A team of Chinese researchers has developed a new interfacial synthesis strategy to fabricate high-performance crystalline sp²-carbon conjugated two-dimensional (2D) polymer films using irreversible chemical reactions. This study, published in Nature Communications, marks a step forward in the field of 2D materials.
2D conjugated polymers, which range from monolayer to multilayer crystalline structures, are characterized by their robust C=C bonds. These bonds impart exceptional chemical stability and extended π-conjugation to sp²-carbon conjugated 2D polymers (sp²c-2DPs), making them promising for applications in membranes, organic electronics, and beyond. However, traditional interfacial synthesis methods, which rely on dynamic covalent chemistry such as C=N linkages, have proven ineffective for constructing C=C linked sp²c-2DPs due to the limited reversibility of C=C bonds.
To address this challenge, a research team led by Prof. ZHANG Tao from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences, in collaboration with Prof. FENG Xinliang from the Max Planck Institute of Microstructure Physics, devised a novel approach. They employed an amphiphilic-pyridinium-assisted aldol-type interfacial polycondensation strategy to synthesize crystalline sp²c-2DP thin films.
The key innovation lies in the use of amphiphilic pyridinium monomers, which self-assemble into ordered monolayers at the water interface. This self-assembly enhances the interfacial reactivity of the monomers with aldehyde counterparts, enabling the synthesis of sp²c-2DPs through irreversible chemistry under mild conditions. The resulting films exhibit long-range molecular ordering, a robust charged framework, and tunable thickness from monolayer to multilayer.
These structural advantages unlock the potential of sp²c-2DPs for applications such as marine salinity gradient energy conversion. When tested in an osmotic power generator under harsh acidic conditions (pH = 3.5), the films demonstrated exceptional performance, achieving a cation selectivity coefficient (S) of 0.68 and an output power density of 51.4 W m⁻².
This study not only enables the large-scale fabrication of sp²c-2DPs thin films with precise thickness control but also highlights their transformative potential in advanced membrane technologies and next-generation organic electronic devices.
Fig. The amphiphilic-pyridinium-assisted aldol-type interfacial polycondensation strategy to synthesize sp²c-2DP thin films (Image by NIMTE)
