The Research Of PS-b-PEO-b-PS/H-PEO Wet And Dry Brush Blending Systems

The micro-phase structure of polymer have been researched widely while the application of polymer become inceasingly in engineering. The relationship of which between the phase structure and the crystallization behaviors of polymer is very important to the mechanical properties of polymer, especially the study of crystalline polymer and widely used in industry make the researchers realized that the importance of the research for the relationship. Due to the complementarity of the mechanical properties of block copolymers consist of crystalline and amorphous blocks, the crystallization behavior and the micro-phase structure of the blends consist of the amorphous blocks and crystalline blocks or homopolymer and block copolymer have been revealed broadly. In this paper, the structure and crystallization behavior of blends consist of polystyrene-b-poly (ethylene oxide)-b-polystyrene and homopolymer PEO (PS-b-PEO-b-PS/h-PEO) has been studied.The "dry-brush" and "wet brush" blending systems could be prepared by blend the homopolymer and block copolymer which have the different molecular, the macromolecular chain of h-PEO can interpenetrate among b-PEO chain homogenously when the molecular weight of homopolymer h-PEO is lower, this system is named "wet brush" system. While on the other hand, the h-PEO with the higher molecular weight, its molecular chain cannot be dispersed by the polymer chain of b-PEO, this is "dry brush" system.Different crystallization behavior for the blending systems has been investigated by DSC measurements. It is shown that the crystallization of the polystyrene-b-poly (ethylene oxide)-b-polystyrene only occurs at-13℃in the bulk, which is attributed to the homogeneous nucleation crystallization behavior. The size of block microdomain increases with addition of PEO homopolymer, and subsequently the crystallization temperature changes. Additionally, the self-seeding domains of heterogeneous nucleation crystallization have been confirmed by self-seeding nucleation method in blending system, and the difference between the "dry brush" and "wet brush" systems has been observed.In this work, crystallization behavior of PEO under different situations were investigated in the blending systems of two block length PS-b-PEO-b-PS with addition of different molecular weights of h-PEO. Crystallization and melting behavior were studied by DSC and it has been discovered that the state of blending system can be confirmed by the data of the thermoanalysis. Using the small Angle X-ray scattering (SAXS) technology confirm the wet and dry brush phase separation condition.