title: Pressure-induced polymerization in solid ethylene.
abstract: Ethylene is the simplest organic molecule containing a double bond and is the starting monomeric unit in the synthesis of polyethylene, one of the most largely produced polymers. Here we report a high pressure infrared study of ethylene at room temperature. A polymerization reaction is observed when the crystalline phase I is compressed above 3.0 GPa. The reaction kinetics was investigated at two different pressures, 3.6 and 5.4 GPa. The recovered product was identified in both cases as polyethylene, but while a conformationally disordered and branched low-density polymer is obtained at the highest pressure, a high-density crystalline polymer is obtained at 3.6 GPa. A reaction mechanism was proposed on the basis of the kinetic data and the structural information.
authors.affiliation: LENS, European Laboratory for Non-Linear Spectroscopy and INFM, Via N. Carrara 1, I-50019, Sesto Fiorentino (FI), Italy.
authors.forename: David
authors.initials: D
authors.lastname: Chelazzi
authors.forename: Matteo
authors.initials: M
authors.lastname: Ceppatelli
authors.forename: Mario
authors.initials: M
authors.lastname: Santoro
authors.forename: Roberto
authors.initials: R
authors.lastname: Bini
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Schettino