On-water surface synthesis of crystalline, few-layer two-dimensional polymers assisted by surfactant monolayers

Abstract

Despite rapid progress in recent years, it has remained challenging to prepare crystalline twodimensional polymers. Here, we report the controlled synthesis of few-layer 2D polyimide crystals on the water surface, through reaction between amine and anhydride monomers, assisted by surfactant monolayers. We obtained 2D polymers with high crystallinity, a thickness of approximately 2 nm, and an average crystal domain size of around 3.5 μm 2. The molecular structure of the materials, their grain boundaries, and their edge structures were characterized using X-ray scattering and transmission electron microscopy techniques, and supported by computations. The formation of crystalline polymers is attributed to the preorganization of monomers at the water-surfactant interface. Depending on its polar head, the surfactant promoted the arrangement of the monomers-and in turn their polymerizationeither horizontally or vertically with respect to the water surface. The latter was observed with a surfactant bearing a carboxylic acid group, which anchored amine monomers vertically through a condensation reaction. In both instances, micrometre-sized 2D polyamide crystals were grown.

Design and Synthesis of Polyimide Covalent Organic Frameworks

“…When the macromolecular dye is loaded into PI-COF-3, the temperature dependence in the emission spectrum is studied. Then we found that the product had unique luminous properties that Yes Yes [40,45] vary with temperature, indicating that dye-doped PI-COFs can be applied for temperature sensor devices.…”

“…In recent years, researchers have been working hard to explore low-cost and large-scale synthesis methods, such as solvothermal synthesis, [17,18,26,27,41,42,44,46,48] condensation polymerization synthesis, [25,45] high-temperature solid-state synthesis, [39] interfacial synthesis, and ionothermal synthesis. [40,45]…”

“…[52][53][54] Liu et al reported that through the reaction of amine and anhydride monomer, 2D PI single crystal thin film, the thickness of about ≈2 nm (five layers) and average crystal domain of about ≈3.5 µm 2 , can be controlled via synthesis with the aid of a monolayer of surfactant in 2019. [40] The study found that the polar head of the surfactant promoted the adsorption and pre-organization of the monomer tetraamine under the surfactant layer through the electrostatic interaction and hydrogen bonding between the monomer tetraamine and the amine through the condensation reaction. The monomer was fixed vertically, and tetraamine was reacted with an anhydride to form PI.…”

Graphene‐Quantum‐Dots‐Induced Centimeter‐Sized Growth of Monolayer Organic Crystals for High‐Performance Transistors

“…2D monolayer organic crystals are usually fabricated by solution‐processed methods at water/air interface, [ 14–22 ] where water surface is usually used to control the diffusion of organic solvent and serves as a substrate for the self‐assembly of organic molecules due to its relatively high surface tension and molecularly flat surface. Langmuir–Blodgett (LB) technique has been previously applied for the fast and simple fabrication of organic monolayer crystals at water/air interface.…”

Highly Crystalline and Semiconducting Imine‐Based Two‐Dimensional Polymers Enabled by Interfacial Synthesis

“…Very recently, our group reported a surfactant‐monolayer‐assisted interfacial synthesis (SMAIS) of few‐layer 2D polyimide and 2D polyamide films on water surface . Nevertheless, the achieved 2D polyimide film showed abundant amorphous areas (≈40 % ratio) interconnected within crystalline domains.…”