Cylindrical and Spherical Supermolecules from Polymer Backbones Jacketed with Dendritic Coats

9708581 Percec这项研究将设计具有定义良好的扁锥形和圆锥形的单树枝状积木的库，这些积木可以自组装成圆柱形和球状。这些超分子将产生柱状、六方和球形的热致和溶致液晶(LC)相。这些LC相将保证其组装的热力学控制，并将允许通过X射线衍射法确定其形状。用可聚合基团功能化的扁锥形和圆锥形单树枝状构建块的文库将通过活的方法聚合，以产生直径和长度分别在纳米级控制的圆柱形和球形的巨型聚合物的第一个例子。这些巨大的树枝状单体在LC组装中的组织也将被用来在聚合过程中人为地提高浓度和限制几何形状的反应器中聚集它们的可聚合基团，因此，将产生一种新的聚合控制方法。这项研究将为聚合物材料的设计提供一个入口，这些材料具有可预测的和截然不同的性能，这些性能由其形状决定。从包裹着树枝状涂层的柔性主链获得的圆柱形和球形巨型聚合物将获得新的机制来控制其柔性链的构象和刚性，而不考虑它们的战术性。阐述了聚合物形状由棒状向球形可逆、可控转变的机理。预计这些圆柱形三维聚合物将产生比目前已知的一维线性刚性杆更多的刚性结构。这项研究将把自然界的概念移植到复杂的合成聚合物材料领域。自然系统为能量和信息的储存和转移以及结构材料的生产提供了最有效的机制。该计划开发的聚合物系统将提供新的技术概念，首次允许开发具有外部调节物理特性的新材料，如功能纤维、薄膜、膜、粘度控制器、电子、光子和控制释放系统，其原理由自然在漫长的进化过程中阐述。***

9708581 Percec This research will design libraries of monodendritic building blocks with well defined flat tapered and conical shapes which self-assemble into cylindrical and respectively spherical shapes. These supermolecules will generate columnar hexagonal and spherical thermotropic and lyotropic liquid crystalline (LC) phases. These LC phases will warrant a thermodynamic control of their assembly and will allow the determination of their shape by X-ray diffraction. Libraries of flat tapered and conical monodendritic building blocks functionalized with polymerizable groups will be polymerized via living methods to generate the first examples of giant polymers with cylindrical and spherical shapes with diameter and length and respectively diameter controlled at the nanoscale level. The organization of these giant dendritic monomers in a LC assembly will also be used to aggregate their polymerizable groups in a reactor of artificially enhanced concentration and restricted geometry during the polymerization process and therefore, will generate a new approach to the control of polymerization. This research will provide an entry into the design of polymeric materials with predictable and dramatically different properties which are determined by their shape. Cylindrical and spherical giant polymers obtained from flexible backbones jacketed with dendritic coats will access new mechanisms to control the conformation and rigidity of their flexible chain regardless of their tacticity. Mechanisms to change in a reversible and controlled way the shape of the polymer from rod-like to spherical will be elaborated. It is expected that these cylindrical 3-D polymers will produce more rigid structures than the currently known 1-D linear rigid-rods. %%% This research will transplant concepts from Nature into the field of complex synthetic polymeric materials. Natural systems provide the most efficient mechanisms for the storage and transfer of energy and information and for the production of structural materials. The polymeric systems developed by this program will provide new technologic concepts which will allow for the first time the development of new materials such as functional fibers, films, membranes, viscosity controllers, electronic, photonic and controlled release systems with externally regulated physical properties via principles elaborated by Nature during the long process of evolution. ***