In polymer chemistry, a structural unit is a building block of a polymer chain. It is the result of a monomer residue which has been polymerized. Contrast this with repeating unit, which is the shortest sequence that can be found repeatedly in a polymer. This distinction is necessary in order to estimate the molecular weight of polymers correctly. Polymer chemistry is the scientific study of the structure, properties, composition, and reactions of polymers. ... A polymer is a generic term used to describe a substantially long molecule. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ...
Consider this example: Take polyethylene terephthalate. The monomers which could be used to create this polymer are ethylene glycol and terephthalic acid:
HO-CH2-CH2-OH and HOOC-Ph-COOH
In the polymer, there are two structural units, which look like -CH2-CH2-O- and -CO-PH-CO-
The repeating unit looks like -CH2-CH2-O-CO-Ph-CO-O-
The water- and oil-repellent fiber according to claim 3, wherein repeatingunit (c) is present in an amount of 0.2 to 2 moles per one mole of repeatingunit (a); and repeatingunit (d) is present in an amount of 0.1 to 2 moles per one mole of repeatingunit (a).
The water- and oil-repellent fiber according to claim 6, wherein repeatingunits (e) and (a) are present in said fiber, and wherein repeatingunit (e) is present in an amount of from 0.2 to 3 moles per one mole of repeatingunit (a).
The polymer contained 56.2% by mole of a repeatingunit derived from the epoxide, 30.3% by mole of a repeatingunit derived from succinic anhydride and 13.5% mole of a repeatingunit derived from phthalic anhydride.
The highlighted unit cells of the adsorbate and substrate are identical in size, shape and orientation to those of the previously illustrated (2 x 2) structure.
The adsorbate unit cell is again twice as large as that of the substrate in both dimensions - it retains the same aspect ratio as the rectangular substrate unit cell (1 : 1.414) and does not exhibit any rotation with respect to the substrate cell.
Again, the adsorbate unit cell is of the same symmetry as the substrate cell but is scaled up by a factor of two in its linear dimensions (and corresponds to a surface area four times as large as that of the substrate unit cell).
Feeds |
Contact