Cryo-TEM and SANS microstructural study of pluronic polymer solutions
Cryo-TEM and SANS microstructural study of pluronic polymer solutions
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DOI：
10.1021/ma00130a016
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发表时间：
1995-12-18
期刊：
影响因子：
5.5
通讯作者：
Talmon, Y
中科院分区：
文献类型：
--
作者：
Mortensen, K;Talmon, Y
低温透射电子显微镜 (cryo-TEM) 和小角中子散射 (SANS) 相结合，给出了 Pluronic F127（一种 (EO)(99)(PO)(65)(EO)(99) 三嵌段共聚物水溶液的完整微观结构表征。通过冷冻透射电镜观察到的玻璃化标本的图像提供了有关这些系统的构建模块（即球形胶束）的直接信息。这证实了通过 SANS 数据分析获得的结构模型，此外还提供了有关系统的定量信息。有时，在样品制备过程中，球形胶束被压得彼此更近，从而局部产生更高的浓度。直接对如此形成的立方相进行成像。这种溶致液晶相的存在通过最初浓度较高的溶液的SANS得到证实。当受到剪切时，多晶相转变为具有立方对称性的单域晶体。该系统还用于展示选择性电子束辐射分解在增强辐射敏感、固有低对比度系统中的对比度的潜力。
Cryogenic temperature transmission electron microscopy (cryo-TEM) and small-angle neutron scattering (SANS) were combined to give complete microstructural characterization of aqueous solutions of Pluronic F127, an (EO)(99)(PO)(65)(EO)(99) triblock copolymer. The images of vitrified specimens observed by cryo-TEM provided direct information about the building blocks of these systems, i.e., spheroidal micelles. This confirmed the structural model obtained from analysis of SANS data, which, in addition, provide quantitative information about the system. Occasionally spheroidal micelles were pressed closer to each other during specimen preparation, thus giving rise locally to higher concentration. The cubic phase that was thus formed was directly imaged. The existence of this lyotropic liquid crystalline phase was confirmed by SANS of an originally higher concentration solution. When exposed to shear, the polycrystalline phase transforms into a monodomain crystal with cubic symmetry. The system was also used to demonstrate the potential of selective electron beam radiolysis to enhance contrast in radiation-sensitive, inherently low-contrast systems.