micelle morphology transition from cylinder to sphere for the same PBLG-b-PEG
block copolymers is achieved by adding a small portion of gold nanoparticles
(AuNPs), as reported in a recent work by Cai et al. [128]. The main reason for the
aggregate morphology transition is the breakage of ordered packing of PBLG rods
in the cylindrical micelle core by the added nanoparticles. As shown in Fig. 18a,
pure block copolymers form cylindrical micelles in solution of CHCl 3 /ethanol
(v/v ¼ 4/6). When the AuNPs is introduced, as shown in Fig. 18b, short cylinders
are produced. These short cylinders have the same diameter as the long cylinders,
which indicates that the short cylinders could be fragments of the long cylinders.
Further increasing the AuNP content to 2–10 wt% leads to the formation of
spherical micelles (Fig. 18c, AuNPs 3 wt%). From the TEM image shown in the
inset of Fig. 18c, it can be observed that AuNPs exist in the micelle core. The
authors also performed a dissipative particle dynamics (DPD) simulation study on
this system. As shown in Fig. 18d, the simulation results from a model system of
rod–coil copolymer/nanoparticles reproduced the experimental findings well. In
addition, the simulations reveal that with the incorporation of NPs into the micelle
core, the ordered packing of rod block in the micelle core is gradually destroyed.
The order parameter of the rod block gradually decreases from about 0.8 for
cylinders to nearly zero for spherical micelles. Fig. 18e schematically presents
the self-assembly behaviors of PBLG-b-PEG/AuNPs mixtures. It can be clearly
seen that when the weight fraction of NPs is lower, the ordered arrangement of
PBLG rods in the micelle core is partially destroyed and short cylinders are
0.0
0.5
1.0
1.5
2.0
2.5
0.0
0.2
0.4
0.6
0.8
Order parameter
NPs wt %
Long Cylinders
Spheres
Short Cylinders
a
d
e
b
c
Fig. 18 TEM images of PBLG-b-PEG/AuNP hybrid micelles with various AuNP content:
(a) 0, (b) 1, and (c) 3 wt%. The inset in (c) shows a magnified image of hybrid micelles.
(d) Simulation prediction for the order parameter of rod blocks as a function of the concentration
of nanoparticles. The insets show the corresponding structures of hybrid micelles. The
nanoparticles are not shown for clarity. (e) Proposed self-assembly behaviors of PBLG-b-PEG/
AuNP mixtures. Reprinted with permission from [128]. Copyright 2012 American Chemical
Society
Ordering of Polypeptides in Liquid Crystals, Gels and Micelles
183
block copolymers is achieved by adding a small portion of gold nanoparticles
(AuNPs), as reported in a recent work by Cai et al. [128]. The main reason for the
aggregate morphology transition is the breakage of ordered packing of PBLG rods
in the cylindrical micelle core by the added nanoparticles. As shown in Fig. 18a,
pure block copolymers form cylindrical micelles in solution of CHCl 3 /ethanol
(v/v ¼ 4/6). When the AuNPs is introduced, as shown in Fig. 18b, short cylinders
are produced. These short cylinders have the same diameter as the long cylinders,
which indicates that the short cylinders could be fragments of the long cylinders.
Further increasing the AuNP content to 2–10 wt% leads to the formation of
spherical micelles (Fig. 18c, AuNPs 3 wt%). From the TEM image shown in the
inset of Fig. 18c, it can be observed that AuNPs exist in the micelle core. The
authors also performed a dissipative particle dynamics (DPD) simulation study on
this system. As shown in Fig. 18d, the simulation results from a model system of
rod–coil copolymer/nanoparticles reproduced the experimental findings well. In
addition, the simulations reveal that with the incorporation of NPs into the micelle
core, the ordered packing of rod block in the micelle core is gradually destroyed.
The order parameter of the rod block gradually decreases from about 0.8 for
cylinders to nearly zero for spherical micelles. Fig. 18e schematically presents
the self-assembly behaviors of PBLG-b-PEG/AuNPs mixtures. It can be clearly
seen that when the weight fraction of NPs is lower, the ordered arrangement of
PBLG rods in the micelle core is partially destroyed and short cylinders are
0.0
0.5
1.0
1.5
2.0
2.5
0.0
0.2
0.4
0.6
0.8
Order parameter
NPs wt %
Long Cylinders
Spheres
Short Cylinders
a
d
e
b
c
Fig. 18 TEM images of PBLG-b-PEG/AuNP hybrid micelles with various AuNP content:
(a) 0, (b) 1, and (c) 3 wt%. The inset in (c) shows a magnified image of hybrid micelles.
(d) Simulation prediction for the order parameter of rod blocks as a function of the concentration
of nanoparticles. The insets show the corresponding structures of hybrid micelles. The
nanoparticles are not shown for clarity. (e) Proposed self-assembly behaviors of PBLG-b-PEG/
AuNP mixtures. Reprinted with permission from [128]. Copyright 2012 American Chemical
Society
Ordering of Polypeptides in Liquid Crystals, Gels and Micelles
183