Fiber‐Like Micelles from the Crystallization‐Driven Self‐Assembly of Poly(3‐heptylselenophene)‐block‐Polystyrene

Abstract

The crystallization-driven self-assembly (CDSA) of crystalline-coil polyselenophene diblock copolymers represents a facile approach to nanofi bers with distinct optoelectronic properties relative to those of their polythiophene analogs. The synthesis of an asymmetric diblock copolymer with a crystallizable, π-conjugated poly(3-heptylselenophene) (P3C7Se) block and an amorphous polystyrene (PS) coblock is described. CDSA was performed in solvents selective for the PS block. Based on transmission electron microscopy (TEM) analysis, P3C7Se 18 -b -PS 125 formed very long (up to 5 μm), highly aggregated nanofi bers in n -butyl acetate ( n BuOAc) whereas shorter (ca. 500 nm) micelles of low polydispersity were obtained in cyclohexane. The micelle core widths in both solvents determined from TEM analysis (≈ 8 nm) were commensurate with fully-extended P3C7Se 18 chains (estimated length = 7.1 nm). Atomic force microscopy (AFM) analysis provided characterization of the micelle cross-section including the PS corona (overall micelle width ≈ 60 nm). The crystallinity of the micelle cores was probed by UV-vis and photoluminescence (PL) spectroscopy and wide-angle X-ray scattering (WAXS).

PFS-b-PNIPAM: A First Step toward Polymeric Nanofibrillar Hydrogels Based on Uniform Fiber-Like Micelles

“…28 In the current state-of-the-art, we have the greatest understanding and the greatest degree of control over rodlike micelle formation of PFS diblock copolymers. Using the seeded growth protocol, 29 one adds a concentrated solution of unimer in a good solvent to a suspension of micelle seed fragments in a selective solvent.…”

Solution self-assembly of ABC triblock terpolymers with a central crystallizable poly(ferrocenyldimethylsilane) core-forming segment

“…1 : 5 -1 : 20, cylindrical micelles are formed, whilst platelets form at block ratios closer to 1 : 1. 28 CDSA been reported for a variety of crystallizable polymers, 29,[31][32][33][34][35] including conjugated materials, [36][37][38] and molecular species that self-assemble by non-covalent πstacking interactions. 39,40 In collaboration with Winnik and coworkers we have shown that a key advantage of CDSA over the self-assembly of BCPs with an amorphous core-forming block is that the termini of many micelles with crystalline cores remain active towards the addition of further incoming BCP unimer via an epitaxial growth mechanism.…”

Lateral Growth of 1D Core-Crystalline Micelles upon Annealing in Solution

“…3,4 The first examples of rodlike core-crystalline micelles were reported almost 20 years ago for poly(ferrocenyldimethylsilane) (PFS) diblock copolymers. [5][6][7] Since that time, particularly after poly(3-heptylselenophene), 32 poly(L-lactide) [33][34][35] and poly(ferrocenyldimethylgermane)9 as the core-forming block. Compared to block copolymers that form 2D platelet crystals, we have a much poorer understanding of how the semicrystalline polymer chains pack in the core of 1D…”