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middle block (PS30-b-PDMAA20-b-PPFS30) was synthesized to electron-rich and electron-deficient blocks were characterized in
1
1
allow for characterization via NOESY and HOESY NMR spectro- different solvents using 2D NMR spectroscopy ( H– H NOESY,
1
19
scopy. GPC analysis of PS -b-PDMAA -b-PPFS revealed Ð of
1
H– F HOESY) and dynamic light scattering. We proved that
.43 and Mn of 11.5 Â 10 g mol . We first run DLS analyses intramolecular single-chain folding of these polymers occurs
of the triblock copolymer with the shorter middle block (PS -b- in chloroform due to this arene–perfluoroarene quadrupole.
3
0
20
30
app
3
À1
3
0
PDMAA20-b-PPFS30). The results are shown in Table 1. In toluene, In DMF, larger aggregates are formed due to intermolecular
the hydrodynamic radius of the triblock copolymer is bigger interactions.
than its precursor diblock copolymer: the molecular weight more
Financial support has been provided by the Department of
than doubles and no folding is observed. In DMF, we observed Energy Office of Basic Energy Sciences through Catalysis
the formation of larger aggregates. Since PPFS homopolymers Contract No. (DEFG02-03ER15459).
are soluble in this solvent (see ESI†), the aggregates can be
ascribed to the interaction between the PS and the PPFS blocks, Notes and references
which is an additional proof for quadrupole interactions. In
chloroform, we prepared the samples at different concentrations
1
2
(a) D. L. Nelson and M. M. Cox, Principles of Biochemistry, W. H.
Freeman and Company, New York, 2005; (b) D. J. Hill, M. J. Mio,
R. B. Prince, T. S. Hughes and J. S. Moore, Chem. Rev., 2001,
101, 3893.
(
ESI,† Table S3) and observed only intramolecular folding when
À1
the concentration is below 50 mg ml . We observed larger aggre-
(a) S. Ghosh and S. Ramakrishnan, Angew. Chem., Int. Ed., 2005,
À1
À1
gates for sample concentration above 80 mg ml . At 30 mg ml
2.6 mM), which is the same concentration as the samples used
for the NMR spectroscopy experiments, the hydrodynamic radius
,
44, 5441; (b) M. Wolffs, N. Delsuc, D. Veldman, N. Van Anh, R. M.
(
Williams, S. C. J. Meskers, R. A. J. Janssen, I. Huc and A. P. H. J.
Schenning, J. Am. Chem. Soc., 2009, 131, 4819; (c) O. Altintas and
C. Barner-Kowollik, Macromol. Rapid Commun., 2012, 33, 958;
(d) O. Altintas, E. Lejeune, P. Gerstel and C. Barner-Kowollik, Polym.
Chem., 2012, 3, 640; (e) N. Hosono, M. A. J. Gillissen, Y. Li,
S. S. Sheiko, A. R. A. Palmans and E. W. Meijer, J. Am. Chem. Soc.,
of the triblock polymer is only marginally higher than the R of
h
the diblock polymer, despite the large increase in molecular
weight, indicating the folding of the triblock polymer chain due
to p–p interaction. Although the long middle block polymer
2
013, 135, 501; ( f ) J. Romulus and M. Weck, Macromol. Rapid
Commun., 2013, 34, 1518.
3 (a) P. Pino and G. P. Lorenzi, J. Am. Chem. Soc., 1960, 82, 4745;
b) R. J. M. Nolte, Chem. Soc. Rev., 1994, 23, 11; (c) T. Nakano and
(PS30-b-PDMAA150-b-PPFS30) exhibits a more obvious size differ-
(
ence through the intramolecular folding, the short middle block
polymer (PS30-b-PDMAA20-b-PPFS30) shows clearer NOE and HOE
cross-peak signals in the 2D NMR spectroscopy experiment.
The 2D NMR spectroscopy experiment results are shown in
Fig. 2. The NOESY spectrum in Fig. 2A indicates a strong NOE
between the aromatic protons on the PS block with the polymer
backbone of the PPFS block at (6.65, 2.07 ppm; the signal at
Y. Okamoto, Chem. Soc. Rev., 2001, 101, 4013; (d) E. Yashima,
K. Maeda, H. Iida, Y. Furusho and K. Nagai, Chem. Rev., 2009,
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A. E. Rowman, Polym. Chem., 2011, 2, 33.
4
5
(a) M. Malke, H. Barqawi and W. H. Binder, ACS Macro Lett., 2014,
3, 393; (b) J. Willenbacher, O. Altintas, P. W. Roesky and C. Barner-
Kowollick, Macromol. Rapid Commun., 2014, 35, 45.
(a) C. A. Hunter, Angew. Chem., Int. Ed., 1993, 32, 1584; (b) J. F.
Gonthier, S. N. Steinmann, L. Roch, A. Ruggi, N. Luisier, K. Severin
and C. Corminbeuf, Chem. Commun., 2012, 48, 9239.
2.07 ppm is unique to the PPFS block) in chloroform. Additionally,
a NOE signal can be observed between the backbone protons of PS
and PPFS at 1.38, 1.98 ppm (ESI,† Fig. S13). In benzene (Fig. 2B)
only a NOE signal can be observed between the aromatic protons
of PS and the PS backbone (ESI†), indicating that the quadrupole
interaction is inhibited by the interaction of the solvent with the
PFS residues.
The HOESY experiments (Fig. 2C and D) give more evidence
of the quadrupole interaction. The ortho-F of the PFS residues
along the PPFS block has several HOE signals with backbone
protons of both the PPFS block and PS block at (À162, 1.7 ppm)
and with aromatic protons in the PS block (ESI†). By contrast,
the only HOE found in benzene is between the ortho-F of the
6 S. Perez-Casas, J. Hernandez-Trujuillo and M. Costas, J. Phys.
Chem. B, 2003, 107, 4157.
7
(a) H. Adams, J.-L. J. Blanco, G. Chessari, C. A. Hunter, C. M. R. Low,
J. M. Sanderson and J. G. Vinter, Chem. – Eur. J., 2001, 7, 3494;
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C. J. Urch and J. M. Sanderson, Chem. – Eur. J., 2001, 7, 4863;
(
c) S. L. Cockroft, C. A. Hunter, K. R. Lawson, J. Perkins and
C. J. Urch, J. Am. Chem. Soc., 2005, 127, 8594; (d) S. L. Cockroft,
J. Perkins, C. Zonta, H. Adams, S. E. Spey, C. M. R. Low, J. G. Vinter,
K. R. Lawson, C. J. Urch and C. A. Hunter, Org. Biomol. Chem., 2007,
5
, 1062.
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9
(a) Y. Sonoda, M. Goto, S. Tsuzuki, H. Akiyama and N. Tamaoki,
J. Fluorine Chem., 2009, 130, 151; (b) R. Xu, W. B. Schweizer and
H. Frauenrath, Chem. – Eur. J., 2009, 15, 9105.
G. W. Coates, A. R. Dunn, L. M. Henling, D. A. Dougherty and
R. H. Grubbs, Angew. Chem., Int. Ed., 1997, 36, 248.
PFS residues and the PFS backbone protons, again indicating 10 L. Shu, Z. Mu, H. Fuchs, L. Chi and M. Mayor, Chem. Commun.,
2
006, 1862.
that no (measurable) quadrupole interaction takes place, and
that no folding occurs.
1
1 M. Weck, A. R. Dunn, K. Matsumoto, G. W. Coates, E. B. Lobkovsky
and R. H. Grubbs, Angew. Chem., Int. Ed., 1999, 38, 2741.
This contribution presents the synthesis of triblock copolymers 12 (a) W. A. Pryor and T.-L. Huang, Macromolecules, 1969, 2, 70;
(
b) C. Pugh, C. N. Tang, M. Paz-Pazos, O. Samtani and A. H. Dao,
with arene and perfluoroarene-containing blocks via the RAFT
polymerization of styrene, N,N-dimethylacrylamide, and 2,3,4,5,6-
Macromolecules, 2007, 40, 8178; (c) N. ten Brummelhuis and
M. Weck, ACS Macro Lett., 2012, 1, 1216.
pentafluorostyrene. The quadrupole interactions between the 13 G. Moad, E. Rizzardo and S. H. Thang, Aust. J. Chem., 2009, 62, 1402.
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