Synthesis and physical characterization of arborescent (dendrigraft) polymers

树状聚合物的合成和物理表征

• 批准号: RGPIN-2014-03887
• 负责人: Gauthier, Mario
• 金额: $ 3.13万
• 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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688718
• 关键词: Synthesis; physical; characterization; arborescent; dendrigraft

Dendritic molecules are characterized by an architecture with multiple branching levels, similar to a tree. These can be subdivided into three distinct families. Dendrimers and hyperbranched polymers are both derived from ABn-type monomers (where functional group A can only react with group B; n = 2 or 3). The perfect structure and uniform size of dendrimers results from strictly controlled cycles of monomer protection, condensation, and deprotection reactions, but an imperfectly branched structure and a broad size distribution often arise when the condensation reaction is carried out without protecting groups. The arborescent (or dendrigraft) polymers, of interest in this proposal, are obtained through successive grafting reactions of linear polymer segments. The growth of these molecules is much faster than for dendrimers over successive generations (reaction cycles), but they display many of their characteristics; they are therefore an interesting alternative to dendrimers for many nanotechnology applications.*This proposal concerns the synthesis and the physical characterization of arborescent polymers (AP). These are novel materials, so there is little understanding of the relationships between their structure/composition and their properties. The information derived from the well-defined AP systems will also help improve the understanding of branched polymer systems in general, many of which are of commercial importance. *The first project involves core-shell AP structures with a hydrophobic polypeptide core and a shell of hydrophilic segments. The research will focus on the solubilization and release properties of these amphiphiles for different model hydrophobes as a function of the structure (branching density, size) and composition of the AP molecules. This will also provide information on the morphology of the AP molecules (extent of phase separation between the core and shell).*In the second project the formation of metallic nanoparticles by AP copolymers with core-shell (CS) and core-shell-corona (CSC) architectures, containing metal-binding poly(2-vinylpyridine) segments, will be examined. We recently observed the formation of intriguing nanomorphologies constrained within the individual AP molecules upon the introduction of metallic ions. These nanostructures likely arise from large differences in interaction (chi) parameter between the metal-rich and metal-poor regions, but their consequences on the physicochemical properties of these hybrid materials are hitherto unexplored. We will examine the formation of these nanostructured materials in a systematic fashion, and ultimately their catalytic properties. The CSC systems display many interesting properties, but their synthesis is very time-consuming and is marred by low yields. We just started investigating a new strategy for the synthesis of these materials, by self-assembly of an AP core-shell structure with a block copolymer where one of the blocks can bind with the AP substrate. This approach looks very promising, but again there is no clear understanding of the rules (thermodynamics) governing this self-assembly process. These will be explored through systematic variations in the structure (e.g. binding block and AP substrate size) of the components and the conditions (solvent, temperature) used.*Finally, to pursue our efforts in developing new methods for the synthesis of AP structures, we will combine a "click" grafting technique which we just developed with atom transfer radical polymerization (ATRP) to considerably expand the range of arborescent polymer compositions available. We will also explore methods for the synthesis or arborescent polybutadiene structures with long side chains, since these are of interest as model highly branched polymer systems.

树突分子的特征是具有多个分支水平的结构，类似于树。这些可以细分为三个不同的家庭。树突聚合物和超支聚合物均源自ABN型单体（其中官能组A只能与B组; n = 2或3反应）。树枝状聚合物的完美结构和均匀的大小是由严格控制的单体保护，冷凝和脱保护反应的循环引起的，但是当在没有保护组的情况下进行冷凝反应时，通常会出现不完美的分支结构和宽尺寸的分布。在该提案中感兴趣的树木（或树枝状）聚合物是通过线性聚合物段的连续移植反应获得的。这些分子的生长比连续几代人（反应周期）的树枝状聚合物的生长快得多，但它们显示出许多特征。因此，它们是许多纳米技术应用的树枝状聚合物的有趣替代方法。这些是新颖的材料，因此对它们的结构/组成与其特性之间的关系几乎没有理解。从定义明确的AP系统中得出的信息还将有助于提高对分支聚合物系统的理解，其中许多是商业上重要的。 *第一个项目涉及具有疏水多肽核心和亲水性片段的核心壳AP结构。这项研究将集中于这些两亲物的溶解和释放性能，用于不同模型的疏水物，这是AP分子的结构（分支密度，大小）和组成的函数。这还将提供有关AP分子形态（核心和外壳之间的相分离程度）的信息。最近，我们观察到在引入金属离子后，在单个AP分子中限制了有趣的纳米形态的形成。这些纳米结构可能是由于金属丰富和金属贫困区域之间的相互作用（CHI）参数的巨大差异引起的，但是它们对这些杂种材料的物理化学特性的后果迄今尚未探索。我们将以系统的方式研究这些纳米结构材料的形成，并最终以它们的催化特性。 CSC系统显示出许多有趣的属性，但是它们的合成非常耗时，并且受到低收率的伤害。我们刚刚开始研究一种新策略来合成这些材料，这是通过与块共聚物的AP核壳结构进行自组装的，其中一个块可以与AP底物结合。这种方法看起来非常有前途，但是同样，对管理这一自组装过程的规则（热力学）没有明确的了解。这些组件的结构（例如结合块和AP底物大小）以及所使用的条件（溶剂，温度）的结构（例如结合块和AP底物大小）的系统变化将探索这些。 可用的。我们还将探索具有长侧链的合成或树状多丁二烯结构的方法，因为这些方法是模型高度分支聚合物系统的感兴趣。