BIOMIMETIC METHODS BASED ON SOLUBLE AMMONIUM PHOSPHATE PRECURSORS FOR THE CONSOLIDATION OF WALL PAINTINGS

技术摘要在材料研究部（DMR）的固态和材料化学（SSMC）项目的支持下，该项目将开发基于羟基磷灰石（HAP）的无机矿物系统，以保存和巩固由富含碳酸钙（CaCO 3）的石膏层组成的粉末壁画，该石膏层具有考古、历史和艺术价值。仿生原理用于通过触发碳酸盐底物与肽和磷酸铵前体之间的反应来诱导HAP在去粘石膏中形成。空间，结构和成分敏感的分析，包括扫描电子显微镜，三维CT成像，动态蒸汽吸附方法和机械和流体传输分析，应用量化HAP治疗。从科学的角度来看，该研究描述了：（1）磷酸盐反应物和CaCO 3石膏之间的化学相互作用和反应，以及（2）HAP形成对加强微观结构和改善绘画的影响？的耐用性，同时保持原有的光学/美学特性。这项研究的跨学科性质，在保护科学，生物技术和材料科学的接口开发量身定制的保护治疗，考虑基质化学和结构的基本特征，规定和度量治疗方案。该研究提高了我们设计，操作和评估多孔多色表面加固处理的能力，并允许改进保护全球文化遗产的方法。重要的是，这项工作为历史文物制定了保护战略，从绘画和岩石艺术到石头结构，古生物化石和考古骨骼，其基础是物理科学和材料工程。壁画是艺术、文化和思想发展的见证，因此具有深刻的考古学、历史和文化意义。不幸的是，随着时间的推移，壁画由于暴露于人类活动和环境力量而经历了相当大的退化。虽然已经提出了几种方法来限制或阻止这种退化，但这些方法往往会损害绘画的内在质量和属性。通过加州大学洛杉矶分校（UCLA）的多学科合作，本研究开发了基于羟基磷灰石的固结处理，以保护多层，多色，异质壁画免受时间和环境影响引起的风化和劣化，而不会导致其物理和化学性质的显着变化。通过使用对材料的组成和结构敏感的分析工具，以上下文敏感的方式应用和计量处理方法;即，注意特定绘画的特征及其执行技术（即，湿壁画或secco）。为一名博士后研究员、一名研究生和几名本科生提供的研究和学术培训向新一代的保护科学家传授知识，他们可以为保护我们的集体文化遗产做出贡献。通过与国家和国际合作者的互动，研究提供了一个学术卓越/交流的平台，同时创造了适用于不同地理领域的保护实践的新知识。最后，该研究还开发了应用于牙齿/骨骼重建和土木工程基础设施修复的生物工程知识。 这项研究得到了材料研究部（DMR）的固态和材料化学（SSMC）计划的支持。

TECHNICAL ABSTRACTWith support from the Solid State and Materials Chemistry (SSMC) program in the Division of Materials Research (DMR), this project will develop hydroxyapatite (HAP) based, inorganic mineral systems to preserve and consolidate powdery wall paintings composed on calcium carbonate (CaCO3) rich plaster layers of archaeological, historic and artistic value. Biomimetic principles are used to induce HAP formation in the decohesive plaster by triggering reactions between the carbonate substrate and the peptidic and ammonium phosphate precursors. Spatially, structurally and compositionally sensitive analytics including scanning electron microscopy, 3D-CT imaging, dynamic vapor sorption methods and mechanical and fluid-transport analyses are applied to quantify HAP treatments. From a scientific perspective, the research describes: (1) chemical interactions and reactions between the phosphate reactant and the CaCO3 plaster and (2) the impact of HAP formation on strengthening the microstructure, and improving the painting?s durability while maintaining the original optical/aesthetic properties. The interdisciplinary nature of this research, at the interface of conservation science, biotechnology and materials science develops tailored conservation treatments that consider fundamental characteristics of the substrate chemistry and structure to prescribe and metricate treatment protocols. The research advances our ability to design, manipulate and evaluate consolidation treatments for porous polychrome surfaces and allows for improved methodologies to preserve global cultural heritage. Significantly, the effort develops conservation strategies for historic objects ranging from paintings and rock-art to stone structures, paleontological fossils and archaeological bone with a basis rooted in the physical sciences and materials engineering. NON-TECHNICAL ABSTRACTWall paintings provide a testimony of artistic, cultural, and intellectual developments and are consequently of profound archaeological, historical and cultural significance. Unfortunately, with the passage of time, wall paintings experience considerable degradation due to their exposure to human activity and environmental forces. While several methods have been proposed to limit or halt such degradation, these methods often compromise the intrinsic quality and attributes of the painting. Through a multi-disciplinary collaboration at the University of California, Los Angeles (UCLA), this research develops hydroxyapatite-based consolidation treatments to enable the protection of multi-layered, polychrome, heterogeneous wall paintings from weathering and deterioration induced by passage-of-time and environmental effects without causing significant change to their physical and chemical properties. By using analytical tools sensitive to the composition and structure of the material, treatment methods are applied and metricated in a context sensitive fashion; i.e., with attention to the characteristics of a specific painting and its execution technique (i.e., fresco or secco). The research and academic training provided to a post-doctoral researcher, a graduate student and several undergraduate students imparts knowledge to a new generation of conservation scientists who can contribute to preserving our collective cultural heritage. Through interactions with national and international collaborators the research offers a platform for academic excellence/exchange and at the same time creates new knowledge of conservation practices applicable across diverse geographical domains. Finally, the research also develops knowledge with applications in bioengineering for tooth/bone reconstruction and for infrastructure rehabilitation in civil engineering. This research is supported by the Solid State and Materials Chemistry (SSMC) program in the Division of Materials Research (DMR).