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Hassanpouryouzband A, Ahadzadeh I, Mehrdad A, Panahpour S. Development and construction of a cost-effective non-contact instrument for measuring the dielectric constant of liquids. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:105101. [PMID: 39352244 DOI: 10.1063/5.0223926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 09/12/2024] [Indexed: 10/03/2024]
Abstract
This research presents the development and construction of a cost-effective instrument, designed to measure the dielectric constant of liquids by employing a non-contact method that relies on determining the capacitance of a cell containing the liquid and its relaxation frequency. This instrument utilizes an astable multi-vibrator integrated with a resistance-capacitor network, in which the cell housing the liquid of interest functions as a capacitor element of the oscillator. The frequency of the generated oscillations is meticulously recorded using a seven-digit frequency meter with a resolution of 1 Hz. The cell was filled with an array of pure liquids with known dielectric constants, and their frequencies were subsequently recorded at ambient temperatures. An equation was fitted to the frequency-dielectric constant curve, which was used as a calibration equation to determine the dielectric constant of subsequent liquids. In addition to pure liquids, dielectric constants for solvent mixtures of varying mole fractions were also calculated using the previously established calibration equation. Our results demonstrated excellent frequency stability of the instrument, and the obtained dielectric constant values displayed significant consistency with both the experimental data and predictions made by computational methodologies. This suggests that the constructed instrument exhibits a high level of accuracy in measuring the dielectric constant of both pure and mixed liquids, establishing its potential utility in relevant research and industrial applications.
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Affiliation(s)
- Akram Hassanpouryouzband
- Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11155-9466, Tehran, Iran
| | - Iraj Ahadzadeh
- Department of Physical Chemistry, Faculty of Chemistry, University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran
| | - Abbas Mehrdad
- Department of Physical Chemistry, Faculty of Chemistry, University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran
| | - Somayyeh Panahpour
- Department of Physical Chemistry, Faculty of Chemistry, University of Tabriz, P.O. Box 51666-16471, Tabriz, Iran
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Sedano LF, Blazquez S, Vega C. Accuracy limit of non-polarizable four-point water models: TIP4P/2005 vs OPC. Should water models reproduce the experimental dielectric constant? J Chem Phys 2024; 161:044505. [PMID: 39046346 DOI: 10.1063/5.0211871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 06/30/2024] [Indexed: 07/25/2024] Open
Abstract
The last generation of four center non-polarizable models of water can be divided into two groups: those reproducing the dielectric constant of water, as OPC, and those significantly underestimating its value, as TIP4P/2005. To evaluate the global performance of OPC and TIP4P/2005, we shall follow the test proposed by Vega and Abascal in 2011 evaluating about 40 properties to fairly address this comparison. The liquid-vapor and liquid-solid equilibria are computed, as well as the heat capacities, isothermal compressibilities, surface tensions, densities of different ice polymorphs, the density maximum, equations of state at high pressures, and transport properties. General aspects of the phase diagram are considered by comparing the ratios of different temperatures (namely, the temperature of maximum density, the melting temperature of hexagonal ice, and the critical temperature). The final scores are 7.2 for TIP4P/2005 and 6.3 for OPC. The results of this work strongly suggest that we have reached the limit of what can be achieved with non-polarizable models of water and that the attempt to reproduce the experimental dielectric constant deteriorates the global performance of the water force field. The reason is that the dielectric constant depends on two surfaces (potential energy and dipole moment surfaces), whereas in the absence of an electric field, all properties can be determined simply from just one surface (the potential energy surface). The consequences of the choice of the water model in the modeling of electrolytes in water are also discussed.
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Affiliation(s)
- L F Sedano
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - S Blazquez
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - C Vega
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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Jorge M, Barrera MC, Milne AW, Ringrose C, Cole DJ. What is the Optimal Dipole Moment for Nonpolarizable Models of Liquids? J Chem Theory Comput 2023; 19:1790-1804. [PMID: 36827585 PMCID: PMC10061682 DOI: 10.1021/acs.jctc.2c01123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Indexed: 02/26/2023]
Abstract
In classical nonpolarizable models, electrostatic interactions are usually described by assigning fixed partial charges to interaction sites. Despite the multitude of methods and theories proposed over the years for partial charge assignment, a fundamental question remains─what is the correct degree of polarization that a fixed-charge model should possess to provide the best balance of interactions (including induction effects) and yield the best description of the potential energy surface of a liquid phase? We address this question by approaching it from two separate and independent viewpoints: the QUantum mechanical BEspoke (QUBE) approach, which assigns bespoke force field parameters for individual molecules from ab initio calculations with minimal empirical fitting, and the Polarization-Consistent Approach (PolCA) force field, based on empirical fitting of force field parameters with an emphasis on transferability by rigorously accounting for polarization effects in the parameterization process. We show that the two approaches yield consistent answers to the above question, namely, that the dipole moment of the model should be approximately halfway between those of the gas and the liquid phase. Crucially, however, the reference liquid-phase dipole needs to be estimated using methods that explicitly consider both mean-field and local contributions to polarization. In particular, continuum dielectric models are inadequate for this purpose because they cannot account for local effects and therefore significantly underestimate the degree of polarization of the molecule. These observations have profound consequences for the development, validation, and testing of nonpolarizable models.
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Affiliation(s)
- Miguel Jorge
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Maria Cecilia Barrera
- Strathclyde
Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral St, Glasgow G4 0RE, United Kingdom
| | - Andrew W. Milne
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Chris Ringrose
- School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne NE1 7RU, United Kingdom
| | - Daniel J. Cole
- School
of Natural and Environmental Sciences, Newcastle
University, Newcastle
upon Tyne NE1 7RU, United Kingdom
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Liu K, Qin H, Tian M, Zhang L, Mi J. Towards a comprehensive optimization of dielectric and viscoelastic performance of poly(ethylene-co-methyl acrylate) through chain sequence regulation. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.124657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zhang Z. A universal dielectric constant calculation method for copolymers. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2021.113528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Wang Y, Zhang Z, Zheng R, Zhang Y. Calculation method for the dielectric constant of thioglycolic acid grafted modified SBS dielectric elastomer. ARAB J CHEM 2021. [DOI: 10.1016/j.arabjc.2021.103361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Jorge M, Milne AW, Barrera MC, Gomes JR. New Force-Field for Organosilicon Molecules in the Liquid Phase. ACS PHYSICAL CHEMISTRY AU 2021; 1:54-69. [PMID: 34939073 PMCID: PMC8679648 DOI: 10.1021/acsphyschemau.1c00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Indexed: 11/29/2022]
Abstract
In this paper, we present a new molecular model that can accurately predict thermodynamic liquid state and phase-change properties for organosilicon molecules including several functional groups (alkylsilane, alkoxysilane, siloxane, and silanol). These molecules are of great importance in geological processes, biological systems, and material science, yet no force field currently exists that is widely applicable to organosilicates. The model is parametrized according to the recent Polarization-Consistent Approach (PolCA), which allows for polarization effects to be incorporated into a nonpolarizable model through post facto correction terms and is therefore consistent with previous parametrizations of the PolCA force field. Alkyl groups are described by the United-Atom approach, bond and angle parameters were taken from previous literature studies, dihedral parameters were fitted to new quantum chemical energy profiles, point charges were calculated from quantum chemical optimizations in a continuum solvent, and Lennard-Jones dispersion/repulsion parameters were fitted to match the density and enthalpy of vaporization of a small number of selected compounds. Extensive validation efforts were carried out, after careful collection and curation of experimental data for organosilicates. Overall, the model performed quite well for the density, enthalpy of vaporization, dielectric constant, and self-diffusion coefficient, but it slightly overestimated the magnitude of self-solvation free energies. The modular and transferable nature of the PolCA force field allows for further extensions to other types of silicon-containing compounds.
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Affiliation(s)
- Miguel Jorge
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom,
| | - Andrew W. Milne
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - Maria Cecilia Barrera
- Department
of Chemical and Process Engineering, University
of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom
| | - José R.
B. Gomes
- CICECO
− Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal
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