SANS Studies of the Configurations of Single Chains in Heterogeneous Block Copolymers
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SANS STUDIES OF THE CONFIGURATIONS OF SINGLE CHAINS IN HETEROGENEOUS BLOCK COPOLYMERS
C.V. BERNEY, P. CHENG, P. KOFINAS AND R.E. COHEN Massachusetts Institute of Technology Cambridge, MA 02139
ABSTRACT Small-angle
neutron
diblock copolymers the effect chains.
scattering
studies
of polystyrene-polybutadiene
of spherical morphology are discussed,
of this morphology on
the spatial
Three particular cases are examined:
the matrix of added (matrix) spherical
microdomains
of
topic effects occurring in
homopolymer,
added
with emphasis
on
organization of the polymer (i)
(ii)
the distribution within
the distribution within the
(microdomain)
homopolymer,
and
(iii)
iso-
the B domains when a B-deuterated diblock SBd is
blended with a normal sample SB.
Deviations from ideal mixing are found in
all three cases.
INTRODUCTION Heterogeneous
block
copolymers
have been the object of numerous
present
well-ordered
morphologies
experimental and theoretical
which
studies [1-3],
including a considerable amount of small-angle neutron scattering work
[4].
In
(SB)
our research program on polystyrene-polybutadiene diblock copolymers
with
spherical
arrangement of
polybutadiene the spheres
[5],
(B)
domains,
we have
the sphere size in
examined
relation to B molecular
weight [6,7] and the nature of the interfacial zones in In
addition we have successfully
trast matching"
[8,9]
to
these materials [7].
exploited the principle
obtain information
diblock B chains within the spherical domains Recently we have been concentrating
our
on
the spatial
the
of isotopic
configurations
"conof
the
[101. efforts
in
this
latter
area,
namely the spatial organization of chain molecules within the block copolymer morphology.
We are particularly interested in this topic because we view the
microphase-separated is
perfectly
morphologies of block copolymers as a host medium which
suited for the examination of spatially constrained
Mat. Res. Soc- Symp. Proc. Vol. 79. , 1987 Materials Research Society
chains,
a
176
class of problems anticipated some time ago by de Gennes
[11).
survey we report on the results of our work on several including:
(i)
weights
block
in
In
this brief
of these problems,
the distribution of matrix homopolymer of various molecular copolymers
of spherical
morphology,
(ii)
the
spatial
confinement of homopolymers of various molecular weights within the spherical domains and (iii) results
[10]
a reexamination, on the
chain
in
light of new theories,
configurations
of
the
of our earlier
portions of
the block
copolymer which form the spherical domains. MATERIALS AND METHODS Except as noted in in
described in
detail elsewhere
ization, spin cast
our
Table 1, all block copolymers and homopolymers were
synthesized
laboratory
using
[7].
techniques
anionic
polymerization
samples of pure diblock or blends of diblock and homopolymer were [12] into film specimens of about one mm thickness which were then
vacuum annealed and laminated
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