Supporting Information
Novel multiwalled carbon nanotube grafted with polyethylene
glycol-block-polystyrene nanohybrids: ATRP synthesis and
detection of benzene vapor
Yan-Ling Luo, Rui-Xue Bai, Feng Xu*, Ya-Shao Chen, Hua Li, Si-Si Dai, Wen-Bo Ma
(Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry
and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, P. R. China)
Contact details for corresponding authors
Yan-Ling Luo and Feng Xu
Fax: +86 29 81530727
E-mail address: luoyanl@snnu.edu.cn (Y. L. Luo) and fengxu@snnu.edu.cn (F. Xu)
Affiliations: Key Laboratory of Macromolecular Science of Shaanxi Province, School
of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062,
People's Republic of China
Fax: +86 29 81530727

Corresponding authors. Tel:
Fax:
+86 29 81530727. E-mail
addresses:
luoyanl@snnu.edu.cn (Y. L. Luo) and fengxu@snnu.edu.cn (F. Xu).
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1 Synthesis processes
The synthesis of MWCNTs graft polyethylene glycol-block-polystyrene copolymers,
MWCNTs-g-PEG-b-PS, was carried out by a four-step reaction procedure. Thionyl
chloride was first used to react with MWCNTs-COOH to produce MWCNTs-COCl,
and then the resultant product reacted with PEG to yield MWCNTs-g-PEG-OH. The
latter, MWCNTs-g-PEG-OH, was adopted to synthesize initiators for ATRP,
MWCNTs-g-PEG-Br,
by
reacting
with
2-bromoisobutyryl
bromide.
MWCNTs-g-PEG-b-PS was finally synthesized by ATRP of styrene on the surface of
using the initiator MWCNTs-g-PEG-Br.
2.2.1 Synthesis of MWCNTs-COCl
MWCNTs-COCl was synthesized by acylchlorination reaction of MWCNTs-COOH
with thionyl chloride. Specifically, dried MWCNT–COOH (1.0 g) was dispersed in 60
mL SOCl2 and then three drops of DMF as catalyst was added and stirred for 0.5 h in
ice bath at 0 °C. The mixed solution was ultrasonically dispersed for 2 h before the
reaction proceeded at 75 °C under protection of dried N2 for 24 h. The resulting mixture
solution was allowed to cool to ambient temperature and then filtered. The solid was
washed with 60 ml chloroform 4 times. Most of chloroform and the residual SOCl 2
were removed by a rotary evaporation apparatus. The remnants were vacuum-dried at
ambient temperature for 24 h, yielding 0.93 g acylchlorinated MWCNTs (yield: 94.3%),
denominated MWCNTs–COCl.
2.2.2 Synthesis of MWCNTs-g-PEG-OH
Freshly-prepared MWCNTs-COCl of 0.3 g (-COCl contents: ca 0.258 mmol) was
immediately mixed with 1.032 mmol excess PEG (0.6192, 1.032, 2.064 and 4.128 g
corresponding to degree of polymerization of about 14, 23, 45 and 91) in a mixture
solution consisting of 10 ml anhydrous CHCl3 and 2 ml anhydrous TEA in a 100 ml
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dried three round bottom flask under protection of dried N2. After ultrasonicated for
about 30 min, the reaction mixture was stirred for 48 h at 120 °C. The solid was
separated from the mixture by filtration, and rinsed with CHCl3 three times to remove
quaternary ammonium salt and residual unreacted PEG. The black solid product was
dried in vacuum at 70 °C overnight, and then PEG grew from the MWCNTs surface
(Mean yield: 97.6%), named MWCNTs graft PEG (MWCNTs-g-PEG-OH). The
theoretical
amount
of
MWCNTs
in
the
graft
MWCNTs-g-PEG14-OH,
MWCNTs-g-PEG23-OH, MWCNTs-g-PEG45-OH and MWCNTs-g-PEG91-OH products
was approximately 66.0, 53.8, 36.8 and 22.5 wt%, respectively, and the actual content
was about 76.7, 71.4, 67.5 and 65.0wt% by TGA.
2.2.3 Synthesis of MWCNTs-g-PEG-Br
All operations were conducted under a nitrogen atmosphere. Typically, 15.06 g
MWCNTs-g-PEG91-OH (Equivalent to PEG91 of 1.088 mmol based on the PEG content
of 28.9 wt% by TGA) was placed in 15.0 ml anhydrous CHCl3 before DMAP (0.023 g,
0.188 mmol) and TEA (0.26 g, 2.569 mmol) were added in a 100 ml dried three-neck
flask. Then, 2-bromoisobutyryl bromide (0.50 g, 2.175 mmol) dissolved in anhydrous
CHCl3 (6 ml) was dropwise added into the above solution at 0 °C within 60 min
through a constant pressure funnel. The mixture was further stirred at 0 °C for 2 h,
followed by stirring at room temperature for an additional 48 h. The filtered solid was
washed with CHCl3 and dried under vacuum at 40 °C for 24 h, affording
MWCNTs-g-PEG-Br (Mean yield: 94%).
2.2.4 Synthesis of MWCNTs-g-PEG-b-PS
Grafting polymerization of styrene from MWCNTs-g-PEG91-Br was carried out by an
in situ ATRP at a molar ratio of PEG-Br:monomer:ligand:catalyst of 1:250 (400, and
600):3:2. Typically, 0.974 g MWCNTs-g-PEG-Br (Equivalent to 0.075 mmol PEG-Br
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initiator), 47 μl (0.225 mmol) PMDETA, 0.0215 g (0.150 mmol) CuBr, and 10 ml DMF
were orderly placed in a 25 ml dried Schlenk flask. The flask was then sealed with a
rubber plug, and air-evacuated and backfilled thrice by means of a ‘freeze-pump-thaw’
operation before 2.16, 3.45 or 5.17 ml styrene was injected into the flask using a
syringe. The flask was immersed in an oil bath at 125 °C for 24 h. The reaction mixture
solution was vacuum filtered to collect the filtered solid, and the solid was rinsed with
ethanol thrice. The purified product was dried under a vacuum oven at 45 °C for 24 h
(mean yield: 60 %), and the content of MWCNTs in the graft product was determined
to be about 34.2wt% by TGA.
The filtrate was diluted with THF, and then passed through an activated neutral Al2O3
column to remove copper complex (catalyst and ligand). The THF was removed by
rotary evaporation and the residual DMF and styrene mixed solution was used for the
content determination of unreacted styrene by gas chromatography (GC).
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