S1
Supporting Information
Efficient Synthesis of Narrowly Dispersed Brush
Copolymers and Study of Their Assemblies: the
Importance of Side Chain Arrangement
Yan Xia, Bradley D. Olsen, Julia A. Kornfield, and Robert H. Grubbs
Division of Chemistry and Chemical Engineering, California Institute of
Technology,
Pasadena, California 91125
S2
Experimental Section
Materials.
(H
2
IMes)(pyr)
2
(Cl)
2
RuCHPh
1
, N,(hydroxyethyl),
cis
,5,norbornene,exo,2,3,
dicarboximide
2
, and N,(pentynoyl decanyl),cis,5,norbornene,exo,2,3,dicarboximide
3
were prepared as described previously. The synthesis and cha
racterization of PMA, P
t
BA,
and PS MMs have been reported previously
3
and the P
n
BA MM was synthesized in a
similar manner.
n
,BA was passed through a column of basic alumina immediately b
efore
use. D, L,lactide was recrystallized from ethyl acetate t
hree times. All other materials
were obtained from commercial sources and used as received.
Synthesis of PLA macromonomers.
A flame,dried Schlenk tube was charged with N,
(hydroxyethyl),
cis
,5,norbornene,exo,2,3,dicarboximide (54 mg, 0.26 mmol), D, L,
lactide (1.5 g, 10.4 mmol), tin (II) 2,ethylhexanoate (2.1 mg, 5.2 6mol), a
nd a stir bar.
The tube was evacuated and backfilled with argon four times, and
was then immersed in
an oil bath at 120 °C. After 4h, the contents were cooled to room tempe
rature, diluted
with dichloromethane, and precipitated into acidic methanol. The MM w
as isolated by
decanting the supernatant and drying
in vacuo
.
1
H NMR (500 MHz, CDCl
3
): δ 1.24 (br d,
1H), 1.40,1.70 (br, 253H), 2.72 (br, 2H), 3.28 (br, 2H), 3.70,3.85 (m, 2H), 4.22,4.40 (m,
3H), 5.00,5.30 (m, 84H), 6.30 (br t, 2H). GPC,MALLS:
M
n
= 7.0 kg/mol,
M
w
/
M
n
= 1.12.
General procedure for synthesis of brush block and random cop
olymers via ROMP
of macromonomers.
An oven,dried vial was charged with 100 mg MM for the first
block and a stir bar. The vial was then degassed, and the desired
amount of degassed
anhydrous THF ([M]
0
= 0.05,0.10 M) was added via syringe under an argon atmosphere
to dissolve the MM. A stock solution of Ru catalyst in degassed anhyd
rous THF was
prepared in a separate vial. The desired amount of catalyst
was injected into the MM
solution to initiate the polymerization. The reaction was allowed t
o proceed at room
temperature for 20,30 min. After the first polymerization was c
omplete, the desired
amount of second MM was added as a solution in THF ([M]
0
= 0.05,0.10 M). After 1h,
the reaction mixture was quenched with one drop of ethyl vinyl ether
. A sample was then
withdrawn for GPC analysis without any purification. The block co
polymer was isolated
either by precipitating into cold methanol, or by simply drying
in vacuo.
S3
The random copolymers were synthesized using a similar proce
dure as the block
copolymers, except that two types of MMs were added togethe
r in the reaction vial
before catalyst injection.
Characterization.
1
H and
13
C NMR spectroscopy
was recorded in CDCl
3
or DMF,
d
7
using a Varian Mercury 300 or Varian Inova 500 spectrometer. Chemica
l shifts (δ) are
expressed in ppm downfield from tetramethylsilane using the resi
dual protiated solvent
signal as an internal standard.
Gel permeation chromatography (GPC)
was carried out in THF on two PLgel 10
μ
m
mixed,B LS columns (Polymer Laboratories) connected in series
with a DAWN EOS
multiangle laser light scattering (MALLS) detector and an O
ptilab DSP differential
refractometer (both from Wyatt Technology). No calibration s
tandards were used, and
d
n
/d
c
values were obtained for each injection by assuming 100% mass e
lution from the
columns.
Atomic Force Microscopy (AFM)
images were taken using a Nanoscope IV Scanning
Probe Microscope Controller (Digital Instruments, Veeco Metr
ology Group) in tapping
mode in air at room temperature using silicon tips (spring const
ant = 40,50 N/m,
resonance frequency = 170,190 kHz, and tip radius of curvature <10 nm). The
samples
for imaging individual polymers were prepared by spin casting
very dilute solutions
(<0.01 wt%) in chloroform onto freshly cleaved mica at 1500 rpm. Thin
film samples
were prepared by spin casting solutions (2.5 wt%) in toluene ont
o Si(100) with a native
oxide layer at 1500 rpm. A Gartner L116,C ellipsometer was used
to measure the film
thickness.
Differential Scanning Calorimetry (DSC)
was performed on a Perkin,Elmer DSC 7.
Samples were heated to 180 °C at 20 °C/min to erase any ther
mal history, then cooled to
0 °C at 20 °C/min, and reheated to 150 °C at 15 °C/min. The second heati
ng scan was
used to determine the
T
g
of PLA.
Small Angle X-ray Scattering (SAXS)
.
Samples for SAXS were prepared by annealing
polymers in vacuum (10 mTorr) at 110 °C for 12 h to form 1 mm thick
disks and then
sealing the samples between Kapton windows. Experiments were
performed on beamline
27X,C at Brookhaven National Lab. The beamline was configured wi
th an X,ray
wavelength of 1.371 Å. Samples were corrected for transmission, thi
ckness, empty cell,
S4
and dark field scattering and radially averaged to produce 1D I vs.
q
plots. Temperature,
dependent experiments were conducted by increasing temperature
in 5 °C steps with 5
minutes of thermal equilibration after reaching each tempera
ture before starting data
acquisition.
S5
(a)
(b)
S6
(c)
Figure S1.
1
H NMR spectra of (a) macromonomer NB(P
n
BA)4.0k; (b) macromonomer
NB(PLA)7.0k; (c) (PNB,
g
,PS)
100
,
b
,(PNB,
g
,P
t
BA)
50
and hydrolyzed (PNB,
g
,PS)
100
,
b
,
(PNB,
g
,PAA)
50
.
(a)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0
20 40 60 80 100
Conversion (%)
M
n
(kDa)
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
PDI
PtBA 4.5k
PS 6.6k
PS 2.2k
PLA 4.7k
PLA 7.0k
PnBA 4.0k
S7
(b)
0
20
40
60
80
100
0
10
20
30
40
50
Time (min)
Conv (%)
PtBA 4.5k
PS 6.6k
PS 2.2k
PLA 4.7k
PLA 7.0k
PnBA 4.0k
Figure S2.
ROMP of MMs:
(a)
Dependence of
M
n,GPC and PDI on conversion; (b) MM
conversion vs time. Conditions: [MM]
0
= 0.05M in THF at room temperature, [MM/C]
0
= 200.
Elution time (min)
10.0
12.0
14.0
16.0
(d)
Elution time (min)
10.0
12.0
14.0
16.0
18.0
(a)
Elution time (min)
10.0
12.0
14.0
16.0
18.0
.0
(b)
Elution time (min)
10.0
12.0
14.0
16.0
18.0
(c)
S8
Elution time (min)
10.0
12.0
14.0
16.0
(f)
Figure S3.
GPC RI traces of brush copolymers in Table 2. All the trac
es were obtained
from crude polymers after ROMP without any purification. (a) r
ed: entry 1 in table 1
(PNB,
g
,PS)
40
,
b
,(PNB,
g
,P
n
BA)
70
;
black: entry 2 in table 1 (PNB,
g
,PS)
40
,
b
,(PNB,
g
,
P
n
BA)
200
; (b) red: entry 3 in table 1 (PNB,
g
,P
t
BA)
100
,
b
,(PNB,
g
,P
n
BA)
100
; black: entry 4
in table 1 (PNB,
g
,P
t
BA)
100
,
b
,(PNB,
g
,P
n
BA)
200
; (c) red: entry 5 in table 1 (PNB,
g
,PS)
50
,
b
,(PNB,
g
,P
t
BA)
50
; black: entry 6 in table 1 (PNB,
g
,PS)
100
,
b
,(PNB,
g
,P
t
BA)
50
; (d) blue:
entry 7 in table 1 (PNB,
g
,PLA)
20
,
b
,(PNB,
g
,P
n
BA)
180
; red: entry 8 in table 1 (PNB,
g
,
PLA)
40
,
b
,(PNB,
g
,P
n
BA)
160
; green: entry 9 in table 1 (PNB,
g
,PLA)
100
,
b
,(PNB,
g
,
P
n
BA)
100
; black: entry 10 in table 1 (PNB,
g
,PLA)
200
,
b
,(PNB,
g
,P
n
BA)
200
; (e) red: entry
11 in table 1 (PNB,
g
,PLA)
50
,
ran
,(PNB,
g
,P
n
BA)
50
; blue: entry 12 in table 1 (PNB,
g
,
PLA)
100
,
ran
,(PNB,
g
,P
n
BA)
100
; green: entry 13 in table 1 (PNB,
g
,PLA)
200
,
ran
,(PNB,
g
,
P
n
BA)
200
; (f) black: entry 14 in table 1 (PNB,
g
,PLA)
160
,
ran
,(PNB,
g
,P
n
BA)
40
; red: entry
15 in table 1 (PNB,
g
,PLA)
130
,
ran
,(PNB,
g
,P
n
BA)
70
.
(a)
Temperature (°C)
20 40 60 80 10
0 120
Heat Flow
NB(PLA)4.7k
(PNB-
g
-PLA)
200
time (min)
1 0.0
12 .0
14.0
16 .0
Elution time (min)
10.0
12.0
14.0
16.0
(e)
S9
(b)
Heat Flow
Temperature (°C)
20 40 60 80 10
0 120 140
PLA
100
-
ran
-P
n
BA
100
PLA
130
-
ran
-P
n
BA
70
PLA
160
-
ran
-P
n
BA
40
PLA
50
-
ran
-P
n
BA
50
PLA
200
-
ran
-P
n
BA
200
(c)
Heat Flow
20 40 60 80 10
0 120 140
Temperature (°C)
PLA
40
-
b
-P
n
BA
160
(PNB-
g
-PLA)
200
PLA
20
-
b
-P
n
BA
180
PLA
100
-
b
-P
n
BA
100
Figure S4.
DSC traces of (a) macromonomer NB(PLA)4.7k and brush homopolymer
(PNB,
g
,PLA)
200
; (b) brush random copolymers (PNB,
g
,PLA)
x
,
ran
,(PNB,
g
,P
n
BA)
y
; (c)
brush block copolymers (PNB,
g
,PLA)
x
,
b
,(PNB,
g
,P
n
BA)
y
.
S10
14x10
-3
12
10
8
6
4
2
1/I (a.u.)
3.2x10
-3
3.0
2.8
1/T (1/K)
g
-
[PLA
130
-
r
-P
n
BA
70
]
g
-
[PLA
160
-
r
-P
n
BA
40
]
Figure S5.
Inverse intensity of peak heights vs inverse temperature for asymmetri
c brush
random copolymers.
Figure S6.
AFM height image of thin films of a mixture of two brush random
copolymers, (PNB,
g
,PLA)
50
,
ran
,(PNB,
g
,P
n
BA)
50
and (PNB,
g
,PLA)
100
,
ran
,(PNB,
g
,
P
n
BA)
100
(1:1), and its cross sectional analysis. A hole layer was formed in this case.
18 nm
5 μm
S11
a
b
c
2.5 μm
500 nm
500 nm
Figure S7.
AFM phase images of brush block copolymer thin films (ca 120 nm) on
silicon wafer: (a) (PNB,
g
,PLA)
100
,
b
,(PNB,
g
,P
n
BA)
100
; (b) (PNB,
g
,PLA)
130
,
b
,(PNB,
g
,
P
n
BA)
70
; (c) (PNB,
g
,PLA)
160
,
b
,(PNB,
g
,P
n
BA)
40
.
References
(1) Love, J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H.
Angew. Chem., Int. Ed.
2002
,
41
, 4035–4037.
(2) Matson, J. B.; Grubbs, R. H.
J. Am. Chem. Soc.
2008
,
130
, 6731,6733.
(3) Xia, Y.; Kornfield, J. A.; Grubbs, R. H.
Macromolecules
2009
,
42
, 3761,3766.