-norbornene-exo-2,3-dicarbox
imide) were prepared as
described previously (
1). Dry solvents were
purified by passing
them through solvent purification
columns, and 3,6-dimethyl-1,4-di
oxane-2,5-dione was purified by
sublimation under vacuum. All
other solvents and chemicals we
re used without further purifica
tion unless otherwise noted.
General Information:
NMR spectra were recorded at room temperature on a Varian Inova
500 (at 500 MHz), and
analyzed on MestReNova software. Gel permeation chromatography
(GPC) was carried out in
THF on two Plgel 10 μm mixed-B LS c
olumns (Polymer Laboratories
) connected in series with a
miniDAWN TREOS multiangle laser light scattering (MALLS) detect
or, a ViscoStar viscometer
and Optilab rex differential refractometer (all from Wyatt Tech
nology). The dn/dc values used for
the polylactide and polystyrene macromonomers were 0.050 and 0.
180 respectively, and dn/dc
values for the brush polymers and random copolymers were obtain
ed for each injection by
assuming 100% mass elution from the columns. SEM images were ta
ken on a ZEISS 1550 VP
Supporting Information - For Review Only - Not for Publication
S2
Field Emission SEM, and reflection measurements were performed
on a Cary 5000 UV/Vis/NIR
spectrophotometer, equipped with
an ‘integrating sphere’ diffus
e reflectance accessory (Internal
DRA 1800); all reflection measurements were referenced to a Lab
Sphere Spectralon 99% certified
reflectance standard. The samples were illuminated through a Sp
ectralon-coated aperature with a
diameter of 1 cm, with a beam area of approximately 0.5 cm
2
. The samples were scanned at a rate
of 600 nm/min with a 1 nm data interval, with detector crossove
r (InGaAs to PMT) at 875 nm.
SAXS Data was collected at beamline 12-ID at Argonne National L
aboratory’s Advanced Photon
Source. The samples were probed using 12 keV (1.033 Å) x-rays,
and the sample-to-detector
distance was calibrated from a silver behenate standard. The be
am was collimated using two sets
of slits and a pinhole was used to remove parasitic scattering.
The beamwidth was approximately
200 – 300 μm horizontally and 50 μm vertically.
Importantly, samples obtained by annealing the polymer blends b
etween two glass
coverslips that were scanned with the X-ray beam perpendicular
to the substrate did not yield
meaningful data in most systems. This was taken as a strong ind
ication that the samples were all
highly aligned in a direction para
llel to the substrate—very fe
w samples showed any meaningful
data, and then only giving very weak signal, despite the large
degree of reflectivity
observed in the
optical data. This was confirmed by aligning the substrates par
allel to the X-ray beam and scanning
through the entirety of a sample. In this arrangement, multiple
scattering peaks could be observed
for most systems. However, due to the small film thickness, sca
ttering from the s
ubstrate or glass
coverslips was unavoidable and
contributed significantly to the
background noise. As a result,
while the samples clearly had ordered lamellae as confirmed by
SEM and optical spectroscopy,
not all samples were able to be properly characterized with SAX
S, especially samples with large
periodicities where the q
0
scattering peak was obscured by the substrate scattering. As a
result,
Supporting Information - For Review Only - Not for Publication
S3
lamellar spacings were not obtainable for all systems and thus
some values were instead inferred
from the optical data by compa
ring the photonic band gaps of sy
stems where SAXS data was
obtained to the SAXS lamellar spacings.
Methods:
The synthesis and characterization of macromonomers, brush blo
ck copolymers, and brush
homopolymers was performed as des
cribed previously. Polystyrene
and polylactic acid
homopolymers were synthesized using the same protocols, and the
polystyrene homopolymers
were synthesized with the same pr
otocol but using methyl α-brom
oisobutyrate as an initiator.
Random copolymers were synthesized using a protocol modified f
rom (2). The random
copolymers containing vinylbenzyl
chloride, methyl methacrylate
, and 4-
(diphenylphosphino)styrene mono
mers were synthesized directly,
while the random copolymers
bearing azide, amine, olefin, an
d nitrile groups were synthesiz
ed via modification of the
vinylbenzyl chloride-styrene random copolymer.
To generate the directly synthe
sized random copolymers, AIBN wa
s first recrystallized
from hot methanol, then filtered and placed under vacuum to rem
ove excess solvent. Styrene,
vinylbenzyl chloride, and methyl
methacrylate were mixed with ba
sic aluminum oxide and stirred
for 30 minutes to remove the stabl
izing agents present in solut
ion that would impede
polymerization, then filtered thr
ough a glass frit; vinylbenzyl
chloride was subsequently passed
through plugs of basic alumina (
typically two purifications wer
e sufficient) to yield a colorless
solution. 4-(diphyenylphosphino)st
yrene was used as a solid pow
der with no further
purification.
In a typical synthesis, styrene
(14.85 ml, 1 equiv.), vinylbenz
ylchloride (4.5 ml, 0.25
equiv.), AIBN (6.75 g, 0.32 equiv.) and THF (54 mL) were combin
ed in a two-necked round
Supporting Information - For Review Only - Not for Publication
S4
bottom flask fitted with a rubber septum and a condenser column
, then degassed with Argon for
~1 hour. The solution was then placed at 65
º
C for 1 hour; conversion was kept low in order to
prevent monomer drift. The polym
er solution was then cooled in
an ice bath and dr
ied on a rotary
evaporator to remove the THF. The remaining solution was precip
itated in methanol 3 times to
remove excess monomer, then dried under vacuum. GPC and NMR wer
e used to determine
molecular weights and relative
monomer fractions within the RCP
s.
The azide-bearing RCPs were synt
hesized by reac
ting the vinylb
enzyl chloride RCP (4.52
g, 1 equiv.) with sodium azide (0.882 g, ~1.5 equiv. per –Cl gr
oup) in DMF (75 mL) at room
temperature overnight; this sample was purified via three preci
pitations in methanol. Complete
conversion was noted by H NMR in accordance with previous proto
cols (3). The amine-bearing
RCP was synthesized by reacting the azide-RCP (0.519 g, 1 equiv
.) with triphenyl phosphine (1.15
g, ~6 equiv.) in a 10:1 mixture of THF and H
2
O (30 mL, 3 mL, respectivel
y) at room temperature
for 24 hours (4). Purification w
as performed by extraction from
cold ether.
Click chemistry was used to synt
hesize the olefin- and nitrile-
RCPs; the azide RCP (0.268
g, 1 equiv.) was combined with either 4-ethynylbenoznitrile (0.
111 g, ~1.5 equiv. per N
3
group)
or N-(propargyl)-cis-5-norbor
nene-exo-2,3-dicarboximide (0.179
g, ~1.5 equiv. per N
3
group,
synthesized using protocols desc
ribed previously (1)), and with
CuBr (35 mg, ~0.4 equiv.), and
PMDETA (50 μL, ~0.4 equiv.). This mixture was then dissolved in
~15 mL degassed THF, and
the solution was further degassed for ~15 minutes, then placed
at 65
º
C overnight. The reaction
mixture was purified by filtering through a basic alumina colum
n followed by two rounds of
precipitation in methanol. For all of the above polymers, molec
ular weights were confirmed using
GPC, and complete conversion of t
he starting material was obser
ved via shift of the H NMR peak
corresponding to the protons gemina
l to the chloride/azide/amin
e/“clicked” triazole groups.
Supporting Information - For Review Only - Not for Publication
S5
Blends were prepared by dissolving BBCPs and HPs in benzene to
generate stock solutions
at known concentrations. These
solutions were then mixed in 20
ml scintillations vials at
appropriate concentrations and fl
ash frozen via submersion in l
iquid nitrogen. Once the samples
were fully frozen, they were placed in a vacuum chamber and pum
ped down to ~200 mbar, then
allowed to heat up to room temperature overnight, resulting in
fluffy white powders that were a
homogenous mixtures of all polymer components.
Lamellar arrays of BBCPs were synthesized by placing the powde
red blends in between
two substrates (glass slides for
reflection and SEM measurement
s, a Si wafer and a glass coverslip
sandwiched between two glass slides for SAXS and IR) and compre
ssed with clamps. Samples
were annealed by placing them in a 140
º
C oven under vacuum overnight, then allowing them to
cool in air. For reflection meas
urements, the glass slides were
left intact—some measurements
were also performed by separating the two glass slides sandwich
ing the polymer and measuring
reflectance from the polymer film on a single glass slide, but
no difference was noted in the
photonic band gap λ
Max
. Glass slides coated in polymer films that were characterized
with SEM
were first fractured to expose a polymer surface perpendicular
to the glass slides, then stained with
fresh RuO
4
vapor for ~ 8 minutes and coated with ~10 nm of amorphous carb
on to allow for SEM
contrast and to prevent charging, respectively. Samples prepare
d on Si wafers for SAXS and IR
were separated from the coversli
p prior to taking measurements.
Modeling Information
Self-Consistent Field Theory (SCFT) was utilized to model syste
ms with bottle brush
copolymers by extending the grafted copolymer melt model (5) wi
th a multi-species exchange
model (Düchs, Delaney and Fredrickson, to be submitted). A poly
norbornene backbone (A) is
Supporting Information - For Review Only - Not for Publication
S6
grafted evenly with constant grafting density by PS side-arms (
B) and PLA side-arms (C). The
grafting density is defined as
τ
୩ା୪
ሻ݈݇ሺ/
where
k
is the number of B arms and
l
is the number of
C arms. The position of each grafted arm,
τ
୨
can be calculated from Wang et al (Langmuir 2009,
25(8), 4735–4742) as:
τ
୨
߬ൌ
ሺ݆െ1ሻሺ1െ߬
ଵ
ሻ
݈݇
݈݆݇1
The detail formalism of SCFT for bottle brush copolymer + homop
olymer blends can be found
from Kim et al (to be published).
To match the experimental conditions,
χ
BC
N
is 12.0, as calculated from the length of
homopolymer PS and PLA, and χ and
N
(the degree of polymerization)
are calculated from Zalusky
et al (6). Additionally,
χ
AB
N =
χ
AC
N
= 0, where the segregation strength of the polynorbornene
backbone and all other sidearms are effectively shielded by the
high grafting density. This
parameterization represents a b
ottle brush copolymer of PS and
PLA grafted arms with molecular
weight equal to 987 kg /mol when the backbone length
α
A
is set to 2.8 and the number of grafted
brushes is 140 each of PS and PLA arms. From this parameter set
up, the period of lamellar
morphology in the bulk is calculated in
R
g
units, where 1
R
g
= 7.1 nm.
Supporting Information - For Review Only - Not for Publication
S7
Supplementary Data:
List of Polymer Information
Table S1
: Macromonomer Physical Data
Table S2
: Brush Block Copolymer Physical Data
Table S3
: Homopolymer Physical Data
Table S4
: Random Copolymer Physical Data
MM ID MW
(
g
/mol
)
PDI DP
PLA-MM 3100
1.113 40
PS-MM
3500
1.019 31
BBCP ID
MW (g/mol)
PDI f
PS
/f
PLA
DP
PS
DP
PLA
A
987000
1.024 52/48 155
143
B
1406000
1.010 51/49 217
209
C
1517000
1.015 50/50 230
230
D
1763000
1.019 50/50 267
267
E
2110000
1.038 50/50 320
320
F
2648000
1.051 50/50 401
401
G
3035000
1.053 51/50 460
460
HP ID
MW
(
g
/mol
)
PDI
DP
PS-3k
3200
1.056
42
PS-6k
6200
1.037
83
PS-12k
12400
1.038 169
Brush PS
139000 1.003
45
PLA-3k
3100
1.286
27
PLA-6k
6700
1.244
62
PLA-12k
13900
1.396 133
Brush PLA 151000 1.006
43
RCP ID
MW (g/mol)
PDI
f
P-X
DP
P-S-VBzCl
5200
1.163 24.4
45
P-S-N
3
5770
1.140 24.0
44
P-S-NB
8010
1.199 18.2
56
P-S-CN
7140
1.144 26.9
46
P-S-NH
2
6500
1.154 7.7
50
P-S-MMA
5210
1.115 29.6
52
P-S-PPh
3
6520
1.508 16.9
49
Supporting Information - For Review Only - Not for Publication
S8
Brush Block Copolymer Blend Photonic Band Gap and Lamellar Spac
ing Data
*d
Lam
for each sample was calculated using small angle X-ray scatter
ing. Values noted with a star could not be
measured directly and thus were interpolated based upon the pho
tonic band gap position and the directly measured
d
Lam
values for other BBCP blends.
Figure S1
: Brush Block Copolymer A Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
A
0.0%
391
128
-
0.238
A 15.0%
413
134 5.63% 0.262
A 30.0%
424
141* 8.44% 0.217
A 45.0%
459
156 17.4% 0.229
A 55.0%
457
171 16.9% 0.228
A 65.0%
528
188 35.0% 0.199
A 67.5%
530
197 35.5% 0.219
A 70.0%
513
191 31.2% 0.390
Supporting Information - For Review Only - Not for Publication
S9
Figure S2
: Brush Block Copolymer B Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
B
0.0%
442
143
-
0.231
B
15.0%
466
152 5.43% 0.206
B
30.0%
499
164 12.9% 0.204
B
45.0%
548
177 24.0% 0.237
B
55.0%
586
194 32.6% 0.215
B
65.0%
667
221* 50.9% 0.249
B
67.5%
685
227* 55.0% 0.301
B
70.0%
659
219* 49.1% 0.285
Supporting Information - For Review Only - Not for Publication
S10
Figure S3
: Brush Block Copolymer C Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
C
0.0%
512
170*
-
0.199
C
15.0%
545
181* 6.45% 0.204
C
30.0%
583
195 13.9% 0.202
C
45.0%
635
205 24.0% 0.191
C
55.0%
676
222 32.0% 0.204
C
65.0%
751
242 46.7% 0.240
C
67.5%
759
251* 48.2% 0.258
C
70.0%
793
263* 54.9% 0.262
C
75.0%
874
290* 70.7% 0.414
Supporting Information - For Review Only - Not for Publication
S11
Figure S4
: Brush Block Copolymer D Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
D
0.0%
574
195
-
0.221
D
15.0%
611
203* 6.45% 0.239
D
30.0%
660
216 15.0% 0.221
D
45.0%
717
230 24.9% 0.250
D
55.0%
772
254 34.5% 0.249
D
65.0%
872
270 51.9% 0.275
D
67.5%
890
295* 55.1% 0.243
D
70.0%
925
307* 61.1% 0.259
D
72.5% 1042
346* 81.5% 0.361
D
75.0%
946
314* 64.8% 0.357
Supporting Information - For Review Only - Not for Publication
S12
Figure S5
: Brush Block Copolymer E Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
E
0.0%
695
227
-
0.322
E 15.0%
716
237* 3.02% 0.332
E 30.0%
768
250 10.5% 0.326
E 45.0%
837
267 20.4% 0.292
E 55.0%
913
284 31.4% 0.278
E 65.0%
961
309 38.3% 0.352
Supporting Information - For Review Only - Not for Publication
S13
Figure S6
: Brush Block Copolymer F Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
F
0.0%
829
275*
-
0.273
F
15.0%
865
287* 4.34% 0.294
F
30.0%
946
314* 14.1% 0.247
F
45.0% 1016
340 22.6% 0.232
F
55.0% 1094
362 32.0% 0.236
F
65.0% 1180
391* 42.3% 0.224
F
70.0% 1253
416* 51.1% 0.271
F
72.5% 1286
426* 55.1% 0.322
Supporting Information - For Review Only - Not for Publication
S14
Figure S7
: Brush Block Copolymer G Blend Information
BBCP ID Wt% HP
λ
Max
(nm) d
Lam
(nm)
%Swollen Δλ/λ
G
0.0%
921
305*
-
0.363
G 15.0%
991
329* 7.60% 0.329
G 30.0% 1041
345* 13.0% 0.284
G 45.0% 1130
374* 22.7% 0.258
G 55.0% 1198
397* 30.1% 0.259
G 65.0% 1333
442* 44.7% 0.234
G 75.0% 1403
485* 52.3% 0.285
Supporting Information - For Review Only - Not for Publication
S15
Images of BBCP Homopolymer Blends
Figure S8
: Photos of BBCP A Blends (fr
om left, 0%, 15%, 30%, 45%, 55%, 6
5%, 67.5%)
Figure S9
: Photos of BBCP B Blends (fr
om left, 0%, 15%, 30%, 45%, 55%, 6
5%)
Figure S10
: Photos of BBCP C Blends (fr
om left, 0%, 15%, 30%, 45%, 55%, 6
5%)
Figure S11
: Photos of BBCP D Blends (fr
om left, 0%, 15%, 30%, 45%, 55%, 6
5%)
Figure S12
: Photos of BBCP F Blends (fr
om left, 0%, 15%, 30%, 45%, 55%, 6
5%)
Supporting Information - For Review Only - Not for Publication
S16
UV-Vis data for RCP Blends
Figure S13
: UV-Vis spectra of P-S-VBzCl/BBCP Blends. Note that the total
weight % of
homopolymer is equal amounts RCP and PLA HP. Samples in which t
he same amount of PLA HP
was added, but the RCP was not a
dded are provided as controls f
or comparison.
Figure S14
: UV-Vis spectra of P-S-N
3
/BBCP Blends. Note that the total weight % of
homopolymer is equal amounts RCP and PLA HP. Samples in which t
he same amount of PLA HP
was added, but the RCP was not a
dded are provided as controls f
or comparison.
Figure S15
: UV-Vis spectra of P-S-Norbornene/BBCP Blends. Note that the t
otal weight % of
homopolymer is equal amounts RCP and PLA HP. Samples in which t
he same amount of PLA HP
was added, but the RCP was not a
dded are provided as controls f
or comparison.
Supporting Information - For Review Only - Not for Publication
S17
Figure S16
: UV-Vis spectra of P-S-Nitrile/BBCP Blends. Note that the tota
l weight % of
homopolymer is equal amounts RCP and PLA HP. Samples in which t
he same amount of PLA HP
was added, but the RCP was not are provided as controls for com
parison.
Figure S17
: UV-Vis spectra of P-S-NH
2
/BBCP Blends. Note that the total weight % of
homopolymer is equal amounts RCP and PLA HP. Samples in which t
he same amount of PLA HP
was added, but the RCP was not a
dded are provided as controls f
or comparison.
Figure S18
: UV-Vis spectra of P-S-MMA/BBCP Blends. Note that the total we
ight % of
homopolymer is equal amounts RCP and PLA HP. Samples in which t
he same amount of PLA HP
was added, but the RCP was not a
dded are provided as controls f
or comparison.