Synthesis and physical characterization of arborescent (dendrigraft) polymers

我们的研究工作集中在树枝状结构的接枝聚合物的合成和物理表征，树枝状聚合物（AP）。这些大分子具有2-100 nm的均匀尺寸、非常高的分子量（1 E4 - 1 E8）和支化官能度（f=10-10000+）以及可控的化学组成。从基本观点来看，对这些材料的结构实现的广泛控制对于在支化聚合物中建立结构-性质相关性以及它们在纳米技术相关应用中的利用是非常有益的。在当前的提案中已经确定了五个不同的活动领域：1）将检查具有双链侧链的AP的溶液性质，特别关注在中等至低极性溶剂中形成凝胶，因为这些材料可能用作pH敏感的智能凝胶。2)两亲性AP将研究其自组装的能力，无论是在空气-水界面或在溶液中，以产生超结构（如棒状和大的化合物胶束组件）和图案表面上的压力计规模。这些共聚物也将被调查的增溶和释放的疏水化合物在水性环境中，作为模型系统的疏水药物的控制输送。3)具有增强的生物相容性的新AP，可能用作实际的药物递送装置，将从氨基酸合成并研究其增溶特性。4)AP纳入弹性体链段的流变性能将被检查，以提高对聚合物加工性的支化的影响的理解。5)一种新的接枝技术，使用“点击”化学将被开发，以允许高产率合成AP与长侧链，这一直是难以捉摸的。从所提出的工作中获得的基础知识将有助于澄清支化对不同物理性质的影响，在更广泛的支化功能范围内，比迄今为止使用其他模型系统（如星形支化聚合物）所实现的功能范围更广。

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.