W. Yuan et al. / Polymer 54 (2013) 5374e5381
5377
GPC should be ascribed to the unique star-shaped topology of POSS-
PEO)
The hydrodynamic radius (R
h
) and the Z-average size distribu-
(
8
.
tions (polydispersity index, PDI) of POSS-(PEO)
POSS-(PEO) -CD supramolecular self-assemblies were charac-
terized by DLS. As shown in Fig. 4(a), the R and PDI of the self-
assemblies increased with increasing of the amount of -CD mol-
ecules in supramolecular system. POSS-(PEO) aggregates pre-
sented an average R of 91.6 nm and a narrow PDI of 0.082. But for
sample E, the molar ratio of -CD to EO unit is 1:5, the R and PDI
increased to 144.6 nm and 0.127, respectively. Further improved the
content of -CD (sample I, the molar ratio of -CD to EO unit is 1:3),
the self-assemblies showed larger R and the wider PDI data
(227 nm and 0.206, respectively). The increase of R and widening
of PDI of the supramolecular self-assemblies with the increase of
the amount of -CD molecules implied that the nanostructure of
the self-assemblies changed due to the host-guest inclusion
8
aggregates and
8
/a
h
3.2. Supramolecular self-assembly of star-shaped inorganice
a
organic hybrid POSS-(PEO) and different amount of -CD
8
a
8
h
Inorganiceorganic hybrid POSS-(PEO)
prepared by the direct dissolution of POSS-(PEO)
adding -CD molecules into the aggregates, the supramolecular
host-guest inclusion complexation between -CD and PEO
8
aggregates was easily
a
h
8
into water. After
a
a
a
a
h
occurred, and the hybrid supramolecular self-assemblies formed.
Fig. 3(a) shows the photographs of these self-assemblies solutions
h
after adding different amount of
a
-CD molecules into POSS-(PEO)
8
a
aggregates solution. It can be seen that the solutions presented an
obvious transition from transparency to turbidity with the increase
complexation of PEO chains with different amount of
molecules.
TEM images were used to directly observe the morphologies
of the inorganic-organic supramolecular self-assemblies.
Fig. 5(a) shows the scheme of the self-assembly process of
a-CD
of the amount of
aggregates or supramolecular self-assemblies are stable and the
aggregation did not occur, indicating that POSS-(PEO) or POSS-
PEO) -CD supramolecular self-assemblies presented good hy-
drophilicity under above conditions. But when the adding amount
of -CD molecules increased, the solutions became turbid to some
extent, which revealed that the hydrophobicity and aggregation of
the supramolecular self-assemblies increased when more -CD
a-CD. Without or with small amount of a-CD, the
8
(
8
/a
8
POSS-(PEO) . The spherical aggregates can be observed after
a
self-assembly, as shown in the TEM image (Fig. 5 (b)). Because
the aggregates are much larger than the contour length of PEO,
they must have a more complicated structure than conventional
a
molecules complexed with PEO chains. The morphologies of the
self-assemblies may be changed in comparison with those at lower
micelles. When small amount of
the aggregates solution (such as sample C, molar ratio of
EO unit is 1:19), the supramolecular self-assembly between PEO
chains and -CD was carried out, and the hydrophobicity of the
system increased to some degree due to the presence of small
amount of hydrophobic microcrystal domains formed from the
a
-CD molecules was added to
a
-CD to
a
-CD molecules condition. Adding more
solution system, the obvious turbidity can be observed, demon-
strating that POSS-(PEO) -CD supramolecular self-assemblies
aggregated into lager self-assemblies.
a-CD molecules into the
a
8
/a
host-guest inclusion complexation of
a-CD with partial PEO
chains. Therefore, the supramolecular self-assemblies presented
deformed spherical structure, as shown in Fig. 6(a). After more
a
-CD molecules complexing with PEO chains (such as sample E,
molar ratio of -CD to EO unit is 1:5), the hydrophobicity of the
a
self-assemblies system increased rapidly owing to more hydro-
phobic microcrystal domains formed at this condition and the
aggregation of self-assemblies were different from those at
lower amount of
lecular self-assemblies presented cylindrical structure. Further
adding more -CD molecules to the above solution (such as
sample I, molar ratio of -CD to EO unit is 1:3), the POSS-(PEO)
-CD supramolecules became more hydrophobic due to the
a-CD molecules. From Fig. 6(b), the supramo-
a
a
8
/
a
presence of large amount of hydrophobic microcrystal domains
and self-assemble and aggregate into sheet-structural self-as-
semblies, as shown in Fig. 6(c). Fig. 7 shows the schematic
illustration of the dynamic change of self-assemblies from reg-
ular spherical aggregates, deformed spherical aggregates, cyl-
inders to sheets. After adding small amount of
only small amount of hydrophobic microcrystal domains formed
from the hosteguest inclusion complexation of -CD with PEO
a-CD molecules,
a
chains. Therefore, the spherical aggregates would present
deformed spherical morphology due to the presence of hydro-
phobic microcrystal domains. When more
were nested to PEO chains, the polypseudorotaxanes of
a
-CD molecules
-CD-
a
PEO would become more rigid and more hydrophobic micro-
crystal domains can be formed due to the self-assembly
and arrangement of these polypseudorotaxanes. So, the aggre-
Fig. 3. Photographs of (a) POSS-(PEO)
(
1
8
hybrid supramolecular self-assemblies solution
1 g L ) after adding different amount of -CD. [ -CD, (B)
-CD]:[EO] ¼ (A) without
:37, (C) 1:19, (D) 1:8, (E) 1:5, (F) 1:4.4, (G) 1:4, (H) 1:3.8, (I) 1:3; (b) POSS-(PEO) -CD
-CD]:[EO] ¼ 1:3) hybrid supramolecular self-assemblies solution (1 g L ) after
adding phenol. [phenol]:[
-CD] ¼ (A) without phenol, (B) 0.16:1, (C) 0.32:1, (D) 0.47:1,
E) 0.62:1, (F) 0.77:1, (G) 0.91:1, (H) 1.01:1, (I) 1.13:1; and PEO-(PEO) -CD ([
ꢀ
1
gates would be changed to cylinders. Further adding more
molecules to the system, all PEO chains would be nested by
-CD and the polypseudorotaxanes become very rigid. Large
a-CD
a
a
a
8
/a
ꢀ
1
(
[
a
a
a
amount of hydrophobic microcrystal domains are formed.
The cylinders would be further changed to nano sheets due to
the presence of large amount of hydrophobic microcrystal
domains.
(
8
/
a
a-
ꢀ
1
CD]:[EO] ¼ 1:3) hybrid supramolecular self-assemblies solutions ((c) 1 g L and (d)
ꢀ
1
ꢁ ꢁ ꢁ ꢁ ꢁ
2
6
g L ) at different temperature: (A) 25 C, (B) 40 C, (C) 45 C, (D) 50 C, (E) 55 C, (F)
0
ꢁ
ꢁ ꢁ ꢁ
C, (G) 65 C, (H) 70 C, and (I) 75 C.