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90plus 納米粒度儀應用案例-19
點擊次數：304 發布時間：2014-12-8
90plus 納米粒度儀應用案例
文獻名：Spontaneous Generation of Multilamellar Vesicles from Ethylene Oxide/Butylene Oxide Diblock Copolymers
作者：J. Keith Harris, Gene D. Rose, and Merlin L. Bruening
Chemistry Department, Michigan State University, East Lansing, Michigan 48824, and The Dow Chemical Company, Corporate Research and Development, Midland, Michigan 48674
摘要：Vesicular structures are promising materials for encapsulation applications, and vesicles composed from block copolymers are attractive in this regard because of their stability and tunability. However, vesicle formation from copolymers generally requires specialized procedures. This article demonstrates that ethylene oxide/butylene oxide diblock copolymers spontaneously form micrometer-sized, multilamellar vesicles (“onions”) over a broad range of concentrations upon simple mixing with water. These structures likely form due to the relatively large volume-to-length ratio of the butylene oxide hydrophobe, and vesicle formation also depends on the length of the ethylene oxide headgroup. Structures were characterized using plane-polarized light microscopy, dynamic light scattering, and cryogenic scanning electron microscopy. The multilamellar vesicles survive sonication and moderate shear. Vesicle size can be reduced by extrusion through a porous membrane, but final diameter is independent of shear rate and membrane pore size.