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A repeat unit or repeating unit (or mer) is a part of a polymer whose repetition would produce the complete polymer chain (except for the end-groups) by linking the repeat units together successively along the chain, like the beads of a necklace.
Traditional polymers are usually consist of one repeating unit or several repeating units, arranged in random sequences. Sequence-controlled polymers are composed of different repeating units, which are arranged in an ordered manner. In order to control the sequence, various kinds of synthetic methodologies are developed.
Two adjacent structural units in a polymer molecule constitute a diad. Diads overlap: each structural unit is considered part of two diads, one diad with each neighbor. If a diad consists of two identically oriented units, the diad is called an m diad (formerly meso diad, as in a meso compound, now proscribed [3]).
Polymers are studied in the fields of polymer science (which includes polymer chemistry and polymer physics), biophysics and materials science and engineering. Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science.
When a monomer adds to a radical chain end, there are two factors to consider regarding its stereochemistry: 1) the interaction between the terminal chain carbon and the approaching monomer molecule and 2) the configuration of the penultimate repeating unit in the polymer chain. [4] The terminal carbon atom has sp 2 hybridization and is planar.
Each polymer chain consists of several thousand repeating units. The backbone is the part of the chain that is on the main path, linking together a large number of repeat units. To customize the properties of a plastic, different molecular groups called side chains hang from this backbone; they are usually attached to the monomers before the ...
The structure of the repeating unit of PPP Space-filling model of a short section of PPP. Poly(p-phenylene) (PPP) is made of repeating p-phenylene units, which act as the precursor to a conducting polymer of the rigid-rod polymer family. The synthesis of PPP has proven challenging, but has been accomplished through excess polycondensation with ...
A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2, or 3 dimensions. [1] [2] It can also be described as a polymer whose repeat units are coordination ...