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[摘要]：The influence of solvent composition on micelle morphology has been investigated for two crystalline-coil poly(ferrocenyldimethylsilane-block-2-vinylpyridine) (PFS-b-P2VP) diblock copolymers with different block ratios (5:1 and 1:1). The solution self-assembly of these materials was explored in solvent mixtures containing different ratios of a good solvent for both blocks (THF) and a selective solvent for the P2VP block (isopropanol). Various micellar morphologies such as spheres and platelets were characterized using transmission electron microscopy (TEM), selected area electron,diffraction (SAED), dynamic light scattering (DLS), wide-angle X-ray,scattering (WAXS), and atomic force microscopy (AFM). The results showed that the solution self-assembly of PFS-b-P2VP block copolymers (5:1, 1:1) gave spherical micelles with an amorphous PFS core at low THF content (10 vol %). Subsequently, the amorphous spheres were slowly transformed into platelet micelles with a lenticular shape that consisted of a crystalline PFS core sandwiched by two coronal P2VP layers. This indicated that the amorphous spherical micelles were in a metastable state. The transformation of spheres into platelets was significantly slower for the 5:1 block copolymer with the longer PFS core-forming segment presumably due to a lower rate of crystallization of the metalloblock. Platelets were found to be dominant for both block copolymers at higher THF content (THF >= 30 vol %). The formation of lenticular rather than regular platelets was attributed to a poisoning effect whereby interference of the P2VP corona-forming blocks in the growth of the crystalline PFS core leads to the creation of defects in the crystal growth fronts. |
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