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Abstract
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Distinct stratified and non-stratified morphologies were developed in poly(3-hexylthiophene) (P3HT) and poly(ethylene glycol)
(PEG)-based homopolymer blends and diblock and triblock copolymer systems. By applying X-ray photoelectron spectroscopy,
only a double-percolation mechanism including assembling of P3HT chains into the nanofibers in solution aging process with a
marginal solvent likep-xylene as well as crystallization of PEG phase in the cast thin films resulted in vertical stratification and
networked fibrils. In cast thin films whose PEG phase, due to low molecular weight or being constrained between two rigid
P3HT blocks in triblock copolymers was not crystallized, a non-stratified discrete fibrillar morphology was acquired. Crystallization
of PEGs in the thin films mainly participated in networking and expelling pre-organized P3HT fibrils to the film surface. By
performing the solution aging step in a good solvent such aso-dichlorobenzene, the P3HTs remained in a coily-like conformation,
and casting the corresponding thin films reflected the non-stratified discrete granular and featureless morphologies. Assembling
the P3HT chains in the presence of PEG phase in cast films at most led to the low-crystalline granules instead of highly crystalline
nanofibrils. No significant crystallization in either homopolymer blends or block copolymer systems conduced to a featureless
morphology with homogeneous distribution of existed materials. The surface morphology and ordering in various morphologies
were studied employing atomic force microscopy, grazing incidence X-ray diffraction, and ultraviolet–visible analyses.
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