Computer Simulation Of Block Polymer Microphase Separation In Preparation Of Nanomaterials

Microphase separation is a phenomenon of block polymer.Microphase separation can lead block polymers to regular structures.These structures are in nanoscale and can be widely used in the fields of microporous membrane,nanomaterial synthesis,drug delivery,etc.In this work,the mechanism and application of microphase separation for preparation of nanomaterials were studied by Dissipative particle dynamics(DPD)simulations.In this paper,SiO₂ nanowires were synthesized by Pluronic microphase separation in water. However,the mechanism of the process of synthesis is still not clearly.First,the microphase separation process of Pluronic in water was simulated by DPD.It was found that the lyotropic liquid crystal structure with cylindrical channels could be formed when the volume fraction of F127 was between 61%-67%.The larger the volume fraction of F127,the smaller the diameter of the channels.When volume fraction of Pluronic is the same,different PEO:PPO and polymerization degrees of polymers were simulated.The PEO:PPO mainly affect the deformation of channel,and the deformation degree is the least when PEO:PPO=20:70.Subsequently,the synthesis process of SiO₂ nanowires was simulated by F127 and TEOS ethanol solution.It was found that the larger the volume fraction of TEOS ethanol solution,the larger the diameter of the nanowires was,but the diameter of the nanowires was always smaller than the template.The larger the diameter of the template is,the larger the diameter of the nanowires will be.SPPO can be used as CPC.SPPO can form water channel by microphase separation in DPD simulation.When the water content increased from 0.1 to 0.25,the diameter of the water chamber increased from 20.5?to 42.7?.The average diameter of water channels also increased significantly with the increase of water content,and the diameter increased from6.5?to 26.4?.When the grafting number of sulfonic acid group is 32,it is most suitable for the preparation of chemical protective clothing.The grafting number of sulfonic acid groups has slightly influence on the porosity,and the porosity of SPPO film is always about 11%.The pH and shearing force have obvious influence on the synthesis of mesoporous silicon SBA-15.It is found that under different volume fraction of P123,spherical micelles with core-shell structure,layered porous structure,cubic framework structure,layered structure,columnar lamellar structure and cylindrical pore structure can be formed.The 20%P123 is the reasonable concentration for the synthesis of SBA-15.The 3D structure cannot be formed in the presence of shear force,and the second critical micelle concentration of P123 decreases.The pH affects the collaborative self-assembly process by influencing the charge of PEO block and TEOS.It is found that the charge of PEO block is-0.3e,and the simulation results are most consistent with the experiment results when TEOS is neutral.That is,the optimal solution pH for the preparation of SBA-15 is at the isoelectric point of silicic acid when the solution pH is 2.