Synthesis and physical characterization of arborescent (dendrigraft) polymers

我们的研究重点是枝状结构的接枝聚合物的合成和物理表征，即树突聚合物（AP）。这些大分子具有2- 100nm的均匀尺寸，非常高的分子量（1E4-1E8）和分支功能（f=10-10000+），以及可控的化学成分。从基本的角度来看，对这些材料结构的广泛控制对于建立支链聚合物的结构-性能相关性以及它们在纳米技术相关应用中的应用是非常有益的。在当前的提案中，已经确定了五个不同的活性领域：1)将研究具有聚电解质侧链的AP的溶液性质，特别关注在中至低极性溶剂中形成凝胶，因为这些材料可能用于ph敏感的智能凝胶。2)将研究两亲性AP在空气-水界面或溶液中自组装的能力，以产生上层结构（例如棒状和大型复合胶束组件），并在压力计尺度上形成表面图形。这些共聚物也将被研究在水环境中对疏水化合物的增溶和释放，作为控制疏水药物递送的模型系统。3)将利用氨基酸合成具有增强生物相容性的新型AP，并研究其增溶性。4)结合弹性体链段的AP的流变特性将被检查，以提高分枝对聚合物可加工性的影响的理解。5)一种新的“点击”化学接枝技术将被开发出来，以实现高收率合成具有长侧链的AP，这是迄今为止难以实现的。从提出的工作中获得的基本知识将有助于澄清分支对不同物理性质的影响，在更广泛的分支功能范围内，比迄今为止使用其他模型系统（如星形支化聚合物）所实现的。

Our research efforts focus on the synthesis and the physical characterization of graft polymers with a dendritic architecture, the arborescent polymers (AP). These macromolecules have a uniform size ranging from 2-100 nm, very high molecular weights (1E4-1E8) and branching functionalities (f=10-10000+), and a controllable chemical composition. The extensive control achieved over the structure of these materials is highly beneficial, from a fundamental viewpoint, for the establishment of structure-property correlations in branched polymers, and for their utilization in nanotechnology-related applications. Five distinct activity areas have been identified in the current proposal: 1) The solution properties of AP with polyelectrolyte side chains will be examined, focusing particularly on the formation of gels in intermediate- to low-polarity solvents, as these materials may be useful as pH-sensitive smart gels. 2) Amphiphilic AP will be studied with respect to their ability to self-assemble, either at the air-water interface or in solution, to yield superstructures (e.g. rod-like and large compound micelle assemblies) and to pattern surfaces on the manometer scale. These copolymers will also be investigated for the solubilization and release of hydrophobic compounds in aqueous environments, to serve as model systems for the controlled delivery of hydrophobic drugs. 3) New AP with enhanced biocompatibility, potentially useful as practical drug delivery devices, will be synthesized from amino acids and investigated for their solubilization properties. 4) The rheological properties of AP incorporating elastomeric chain segments will be examined to improve the understanding of the influence of branching on polymer processability. 5) A new grafting technique using "click" chemistry will be developed to allow the high yield synthesis of AP with long side chains, which have been elusive so far. The fundamental knowledge gained from the proposed work will help clarify the influence of branching on different physical properties, over a much wider range of branching functionalities than has been achieved so far using other model systems such as the star-branched polymers.