Double-stranded surface-grafted polymer brushes with ladder-like architecture

This feature paper focuses on recently introduced double-stranded surface-grafted polymer brushes with ladder-like architecture, the method of their synthesis, self-templating surface-initiated polymerization (ST-SIP), as well as their unique properties. ST-SIP synthetic approach is based on a sequential polymerization of a bifunctional monomer leading to formation of multimonomer chains in the first step followed by a second polymerization producing ladder-like structures. This approach was developed primarily for conjugated polymer brushes, which synthesis using other methods is challenging. Such brushes enable anisotropic conductance at the nanometer scale that is highly demanded for e.g., photovoltaic and optoelectronic applications. ST-SIP was applied to form ladder-like brushes containing polyacetylene, polythiophene and polyethynylpyridine conjugated chains arranged normally to the grafting surface and exhibiting high electrical conductance as measured using conductive atomic force microscopy. The conjugated chains were shown to exhibit long term stability that is one of the crucial benefit of this novel brush topology. The nanomechanical characterization revealed enhanced stiffness and high elasticity of the ladder-like structures compared to the parent single-stranded brushes. The double-stranded brush topology due to anisotropic conductance, unique nanomechanical properties and versatility of ST-SIP approach, have a high potential for fabrication of robust nanocoating for tailoring (bio)interafaces.