When a system is driven, sheared, stretched, heated, or pressurized under varying thermodynamic gradients and kept away from equilibrium, ultra-microscopic rearrangements begin to occur, indicating continuous energy dissipation. Along these energy pathways, the microstructures of complex fluids undergo multiple stages of reforming and rearrangement. In complex fluids composed of identical compounds (chemically identical species), these interactions play a supportive role and reduce the overall entropy of the system. However, when non-identical compounds are used in the fluid mixture, they tend to increase the entropy. The extent of rearrangements dictates entropy generation: maximum rearrangements correspond to maximum entropy, while minimal rearrangements correspond to minimal entropy, primarily due to the chemical nature and compatibility of the compounds involved. At the initial stage of a reaction, entropy remains low because microscopic rearrangements occur slowly. At the advanced stage, rearrangements become rapid, producing higher entropy. As the reaction slows down and rearrangements cease, the entropy of the system approaches nearly zero. Overall, the study shows that “the complexities of fluid composition directly influence the entropy of the system.” A proper selection of chemically compatible fluid components reduces microscopic rearrangements, lowers energy requirements, and results in minimal entropy. In contrast, poorly selected fluid combinations increase disorder and energy demand. This work emphasizes that thermodynamic systems are influenced not only by physical thermodynamic variables but also by chemical thermodynamic variables, making the findings highly valuable for optimizing chemical reactions and improving mechanistic understanding.

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1. Kim EJ. Information geometry, fluctuations, non-equilibrium thermodynamics, and geodesics in complex systems. Entropy. 2021;23(11):1393.
2. Romatschke P. Relativistic viscous fluid dynamics and non-equilibrium entropy. Class Quantum Grav. 2009;27(2):025006.
3. Luzzi R, Vasconcellos ÁR, Ramos JG. Non-equilibrium statistical mechanics of complex systems: An overview. Riv Nuovo Cimento. 2007;30(3):95–157.
4. Müller I. Entropy in nonequilibrium. Entropy. 2003;5:79–105.
5. Mezzenga R. Equilibrium and non-equilibrium structures in complex food systems. Food Hydrocoll. 2007;21(5–6):674–82.
6. Bestehorn M. Non-Equilibrium Thermodynamics: Entropy, Heat and Mass Transfer. Berlin: Walter de Gruyter GmbH & Co KG; 2024.
7. De Groot SR, Mazur P. Non-equilibrium thermodynamics. Mineola (NY): Courier Corporation; 2013.
8. Kleidon A. Non-equilibrium thermodynamics, maximum entropy production and Earth-system evolution. Philos Trans A Math Phys Eng Sci. 2010;368(1910):181–96.
9. Chigullapalli S, Venkattraman A, Ivanov MS, Alexeenko AA. Entropy considerations in numerical simulations of non-equilibrium rarefied flows. J Comput Phys. 2010;229(6):2139–58.
10. Rastogi RP. Introduction to non-equilibrium physical chemistry. Amsterdam: Elsevier; 2007.
11. Gnesotto FS, Mura F, Gladrow J, Broedersz CP. Broken detailed balance and non-equilibrium dynamics in living systems: A review. Rep Prog Phys. 2018;81(6):066601.

When a system is driven, sheared, stretched, heated, or pressurized under varying thermodynamic gradients and kept away from equilibrium, ultra-microscopic rearrangements begin to occur, indicating continuous energy dissipation. Along these energy pathways, the microstructures of complex fluids undergo multiple stages of reforming and rearrangement. In complex fluids composed of identical compounds (chemically identical species), these interactions play a supportive role and reduce the overall entropy of the system. However, when non-identical compounds are used in the fluid mixture, they tend to increase the entropy. The extent of rearrangements dictates entropy generation: maximum rearrangements correspond to maximum entropy, while minimal rearrangements correspond to minimal entropy, primarily due to the chemical nature and compatibility of the compounds involved. At the initial stage of a reaction, entropy remains low because microscopic rearrangements occur slowly. At the advanced stage, rearrangements become rapid, producing higher entropy. As the reaction slows down and rearrangements cease, the entropy of the system approaches nearly zero. Overall, the study shows that “the complexities of fluid composition directly influence the entropy of the system.” A proper selection of chemically compatible fluid components reduces microscopic rearrangements, lowers energy requirements, and results in minimal entropy. In contrast, poorly selected fluid combinations increase disorder and energy demand. This work emphasizes that thermodynamic systems are influenced not only by physical thermodynamic variables but also by chemical thermodynamic variables, making the findings highly valuable for optimizing chemical reactions and improving mechanistic understanding.

🔒 This is a subscription article

Full text is available to subscribers and institutional members. Please choose an option below to access it.

1. Kim EJ. Information geometry, fluctuations, non-equilibrium thermodynamics, and geodesics in complex systems. Entropy. 2021;23(11):1393.
2. Romatschke P. Relativistic viscous fluid dynamics and non-equilibrium entropy. Class Quantum Grav. 2009;27(2):025006.
3. Luzzi R, Vasconcellos ÁR, Ramos JG. Non-equilibrium statistical mechanics of complex systems: An overview. Riv Nuovo Cimento. 2007;30(3):95–157.
4. Müller I. Entropy in nonequilibrium. Entropy. 2003;5:79–105.
5. Mezzenga R. Equilibrium and non-equilibrium structures in complex food systems. Food Hydrocoll. 2007;21(5–6):674–82.
6. Bestehorn M. Non-Equilibrium Thermodynamics: Entropy, Heat and Mass Transfer. Berlin: Walter de Gruyter GmbH & Co KG; 2024.
7. De Groot SR, Mazur P. Non-equilibrium thermodynamics. Mineola (NY): Courier Corporation; 2013.
8. Kleidon A. Non-equilibrium thermodynamics, maximum entropy production and Earth-system evolution. Philos Trans A Math Phys Eng Sci. 2010;368(1910):181–96.
9. Chigullapalli S, Venkattraman A, Ivanov MS, Alexeenko AA. Entropy considerations in numerical simulations of non-equilibrium rarefied flows. J Comput Phys. 2010;229(6):2139–58.
10. Rastogi RP. Introduction to non-equilibrium physical chemistry. Amsterdam: Elsevier; 2007.
11. Gnesotto FS, Mura F, Gladrow J, Broedersz CP. Broken detailed balance and non-equilibrium dynamics in living systems: A review. Rep Prog Phys. 2018;81(6):066601.