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Variation of the functional
group of the flexible block in conjunction
with the ability to generate diblock copolymers with
different regioregular poly(3-hexylthiophene) compositions constitute a versatile approach
towards novel materials with tunable electrical and
mechanical properties. We have established that utilization of living GRIM in combination with ATRP yielded diblock copolymers with well-defined molecular weights and
variable molar compositions. It is also shown that changes in
the structure of the poly(methacrylate) segment and/
or variation of the molar composition of the diblock
copolymers can drive the formation of a range of
nanofibrillar morphologies, from distinct nanofibrillar morphology with densely
packed, elongated, and locally parallel nanofibrils to nanofibrillar morphology with shorter, isolated
and randomly oriented nanofibrils. Moreover, we show that thin film of compact nanofibrillar morphology exhibited one to two
orders of magnitude higher conductivity than isolated nanofibrillar thin film.
The marked correlation
between the conductivities of
these two groups of materials and their
morphologies suggests that densely
packed nanofibrillar structures play an
important role in assuring formation of
extended carrier transport pathways in phase-separated
block copolymers.
Iovu M. C., Zhang, R., et. al, Macromol. Rapid Commun. 2007, 28, 1816-1824 |
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Tapping mode atomic force microscopy (TMAFM) phase images of poly(3-hexylthiophene) (PHT) diblock copolymers:
(left) PHT-b-poly(t-BuMA) (15 mol% PHT); (right) PHT-b-poly(IBMA) (15 mol% PHT)
GISAXS patterns of poly(3-hexylthiophene) (PHT) diblock copolymers: (left) PHT-b-poly(t-BuMA) (15 mol% PHT); (right) PHT-b-poly(IBMA) (15 mol% PHT)
Dependence of conducting properties on nanoscale morphologies in coductive block copolymer thin films
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