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Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
Published on: November 27, 2015
Dimerization and polymerization of isoprene at high pressures
Margherita Citroni1, Matteo Ceppatelli, Roberto Bini
1LENS, European Laboratory for Non-linear Spectroscopy and INFM, Via Carrara 1, I-50019 Sesto Fiorentino, Firenze, Italy.
The Journal of Physical Chemistry. B
|March 29, 2007
Summary
High pressure induces isoprene dimerization and polymerization above 1.1 GPa, forming polyisoprene. Photoinduced reactions at 0.5 GPa also yield these products, with increasing pressure enhancing selectivity.
Area of Science:
- High-pressure chemistry
- Polymer science
- Organic reaction mechanisms
Background:
- Isoprene is a key volatile organic compound with significant atmospheric and industrial relevance.
- Understanding isoprene's reactivity under extreme conditions like high pressure is crucial for various chemical processes.
Purpose of the Study:
- To investigate the high-pressure reactivity of isoprene at room temperature.
- To elucidate the mechanisms and products of pressure-induced and photoinduced reactions of isoprene.
- To determine the activation volume for isoprene dimerization.
Main Methods:
- Diamond anvil cell (DAC) technique for generating high pressures up to 2.6 GPa.
- Fourier transform infrared (FTIR) spectroscopy for reaction monitoring.
- Kinetic analysis to determine activation volume.
Main Results:
- Dimerization and polymerization of isoprene initiate above 1.1 GPa.
- Reaction products include volatile sylvestrene and solid cis-1,4- and 3,4-polyisoprene.
- Photoinduced reactions occur via a two-photon process, with a threshold pressure of 0.5 GPa.
- Increasing pressure enhances selectivity in both pressure-induced and photoinduced reactions.
Conclusions:
- High pressure is an effective tool for controlling isoprene's dimerization and polymerization.
- Photoinduced reactions offer an alternative pathway with a lower pressure threshold.
- The study provides insights into the formation of polyisoprene under pressure.
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