이중계면활성 효과를 가진 블록 공중합체 블렌드의 상 거동에 관한 연구

Abstract

Block copolymers have been investigated to understand the self-assembled property and to use them in nanotechnology. The property is controllable by blending a homopolymer or a block copolymer with a block copolymer. The location of the introduced homopolymers or block copolymers is important to the self-assembled property. In this research, the phase behaviors of blends were investigated according to the blend type, blend composition and/or temperature. In chapter 3 and 4 of this thesis, the binary blends of block copolymers were studied. In chapter 5, the blends composed of a block copolymer and a homopolymer, which can form hydrogen bonding, were used.Chapter 1 details the fundamentals and literature surveys of block copolymers and blends such as segregation regime, factors affecting on the phase behaviors. Moreover, the ways to induce the perpendicular orientation in thin film, which is essential to the block copolymer lithography, were enumerated.The used experimental methods, small angle x-ray scattering and atomic force microscopy, were explained in chapter 2.In chapter 3, The phase behaviors of binary blends of poly(styrene-b-butadiene) block copolymers were investigated by a small-angle X-ray scattering technique. The blends were composed of weakly segregated one in a random micellar phase and the other in a cylindrical phase with similar molecular weights and complementary volume fractions. Morphologies, domain spacings and order-disorder transition temperatures of the blends indicated that the junctions of the constituent block copolymers share the interface at low temperatures. The domain spacing decreased as temperature increased in a blend with a small amount of the weakly segregated block copolymer. In the cases of the blends with a large amount of the weakly segregated constituent, domain spacing increased with increasing temperature. These results implied that some of the weakly segregated block copolymer moved from the interface to one microdomain at higher temperatures.In chapter 4, Thin binary blends of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymers films that is controllable the lamellar thickness of one domain while preserving the thicknesses of the other domain were demonstrated with perpendicular orientation. One of the block copolymers used here was short and symmetric, and the other was long and asymmetric with a condition that the molecular weights of the PMMA block chains in the constituents were similar. Random copolymer brush was introduced and film thickness and composition of brush were adjusted to induce the perpendicular orientation in thin film. As the blend composition of a long asymmetric block copolymer increased, the PS lamellar thickness increased from 15.8 nm to 25.1 nm whereas the PMMA lamellar thickness remained constant, approximately 14 nm (the thickness decreased slightly from 14.0 nm to 13.3 nm). The domain spacing behavior in thin film was consistent in bulk. These results were compared with the Birshtein, Zhulina, and Lyatskaya (BZL) model and the theories for pure block copolymers in the strong segregation limit and in the intermediate segregation regime.The domain spacing behavior of blends composed of a block copolymer and a homopolymer that can form hydrogen bonding was discussed in chapter 5. The domain spacing of the blend was smaller than the domain spacing of a blend that cannot form hydrogen bonding. The hydrogen bonded fraction of the homopolymer was calculated by using a BZL equation and an equation for wet brush typed homopolymers. The hydrogen bonded fraction decreased as the blend composition of the homopolymer increased.