High‐Sensitivity Acoustic Molecular Sensors Based on Large‐Area, Spray‐Coated 2D Covalent Organic Frameworks

Abstract

2D covalent organic frameworks (2D COFs) are structurally regular and synthetically versatile (>400 reported structures) layered 2D polymers with high surface areas (>2000 m 2 g-1) and robust covalent bonds. [1,2] This combination of properties makes 2D COFs promising for a variety of applications, 2D covalent organic frameworks (2D COFs) are a unique materials platform that combines covalent connectivity, structural regularity, and molecularly precise porosity. However, 2D COFs typically form insoluble aggregates, thus limiting their processing via additive manufacturing techniques. In this work, colloidal suspensions of boronate-ester-linked 2D COFs are used as a spray-coating ink to produce large-area 2D COF thin films. This method is synthetically general, with five different 2D COFs prepared as colloidal inks and subsequently spray-coated onto a diverse range of substrates. Moreover, this approach enables the deposition of multiple 2D COF materials simultaneously, which is not possible by polymerizing COFs on substrates directly. When combined with stencil masks, spray-coated 2D COFs are rapidly deposited as thin films larger than 200 cm 2 with line resolutions below 50 µm. To demonstrate that this deposition scheme preserves the desirable attributes of 2D COFs, spray-coated 2D COF thin films are incorporated as the active material in acoustic sensors. These 2D-COF-based sensors have a 10 ppb limit-of-quantification for trimethylamine, which places them among the most sensitive sensors for meat and seafood spoilage. Overall, this work establishes a scalable additive manufacturing technique that enables the integration of 2D COFs into thin-film device architectures.

25 Jahre retikuläre Chemie

“…Synthesemethoden Einer der naheliegendsten Wege,r etikuläre dünne Filme zu erhalten, ist die Abscheidung von mittels konventioneller Methoden hergestellten Partikeln auf einem festen Tr äger. [259][260][261][262] Alternativ ermçglichen nicht-konventionelle Syntheseschemata das direkte Wachstum solcher Filme auf entsprechend modifizierten Substraten (z. B. durch die Bildung von selbst-assemblierten Monoschichten).…”

25 Years of Reticular Chemistry

“…Synthesis Methods One of the most obvious routes to reticular thin films is to deposit particles fabricated by conventional methods on as olid support. [259][260][261][262] Alternatively,n onconventional syn-thesis schemes allow the direct growth of such films on appropriately modified substrates (e.g.,via formation of selfassembled monolayers). [263] This type of direct synthesis can be realized either by heterogeneous nucleation on as ubstrate [264] or by using layer-by-layer methods where the reactants are kept apart.…”

Have Covalent Organic Framework Films Revealed Their Full Potential?

“…Additionally, suspending COF powders in a highly vis polymer matrix and the subsequent film formation was also reported, and the films applied in organic light-emitting diodes (OLEDs) [69]. Synthesis of colloidal COF par and the subsequent casting of their films from those solutions were also presented Spray coating of COF powders dispersed in inks to yield large area COF films was an interesting method [71]. Moreover, electrophoretic deposition of COFs onto subst was also successfully presented in the literature (Figure 5) [72].…”

“…Synthesis of colloidal COF particles and the subsequent casting of their films from those solutions were also presented [70]. Spray coating of COF powders dispersed in inks to yield large area COF films was another interesting method [71]. Moreover, electrophoretic deposition of COFs onto substrates was also successfully presented in the literature (Figure 5) [72].…”