Page 61 - Plastics News October 2019

TECHNOLOGY

Bottom-up synthesis of crystalline 2D polymers

cientists at the Center (2.6 -- 30 nm). The superior charge transport properties
Sfor Advancing Electronics and chemiresistivity toward ammonia and volatile organic
Dresden at TU Dresden have compounds render the quasi-2D polyaniline films as
succeeded in synthesizing SURPLVLQJ HOHFWURDFWLYH PDWHULDOV IRU WKLQ ÀOP RUJDQLF
sheet-like 2D polymers by a electronics. To further explore the potential of SMAIS, Mr.
bottom-up process for the Kejun Liu, Dr. Tao Zhang, Dr. Zhikun Zheng and Dr. Renhao
ÀUVW WLPH $ QRYHO V\QWKHWLF Dong achieved controlled synthesis of highly-crystalline
reaction route was developed IHZ OD\HU ' SRO\LPLGH DQG SRO\DPLGH IRU WKH ÀUVW WLPH
for this purpose. The 2D The 2D polymers have a thickness of only a few nanometers
polymers consist of only a and can be readily transferred onto arbitrary substrates,
few single atomic layers and, due to their very special opening up exciting opportunity for the integration of 2D
properties, are a promising material for use in electronic polymers into next-generation devices and systems. Along
components and systems of a new generation. The with the pivotal developments on the synthesis front, the
research result is a collaborative work of several groups transmission electron microscopy group led by Prof. Dr. Ute
at TU Dresden and Ulm University and was published this Kaiser (Uni Ulm) provided another indispensable pillar of
ZHHN LQ WZR UHODWHG DUWLFOHV LQ WKH VFLHQWLÀF MRXUQDOV the joint research. Since the development of aberration
Nature Chemistry and Nature Communications. Ever since correction, high-resolution TEM imaging has been a
Hermann Staudinger discovered the linear polymers in powerful technique in structural characterization down
1920, it has been a dream of synthetic scientists to extend to the atomic scale. Yet, hydrogen-containing organic
the polymerization into the second dimension.

A two-dimensional (2D) polymer is a sheet-like
monomolecular macromolecule consisting of laterally
connected repeat units with end groups along all edges.
Given the enormous chemical and structural diversity of
the building blocks (i.e., monomers), 2D polymers hold
great promise in the rational material design tailored
for next-generation applications, such as membrane
separation, electronics, optical devices, energy storage
and conversion, etc. However, despite the tremendous
developments in synthetic chemistry over the last materials are extremely prone to structural disintegration
century, the bottom-up synthesis of 2D polymers with under the electron beam, rendering HRTEM imaging of
defined structures remains a formidable task.Since 2D polymers a highly demanding mission. By utilizing the
2014, a group of scientists from Technische Universität spherical-aberration-corrected HRTEM, Dr. Haoyuan Qi has
Dresden and Universität Ulm joined forces to pursue this successfully unraveled the micro-morphology, molecular
intriguing yet challenging goal. The research team led by structures, grain boundary and edge structures, of the
Prof. Dr. Xinliang Feng (TU Dresden) innovatively developed synthetic 2D polymers: an achievement which is rarely
a novel synthetic route: using surfactant monolayer as a reported in literature.The molecular structures and overall
soft template to guide the supramolecular organization crystallinity have been further elucidated via synchrotron
of monomers and the subsequent 2D polymerization at grazing-incidence X-ray scattering (cfaed Chair for Organic
an air-water interface. This synthetic methodology is Devices, Prof. Dr. Stefan Mannsfeld, TU Dresden). The
now termed as surfactant-monolayer-assistant interfacial group of Prof. Dr. Thomas Heine (TU Dresden) provided
synthesis (SMAIS). By using the SMAIS method, Dr. Tao density-functional tight-binding calculations which offers
VLJQLÀFDQW LQVLJKWV LQWR WKH DWRPLVWLF VWUXFWXUHV RI WKH
Zhang synthesized crystalline quasi-2D polyaniline
ÀOPV ZLWK ODWHUDO VL]H a FP DQG WXQDEOH WKLFNQHVV synthetic 2D polymers.

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63 October 2019 Plastics News