A Two‐Dimensional Polymer Synthesized at the Air/Water Interface

Abstract

A trifunctional, partially fluorinated anthracene‐substituted triptycene monomer was spread at an air/water interface into a monolayer, which was transformed into a long‐range‐ordered 2D polymer by irradiation with a standard UV lamp. The polymer was analyzed by Brewster angle microscopy, scanning tunneling microscopy measurements, and non‐contact atomic force microscopy, which confirmed the generation of a network structure with lattice parameters that are virtually identical to a structural model network based on X‐ray diffractometry of a closely related 2D polymer. The nc‐AFM images highlight the long‐range order over areas of at least 300×300 nm2. As required for a 2D polymer, the pore sizes are monodisperse, except for the regions where the network is somewhat stretched because it spans over protrusions. Together with a previous report on the nature of the cross‐links in this network, the structural information provided herein leaves no doubt that a 2D polymer has been synthesized under ambient conditions at an air/water interface.

Comparing a porphyrin- and a coumarin-based dye adsorbed on NiO(001)

“…Fig. 2 shows the frequency-shift signal acquired using the multipass imaging technique [14–15 35–36] clearly showing atomic resolution of the NiO(001) surface. Employing this method, the crystallographic directions of the substrate are resolved with atomic accuracy, and upon comparing them with the large-scale image, one can deduce that the step edges of NiO(001) as well as the observed defects run along the [110] direction (see violet dotted lines in Fig.…”

2D Polymer Nanosheets for Membrane Separation

“…It entails the efficient dispersion, rearrangement, and assembly of the building units in order to produce 2D polymer nanosheets via chemical processes. [39] This technique could be used in the homogeneous solution, [40][41][42] or at the interface, such as the liquid/solid, [43] air/water, [44][45][46] and liquid/liquid interfaces. [47] In homogeneous solution synthesis, 2D polymer nanosheets are very prone to stacking into bulk materials due to various noncovalent interactions.…”

Mastering polymer chemistry in two dimensions

“…Putting this remarkable finding into perspective is not easy, primarily because there are no suitable few-layer synthetic organic systems for direct comparison. We can however look to two of the few recently published 2D organic monolayers for comparative discussion 4,5 . Yu Zhong, Jiwoong Park and collaborators from the University of Chicago, USA, reported on the creation of a covalent network, 2DPII, by the condensation of a tetra-functional porphyrin derivative and a terephthalaldehyde at a pentane/water interface 4 .…”

“…Thus, there is still a way to go to achieve long-range order by this synthetic strategy. Another recent report detailing a monolayer 2D polymer was published by a group of researchers at ETH Zürich and the University of Basel collaborating with the author of this Comment 5 . Photochemical fixation of a monomer monolayer preordered at an air/water interface gave a crystalline network, the long-range order of which was demonstrated by non-contact mode high-resolution atomic force microscopy (nc HRAFM) in ultra-high vacuum after transfer onto highly oriented pyrolytic graphite.…”

“…Additionally, the monomer components used for this surfactant-assisted synthesis, the tetraaminoporphyrin derivative 1 and the dianhydrides 2 (for 2DPI) and 3 (for 2DPA), are commercially available. This removes the need of having to go through even simple steps of monomer synthesis, which are required for the Zürich 2D polymer 5 . Given the fact that chemical synthesis is often an unsurmountable obstacle for physicists and engineers, this is a plus.…”