»ã±¨¹¦·ò£º2014-06-11 13:30
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»ã±¨ÄÚÈݼò½é£ºDendrimer-like star-branched polymers (DSP) have emerged since 1995 as a novel class of structurally well-defined hyperbranched polymers. The DSPs are highly ordered and regularly branched polymers and, therefore, differentiated from many already-synthesized hyperbranched polymers by their structural perfection. In order to aid the understanding of specific hyperbranched architectures of DSPs, a typical fifth-generation (5G) DSP composed of five layers and the same generation block copolymer with layers/generations superimposed (dotted lines) are shown below. As can be seen, these polymers are very similar in branched architecture to dendrimers, but composed of many polymer chains that are linked to each other between the junctions in all layers. Accordingly, DSPs are much higher in molecular weight and much larger in molecular size than dendrimers of the same generation and believed to be nano-scale globular macromolecules. These polymers have many characteristic structural features, such as specific topological hyperbranched architectures, hierarchical generation-based (or layered) structures, different branch densities between core and outermost layer, and many junctions and chain-end groups that are capable of carrying many functional groups and molecules. Dendrimer-like star-branched block polymers composed of different segments introduced at each generation have also been synthesized as the new type block polymers composed of hierarchical generation-based block structures. Their thermodynamically immiscible different segments may possibly be phase-separated at the molecular level, followed by self-organizing, to produce quite newly ordered periodic suprastructures and supramolecular assemblies that should be different from those formed by linear block polymers and even mixed arm star-branched polymers having chemically different arms. Thus, DSPs and their block polymers may become promising specialty functional polymers with many potential applications in the field of nanoscience, such as nano-size reactors carrying enzymes and catalysts arranged along the layers, multicompartment micelles carrying drugs and genetic materials, scaffolds for further branched polymer synthesis, and shape-persistent nanoscale electronic and optical devices. In this talk, the synthesis of precisely controlled DSPs by living anionic polymerization and some characterization results are introduced.