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The fibrillar poly(3-hexyl thiophene) single crystals were prepared from dilute solutions of toluene, xylene, and anisole (0.01 wt%), and were investigated from the perspective of structural properties. Next, the rectangular and hexagonal poly(ethylene glycol) single crystals were developed from the dilute solutions and molten thin polymer films. The developing methodology used for all growth systems was self-seeding. The dimensions of fibrillar and rectangular/hexagonal single crystals ranged from several nanometers to some microns. Random single-co-crystals were also grown from dilute solution (0.018 wt% in amyl acetate) of crystalline-amorphous diblock copolymers and homopolymers. The small-angle X-ray scattering, grazing incidence wide-angle X-ray scattering, and atomic force microscopy analyses were employed to characterize prepared grained samples. The incident X-ray experiments demonstrated highly ordered and lamellar crystalline structures. [ABSTRACT FROM AUTHOR]

The effects of PS and PMMA brushes on the crystallization of PEG in poly(ethylene glycol)- block-polystyrene (PEG- b-PS) and poly(ethylene glycol)- block-poly(methyl methacrylate) (PEG- b-PMMA) single crystals that have the same crystalline block molecular weight but different amorphous block molecular weights were investigated. The quality of the solvent (amyl acetate) employed and the interaction of the single-crystal substrate with the brush were found to influence the conformations of the PS and PMMA brushes, leading to more extended and packed pancake conformations, respectively. For PS and PMMA brushes with similar features, the conformation of the PMMA brushes led to a higher osmotic pressure on the substrate, so the substrate thickness was found to be significantly less than that seen when PS brushes were used. Even when the molecular weight of PMMA ( M = 8,700 g/mol) is considerably lower than that of PS ( M = 14,800 g/mol), the substrate in the presence of PMMA is thinner than that in the presence of PS (3.65 vs. 4.14 nm). Moreover, because there is less entropic repulsion between PS brushes than between PMMA brushes, the thickening of the substrate chains beneath them was more conspicuous when the crystallization temperature was increased. [ABSTRACT FROM AUTHOR]

For designing the responsive polymer brushes, and tuning the local and chemical surface responses to the external stimuli, the epitaxial single crystals were patterned by combination of bared surfaces of poly(ethylene glycol) (PEG) substrate, polymer homo-brushes constructed from poly(ethylene glycol)- b-polystyrene (PEG- b-PS) as well as poly(ethylene glycol)- b-poly(methyl methacrylate) (PEG- b-PMMA), and PEG- b-PS/PEG- b-PMMA mixed-brush channels. To achieve this target, various single crystals and epitaxial structures grown from dilute solutions through self-seeding approach were utilized as seeds to fabricate the next channels. The characteristics and morphologies of different channels were detectable by atomic force microscopy (AFM). The influence of chemical (solvent quality and interaction of substrate with different brushes) and physical (presence of brushes from another type in their vicinity) environments on crystallization was studied. Due to the effect of chemical environment, the PS brushes hampered the growth of PEG crystals at M = 10,000 g/mol. However, the PMMA brushes allowed PEG crystals to grow completely at M =13,100 g/mol, and indicated their hindrance at higher molecular weights (here, M = 17,100 g/mol). It was feasible to neutralize the mentioned hindrance through fabricating the channels with brushes having the highest hindrance ( M = 14,800 g/mol and M = 17,100 g/mol), and altering the physical environment from homo- to mixed-brush morphology. The characteristics (thickness, tethering density, and domain size) of developed channels from a certain material, in all arrangements and in various channels were in good agreement with those of corresponding non-epitaxial single crystals grown under the same conditions. [ABSTRACT FROM AUTHOR]

Surfaces of poly(ethylene glycol) (PEG) single crystals were designed by homo and copolymer self-assembling. Due to the distinct qualities of applied solvent and different interactions of the substrate with polymer brushes, matrix-dispersed surface morphologies with different dispersed phase regions were developed on poly(ethylene glycol)- b -polystyrene (PEG- b- PS)/polyethylene glycol (PEG) and poly(ethylene glycol)- b -poly(methyl methacrylate) (PEG- b- PMMA)/(PEG) single-co-crystals. Characteristics of different morphologies were detected by atomic force microscopy. Sizes of the domains dispersed in PS-, PMMA-, and bared-substrate (PEG-) matrixes were on the scale of 93–147, 169–195, and 104–126 nm, respectively. While the sizes of dispersed domains did not considerably change with crystallization temperature, they decreased by enhancing the molecular weight of the amorphous blocks. Besides, the same samples were grown in melt state to compare the features of single-co-crystals in two different growth environments. The lateral sizes, thicknesses, growth prisms, and surface morphologies were completely different, which could be attributed to dominant kinetic effect in melt growth conditions. [ABSTRACT FROM AUTHOR]