page_title: Two-dimensional polymer
section_title: Supramolecular polymers
hierarchical_section_title: Two-dimensional polymer / Supramolecular polymers
caption_attribution_description: English: Figure 8. Self-assembly of a PTCDI–melamine supramolecular network. a, b, Chemical structure of PTCDI (a) and melamine (b) cyanuric acid. Dotted lines represent the stabilizing hydrogen bonds between the molecules.
context_page_description: A two-dimensional polymer is a sheet-like monomolecular macromolecule consisting of laterally connected repeat units with end groups along all edges. This recent definition of 2DP is based on Hermann Staudinger's polymer concept from the 1920s. According to this, covalent long chain molecules do exist and are composed of a sequence of linearly connected repeat units and end groups at both termini.
  Moving from one dimension to two offers access to surface morphologies such as increased surface area, porous membranes, and possibly in-plane pi orbital-conjugation for enhanced electronic properties. They are distinct from other families of polymers because 2D polymers can be isolated as multilayer crystals or as individual sheets.
  The term 2D polymer has also been used more broadly to include linear polymerizations performed at interfaces, layered non-covalent assemblies, or to irregularly cross-linked polymers confined to surfaces or layered films. 2D polymers can be organized based on these methods of linking: covalently linked monomers, coordination polymers and supramolecular polymers.
context_section_description: Supramolecular assembly requires non-covalent interactions directing the formation of 2D polymers by relying on electrostatic interactions such as hydrogen bonding and van der Waals forces. To design artificial assemblies capable of high selectivity requires correct manipulation of energetic and stereochemical features of non-covalent forces.  Some benefits of non-covalent interactions is their reversible nature and response to external factors such as temperature and concentration. The mechanism of non-covalent polymerization in supramolecular chemistry is highly dependent on the interactions during the self-assembly process. The degree of polymerization depends highly on temperature and concentration. The mechanisms may be divided into three categories: isodesmic, ring-chain, and cooperative.
  One example of isodesmic associations in supramolecular aggregates is seen in Figure 7, (CA*M) cyanuric acid (CA) and melamine (M) interactions and assembly through hydrogen bonding. Hydrogen bonding has been used to guide assembly of molecules into two-dimensional networks, that can then serve as new surface templates and offer an array of pores of sufficient capacity to accommodate large guest molecules.  An example of utilizing surface structures through non-covalent assembly uses adsorbed monolayers to create binding sites for target molecules through hydrogen bonding interactions. Hydrogen bonding is used to guide the assembly of two different molecules into a 2D honeycomb porous network under ultra high vacuum seen in figure 8. 2D polymers based on DNA have been reported
caption: Self-assembly of a PTCDI–melamine supramolecular network. Dotted lines represent the stabilizing hydrogen bonds between the molecules.
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