| Summary: | 碩士 === 國立清華大學 === 化學工程學系 === 101 === In this thesis, the impact of the volume fraction and affinity of nanoparticles that are in diblock copolymer composites, on the morphology transition and viscosity of diblock copolymers is investigated via the experiments done by dissipative particle dynamics simulation. The morphology and viscosity of A-affinity system and non-affinity system are analyzed under various condition combinations of the nanoparticle volume fraction and shear rate of those simulation systems.
1. For the morphology
The A-affinity system shows more structure types than the non-affinity on copolymer morphology. Because with the appearance of A-affinity nanoparticle, the effect of A domain can increase to activate the order-order transition of the diblock copolymer morphology, While non-affinity nanoparticle cannot activate the order-order transition. Nevertheless, the particles of non-affinity nanoparticle will congregate in copolymer lamellar to reduce interfacial tension of copolymer lamellar to stimulate the phenomenon of shear thinning. Besides, when the non-affinity particle concentration increases to 40%, a single-lamellar structure is formed by the particles to cut off the copolymer lamellar.
2. For the viscosity
A-affinity system is formed as hexagonal cylinder structure when the concentration is larger than 30%. The viscosity is stable and not changed as shear flow varying. Therefore, the occurrence of shear thinning can be controlled by varying the concentration of particles. On the other hand, in non-affinity system, the phenomenon of shear thinning can occur earlier due to decreased interfacial tension of copolymer. Because of decreased interfacial tension of copolymer, the viscosity is lower than in A-affinity system. The lowest viscosity is observed in this study when the nanoparticles are formed as a single-lamellar structure.
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