Combination of methylthio-chemistry with living crystallization-driven self-assembly toward uniform π-conjugated nanostructures with antibacterial activity, surface tailorability, tunable morphology and dimension

Abstract

Living crystallization-driven self-assembly (CDSA) provides robust access to uniform π-conjugated nanostructures (CNSs) from block copolymers (BCPs) containing a crystalline π-conjugated segment with controlled dimension, morphology and composition, which show appealing applications in biomedicine, photocatalysis and microelectronics. To further expand the application spectrum of these CNSs, the development of facile strategies toward diverse CNSs with varying structures/functionalities is highly desired. Herein, BCPs consisting of oligo(p-phenylene ethynylene)-b-poly(polypropyl-3-methanethiol acrylate) (OPE₉-b-PMTPA₃₅ and OPE₉-b-PMTPA₅₈; the subscript represents the number of repeat unit of each block) consisting of a crystalline π-conjugated core-forming OPE₉ segment and a corona-forming PMTPA block are synthesized. By efficient “click-type” alkylation of methylthio groups, OPE₉-b-PMTPA with varying contents of sulfonium unit is obtained. Uniform ribbon-like micelles with different widths and lengths can then be generated in a controlled manner via the self-seeding approach of living CDSA. Additionally, negatively charged polymeric and Ag nanoparticles can be immobilized on sulfonium/methylthio-containing shells by taking advantage of electrostatic attraction and coordination interaction, respectively. Interestingly, the ribbon-like micelles with positively charged shells exhibit antibacterial activity against E. coli. Given the ease of modification of PMTPA-based shell and attractive opto-electronic/photocatalytic properties of π-conjugated units, the combination of methylthio-chemistry and living CDSA opens a new avenue to generate multi-functional CNSs for widespread applications from biomedicine to photocatalysis.