The crystalline form II of isotactic poly(vinylcyclopentane) was studied on the basis of fiber X-ray diffraction and of potential energy calculations of both isolated and packed chains. The hypothesis of a s(6*4/3) conformation of the chain has been investigated in detail. According to our interpretation, s(6*4/3) helices, which represent an anomalous case among isotactic poly(R-olefins), result from the superposition of a basically s(2*4/1) conformation of the backbone chain and of side groups following one another with a regular sequence of three conformations, mainly different for their orientation. Slight deformations of the main chain torsion angles from s(2*4/1) symmetry are found to be relevant to improve the data fitting. The resulting structure is indicative of a quite singular polymorphism, mainly ascribable to the different conformations accessible to the side groups.

An Unusual Chain Conformation: s(6*4/3) Helices in Form II ofIsotactic Poly(vinylcyclopentane)

ANTINUCCI, Simona;MONACO, Guglielmo;IMMIRZI, Attilio
2001

Abstract

The crystalline form II of isotactic poly(vinylcyclopentane) was studied on the basis of fiber X-ray diffraction and of potential energy calculations of both isolated and packed chains. The hypothesis of a s(6*4/3) conformation of the chain has been investigated in detail. According to our interpretation, s(6*4/3) helices, which represent an anomalous case among isotactic poly(R-olefins), result from the superposition of a basically s(2*4/1) conformation of the backbone chain and of side groups following one another with a regular sequence of three conformations, mainly different for their orientation. Slight deformations of the main chain torsion angles from s(2*4/1) symmetry are found to be relevant to improve the data fitting. The resulting structure is indicative of a quite singular polymorphism, mainly ascribable to the different conformations accessible to the side groups.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/1062398
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 5
  • ???jsp.display-item.citation.isi??? ND
social impact