Fiber‐Like Micelles from the Crystallization‐Driven Self‐Assembly of Poly(3‐heptylselenophene)‐block‐Polystyrene. Issue 6 (22nd January 2015) - Kynaston, Emily L.
Abstract : The crystallization‐driven self‐assembly (CDSA) of crystalline‐coil polyselenophene diblock copolymers represents a facile approach to nanofibers 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, P3C7Se18 ‐ b ‐PS125 formed very long (up to 5 μm), highly aggregated nanofibers 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 P3C7Se18 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). Abstract : Polyselenophene block copolymers: a synthetic route to crystalline‐coil diblock copolymers with a crystallizable poly(3‐heptylselenophene) (P3C7Se) block and an amorphous polystyrene (PS) coblock is outlined via a Cu‐catalyzed, azide–alkyne click method. Crystallization‐driven self‐assembly (CDSA) in block‐selective solvents leads to the formation of nanofibers with a crystalline P3C7Se core and a solvent‐swollen PS corona.