The Invesigation Of Phase-separating Of The Complex Polymer Fluids Polymer Confined Systen Under Shear Flows

With the expanding and indepth of the study of the soft materialsself-assembly, the investigation of phase-separating of the polymersystem under symmetry-breaking fields as an independent field ofstudy has become a hot topic in the field of polymer science. Theimposed symmetry-breaking fields such as steady shear andoscillatory shear have important influence on the self-assemblyprocess, and it can provide some reference on the experiment thatcontrol the formation of ordered structure and the microphasetransition. In this thesis, by using the Cell Dynamical System (CDS),we study the self-assembly behavior of the complex polymer fluidsand polymer cylindrical nanopore confined system under steady andoscillatory shear fields, respectively.Firstly, by using the TDGL and CDS methods, we study the phasebehaviour and rheological properties of copolymer-homopolymermixtures under steady shear field. It turned out that the shear-induced reorientations and phase transitions from the transverse toparallel and then to perpendicular lamellar structures with theincreasing of shear rates. And the low shear rates are beneficial toform parallel lamellar structure; the lamellar phase preferentiallyadopts the perpendicular orientation at the high shear rate. Inaddition, we analyze qualitatively the domain size and the rheological properties, and explore the dynamic mechanics offorming parallel and perpendicular lamellar structure under weakand strong shear, respectively. It provides a simple method thatcontrol self-assembly of soft matter experimentally.Secondly, we explored the behavior of phase separation of diblockcopolymer confined by cylindrical nanopore under oscillatory shearflows. It observed that the final domain morphology have no changealong with the increasing of the shear rates when the amplitude issmaller, while in larger amplitude, increasing the shear rates, phasetransitions from the single helical structure to the parallel lamellarstructure, and then turn to the single helical structure. Our resultshave a certain guiding significance that realize orientational ordertransition of soft materials by applying the symmetry-breakingfields.Through the above research, we know that the complex polymerfluid and polymers confined system under the shear flow will beformed a variety of ordered structure. Our model is easy, simple,and operable to apply the shear fields, so it provides a usefulreference for achieving the ordered structure of soft mattersystems in experiment, even in the industrial applications.