278
M. Tress et al.
f RAF =
A RAF
A total
ε sc
ε am
+ 1 −
ε sc
ε am
− f c
(12)
Based on these considerations, domain thicknesses of d RAF /2 = 0.46 (±0.09) nm,
d MAF /2 = 0.45 (±0.09) nm and d CAF = 1.66 (±0.23) nm are obtained for the rigid
amorphous, mobile amorphous and confined amorphous fraction, respectively [the
corresponding volume fractions are f RAF = 0.26 (±0.04), f MAF = 0.25 (±0.04) and
f CAF = 0.46 (±0.04)].
Although one can expect to find smaller domain thicknesses than in linear iPS,
particularly the calculated thickness of the crystalline domain is unphysically small
(about half of a typical repeat unit length of polystyrene). Consequently, we presume
that the crystallites actually grow thicker, but instead of expanding through the entire
plane they are rather limited to small islands (Fig. 4b). This suggested limitation in
growth may also be plausible in view of the reduced values of the Avrami exponents
compared to the linear iPS.
Fig. 4 Sketches of
a extended lamellae of
crystalline domains and
b small crystalline domains.
Each large hexagon
approximates the extension
of one POSS-iPS
star-molecule. Taken with
permission and modified
after [12]
M. Tress et al.
f RAF =
A RAF
A total
ε sc
ε am
+ 1 −
ε sc
ε am
− f c
(12)
Based on these considerations, domain thicknesses of d RAF /2 = 0.46 (±0.09) nm,
d MAF /2 = 0.45 (±0.09) nm and d CAF = 1.66 (±0.23) nm are obtained for the rigid
amorphous, mobile amorphous and confined amorphous fraction, respectively [the
corresponding volume fractions are f RAF = 0.26 (±0.04), f MAF = 0.25 (±0.04) and
f CAF = 0.46 (±0.04)].
Although one can expect to find smaller domain thicknesses than in linear iPS,
particularly the calculated thickness of the crystalline domain is unphysically small
(about half of a typical repeat unit length of polystyrene). Consequently, we presume
that the crystallites actually grow thicker, but instead of expanding through the entire
plane they are rather limited to small islands (Fig. 4b). This suggested limitation in
growth may also be plausible in view of the reduced values of the Avrami exponents
compared to the linear iPS.
Fig. 4 Sketches of
a extended lamellae of
crystalline domains and
b small crystalline domains.
Each large hexagon
approximates the extension
of one POSS-iPS
star-molecule. Taken with
permission and modified
after [12]