Title of article :
Chain conformations of syndiotactic poly(m-methylstyrene) in the crystalline state
Author/Authors :
De Rosa، نويسنده , , Claudio and Esposito، نويسنده , , Simona and Buono، نويسنده , , Annamaria and Auriemma، نويسنده , , Finizia، نويسنده ,
Issue Information :
دوهفته نامه با شماره پیاپی سال 2003
Abstract :
A conformational energy analysis of the isolated chain of syndiotactic poly(m-methylstyrene) under the constraint of a crystalline field is reported. Two different minimum energy conformations having similar energy have been found; the trans-planar conformation with tcm symmetry and the two-fold helical conformation with s(2/1)2 symmetry, according with the observed polymorphic behavior of this polymer. The calculated chain axes are in agreement with the experimental axes of 5.1 and 7.9 إ found for the different polymorphic forms of syndiotactic poly(m-methylstyrene). However, only a metastable disordered modification (form III) having chains in trans-planar conformation has been described. This indicates that, even though the trans-planar conformation is, in the isolated chain as stable as the helical conformation, the packing of the chains in helical conformation is probably more efficient than that of the trans-planar chains.
Keywords :
Chain conformations , Energy calculations , Syndiotactic poly(m-methylstyrene)