Polymer and Liquid Crystal Assembled Nanomaterials

聚合物和液晶组装纳米材料

• 批准号: RGPIN-2019-05149
• 负责人: Reven, Linda
• 金额: $ 2.62万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748065
• 关键词: Polymer; Liquid; Crystal; Assembled; Nanomaterials

The main theme of this research program is the assembly of nanomaterials into organized, stimuli-responsive structures, assisted by solid-state NMR characterization. 1. Patchy Nanoparticles (NPs). This topic concerns the preparation, characterization and assembly of polymer-based "patchy nanoparticles", defined as particles with at least one well defined patch to allow directional interactions with other particles or surfaces. Patchy particles are of interest for photonic colloidal crystals, multi-compartmental drug delivery agents and catalysts. Obstacles include a lack of large-scale preparations and suitable characterization tools. Theoretical studies of NPs with mixed polymer shells predict phase separated coronas that provide soft, deformable "patches". We recently developed a facile ligand exchange method to produce NPs with mixed polymer brushes and characterized the nanophase separation by NMR. Controlled assembly of patchy NPs into hierarchical superstructures will be tested by varying the NP size and shape and the ratios and chain lengths of the polymer ligands. 2. Polymer Functionalized NPs in LCs. The second topic merges two areas of expertise of my group, polymer functionalized NPs and NP-liquid crystal dispersions. The main goal will be to develop suitable polymer ligands to replace custom-synthesized mesogenic ligands typically used to form stable NP-LC dispersions, combining the advantages of polymer and NP additives to LCs. NP dopants can enhance LC electro-optical properties and conversely LCs can template NPs into regular spatial structures. LC-polymer blends are widely used for display applications but the LC-polymer interface remains poorly understood. Theoretical/experimental studies of LC-polymer blends, followed by studies of the same polymers tethered to NPs, will examine the chain conformation and dynamics to understand the molecular level polymer-LC interactions. Since the miscibility of polymers in LCs is strongly correlated with the chain stiffness, both flexible and rigid rod polymers will be studied. 3. Tuning NP Properties via Surface Chemistry. A third topic focuses on the effect of the surface chemistry on the properties of inorganic NPs. Since the surface atoms make up a significant fraction of a NP, the ligand shell composition can determine the NP structure. Lead halide perovskites are a promising new class of semiconductor nanocrystals (NCs). Before these NCs can be used for solar cells or opto-electronic devices, an effective surface chemistry is needed to prevent degradation from moisture, light or heat. Another new nanomaterial, ferroelectric BaTiO3 (BTO) nanocubes, will be studied to understand why it remains ferroelectric down to sizes smaller than theoretical predictions, critical for non-volatile memory and other applications. NMR experiments will allow detection of surface reconstruction by ligand exchange reactions as well as matching of ligands to specific surface binding sites.

该研究计划的主题是在固态核磁共振表征的辅助下，将纳米材料组装成有组织的刺激响应结构。 1. 片状纳米颗粒 (NP)。本主题涉及基于聚合物的“斑状纳米颗粒”的制备、表征和组装，其定义为具有至少一个明确的斑块的颗粒，以允许与其他颗粒或表面的定向相互作用。片状颗粒对于光子胶体晶体、多室药物输送剂和催化剂很有意义。障碍包括缺乏大规模准备工作和合适的表征工具。对具有混合聚合物壳的纳米粒子的理论研究预测，相分离的冠可提供柔软、可变形的“补丁”。我们最近开发了一种简便的配体交换方法，用混合聚合物刷生产纳米粒子，并通过核磁共振表征纳米相分离。通过改变纳米粒子的尺寸和形状以及聚合物配体的比例和链长，可以测试将片状纳米粒子控制组装成分层超结构。 2. 液晶中的聚合物功能化纳米粒子。第二个主题融合了我小组的两个专业领域：聚合物功能化纳米颗粒和纳米颗粒液晶分散体。主要目标是开发合适的聚合物配体来取代通常用于形成稳定的NP-LC分散体的定制合成介晶​​配体，将聚合物和NP添加剂的优点结合到LC中。纳米粒子掺杂剂可以增强液晶的电光特性，相反，液晶可以将纳米粒子模板化为规则的空间结构。液晶聚合物共混物广泛用于显示器应用，但人们对液晶聚合物界面仍然知之甚少。 LC-聚合物共混物的理论/实验研究，以及与纳米粒子相连的相同聚合物的研究，将检查链构象和动力学，以了解分子水平的聚合物-LC相互作用。由于液晶中聚合物的混溶性与链刚度密切相关，因此将研究柔性和刚性棒状聚合物。 3. 通过表面化学调整纳米颗粒性质。第三个主题重点关注表面化学对无机纳米粒子性能的影响。由于表面原子占 NP 的很大一部分，因此配体壳的组成可以决定 NP 的结构。卤化铅钙钛矿是一种有前途的新型半导体纳米晶体（NC）。在将这些NC用于太阳能电池或光电设备之前，需要有效的表面化学来防止因湿气、光或热而降解。我们将研究另一种新型纳米材料——铁电 BaTiO3 (BTO) 纳米立方体，以了解为什么它在尺寸小于理论预测的情况下仍保持铁电性，这对于非易失性存储器和其他应用至关重要。核磁共振实验将允许通过配体交换反应以及配体与特定表面结合位点的匹配来检测表面重建。