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

Abstract

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.

High‐Quality Nano/Micro Hairy Single Crystals Developed from Poly(3‐hexylthiophene)‐Based Conductive–Dielectric Block Copolymers Having Flat‐on and Edge‐on Orientations

“…Besides single crystals, the crystalline whisker, the crystalline nanofibrils, and the single crystalline 2D nanosheets were also reported for the P3HT. Very recently, distinct orientations of conductive polymer based systems subsuming edge‐on, flat‐on, and face‐on were also thoroughly investigated in different conditions such as solution‐sheared and surface segregated films, molecular movement controlled systems, scrolled and flat ordered crystals, etc.…”

Enhanced properties of photovoltaic devices tailored with novel supramolecular structures based on reduced graphene oxide nanosheets grafted/functionalized with thiophenic materials

“…Therefore, the interactions between the hexyl side chains of P3HTs and 2‐thiophene acetic acid functional groups on the rGO surface led to the edge‐on P3HT crystals. In these systems, the growth fronts of (020) in π‐π stacking direction and (002) in the longitude of P3HT backbones appeared in SAED and (100) OOP and (020) IP peaks were also detected in GIWAXS patterns, demonstrating an edge‐on orientation . The a , b , and c dimensions of P3HT short fibrils patterned on rGO‐ f ‐TAA in toluene within 6 h were 3, 42, and 31 nm, respectively.…”

Conjugated polymer single crystals and nanowires

“…This could explain why Cho et al and Reiter et al obtained P3HT single crystals with different orientations by using the same method. Using the self‐seeding method, P3AT or P3AT block copolymer single crystals have also been prepared by several groups …”