Synthesis of Nanowires via Temperature-Induced Supramolecular Step-Growth Polymerization

Supramolecular polymerization of nanoscale particles has been considered as an effective route to prepare hierarchical nanostructures with controlled geometry and functions. However, so far, less is known about its mechanism, especially the polymerization kinetics which is fundamentally Decrease important for the controllable synthesis of hierarchical Temperature structures. In the present work, we discovered a temperature-induced supramolecular step-growth polymerization which can provide a simple and robust route for preparing one-dimensional hierarchical nanowires. The polymerization units are spindlelike micelles self-assembled from amphiphilic poly(gamma-benzyl-L-glutamate)-graft-polyethylene glycol) (PBLG-g-PEG) graft copolymers. Because of the imperfect coverage of PEG grafts on PBLG cores at both ends of the micelles, structural defects appear. At low temperatures, PBLG tends to be more hydrophobic, and resultantly, these defects become reactive and induce polymerization. Kinetic studies revealed that at low temperatures and high micelle concentrations, the polymerization rate becomes relatively faster. The present work demonstrates a new kind of supramolecular polymerization and its reaction kinetic mechanism. The obtained results could provide a guidance for the controllable construction of hierarchical structures.