Stereoregular Two-Dimensional Polymers Constructed by Topochemical Polymerization

Abstract

Two stereoregular 2D polyesters were synthesized by using topochemical polymerization of symmetric four-armed monomers. The monomers contain reactive carbon–carbon double bond(s) on each arm. The critical assemblies with multiple preorganized reactive centers were characterized by powder and single crystal X-ray diffraction. The solvent-free polymerization could be carried out with sunlight or UV irradiation. The locally confined photopolymerization process dimerized all of the olefins within the 2D bricklayer packing, which led to the formation of 2D polymers in the solid state. The process was monitored by FT-IR, and the products were confirmed by solid state NMR. After hydrolysis of the 2D polyester, the newly formed carbon–carbon single bonds during the [2 + 2] photocyclization were directly revealed by the single crystal structure of the hydrolysis product. Ultrathin sheets of the 2D polymer were observed under SEM and TEM after exfoliation.

Synthetic 2D Polymers: A Critical Perspective and a Look into the Future

“…d) Chemical structure of the 2D polymer obtained from monomer 11 in a solid state photoreaction. Reproduced with permission . Copyright 2015, American Chemical Society.…”

“…The last example, monomer 11 , concerns another case where [2 + 2]‐cycloaddition successfully furnishes a 2D polymer (Figure d) . Chronologically, monomer 11 was actually published before 3 .…”

“…Besides monomers 3 and 5 , monomer 11 , published by the Chu group, appears to have potential concerning multigram or even larger scale synthesis. The authors do not know whether this is being pursued.…”

Polymers with advanced structural and supramolecular features synthesized through topochemical polymerization

“…Monomers containing multiple olefin units pre-organized in a reactive orientation are also known to undergo TP to yield 2D polymers through [2+2] cycloaddition. 43,44 Monomer 22 possesses three styrylpyrylium arms ( Fig. 7e ).…”

Photoinduced Reversible Morphological Transformation of Azobenzene‐Containing Pseudo‐2D Polymers

“…Up to now, several approaches have been developed for preparation of single‐layer 2D polymers, such as liquid phase exfoliation of bulk‐layered 2D materials, polymerization at the air/liquid interface, or in solution with the steric hindrance. Free radical solution polymerization has exceptional advantages, such as cost effectiveness, high throughput, and mild condition.…”