Supporting Information for:
Aggregation
behaviors
of
pH-
and
thermo-responsiveblock copolymer Protected Gold
Nanoparticles
Junbo Li · Wenlan Wu· Chen Han · Shijie Zhang · Huiyun Zhou · Jinwu Guo
S1. Materials. Tert-butyl methacrylate (t-BMA) was purchased from Fluka and
distilled under vacuum prior to use. 2, 2-Azobis (isobutyronitrile) (AIBN) was
purchased from J&K Chemical and recrystallized before as an initiator.
N-isopropylacryl-amide (NIPAM) was purchased from Aldrich and recrystallized
twice from benzene. Dioxane, tetrahydrofuran, N, N-Dimethylformamide were
purchased from National Pharmaceutical Group Chemical Reagent and distilled
before use. HAuCl4·4H2O, sodium citrate, Trifluoroacetic acid were purchased from
National Pharmaceutical Group Chemical Reagent and used as received. The RAFT
agent, 2-(2-cyanopropyl) dithiobenzoate (CPDB) was systhesized according to the
literature procedure [1]. All other reagents were used as received.
S2. Synthesis of the PNIPAM-CTA. The RAFT agent CPDB (0.1470 g, 0.6670
mmol), AIBN (0.0273 g, 0.1662 mmol), NIPAM (10.0002 g, 0.0883 mol), and dry
Dioxane (10 mL) added to a sealed dry ampule with a magnetic stirring bar. After the
solution was degassed using three freeze-pump-thaw cycles, the polymerization was
conducted at 70oC over 24 h. The final polymer was purified using a two-step
precipitation in diethyl ether and isolated by filtration to give PNIPAM-CTA.
_____________________
J. Li* ·. W. Wen · C. Han · S. Zhang · H. Zhou · J. Guo
College of Chemical Engineering & Pharmaceutics, Henan University of Science & Technology,
Luo Yang 471023, Henan, China
E-mail: Lijunbo@haust.edu.cn
S3. Synthesis of the SH-PNIPAM-b-PMAA. The PNIPAM-CTA (0.2344 g, 0.0494
mmol), AIBN (0.0020 g, 0.0123 mmol), tBMA (1.9001 g, 0.0134 mol), and dry DMF
(1.0 mL) were placed in a sealed dry ampule. After the solution was degassed using
three freeze-evacuate-thaw cycles, the polymerization was conducted at 70oC over 48
h. The reaction mixture was obtained using a two-step precipitation from DMF in
methanol and water mixxed sloution(v:v=4:1) and isolated by filtration to give
PNIPAM-b-PtBMA. SH-PNIPAM-b-PMAA was prepared by hydrolyzing the
PNIPAM-b-PtBMA in a 1.5ml trifluoroacetic acid and 25 ml dioxane solution. The
reaction mixture was stirred at room tempreture for 24 h. Then, the solution was
concentrated and precipitated in diethyl ether and isolated by filtration to give a white
powder of SH-PNIPAM-b-PMAA.
S4. Preparation of PNIPAM-b-PMAA-SH. The PNIPAM-b-PMAA-SH was
prepared by the hydrolysis of Pt-BMA-b-PNIPAM. Pt-BMA-b-PNIPAM was
synthesized by two-step RAFT polymerization using CPDB as initial chain trasfer
agent via different order of feed.
S5. Characterization of SH-PNIPAM-b-PMAA and PNIPAM-b-PMAA-SH.
RAFT polymerization became a widely method of the preparation of block
copolymers due to the mild condition of the reaction and the widely use of the
monomer. In this paper, PNIPAM-b-PtBMA is synthesized by the RAFT
polymerization of tBMA with PNIPAM-CTA as chain transit agent. The 1H NMR
spectrum of PNIPAM-CAT, PNIPAM-b-PtBMA and SH-PNIPAM-b-PMAA is
displayed in Fig. 1. From Fig. 1a, besides the presence of signals characteristic of
PNIPAM at δ:=5.8-7.1 (for NH), 4.0 (for CH connected to NH), and 1.1 ppm (for
CH3), the 1H NMR spectrum of PNIPAM-CAT in CDCl3 also reveals the signals at
δ=7.9, 7.6, and 7.4 ppm ascribing to the dithiobenzoyl groups located at the PNIPAM
chain end. The degrees of polymerization (DP) of the PNIPAM homopolymer were
determined by 1H NMR to be 40 and the molecular weight was calculated to be 4740.
The peak of methyl hydrogens of the tert -butyl ester at 1.5 ppm was appeared in the
1
H NMR spectrum of PNIPAM-b-PtBMA. So, the molecular weight of
PNIPAM-b-PtBMA was 12580 calculated by
1
HNMR. Therefore, the block
copolymer was denoted PNIPAM40-b-PtBMA60, where the subscript indicates the
number of the repeating units. After hydrolysis of PNIPAM40-b-PtBMA64, the
SH-PNIPAM40-b-PMAA64 was obtained conformed by the disappearance of tert-butyl
resonance at δ=1.5 ppm, and the emerging of carboxyl at δ=12.3 ppm. In the
meantime, the disappearance signals at δ=7.9, 7.6, and 7.4 ppm indicated the
dithiobenzoyl end is also hydrolyzed. The molecular weight distribution of
PNIPAM-CTA and PNIPAM-b-PtBMA was characterized by GPC in THF using
polystyrene as calibration. The polydispersity indexes of PNIPAM-CAT (a) and
PNIPAM-b-PtBMA (b) 1.17 and 1.34, respectively.
Fig. 1S. 1HNMR spectrum of PNIPAm-CAT (a) and PNIPAM-b-PtBMA (b) in CDCl3, SH
-PNIPAM-b-PMAA in DMSO(c)
Fig. 2S. GPC traces of PNIPAm-CAT (a) and PNIPAM-b- PtBMA (b) in THF at room temperature
The process and characterization of PMAA35-b-PNIPAM64 was similar to
PNIPAM40-b-PMAA60. Finally, Molecular weight and polydispersity of all polymers
are listed in the Table S1.
Table S1. Molecular weight and polydispersity of all polymers measured by 1H NMR
and GPC method.
1
H NMR
GPC
Samples
PtBMA-CAT
PNIPAM-CAT
PtBMA-b- PNIPAM
PNIPAM-b- PtBMA
SH-PMAA64-b- PNIPAM35
SH-PNIPAM40-b- PMAA60
Mn(g/mol)
Mn(g/mol)
Mw/Mn
5300
4740
12000
12580
9560
9220
4970
5120
13120
13740
1.12
1.17
1.38
1.24
References
1.
Zhao, D., X. Chen, Y. Liu, C. Wu, R. Ma, Y. An, and L. Shi (2009) Thermosensitive and
pH-sensitive Au–Pd bimetallic nanocomposites. Journal of Colloid and Interface Science 331:
104-112.