scholarly journals Temperature-Induced Liquid Crystal Microdroplet Formation in a Partially Miscible Liquid Mixture

2019 ◽  
Author(s):  
Mehzabin Patel ◽  
Anand N. Pallipurath Radhakrishnan ◽  
Ludovic Bescher ◽  
Elwin Hunter-Sellars ◽  
Benjamin Schmidt-Hansberg ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Solution Temperature ◽  
Material System ◽  
Reversible Process ◽  
Critical Solution Temperature ◽  
Binary Liquid ◽  
Partially Miscible ◽  
Extraction Processes

The controlled formation of microdroplets through temperature variation is an intriguing concept for binary liquid mixtures with a critical solution temperature. Here, we investigate this phenomenon for a blend of methanol (MeOH) and a thermotropic liquid crystal (LC) 4-Cyano-4’-pentylbiphenyl (5CB). A near-room-temperatureinduced phase separation leads to nucleation, growth and coalescence of mesogen-rich droplets. The size and number of the droplets is tunable on the microscopic scale by variation of temperature quench depth and cooling rate. Further cooling induces a phase transition to nematic droplets with radial configuration, well-defined sizes and stability over the course of an hour. This fully reversible process is an interesting material system with relevance in diagnostics, optoelectronics, materials templating and extraction processes.<br>

scholarly journals Temperature-Induced Liquid Crystal Microdroplet Formation in a Partially Miscible Liquid Mixture

2019 ◽  
Author(s):  
Mehzabin Patel ◽  
Anand N. Pallipurath Radhakrishnan ◽  
Ludovic Bescher ◽  
Elwin Hunter-Sellars ◽  
Benjamin Schmidt-Hansberg ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Solution Temperature ◽  
Material System ◽  
Reversible Process ◽  
Critical Solution Temperature ◽  
Binary Liquid ◽  
Partially Miscible ◽  
Extraction Processes

The controlled formation of microdroplets through temperature variation is an intriguing concept for binary liquid mixtures with a critical solution temperature. Here, we investigate this phenomenon for a blend of methanol (MeOH) and a thermotropic liquid crystal (LC) 4-Cyano-4’-pentylbiphenyl (5CB). A near-room-temperatureinduced phase separation leads to nucleation, growth and coalescence of mesogen-rich droplets. The size and number of the droplets is tunable on the microscopic scale by variation of temperature quench depth and cooling rate. Further cooling induces a phase transition to nematic droplets with radial configuration, well-defined sizes and stability over the course of an hour. This fully reversible process is an interesting material system with relevance in diagnostics, optoelectronics, materials templating and extraction processes.<br>

scholarly journals Microfluidics of Temperature-Responsive Partially Miscible Binary Liquid Mixtures

2018 ◽  
Author(s):  
Maximiliano J. Fornerod ◽  
Esther Amstad ◽  
Stefan Guldin
Keyword(s):  
Phase Separation ◽  
Flow Regimes ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Solution Temperature ◽  
Microfluidic Channels ◽  
Critical Solution Temperature ◽  
Binary Liquid ◽  
Temperature Responsive ◽  
Partially Miscible

Two-phase liquid-liquid microfluidics relies on the intricate control over the fluid properties of liquid mixtures. Herein, we report on the use of partially miscible binary liquid mixtures that lend their microfluidic properties from a highly temperature-sensitive mixing and phase separation behaviour. For a blend composed of the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB) and methanol, mixing at temperatures above the upper critical solution temperature (UCST) leads to a uniform single phase while partial mixing can be achieved at temperatures below the UCST. Thermally-driven phase separation inside the microfluidic channels results in the formation of very regular phase arrangements, namely in droplets, plug, slug and annular flow. We map different flow regimes and relate findings to the role of viscous, interfacial and inertial forces. As the interfacial tension of the mixture and the dynamic viscosity of the separated phases are inversely proportional to temperature, different flow regimes can be achieved at constant channel architecture and flow rate. A consistent behaviour is observed for a binary liquid mixture with lower critical solution temperature, namely 2,6-lutidine and water. This temperature-responsive approach to microfluidics is an interesting candidate for multi-stage processes, selective extraction and sensing applications.

scholarly journals Microfluidics of Binary Liquid Mixtures with Temperature-Dependent Miscibility

2019 ◽  
Author(s):  
Maximiliano J. Fornerod ◽  
Esther Amstad ◽  
Stefan Guldin
Keyword(s):  
Phase Separation ◽  
Flow Regimes ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Solution Temperature ◽  
Microfluidic Channels ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Binary Liquid ◽  
Sensing Applications

Liquid-liquid microfluidic systems rely on the intricate control over the fluid properties of either miscible or immiscible mixtures. Herein, we report on the use of partially miscible binary liquid mixtures that lend their microfluidic properties from a highly temperature-sensitive mixing and phase separation behaviour. For a blend composed of the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB) and methanol, mixing at temperatures above the upper critical solution temperature (UCST; 24.4°C) leads to a uniform single phase while partial mixing can be achieved at temperatures below the UCST. Thermally-driven phase separation inside the microfluidic channels results in the spontaneous formation of very regular phase arrangements, namely in droplets, plug, slug and annular flow. We map different flow regimes and relate findings to the role of interfacial tension and viscosity and their temperature dependence. Importantly, different flow regimes can be achieved at constant channel architecture and flow rate by varying the temperature of the blend. A consistent behaviour is observed for a binary liquid mixture with lower critical solution temperature, namely 2,6-lutidine and water. This temperature-responsive approach to microfluidics is an interesting candidate for multi-stage processes, selective extraction and sensing applications.

scholarly journals Microfluidics of Binary Liquid Mixtures with Temperature-Dependent Miscibility

2019 ◽  
Author(s):  
Maximiliano J. Fornerod ◽  
Esther Amstad ◽  
Stefan Guldin
Keyword(s):  
Phase Separation ◽  
Flow Regimes ◽  
Liquid Mixtures ◽  
Binary Liquid Mixtures ◽  
Solution Temperature ◽  
Microfluidic Channels ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Binary Liquid ◽  
Sensing Applications

Liquid-liquid microfluidic systems rely on the intricate control over the fluid properties of either miscible or immiscible mixtures. Herein, we report on the use of partially miscible binary liquid mixtures that lend their microfluidic properties from a highly temperature-sensitive mixing and phase separation behaviour. For a blend composed of the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB) and methanol, mixing at temperatures above the upper critical solution temperature (UCST; 24.4°C) leads to a uniform single phase while partial mixing can be achieved at temperatures below the UCST. Thermally-driven phase separation inside the microfluidic channels results in the spontaneous formation of very regular phase arrangements, namely in droplets, plug, slug and annular flow. We map different flow regimes and relate findings to the role of interfacial tension and viscosity and their temperature dependence. Importantly, different flow regimes can be achieved at constant channel architecture and flow rate by varying the temperature of the blend. A consistent behaviour is observed for a binary liquid mixture with lower critical solution temperature, namely 2,6-lutidine and water. This temperature-responsive approach to microfluidics is an interesting candidate for multi-stage processes, selective extraction and sensing applications.

Phase behaviour and applications of a binary liquid-liquid mixture of methanol and a thermotropic liquid crystal

2017 ◽  
Author(s):  
Luis A Serrano ◽  
Maximiliano J Fornerod ◽  
Ye Yang ◽  
Simon Gaisford ◽  
Francesco Stellacci ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Mixture ◽  
Phase Behaviour ◽  
Solution Temperature ◽  
Eosin Y ◽  
Phase Mixing ◽  
Binary Liquid ◽  
Thermotropic Liquid Crystal ◽  
Upper Critical Solution Temperature ◽  
Sudan Iv

Herein, we report on the phase behaviour of a binary liquid-liquid mixture composed of methanol (MeOH) and the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB). The corresponding phase diagram combines features of a conventional liquid-liquid mixture with characteristics that are particular to the nematic liquid crystal. We observe four arrangements as a function of composition and temperature, namely monophasic isotropic, monophasic nematic, biphasic isotropic-isotropic and biphasic isotropic-nematic, with an upper critical solution temperature of 298 K. The interplay of nematogenic and non-nematogenic species offers a number of applications. Dilution of mesogens with MeOH allows to control the isotropic-to-nematic phase transition of 5CB over a range of 35 K. The tunability of phase mixing and phase composition in an accessible temperature window provides novel routes for the extraction of target compounds, here shown for Eosin Y, Doxorubicin, Crystal Violet and Sudan IV.

Phase behaviour and applications of a binary liquid-liquid mixture of methanol and a thermotropic liquid crystal

2017 ◽  
Author(s):  
Luis A Serrano ◽  
Maximiliano J Fornerod ◽  
Ye Yang ◽  
Simon Gaisford ◽  
Francesco Stellacci ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Mixture ◽  
Phase Behaviour ◽  
Solution Temperature ◽  
Eosin Y ◽  
Phase Mixing ◽  
Binary Liquid ◽  
Thermotropic Liquid Crystal ◽  
Upper Critical Solution Temperature ◽  
Sudan Iv

Herein, we report on the phase behaviour of a binary liquid-liquid mixture composed of methanol (MeOH) and the thermotropic liquid crystal 4-Cyano-4'-pentylbiphenyl (5CB). The corresponding phase diagram combines features of a conventional liquid-liquid mixture with characteristics that are particular to the nematic liquid crystal. We observe four arrangements as a function of composition and temperature, namely monophasic isotropic, monophasic nematic, biphasic isotropic-isotropic and biphasic isotropic-nematic, with an upper critical solution temperature of 298 K. The interplay of nematogenic and non-nematogenic species offers a number of applications. Dilution of mesogens with MeOH allows to control the isotropic-to-nematic phase transition of 5CB over a range of 35 K. The tunability of phase mixing and phase composition in an accessible temperature window provides novel routes for the extraction of target compounds, here shown for Eosin Y, Doxorubicin, Crystal Violet and Sudan IV.

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