Interrogating the dynamics of conjugated polymers using neutron scattering & molecular dynamics

使用中子散射研究共轭聚合物的动力学

• 批准号: 2123256
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2123256
• 关键词: Interrogating; dynamics; conjugated; polymers; using

The electronic and optical properties of conjugated polymers depend critically upon the structuresadopted by the polymer chains and the structural dynamics. Whilst the organisation of polymerchains in crystalline regions can be probed using diffraction techniques such as X-ray diffraction, mostof the polymer in a thin film is composed of amorphous phases with no long-range order. Moreover,at room temperature the polymer chains are not frozen, and this strongly affects the electronicmechanisms such as charge carrier transport in electronic devices or charge separation in solar cells.Structure and dynamics can be simulated using atomistic molecular dynamics, but experimentalprobes of structure are required to validate the models. One of the most powerful probes ofmolecular structure and dynamics is neutron scattering (NS), where the interactions of neutrons withthe polymer backbone and side chains can be measured as a function of temperature. Differenttechniques of NS allow to probe the structure and dynamics in different environments. Quasi-elasticneutron scattering (QENS) probes the polymer dynamics, inelastic neutron scattering is used to probevibrational modes, while small angle neutron scattering (SANS) is used to probe the conformation ofchains, for example, whether rigid or coiled. Despite of their potential, NS methods have seldom beenapplied to conjugated polymers partly because of the limited access to the hosting large scalefacilities, and also because the interpretation of resulting data is complex.

共轭聚合物的电子和光学性质主要取决于聚合物链所采用的结构和结构动力学。虽然聚合物链在结晶区的组织可以使用衍射技术如X射线衍射来探测，但薄膜中的大多数聚合物是由无定形相组成的，没有长程有序。此外，在室温下，聚合物链不会冻结，这强烈地影响了电子机制，如电子器件中的电荷载流子传输或太阳能电池中的电荷分离。结构和动力学可以用原子分子动力学模拟，但需要结构的实验探针来验证模型。中子散射（NS）是分子结构和动力学最有力的探测手段之一，它可以测量中子与聚合物主链和侧链的相互作用随温度的变化。NS的不同技术允许探测不同环境中的结构和动力学。准弹性中子散射（QENS）用于探测聚合物动力学，非弹性中子散射用于探测振动模式，而小角中子散射（SANS）用于探测链的构象，例如，是刚性的还是卷曲的。尽管它们的潜力，NS方法很少被应用于共轭聚合物，部分原因是有限的访问托管大型设施，也因为所得数据的解释是复杂的。