Co-Self-seeding: A facile approach to generate heterogeneous p-Conjugated Fiber-Like comicelles with tunable Length, composition and morphology

Co-self-seeding approach of living crystallization-driven self-assembly (CDSA) enables the generation of fiber like micelles with a & pi;-conjugated core of tunable length/composition/ morphology with appealing photo physical and photochemical properties. However, our understanding on the co-self-seeding strategy in the preparation of fiber-like comicelles containing a heterogeneous & pi;-conjugated core is limited owing to very rare reports associated to this recently emerging strategy. Herein, we report that polydisperse comicelles containing a heterogeneous OPE9/OPV5 (OPE = oligo(p-phenylene ethynylene), OPV = oligo(p-phenylene vinylene), the subscripts indicate the exact number of repeat unit of OPE and OPV segments) core can be formed from the mixture of OPE9-b-P2VP56 and OPV5-b-PNIPAM47 (P2VP = poly(2-vinylpyridine), PNIPAM = poly(N-iso-propylacrylamide), the subscripts denote the degree of polymerization) with different mass ratios of OPE9-b- P2VP56 to OPV5-b-PNIPAM47 (MOPE9/MOPV5) by crystallization-driven co-self-assembly via heating/cooling protocol. Subsequently, by co-self-seeding from the seed comicelles obtained by the fragmentation of as-prepared polydisperse comicelles, apparent continuous (gradient) and segmented (block) fiber-like comicelles containing a heterogeneous OPE9/OPV5 core of controlled length/composition/morphology can be generated with varying annealing temperature and MOPE9/MOPV5. Co-self-seeding from pairs of separated seed micelles of OPE9-b-P2VP56 and OPV5-b-PNIPAM47 with different MOPE9/MOPV5 also can give apparently continuous and segmented fiber-like comicelles containing a heterogeneous OPE9/OPV5 core. These two co-self-seeding approaches have some common and different characteristics. It is found that for these samples with the MOPE9/MOPV5 = 1/1 and 2/1, the Ln of comicelles obtained from seed comicelles showed much sharper increase with the increase of temperature relative to the Ln of comicelles generated from mixed seed micelles as the temperatures were above 70 degrees C. On the contrary, for the MOPE9/MOPV5 = 5/1, both sets of samples showed very similar trend of dependence of Ln of resulting comicelles on the annealing temperature. These results revealed that both packing modes and mass ratios (MOPE9/MOPV5) of seed (co)micelles affected the co-self-seeding behavior.

Automated summary

The co-self-seeding approach of living crystallization-driven self-assembly (CDSA) allows for the generation of fiber-like micelles with a tunable length/composition/morphology of the π-conjugated core. However, the understanding of this approach in the preparation of fiber-like micelles with a heterogeneous π-conjugated core is limited. This study demonstrates that polydisperse comicelles with a heterogeneous OPE9/OPV5 core can be formed via crystallization-driven co-self-assembly, and that apparent continuous and segmented fiber-like comicelles can be generated through co-self-seeding.