Structure And Osmotic Pressure Of Hydrogen Bonding Fluid On The Mesoscale

Hydrogen Bonding(HB)fluid,being a universal existence in nature,is widely utilized in the fields of physics,chemistry and biology.The structure of HB fluids,though the general behavior of short-ranged order and long-ranged disorder,has its own characteristics,especially on mesoscale.It is well known that osmotic pressure plays a vital role in the process of biological physiology.On the basis of this point of view,it is necessary to understand the aggregation structure and osmotic pressure of complex fluid on mesoscale.Based on the density functional theory(DFT)for classical fluids,fundamental measure theory(FMT)and its modified version,the local structure of colloid and hydrogen bonding(HB)fluid near the semipermeable membrane is studied,where the colloidal particles and HB fluid serve as solute and solvent,respectively.In the present study,the semipermeable membrane allows the passage of solvent molecules but not of solute particles,and therefore,it divides the system into solution and pure solvent or two solutions of different concentration.At first,the grand potential is expressed as a functional of density profile,and then the equilibrium density profile can be obtained by minimizing the grand potential functional.Thereafter,the osmotic pressure of the system is also calculated.Based on these results,the effects of bulk density,the size ratio of two species,HB strength,and functionality on the fluid structure and osmotic pressure are discussed under different conditions.The present dissertation can be divided into three parts,which is listed as follows:Chapter I: Introduction.An introduction to the research background and significance of HB fluid is given in the present dissertation,which includes the characteristics of restricted fluid,the essence and significance of osmotic pressure and HB fluid.Furthermore,the history of DFT for classical fluid is briefly reviewed and its general method for the construction of grand potential functional based on the fundamental measure theory and statistical mechanics is described.Chapter II: Study on structure and osmotic pressure of colloid and HB fluids near a semipermeable membrane.The theoretical model and calculation method are expounded in detail.Based on the DFT,the equilibrium density profiles of the fluids near the semipermeable membrane under various conditions are calculated,and thus the osmotic pressure of the system is calculated according to the equilibrium density distribution.In addition,the effects of hydrogen bonding,bulk density,molecular size ratio on the aggregation structure and osmotic pressure are discussed.Chapter III: The structure of colloid and HB fluids near a semipermeable vesical membrane.The equilibrium density profiles of the fluids near the semipermeable vesical membrane under various conditions are calculated in this chapter.Moreover,the effects of bulk density of two species,molecular size ratio,HB interaction,and the size of vesical membrane on the density profiles are also presented.Chapter IV: Summary.Some conclusions of the investigation of HB fluids on the mesoscale are outlined and the deficiencies for the present study are also pointed out.Furthermore,the potential application of the present research in biology is introduced.It is expected that the investigation of HB fluids on mesoscale could be paid much more attention in the field of biophysics.