Self-Assembly of Monotethered Single-Chain Nanoparticle Shape Amphiphiles

Abstract

Shape amphiphiles with distinct shapes and amphiphilic properties can be used as fundamental building blocks in the fabrication of novel structures and advanced materials. In this research synthesis and self-assembly of monotethered single-chain nanoparticle shape amphiphiles are reported. Poly­(2-(dimethylamino)­ethyl methacrylate)-<i>block</i>-polystyrene (PDMAEMA-<i>b</i>-PS) was synthesized by two-step reversible addition–fragmentation chain transfer (RAFT) polymerization. The PDMAEMA blocks were intramolecularly cross-linked by 1,4-diiodobutane (DIB) at significantly low concentrations, and PS-tethered PDMAEMA single-chain nanoparticles were prepared. Gel permeation chromatograph, ¹H NMR and transmission electron microscopy results all indicated successful synthesis of the structures. The controlled self-assembly of the shape amphiphiles in selective solvents was investigated. Depending on the size of the single-chain nanoparticles, the shape amphiphiles self-assemble into strawberry-like micelles, a structure with single-chain nanoparticles in the corona and PS in the core, or vesicles in aqueous solutions. Similar to the self-assembled structures in aqueous solution, the morphology of the aggregates in methanol changes from micellar structure to vesicular structure with the decrease of the PDMAEMA single-chain nanoparticles size. In cyclohexane, the shape amphiphiles self-assemble into bunchy micelles with single-chain nanoparticles in the cores and linear PS in the coronae