The creation of 1D π-conjugated nanofibers with precise control and optimized optoelectronic properties is of widespread interest for applications as nanowires. “Living” crystallization-driven self-assembly (CDSA) is a seeded growth method of growing importance for the preparation of uniform 1D fiber-like micelles from a range of crystallizable polymeric amphiphiles. However, in the case of polythiophenes, one of the most important classes of conjugated polymer, only limited success has been achieved to date using block copolymers as precursors. Herein, we describe studies of the living CDSA of phosphonium-terminated amphiphilic poly­(3-hexylthiophene)­s to prepare colloidally stable nanofibers. In depth studies of the relationship between the degree of polymerization and the self-assembly behavior permitted the unveiling of the energy landscape of the living CDSA process. On the basis of the kinetic and thermodynamic insight provided, we have been able to achieve an unprecedented level of control over the length of low dispersity fiber-like micelles from 40 nm to 2.8 μm.

Aggregation-induced emission (AIE) represents a powerful tool in nanoscience as a result of enhanced luminescence in the condensed state. Although AIEgenic materials have been utilized in a wide range of applications, well-defined self-assembled nanoparticles with tailorable and uniform dimensions and morphology remain challenging to access. Herein, we use the seeded growth, living crystallization-driven self-assembly (CDSA) method to prepare size-tunable and uniform AIE-active 2D nanoplatelets from amphiphilic block copolymer (BCP) precursors with a crystallizable core-forming block and a corona-forming block to which tetraphenylethene (TPE) groups were covalently grafted as AIE-active pendants. The nanoplatelets were formed as a result of a solvophobicity-induced 1D to 2D morphology preference change, which accompanied the seeded growth of a BCP with a quaternized corona-forming block bearing the TPE luminogen. The 2D nanoplatelets exhibited a solvent-responsive fluorescent emission, and examples with coronas containing homogeneously distributed AIE-active TPE groups and Hg­(II)-capturing thymine units exhibited excellent performance as proof-of-concept “turn-on” sensors for Hg­(II) detection with a rapid response, high selectivity, and a low detection limit (5–125 × 10–9 M, i.e., 1–25 ppb). The fluorescence intensity was found to be nonlinear with respect to analyte concentration and to increase with the area of the nanoplatelet. This behavior is consistent with a cooperative mechanism based on changes in the steric compression of the corona chains, which gives rise to a restriction of the intramolecular motion (RIM) effect.

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Seeded growth of crystallizable block copolymers and π-stacking molecular amphiphiles in solution using the living crystallization-driven self-assembly (CDSA) method is attracting growing interest as a route to uniform 1D and 2D core-shell micellar nanoparticles of controlled size with a range of potential applications. Although experimental evidence indicates that the process proceeds via an epitaxial growth mechanism and that the resulting crystalline core is highly ordered, direct observation of the crystal lattice has not been successful. Herein we report the results of high-resolution cryo-TEM studies that permit direct observation of both the solvated corona chains and the crystalline core from studies of frozen solution of nano ber micelles prepared by living CDSA. Together with complementary characterization data, this provides key insight into the structure of the corona and the detailed arrangement of the polymer chains in the crystalline micellar nano ber core.