CONFORMATIONAL-ANALYSIS BY MOLECULAR MECHANICS ON SINGLE CHAINS OF POLYKETONES

A geometrical and energy analysis has been performed on the isolated c hain of syndiotactic polymers having the formula (-CHR-CH2-CO-)(n) whe re R = C6H5, (o-, m-, p-) C6H4CH3, in comparison with (-CH2-CH2-CO-)(n ) with the aim of predicting the best conformations in the crystalline field. By geometrical analysis the relations between the bond and tor sion angles in the main chain have been found in the framework of the tc line repetition group. The results of the conformational energy cal culations show that the presence of the side groups gives rise to sign ificant deviations from the all trans conformation. On the contrary, s econdary effects on the chain conformation are found in relation to th e kind of side group. All the results obtained by energy calculations are in good agreement with experimental data.