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Polyethylene was first synthesized by the German chemist Hans von Pechmann, who prepared it by accident in 1898 while investigating diazomethane. [12] [a] [13] [b] When his colleagues Eugen Bamberger and Friedrich Tschirner characterized the white, waxy substance that he had created, they recognized that it contained long −CH 2 − chains and termed it polymethylene.
Polyacrylic acid is a weak anionic polyelectrolyte, whose degree of ionisation is dependent on solution pH. In its non-ionised form at low pHs, PAA may associate with various non-ionic polymers (such as polyethylene oxide, poly-N-vinyl pyrrolidone, polyacrylamide, and some cellulose ethers) and form hydrogen-bonded interpolymer complexes. [17]
Consider the example of polyethylene terephthalate (PET or "polyester"). The monomers which could be used to create this polymer are ethylene glycol and terephthalic acid: HO-CH 2-CH 2-OH and HOOC-C 6 H 4-COOH In the polymer, there are two structural units, which are -O-CH 2-CH 2-O- and -CO-C 6 H 4-CO- The repeat unit is -CH 2-CH 2-O-CO-C 6 H 4 ...
Alpha-olefins such as 1-hexene may be used as co-monomers to give an alkyl branched polymer (see chemical structure below), although 1-decene is most commonly used for lubricant base stocks. [8] 1-hexene, an example of an alpha-olefin. Many poly-alpha-olefins have flexible alkyl branching groups on every other carbon of their polymer backbone ...
The polymerization of one kind of monomer gives a homopolymer. Many polymers are copolymers, meaning that they are derived from two different monomers. In the case of condensation polymerizations, the ratio of comonomers is usually 1:1. For example, the formation of many nylons requires equal amounts of a dicarboxylic acid and diamine. In the ...
When prepared from amino-carboxylic acids, e.g. amino acids, the stoichiometry of the polymerization includes co-formation of water: n H 2 N-X-CO 2 H → [HN-X-C(O)] n + (n-1) H 2 O When prepared from diamines and dicarboxylic acids , e.g. the production of nylon 66 , the polymerization produces two molecules of water per repeat unit:
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. [1] [2] [3] There are many forms of polymerization [4] and different systems exist to categorize them. IUPAC definition for ...
An example of polyester is polyethylene terephthalate (PET), which is made from the monomers terephthalic acid and ethylene glycol. If one of the components in the polymerization is in excess, then that polymers functionality will be at the ends of the polymers (a carboxylic acid or alcohol group respectively).