Structure Elucidation of 2D Polymer Monolayers Based on Crystallization Estimates Derived from Tip-Enhanced Raman Spectroscopy (TERS) Polymerization Conversion Data

Abstract

Structural elucidation of 2D polymer monolayers proving long-range order is a challenge that limits the pace in which this recent field of polymer chemistry and of synthetic 2D materials develops. To overcome this bottleneck, we here present a method in which tip-enhanced Raman spectroscopy is combined with a random growth crystallization model to obtain global features from local spectroscopic information. Concretely, we prove the nature and determine the conversion number X of the cross-links for two new 2D homopolymers and one (of three) new 2D copolymers. Assuming random and in-plane growth, our model results in crystallinity degrees of 93.1% to 99.7% and mean radii of defect-free crystalline areas of 3−15 nm for conversion numbers of 84% < X < 98%. Thus, we provide strong evidence for the synthetic monolayer 2D materials presented that they qualify as 2D polymers and are therefore perfectly suited for indepth studies both in a more fundamental direction as well as toward application. This example shows how our method can affect current research on covalent sheets.

Cross‐Conjugated Polycatechol Organic Cathode for Aqueous Zinc‐Ion Storage

“…[22] However,t he I D /I G ratios are PC (0.9) < graphene (1.1) % PC/G composite (1.1), delivering ab etter regularity of PC. [24] Compared with that of graphene, as mallb lueshift can be observed on the Gb and of the spectrumf or the PC/G-2 sample (Figure 2e), which is attributed to the p-p interactions between the graphene and PC. [21] Figure 2f expresses the nitrogen adsorption/desorption isothermso ft he PC and PC/G samples.…”

“…All the Raman spectra are analogous and all these curves have two bands of I D and I G located at 1332 and 1586 cm −1 , respectively, corresponding to the defective and graphitized carbon in these samples . However, the I D / I G ratios are PC (0.9)<graphene (1.1)≈PC/G composite (1.1), delivering a better regularity of PC . Compared with that of graphene, a small blueshift can be observed on the G band of the spectrum for the PC/G‐2 sample (Figure e), which is attributed to the π–π interactions between the graphene and PC .…”

The Expanding Frontiers of Tip-Enhanced Raman Spectroscopy

“…TERS has also shown great potential as a tool to measure the local crystallinity of a sample, providing a means to validate fabrication methods prior to more application-based studies. 142–144

Figure 5.Synthesis and characterization of a 2D covalent monolayer (ML) sheet. (a) Synthesis of the ML sheet 3 with nanodefects from dialdehyde 1 and triamine 2.

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“…TERS has also shown great potential as a tool to measure the local crystallinity of a sample, providing a means to validate fabrication methods prior to more application-based studies. [142][143][144] With the growth of research into new 2D materials, new applications for TERS are continuously being discovered. Transition metal dichalcogenides, with a general formula of MX 2 (M ¼ Mo, W, V, Nb, Ta, Hf, Pt, and X ¼ S, Se, Te) are a very broad family of layered materials which have earned tremendous attention because of their diverse physical properties and a variety of potential applications.…”

In-situ nanospectroscopic imaging of plasmon-induced two-dimensional [4+4]-cycloaddition polymerization on Au(111)

“…Upon UV-irradiation, photopolymerization leading to 2D polymers has also been realized on a Au(111) substrate 45 . Preparation of amphiphilic monomer/polymer MLs at an air/water interface allows for convenient transfer onto Au(111) by the Schäfer technique 46 . For MLs of structurally closely related monomers 47 – 49 , earlier work has shown that the excimer fluorescence of anthracene pairs contained in the monomer lattice before and after transfer remained unchanged.…”