INVESTIGATION OF MACROSCOPICALLY COHERENT GYROIDAL DOMAINS IN THE EVAPORATION INDUCED SELF-ASSEMBLY OF TRIBLOCK TERPOLYMER DIRECTED HYBRID MATERIALS
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The self-assembly of Block Copolymers (BCPs) is a facile route to obtain materials with periodic nanostructures. On the mesoscale, these materials exhibit several interesting properties that are often inaccessible in the bulk at macroscopic length scales due to the lack of long-range coherent orientational order of the crystal domains. Producing macroscopic single crystals with a co-continuous cubic gyroidal structure has proven to be especially challenging due to the highly symmetrical, 3 dimensionally isotropic nature of this morphology. This work follows a recently developed technique combining evaporation induced self-assembly of an ABC triblock terpolymer structure directing a precursor for an inorganic ceramic with solvent recirculation to the evaporating film to produce gyroidal single crystals with coherent scattering areas of over 10 mm2. Calcination at high temperature allows to conversion of these hybrid materials into macroscopic single crystals of mesoporous ceramics. Varying polymer concentration and solution volume as control parameters in separate experiments brings to light the factors affecting the formation, spatial distribution and size of these large crystals. Based on these results and model calculations, a hypothesis for the mechanism of alignment of the crystal domains in solution is discussed. It is expected, that this work will initiate further investigations into the formation pathways of these single crystals to allow for finer control over their size as well as studies of anisotropic properties of various inorganic materials backfilled into the pores of these mesoporous single crystals.
Block copolymers; Evaporation induced self assembly; Hybrid Materials; Single Crystals
Wiesner, Uli B.
M.S., Chemical Engineering
Master of Science
dissertation or thesis