CONFIGURATIONAL-CONFORMATIONAL ENTROPY OF 1,4-POLYDIENES

A method based on matrix algebra and on the rotational isomeric state scheme to study the configurational-conformational entropy of 1,4-poly dienes with geometrical isomerism has been developed. Bernoullian and first- and second-order Markovian statistics for the sequences of cis and trans units along the chains have been considered, and the explici t relation between entropy and mole fraction of cis units has been der ived. Calculations performed by using available experimental data for the configurational parameters and the conformational partition functi ons of 1,4-polybutadiene and 1,4-polyisoprene show that entropy is a m onotonic function of the geometrical isomer composition. While the ent ropy of polybutadiene increases with the content of cis units, the rev erse is true for polyisoprene.