Scrolled/Flat Crystalline Structures of Poly(3-hexylthiophene) and Poly(ethylene glycol) Block Copolymers Subsuming Unseeded Half-Ring-Like and Seeded Cubic, Epitaxial, and Fibrillar Crystals

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• 作者：Samira AgbolaghiSahar Zenoozi ; Zahra Hosseini ; Farhang Abbasi
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：December 27, 2016
• 年：2016
• 卷：49
• 期：24
• 页码：9531-9541
• 全文大小：729K
• ISSN：1520-5835

文摘

Three distinct types of poly(3-hexylthiophene) (P3HT)-based crystals were developed using unseeded and seeded protocols. First, unseeded flat fibrillar and scrolled half-ring-like crystals were prepared by isothermal crystallization of homo-P3HT and P3HT-b-poly(ethylene glycol) (PEG) block copolymers. Anisotropic accumulation of grafted coily PEG blocks on the opposite surfaces of P3HT half-rings having extended backbones reflected scrolling, and their subsequent crystallization also further intensified this scrolling. The PEGs assembled into lamellae on both sides of P3HT half-rings with dissimilar crystalline features, i.e., the outer PEG lamella was thicker (17.4 nm) and wider (23.1 nm) compared to the inner one (15.0 and 18.1 nm). Furthermore, the crystallinity of PEG coily blocks accumulated on the P3HT crystals did not change the extended state of P3HT backbones (17.5 nm) and also the thickness of half-rings (11.0 nm). Second, with seeding homogeneous P3HT₇₀₀₀-b-PEG₅₀₀₀ solution using homo-PEG₅₀₀₀ tiny crystals, the cubic PEG single crystals were sandwiched between grafted regioregular P3HT chains (>99%). The appearance of (020)_P3HT and (100)_P3HT spots for tethered P3HTs beside (120)_PEG prisms demonstrated flat-on orderly tethered P3HT backbones on the PEG single crystalline substrate. Via conjunction between block copolymer and homopolymer single crystals in channel (PEG)/wire (P3HT-covered PEG)/channel (PEG) epitaxials, the P3HT rigid brushes were found to be extended (17.35 nm) on lamellar PEG substrate (6.15 nm). Third, when homogenized P3HT₇₀₀₀-b-PEG₅₀₀₀ solutions were seeded by homo-P3HT₇₀₀₀ tiny crystals, the edge-on orientated fibrillar P3HT single crystals were acquired. Although the thickness (20–22 nm) and length (60–63 μm) of P3HT₇₀₀₀-b-PEG₅₀₀₀ fibrillar single crystals resembled those of homo-P3HT₇₀₀₀ ones, their backbone lamination in the c axis were significantly different (2 versus 21); because the P3HT backbones were not capable of laminating from the coily block sides.