Synthesis and characterization of arborescent (dendrigraft) polymers

树状（树枝状）聚合物的合成和表征

• 批准号: RGPIN-2020-05057
• 负责人: Gauthier, Mario
• 金额: $ 2.62万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739859
• 关键词: Synthesis; characterization; arborescent; dendrigraft; polymers

Dendritic molecules have multiple branching levels, similarly to a tree. Dendrimers and hyperbranched polymers are derived from ABn-type monomers (where functional group A can only react with group B; n = 2 or 3). The perfect structure of dendrimers results from laborious syntheses, while less controlled conditions lead to the imperfect structure of hyperbranched systems. Arborescent polymers (AP), of interest in this proposal, are obtained through successive grafting reactions of linear polymer segments. They grow much faster than dendrimers but display many of their properties, so they can replace them in multiple nanotechnology applications. This proposal focuses on the synthesis and the physical characterization of APs. We recently developed a "click" grafting scheme for the synthesis of APs. The scope of this methodology can be expanded considerably if combined with atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer (RAFT) polymerization to generate polymeric building blocks, and provide AP compositions hitherto inaccessible. Beyond the short-term goal of developing efficient techniques for AP synthesis, structure-property relations will be established for these novel materials that will improve the understanding of branched polymers in general, many of which are of commercial importance. More complex AP structures, with core-shell (CS) or core-shell-corona (CSC) architectures, are obtained by using polymers with different compositions in successive grafting reactions. CS AP micelles potentially useful as drug delivery systems (DDS) were thus obtained using hydrophobic polypeptide chains for the core of the molecules, and hydrophilic chains for the shell. Over the next five years, this research will focus on designing these molecules to control their drug loading capacity and release kinetics, but also their ability to cross cell membranes. The long term goal of this research is the development of efficient DDS targeting tumor sites in cancer therapy. We also investigated CSC APs containing metal-binding polymer segments within their inner shell as templates for the preparation of metallic nanoparticles, and observed intriguing nanomorphologies upon loading with metallic ions. This nm-scale phase separation should have important consequences on the physicochemical properties of CSC polymers, but the synthesis of these materials is marred by very low yields. We just developed a new synthetic approach based upon the self-assembly (SA) of a CS AP with a block copolymer where one of the blocks can bind with the AP substrate. SA is very promising, but reversible in some cases. Our short term goal is to develop a better understanding of the SA thermodynamics, and strategies to stabilize the CSC structures obtained. On a longer timescale, this will allow their synthesis in amounts sufficient to enable detailed properties studies, with applications in nanotechnology and catalysis.

树枝状分子具有多个分支水平，类似于树。树枝状聚合物和超支化聚合物衍生自ABn型单体（其中官能团A只能与基团B反应; n = 2或3）。树枝状聚合物的完美结构来自于费力的合成，而较少控制的条件导致超支化体系的不完美结构。在该提议中感兴趣的树状聚合物（AP）通过线性聚合物链段的连续接枝反应获得。它们的生长速度比树枝状聚合物快得多，但显示出它们的许多特性，因此它们可以在多种纳米技术应用中取代它们。本提案的重点是对适应性方案进行综合并确定其物理特性。我们最近开发了一种用于合成AP的“点击”接枝方案。如果与原子转移自由基聚合（ATRP）或可逆加成-断裂链转移（RAFT）聚合结合以产生聚合物结构单元，并提供迄今为止无法获得的AP组合物，则该方法的范围可以大大扩展。除了开发AP合成的有效技术的短期目标之外，还将为这些新材料建立结构-性能关系，这将提高对一般支链聚合物的理解，其中许多具有商业重要性。通过在连续接枝反应中使用具有不同组成的聚合物，获得具有核-壳（CS）或核-壳-冠（CSC）结构的更复杂的AP结构。因此，使用疏水性多肽链作为分子核心，亲水性链作为外壳，获得了可能用作药物递送系统（DDS）的CS AP胶束。在接下来的五年里，这项研究将集中在设计这些分子，以控制它们的载药能力和释放动力学，以及它们穿过细胞膜的能力。本研究的长期目标是开发在癌症治疗中靶向肿瘤部位的有效DDS。我们还研究了CSC AP包含金属结合聚合物片段在其内壳作为模板制备金属纳米粒子，并观察到有趣的纳米形态加载金属离子后。这种纳米级的相分离应该对CSC聚合物的物理化学性质具有重要的影响，但是这些材料的合成受到非常低的产率的损害。我们刚刚开发了一种新的合成方法，基于CS AP与嵌段共聚物的自组装（SA），其中一个嵌段可以与AP底物结合。SA非常有前途，但在某些情况下是可逆的。我们的短期目标是发展一个更好的理解SA热力学，和策略，以稳定CSC结构获得。在更长的时间尺度上，这将使它们的合成量足以进行详细的性能研究，并应用于纳米技术和催化。