Chain Folding in Poly(p-phenylene sulfide): A Study of the Packing of the Adjacent Re-Entry Folds by Molecular Mechanics

Models of Adjacent Re-Entry Folds in the β Form of Syndiotactic Polystyrene. Conformational and Packing Analysis by Molecular Mechanics

“…On the other hand, the number of models found in the previously studied polymers could be lowered if the packing of the chains was taken into account. In fact, for poly(p-phenylene sulfide) [31] some models of low conformational energy were excluded on the basis of the highly repulsive interactions found in the calculations of the packing of the folds. We have found that the best models of fold are constituted by five monomeric units both for the fold 1 and for the fold 2.…”

“…We underline that, while theoretical models of isolated folds were reported in the past years for various polymers, [22 -31] the packing analyses of folded chains have, until now, been applied only to polyethylene, [24,27,29] and recently by us, to poly(p-phenylene sulfide), [31] both polymers being constitutionally simpler as they do not contain side groups.…”

Crystal Structure and Adjacent Reentry Folds of the α Form of Syndiotactic Polystyrene. Conformational and Packing Analysis by Molecular Mechanics

“…The internal energy values of the folds have been used to estimate the work of fold. Energy calculations of adjacent reentry folds taking also into account the packing of the chains have been performed in the past for polyethylene − and recently by us for syndiotactic polypropylene, poly( p -phenylene sulfide), and the β form of sPS . This work presents a more complete analysis of the influence of the crystalline field on the folds for a polymer with crystal structure more complex than those studied in the past.…”

Time-of-Flight-Secondary Ion Mass Spectrometry and Principal Component Analysis: Determination of Structures of Lamellar Surfaces

“…Yet these data did not reveal the important details of the molecular structures of the folding surfaces . The fold models proposed to describe the chain structure at the folding surfaces were derived from indirect evidence, including spectroscopic conformation measurements as well as bulk properties, such as density, crystallinity, and heat of fusion. – In addition, various fold structures were also proposed based on results of molecular computations. − In the 1970s, neutron scattering was utilized to investigate the chain configurations of semicrystalline polymers, but conflicting results regarding the effects of molecular weight and the crystallization conditions on the fold nature were obtained. , One of the classic controversial debates was held in Faraday Discussions between the proponents of regular and disordered folding surfaces. The discussion was biased by the examination of small-angle neutron scattering data, which could yield equivocal interpretations for the correlation between stem distribution and fold trajectory .…”