Ultrahigh-resolution, high interface contrast ionic homopolymers induced by acid–base mixed electrostatic interactions and nanopattern evolution

Abstract

Ultrahigh-resolution polymer materials with good thermal stability and high interface contrast have a wide range of application prospects in photolithography and nanomanufacturing processes. Here, we report a series of comb-like homopolymers based on polystyrene sulfonate imidazolium salts (PSS_M-(i)imi), achieving efficient self-assembly under solvent-free conditions and obtaining sub-3 nm hexagonally packed cylinders and sub-4 nm lamellar nanopatterns with high interface contrast. The sulfonic acid groups in the main chain of the homopolymers are connected to imidazole groups containing hydrophobic alkyl side chains through acid–base mixed electrostatic interactions. The electrostatic interactions enhance the incompatibility between the two functional groups, while the alkyl side chain can precisely control the domain spacing and nanostructure of the pattern, regardless of their molecular weight. Through the effect of temperature fields, the thermal stability and spatial orientation of the homopolymer nanostructures were further studied, promoting the practical application of nanopatterned materials.