Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2008
Supporting Information
Copolymer logical switches adjusted through core-shell micelles:
from temperature response to fluorescence response
Qiang Yana, Jinying Yuan*a, Weizhong Yuana, Mi Zhoua, Yingwu Yina and Caiyuan Pan*b
Received (in XXX, XXX) 1st January 2008, Accepted 1st January 2008
First published on the web 1st January 2008
DOI: 10.1039/b000000x
Experiment Section
Materials. N-isopropylacrylamide (NIPAM, Acros, 98%) was recrystallized from benzene and n-hexane (1:3).
Maleic anhydride (MAh, Beijing Chemical Reagents Co., 99%) was recrystallized from anhydrous chloroform free of
ethanol. 2,2-Azobis(isobutyronitrile) (AIBN, Beijing Chemical Reagents Co., 98%) was recrystallized from ethanol
twice. Styrene (St, Acros, 99%) were washed with an aqueous solution of sodium hydroxide (5 wt%) three times and
then with water until neutralization, after being dried with anhydrous magnesium sulfate for 24 h, the monomer was
distilled at reduced pressure. Tetrahydofuran (THF, Beijing Chemical Reagents Co.) was distilled from a purple
sodium solution. Dimethylformamide (DMF, Beijing Chemical Reagents Co.) was distilled from CaH2 under reduced
pressure. Bromobenzene, carbon disulfide, magnesium powder, 9H-cabarzole, sodium hydroxide, methanol,
cyclohexane and n-hexane (Beijing Chemical Reagents Co. analytical grade), 2-chloroethanamine hydrochloric
(Aldrich, 99%) and (bromomethyl)benzene (Aldrich, 99%) were used as received.
Characterization. Fourier transform infrared (FT-IR) spectra were recorded on an AVATAR 360 ESP FT-IR
spectrometer. 1H NMR spectra were obtained from JEOL JNMECA300 NMR instrument with CDCl3 as a solvent,
and tetramethylsilane as reference. The molecular weight and molecular weight distribution were measured on a
Viscotek TDA302 gel permeation chromatograph equipped with two columns (GMHHR-H, M Mixed Bed) at 30 oC,
and the THF was used as eluent at a flow rate of 1.0 mL/min. UV-vis spectra were measured on a UV 2100
spectrophotometer (SHIMADZU, Japan). Dynamics light scattering (DLS) and statistic light scattering (SLS) studies
of the block copolymer micelles in aqueous solution were conducted using Malvern Instrument equipped with a 22
mW He-Ne laser operating at λ= 632.8 nm, an ALV/LSE-5003 multiple tau digital correlator electronics system. The
fluorescence measurements were carried out on a fluorescence spectrometer (Perkin-Elmer, LS55). The solution of
CEA and copolymer in DMF/H2O (3.5: 1) was poured into quartz cuvette. The emission spectra were recorded with
1
Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2008
an excitation wavelength at 295 nm.
Synthesis of Benzyl dithiobenzoate (BDB, 1). The synthesis of BDB was carried out according to the method
reported.1 Yield: 49%. IR νmax: 1047cm-1, 1230cm-1 (S=C=S). 1H NMR δ (CDCl3): 7.20~7.60 (8H, m, Ar-H),
7.90~8.02 (2H, t, Ar-H), 4.60 (2H, s, (S=)C-S-CH2-Ph).
Synthesis of 2-(9H-carbazol-9-yl)-ethanamine (CEA). The synthesis of the fluorescent molecule CEA was
carried out according to the method reported.2 Yield: 28%. 1H NMR δ (CDCl3): 8.05~8.10 (2H, d, Ar-H), 7.42~7.48
(6H, m, Ar-H), 5.32~5.91 (2H, s, -NH2), 3.22 (2H, t, -CH2-NH2), 3.88 (2H, t, N-CH2).
Synthesis of PS (2) via RAFT Polymerization. BDB (0.246 g, 1 mmol), AIBN (0.0172 g, 0.1 mmol) and St
(10.02 g, 96 mmol) were added into a 25 mL round-bottom flask, followed by three freeze-vacuum-thaw cycles. The
flask was immersed into an oil bath at 80 oC with magnetic stirring. After reaction for 8 h, the flask was cooled to
room temperature and opened to the air. The polymer was dissolved in 25 mL THF, and then precipitated by pouring
the solution into anhydrous methanol (500 mL). Repeating the dissolving-precipitation three times, the obtained pink
product (conversion: 45%) was dried in vacuum at 40 oC.
Mn,GPC=3550 g/mol, Mw/Mn=1.14, Mn,NMR=3700 g/mol. IR (KBr, cm-1): 3081, 3059 (νAr-H); 2922,2849 (νC-H); 1601,
1583 (νC=C); 1493, 1452 (νCH2-CH2); 1181, 1069 (νC=S). 1H NMR δH (CDCl3, ppm): 7.58 (aromatic proton), 6.30~7.20
(aromatic proton), 3.92 (s, CH-SC(=S)), 3.79 (d, Ph-CH2), 1.30~2.10 (CH2-CH).
Synthesis of PS-MAh (3). PS (1.991 g, 0.56 mmol), MAh (1.192 g, 12 mmol), and THF (8 mL) were added into a
25 mL round-bottom flask, followed by three freeze-vacuum-thaw cycles. The flask was reflux at 80 oC for 6 h while
magnetic stirring. After the reaction was completed, the flask was cooled to room temperature and opened to the air.
The polymer was dissolved in 10 mL THF, and then precipitation three times in anhydrous methanol to remove the
excess MAh. The light pink polymer obtained was dried in a vacuum at 30 oC for 24 h. Yield (1.59 g, 78%).
Mn,GPC=3720 g/mol, Mw/Mn=1.19, Mn,NMR=3900 g/mol. IR (KBr, cm-1): 1781,1737 (νC=O); 1181, 1069 (νC=S). 1H
NMR δH (CDCl3, ppm): 7.58 (aromatic proton), 6.30~7.20 (aromatic proton), 4.38 (s, CH(C=O)-CH(C=O)), 3.79 (s,
Ph-CH2), 1.30~2.10 (CH2-CH).
Synthesis of PS-MAh-b-PNIPAM (4, 5). PS-MAh (Sample 3 in Table S1, 0.504 g, 0.135 mmol), AIBN (4.4 mg,
0.027 mmol), NIPAM (2.992 g, 26.5 mmol), and THF (8 mL) were added into a 25 mL round-bottom flask, followed
by three freeze-vacuum-thaw cycles. The polymerization was carried out at 80 oC for 8 h with magnetic stirring. After
reaction, the flask was cooled to room temperature and opened to the air. The polymer was dissolved in 10 mL of
THF, and then precipitated in n-hexane three times for removal of unreacted NIPAM. The white polymer (conversion:
56%) obtained was dried in a vacuum oven for 24 h.
2
Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2008
Mn,GPC = 12900 g/mol, Mw/Mn = 1.31, Mn,NMR = 13700 g/mol. IR (KBr, cm-1): 3297~3520 (νN-H), 1647 (νNH-C=O).
1
H NMR δ (CDCl3, ppm): 6.25~7.20 (aromatic proton), 5.70~6.15 (b, CH=CH-CO-NH-), 3.98 (N-CH), 2.10~2.32
(N-(O=C)-CH-CH2), 1.34~2.08 (Ph-CH-CH2), 1.10 (s, -CH(CH3)2).
Synthesis of PS-(MAh-g-CEA)-b-PNIPAM (6, 7). PS-MAh-b-PNIPAM (Sample 4 in Table S1, 0.381 g, 0.0295
mmol), CEA (0.310 g, 1.48 mmol), and DMF (8 mL) were added into a 25 mL round-bottom flask, followed by three
freeze-vacuum-thaw cycles. The reaction mixture was refluxed at 70 oC for 24 h with magnetic stirring. After reaction
was complete, the flask was cooled to room temperature and opened to the air. The polymer was precipitated three
times in n-hexane. The light yellow polymer obtained in yield of 25%was dried in a vacuum oven for 48 h.
Mn,NMR = 13470 g/mol, 1H NMR δ (CDCl3, ppm): 8.06~8.08 (d, carbazole-H), 7.42~7.48 (m, carbazole-H),
6.10~7.20 (aromatic proton), 4.02 (N-CH), 3.45 (N-CH2-CH2-N), 2.10~2.30 (N-(O=C)-CH-CH2-), 1.34~2.08
(Ph-CH-CH2-), 1.10 (s, -CH(CH3)2).
Preparation of the Micelle Solution. The amphiphilic copolymer PS-(MAh-g-CEA)-b-PNIPAM was dissolved
in DMF to form a solution with concentration of 2 mg/mL at room temperature. Then, deionized water was dropped
into the solution at a rate of 0.2 mL/min by a microsyringe. The ratio of [DMF]: [H2O] of solvent mixture was 3.5: 1
(v/v), and the concentration of the polymer was 0.44 mg/mL.
Dynamics Light Scattering and Static Light Scattering Measurements. In the dynamics light scattering
characterization, the intensity-intensity time correlation function G(2)(t,q) in the self-beating mode can result in a
line-width distribution G(Г). The hydrodynamic diameter distribution f(Dh) is calculated by the Stokes-Einstein
equation as eq.1, where kB, T, η are all constant.
Dh=kBT/(3πηD)
(1)
On the basis of static light scattering, for a given solution concentration and the scattering angle θ, the value of
gyration radius Rg is determined based on eq.2:
[
KC
2
] = [1 / M w ] × [1 + Rg q 2 / 3]
R(θ , C )
(2)
3
Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2008
Table S1. Preparation of PS-MAh and PS-MAh-b-PNIPAM via RAFT polymerization
Sample
No.
T/ C
Time/h
Conv./%
Mn,tha
Mn,NMRb
Mn,GPCc
Mw/Mnc
3
Pt32-MAhd
80
6
78
2950e
3900f
3720c
1.19
4
PS32-MAh-b-PNIPAM81
80
8
56
16200
13700
12900
1.31
5
PS32-MAh-b-PNIPAM59
80
6
48
14700
11800
10400
1.26
6
PS32-MAh-b-PNIPAM41
80
4
37
10500
8900
8400
1.22
7
PS32-MAh-b-PNIPAM35
80
2
30
9700
8300
7700
1.29
a
Mn,th calculated by Mn,th(PS-MAh-b-PNIPAM)=[NIPAM]×MNIPAM×conversion/[macro-CTA]+Mn,th(PS-MAh)
Mn,NMR calculated by Mn,NMR(PS-MAh-b-PNIPAM)= (5×I3.98/I6.10~7.20)×DPSt×113+ Mn,NMR(PS-MAh).
c
Mn,GPC were determined by GPC analysis with polystyrene standard, and THF was used as eluent.
d
The molar ratio of [AIBN]:[macro-CTA]:[NIPAM]=0.2:1:200.
e
The Mn,th calculated by Mn,th(PS-MAh)=mproduct/[macro-CTA]+MMAh.
f
Mn,NMR calculated by Mn,NMR(PS-MAh)=(2×I6.30~7.20/5×I7.85)×104+244+98, where 104,244, 98 and 113 are the
molecular weight of styrene, BDB, MAh and NIPAM
b
Table S2. Preparation of PS-(MAh-g-CEA)-b-PNIPAM
No.
Samplea
Time/h
Temp./ oC
Conv./%
Abs. Length/nmb
9
10
4a
6a
24
24
70
70
28
33
294.5, 267.0
294.0, 267.0
a
4a. graft to the PS32-MAh-b-PNIPAM81,Mn,NMR =13470g/mol
6a. graft to the PS32-MAh-b-PNIPAM41,Mn,NMR =9120g/mol
b
UV-vis measurement, DMFsolution, 25 oC
17000
2.0
Mn,th
16000
15000
1.9
Mn,GPC
1.8
13000
1.7
12000
1.6
11000
1.5
10000
9000
Mw/Mn
Molecular Weight
14000
Mn,NMR
1.4
Mw/Mn
8000
1.3
7000
6000
25
30
35
40
45
50
55
1.2
60
Conversion(%)
Fig. S1. Relationship of Mn and Mw/Mn of copolymer PS-MAh-b-PNIPAM with conversion for RAFT
polymerization of NIPAM at 80 oC. The molar ratio of [AIBN]: [macro-CTA]: [NIPAM] = 0.2: 1: 200
4
Supplementary Material (ESI) for Chemical Communications
This journal is (c) The Royal Society of Chemistry 2008
Fig. S2. 1H-NMR spectrum of (a) PS32, (b) PS32-MAh, (c) PS32-MAh-b-PNIPAM81,
(d) PS32-(MAh-g-CEA)-b-PNIPAM81
References
(1) X.S. Feng, and C.Y. Pan, Macromolecules 2002, 35, 4888-4893.
(2) A.M. Cuadro, M.P. Matia, J.L. Garcia, J.J. Vaquero, and J.A-Builla, Syn. Commun. 1991, 21, 535-544.
5