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Optimised use of dielectric spectroscopy at microwave frequencies for direct online monitoring of polymerisation reactions

Kalamiotis, Alexis; Ilchev, Alexander; Irvine, Derek J.; Dimitrakis, Georgios


Alexis Kalamiotis

Alexander Ilchev

Professor of Materials Chemistry


This study reports the first use of dielectric spectroscopy over at a wide frequency range to monitor, in real time, the progress of a ring opening polymerisation. An open-ended coaxial line sensor was placed directly into the reaction medium of a polymerisation of ε-caprolactone and used to characterise the dielectric properties of the polymerisation mixture both ‘in-situ’ and with time at microwave frequencies. In addition to measurements obtained by the sensor, samples of the medium were extracted at various time points for off-line analysis, to confirm the level of conversion and polymer molecular weights that had been achieved. The results demonstrated that the dielectric properties values exhibited by the reaction medium with time could be correlated directly to the progress of the reaction. Thus, the experimental data allowed the construction of a calibration curve which could be used to predict the conversion of monomer to polymer at any given point of the reaction. The dielectric data permitted also the identification of key reaction parameters, such as the optimum point of termination for the reaction. Furthermore, the analysis of the dielectric data over a wide frequency spectrum enabled the identification of the most suitable frequencies for the practical operation of the sensor, in terms of linearity and sensitivity. This will enable the development of suitable instrumentation and an improved strategy for the online monitoring and control of a broad range of polymerisation reactions.


Kalamiotis, A., Ilchev, A., Irvine, D. J., & Dimitrakis, G. (2019). Optimised use of dielectric spectroscopy at microwave frequencies for direct online monitoring of polymerisation reactions. Sensors and Actuators B: Chemical, 290C, 34-40.

Journal Article Type Article
Acceptance Date Mar 26, 2019
Online Publication Date Mar 27, 2019
Publication Date Jul 1, 2019
Deposit Date Apr 1, 2019
Publicly Available Date Mar 28, 2020
Journal Sensors and Actuators B: Chemical
Print ISSN 0925-4005
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 290C
Pages 34-40
Keywords Instrumentation; Electrical and Electronic Engineering; Materials Chemistry; Electronic, Optical and Magnetic Materials; Surfaces, Coatings and Films; Condensed Matter Physics; Metals and Alloys
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