Block copolymer (BCP) structure and dynamics were studied
using
small-angle neutron scattering (SANS), neutron spin echo (NSE) spectroscopy,
and molecular dynamics (MD) simulations to obtain a fundamental understanding
of the impact of an interfacial block on chain dynamics. A glassy
block acted as the interface, and the dynamics of a rubbery block
was studied. The rubbery block was protonated near the interface in
one sample and near the chain end in another sample to observe the
interfacial effect on the rubbery polymer. Analysis of the structure
and dynamics revealed that the interfacial rubbery block was confined
in layered morphologies and exhibited much slower dynamics than the
chain-end rubbery block that was dispersed in the rubbery matrix.
The interfacial rubbery block showed weaker dynamical relaxation than
that at the chain end, and it also had critically important length
scale dependence. Dynamical slowing was only observed at length scales
significantly larger than the characteristic segmental length, and
the disparity between interfacial and chain-end dynamics increased
with increasing length.
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