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What are polymers and how do they form?
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Chemistry Open Book Exam Firstly a polymer is a long chained molecule which is made up of many hundreds or thousands on monomer units. Addition polymerisation is the joining of these monomers to produce the polymer molecule. In most cases there are C=C double bonds, which are found in alkenes. These double bonds are then broken in order to form a long chain of monomer units. The mechanism of polymerisation of ethene to form low density polyethene requires a catalyst, which can be dioxygen or an organic peroxide. The reaction involves radicals and can be shown in three steps. The first step is the initiation which involves the creation of the radical: R* + H2C=CH2 R-CH2-CH2* Where R is the alkyl group From the Peroxide and * Indicates the Radical The radical formed now reacts with another ethene molecule, during the propagation reaction, which then happens again and again to form a long chain polymer R-CH2-CH2* + H2C=CH2 R-CH2-CH2-CH2-CH2* R-CH2-CH2-CH2-CH2*...
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