Lewis-Acid-Catalyzed Interfacial Polymerization of Covalent Organic Framework Films

Abstract

Interfacial polymerization with COF monomers and Sc(OTf) 3 afforded large-area (several cm 2) free-standing films with tunable thickness (2.5 nm to 100 mm). When the films were thick (100 mm), they exhibited X-ray diffraction corresponding to the expected crystalline structure. The films were integrated into the thin-film composite membranes for water nanofiltration, where they showed enhanced rejection of model pollutant Rhodamine WT.

Large Area Self‐Assembled Ultrathin Polyimine Nanofilms Formed at the Liquid–Liquid Interface Used for Molecular Separation

“…On the other hand, integrally skinned asymmetric membranes are known for separating small molecules from the organic feed, with marginal selectivity . Recently, interest in imine based porous organic polymers (POPs), and covalent organic frameworks (COFs), has grown due to their unique porous structures, which could be used for molecular separation with high MWCO . Caro and co‐workers demonstrated the excellent performance of COF‐LZU1 membranes for selective separation of dyes with water permeance of ≈76 L m −2 h −1 bar −1 and favorable rejection (rates exceeding 90%) for water‐soluble dyes larger than 1.2 nm.…”

2D Nanosheets and Their Composite Membranes for Water, Gas, and Ion Separation

“…prepared 2D COF-1 membranes, which were synthesised from 1,4-benzenediboronic acid in a1 ,4-dioxane/mesitylene mixture,b yu ltrafiltration exfoliation followed by assembly on ap orous substrate. [34] Shan et al developed ultrathin POF membranes,called benzimidazole-linked polymers (BILP-101x), using IP. [33] TheC OFs with highly ordered hexagonal networks and sheet-like morphology were easily exfoliated by ultrasonication due to the weak interlayer stacking force between the flexible building blocks.Afacile synthesis of COFs or porous organic frameworks (POFs) is possible when polymer synthesis techniques such as interfacial polymerisation (IP) are applied.…”

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

“…The subsequent interfacial polymerization at 50 °C yielded a PI‐2DP 1 film with a substantial increase in average crystalline domain size up to ≈150 nm (Figure a), which is larger than that with acetic acid as catalyst (Figure S8) and without catalyst (Figure S6). Here, water‐tolerant Yb(OTf) 3 can efficiently catalyze imine formation and transamination reaction, thus enabling the enhancement of the crystallinity of 2D polyimine . SAED performed on a single‐crystalline domain (Figure b) displays a square diffraction pattern with nearest reflections at 0.4 nm −1 (i.e., a = b =2.5 nm, γ =90°).…”

“…To address these issues, considerable progress has been made in developing methods for the synthesis of 2D COF films/nanosheets or single‐/few‐layer 2D polymers including top‐down exfoliation, bottom‐up on‐surface synthesis and interfacial synthesis methods . In particular, air–water and liquid–liquid interfaces assisted synthesis offers a reliable pathway to prepare large‐area, single‐/few‐layer 2D polymers which can be easily transferred directly from the interface to various substrates for further characterization and device fabrication . For instance, large‐area, imine‐based 2D COF films (polyTB) with varied thickness from ≈2 to 200 nm were prepared at the DMF/air interface, which could function as a semiconductor layer in a field‐effect transistor (FET) device and exhibited a charge carrier mobility of 3.0×10 −6 cm −2 V −1 s −1 .…”