Collaborative Research: Water Mediated Transport of Ions and Molecules in Ionomeric Paint Films: An Integrated Multi-Technique Investigation

从14世纪到20世纪的不可替代的艺术杰作，由于颜料成分之间的化学反应，正在慢慢变质。在这个复杂的过程中，离子和分子在油漆中的运动被认为是重要的一步。在这个项目中，检查了漆膜中水和溶剂等材料的动态和传输，以确定(1)该过程的性质，(2)影响该过程的因素。漆膜是复杂的材料，必须用多种技术来研究，以尽可能完整地表征过程。在材料研究部固态与材料化学项目和化学部化学测量与成像项目的支持下，通过布鲁克海文国家实验室和太平洋西北国家实验室的科学家的参与，扩大了特拉华大学和大都会艺术博物馆之间正在进行的合作，利用现代技术解决绘画的退化问题，对大都会艺术博物馆和特拉华大学准备的材料以及从受影响的艺术作品中提取的显微样本进行了额外的独特分析。提供诸如“这个过程为什么以及如何发生？”和“采取什么行动可以减少或消除这些最终破坏无价艺术品的过程？”等问题的答案。该项目通过大都会艺术博物馆和特拉华大学的推广，为公众提供了科学发现与文化和历史元素之间的有形联系，同时也发展了对复杂化学过程的理解，而不仅仅是绘画。技术摘要：油画中含有重金属的颜料与脂肪酸发生反应，产生金属羧酸盐，又称皂。这些肥皂可能会产生难看的夹杂物、表面结壳和/或增加油漆的透明度，导致不必要的和最终有害的影响。大多数油画都在某种程度上经历了这个过程。从科学的角度来看，这一过程包括一系列步骤：(1)通过油的水解产生游离脂肪酸；(2)酸和色素离子的迁移；(3)反应性事件；(4)产品团聚产生皂聚集体或迁移到漆膜表面产生结皮。每一步都是重要而复杂的，部分原因是材料的不均匀性。该项目主要关注漆膜中材料的动力学，主要是第二步的特征，但动力学也很重要，因为水和溶剂等材料，有时来自修复干预，以及环境影响可能涉及步骤1和步骤4。此外，由于这些材料是异质的，在理解这些过程的本质时，必须同时考虑颜料颗粒大小和形状以及油漆孔隙率等特性的影响。这只能通过多管齐下的方法来表征以不同方式处理的样品来实现。通过结合大都会博物馆、特拉华大学的优势，以及布鲁克海文国家实验室和太平洋西北实验室的专业知识，一些复杂的技术被用于理解这一过程。提出的研究复杂非均质多层系统的新策略适用于软物质科学领域类似问题的表征。

Non-technical AbstractIrreplaceable masterworks of art dating from the 14th century through the 20th century are slowly deteriorating due to chemical reactions among the paint components. One step believed to be important in this complex process is the movement of ions and molecules through the paint. In this project, the dynamics and transport of materials such as water and solvents in paint films are examined to determine (1) the nature of the process, and (2) what factors affect this process. Paint films are complex materials, and they must be studied with multiple techniques to characterize the processes as completely as possible. With the support from the Solid State and Materials Chemistry program in the Division of Materials Research and the Chemical Measurement and Imaging program in the Division of Chemistry, the ongoing collaboration between the University of Delaware and The Metropolitan Museum of Art to address the deterioration of paintings with modern technologies is expanded by the involvement of scientists at Brookhaven National Laboratory and Pacific Northwest National Laboratory to provide additional unique analyses of materials prepared at The Metropolitan Museum of Art and the University of Delaware and of microscopic samples removed works of art affected, to provide answers to questions like "Why and how does this process occur?" and "What types of actions can be taken to minimize or eliminate these processes that ultimately destroy priceless art objects?" The project, through outreach carried out by The Metropolitan Museum of Art and the University of Delaware, provides the public with a tangible connection between scientific discovery and the elements of culture and history, at the same time as it develops an understanding of complex chemical processes that affect more than just paintings. Technical AbstractThe reaction of heavy-metal-containing pigments with fatty acids in oil paintings, derived from the oil paint binders, produces metal carboxylates also called soaps. These soaps may produce disfiguring inclusions, surface crusts and/or increased transparency of the paints, resulting in unwanted and ultimately deleterious effects. Most oil paintings suffer from this process to some degree. From a scientific perspective, the process consists of a series of steps: (1) production of free fatty acids by hydrolysis of the oil; (2) migration of acids and pigment-derived ions; (3) the reactive event; and (4) agglomeration of the products to produce soap aggregates or migration to the paint film surface to produce crusts. Each step is important and complex, in part due to the heterogeneity of the material. This project focuses on the dynamics of materials in the paint films, predominantly characterizing step 2, but the dynamics are also important as materials like water and solvents, sometimes from restoration interventions, and environmental effects may be involved in steps 1 and 4. Additionally, because these materials are heterogeneous, one must simultaneously consider the effects of properties such as pigment particle size and shape, and porosity of the paint in understanding the nature of these process. This can only be achieved by a multi-pronged approach to characterize samples treated in different ways. By combining the strengths of the Metropolitan Museum, the University of Delaware together with expertise at Brookhaven National Laboratory and Pacific Northwest Laboratory, several sophisticated technologies are directed towards understanding the process. The novel strategy proposed to study a complex heterogeneous multilayered system is applicable to the characterization of analogous problems in the field of soft matter science.