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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=716945
• 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.

树突分子有多个分支层，类似于树。树状大分子和超支化聚合物来源于abn型单体（其中A官能团只能与B官能团反应，n = 2或3）。树状大分子的完美结构是人工合成的结果，而控制条件较差则导致了超支化体系的不完美结构。树形聚合物（AP）是通过线性聚合物段的连续接枝反应得到的。它们的生长速度比树状大分子快得多，但具有树状大分子的许多特性，因此它们可以在多种纳米技术应用中取代树状大分子。本文主要介绍了APs的合成及其物理特性。