Indan-containing polymers structures

Polyindanes have been obtained from a variety of monomers which are capable of forming benzyl carbenium ions stabilized with dialkyl groups upon the appropriate initiation. Linear polymers containing indane units in the main chain have been obtained by the BClj-initiated polymerization of 1,4-diisopropenylbenzene [Eq. (6)] [8]. Polyindanes with structural unit IS have also been obtained when difunctional monomers capable of forming a,a-dimethylbenzylic carbenium ions upon treatment with an initiator [8-12] (Fig. 4). 

These polymers contained indane structural units 49 and 52 (Fig. 9). This is because of the facile isomerization of 47 and 50 under the acidic reaction conditions. The relative proportion of 47 to 50 is determined by the equilibrium constant. Thus the two isomeric structural units are formed as a result of the electrophilic addition of 46 to 47 or to 50. 

Polyketones containing indane structural units have been prepared by Friedel-Crafts acylation [Eq. (12)] [17]. However, oligomers and/or insoluble polymers were obtained. 

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