X光和中子散射方法在团簇及其聚合物复合材料表征中的应用

The application of X-ray and neutron scattering techniques in the characterization of molecular clusters and their polymer composites

复杂材料体系多组分且跨多空间尺度的层级结构、同组分的多聚集态共存以及难以定量描述的组分界面相互作用和非晶态结构,致使目前对于其形成机制和构效关系缺乏清晰认识.作为一种非破坏性的、跨多个时空尺度的材料表征方法,散射技术广泛应用于复杂材料体系多级结构和动力学研究.团簇具备明确和单分散结构,其与聚合物可通过多能级相互作用形成复合物,为研究材料共性科学问题提供了模型体系.基于大科学装置弹性和准弹性X光和中子散射多模式联用,可提供衬度互补、多时空维度原位实验表征方案,实现结构演变动力学、溶液动力学和结构松弛动力学在单链(单粒子)精度上的解析,结合材料中物质、动量和能量传输规律,实现定量化材料构效关系解析.本文首先介绍X射线和中子散射技术原理和基本数据分析方法,包括以小角散射和超小角散射为主的弹性散射以及准/非弹性散射,之后结合具体团簇复合材料体系总结散射技术联用在研究形成机制和构效关系中的应用,进而评述X光和中子散射方法在材料表征中的研究特点,为解决共性材料科学问题提供可借鉴的实验方案.

Complex material systems show the features of multi-component and multi-scale hierarchical structures,the coexistence of multiple aggregated states of the same component,interfacial interactions,and amorphous structures that are difficult to quantify,resulting in the lack of clear understanding of their formation mechanisms and structureproperty relationships.As a non-destructive,multi-temporal,and multi-spatial scale material characterization method,scattering techniques are widely used in the study of complex material systems’multi-level structures and dynamics.Clusters have well-defined and monodisperse structures,and can form composites with polymers through multi-level interactions,providing model systems for studying common scientific problems in materials.Based on the combined use of elastic and quasi-elastic X-ray and neutron scattering modes on large-scale scientific facilities,contrastcomplementing,multi-temporal,and multi-spatial dimensional in-situ experimental characterization schemes can be provided,capturing structural evolution dynamics,solution dynamics,and structural relaxation dynamics at single-chain(single-particle)precision,and quantitatively analyzing the relationships between structure and property of materials by combining the laws of mass,momentum and energy transfer in materials.This paper first introduces the principles and basic data analysis methods of X-ray and neutron scattering techniques,including elastic scattering mainly based on small-angle scattering and ultra-small-angle scattering,as well as quasi-elastic and inelastic scattering.Then,the applications of combined scattering techniques in studying formation mechanisms and structure-property relationships by using a specific cluster-polymer composite system is summarized.Finally,the research characteristics of X-ray and neutron scattering methods in material characterization is evaluated,providing reference experimental schemes for solving common material science problems.