An intrinsic crystallographic disorder in the frustrated α″ phase of syndiotactic polystyrene. (15th January 2015)

• Record Type: Journal Article
• Authors: Lotz, Bernard
• Is Part Of: Polymer. Volume 56(2015)
• Page Start: 245
• Page End: 251
• Publication Date: 2015-01-15
• Subjects: Syndiotactic polystyrene -- Frustrated structure -- Structural disorder; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2014.11.018
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: The α″ phase of syndiotactic polystyrene (α″sPS) is a frustrated "superstructure" that houses three triplets (three clusters of three chains, thus nine chains) in a trigonal unit-cell. The hk 0 electron diffraction pattern of α″sPS single crystals displays, in addition to sharp spots, a number of diffuse spots located at 1/3 and 2/3 between the sharp spots. The diffuse spots correspond to the intersection of streaks. They are due to a structural disorder linked with the fact that the "frustrated" triplet in the cell has three-fold-symmetry but is housed in a hexagonally symmetric environment. Two equivalent crystallographic positions of this triplet, corresponding to 0° and 180° (or 60°) azimuthal settings are thus possible. Modeling of the diffraction features associated with this disorder reproduces to a significant detail the experimentally observed pattern. The frustrated character of the sPS α″ phase structure thus accounts for both the very detailed sharp reflections and for the diffuse components of the diffraction pattern. Graphical abstract: