Toward Uniform Nanofibers with a π-Conjugated Core: Optimizing the “Living” Crystallization-Driven Self-Assembly of Diblock Copolymers with a Poly(3-octylthiophene) Core-Forming Block

Abstract

Crystalline poly(3-alkylthiophene) (P3AT) nanofibers are promising materials for a myriad of device applications but nanofiber length control and colloidal stability are difficult to achieve. We report an in depth study of the solution self-assembly of regioregular poly(3-octylthiophene)-bpoly(dimethylsiloxane) (P3OT-b-PDMS) diblock copolymers with a crystallizable p-conjugated coreforming block. Use of "living" crystallization-driven self-assembly (CDSA) seeded-growth method in solvents selective for PDMS allowed access to relatively low length dispersity, colloidally stable P3OTb-PDMS fiber-like micelles with a crystalline, tape-like P3OT core and a PDMS corona and lengths up to ca. 600 nm under optimised conditions. Significantly, the presence of a small percentage of common solvent and the use of slightly elevated temperature (35°C) was found to enhance the length control. Analogous studies for P3OT-b-PS (PS = polystyrene) suggest that solvent composition and temperature represent key parameters for the general optimisation of fiber formation by living CDSA for P3AT block copolymers.

Rapid formation and real-time observation of micron-sized conjugated nanofibers with tunable lengths and widths in 20 minutes by living crystallization-driven self-assembly

“…This may be due to competitive homogeneous nucleation occurring simultaneously with the seeded-growth, because the solubility of the P2 block became slightly lower in DCM. 54,55 The living CDSA was also qualitatively supported by DLS analysis, where their D h values gradually increased with higher U/S ratios (Fig. 5d).…”

“…In both cases, a rise in temperature to prepare the unimer solutions might dissolve some seeds as a result of the improved solubility of the BCPs, resulting in the longer 1D nanobers than the theoretically predicted length. 54 Also, L n s in both cases remained aer aging for 1 d suggesting that end-to-end coupling did not occur in chloroform (Fig. S34 †).…”

Modulating the Molecular Geometry and Solution Self-Assembly of Amphiphilic Polypeptoid Block Copolymers by Side Chain Branching Pattern

“… 2 , 10 , 20 , 24 , 25 In some cases, the solution self-assembly of crystallizable and liquid crystalline block copolymers can proceed in a living fashion, enabling access to low-dispersity anisotropic nanostructures or hierarchical assemblies with varying levels of structural complexity. 21 , 26 , 27 It should be noted that for crystallizable and liquid crystalline polymers (e.g., polyfluorenes or polythiophenes), 28 , 29 side chain engineering often serves as an effective strategy to modulate their inter- and intramolecular interactions and packing, thus allowing their morphology, solubility, and functionality to be systematically tailored. Yet, how the side chain geometry influences CDSA or LCDSA of block copolymers in solution remains largely unexplored.…”

One‐dimensional growth kinetics for formation of cylindrical crystalline micelles of block copolymers

“…Besides, T c and solvent also affect the uniformity of the formed crystalline micelles. It was reported that addition of a small fraction of cosolvent and a slightly higher crystallization temperature were favorable to the length control of poly(3‐octylthiophene)‐ b ‐PDMS fiber‐like micelles . However, a too high crystallization temperature and excessive cosolvent may broaden the length distribution of fiber‐like micelles …”