Emerging Complexity and Hierarchical Order in Precipitation Reactions

Florida State University, Tallahassee FL

Investigators

Abstract

Non-Technical Abstract: Living systems produce materials and device-like structures in ways that differ profoundly from most existing engineering strategies. They are capable of growing high-performance materials (e.g. bone and tooth enamel) with intricate micro-to-macro architectures by tightly regulating the process conditions. In addition, life accomplishes these feats from inexpensive and abundant starting materials. With the support of the Solid State and Materials Chemistry program, the overarching goal of this project is to find and develop examples that use similar strategies in the realm of non-biological, inorganic chemistry. If successful this research could form an important stepping stone towards an entirely new engineering paradigm under which materials are produced by externally controlling chemical self-organization and other complexity-generating mechanisms. This research effort is integrated with educational and outreach activities that include the training of undergraduate and graduate students and the dissemination of research videos via social media. The principal investigator also plans to develop a website dedicated to "chemical gardens" which are the most iconic example of self-organizing inorganic reactions. The website aims to provide information for high school teachers and invites photo competitions documenting these chemical structures. Technical Abstract: This project explores pattern-forming, nonequilibrium processes in the context of inorganic precipitates with the aim to advance the understanding of macroscopic tube structures and micro-scale nanorod assemblies called biomorphs. Some of these studies are inspired by origins-of-life hypotheses under which prebiotic chemistry developed in the microporous and catalytically active precipitates of off-axis alkaline hydrothermal vents. Specific goals include the prediction of tube formation from simple chemical and physical parameters and the use of related materials for the study of transmembrane transport, thermophoretic effects, and specific aspects of the formose reaction. This calcium-hydroxide-catalyzed reaction generates numerous products including ribose from formaldehyde and has been discussed in the context of RNA world theories. The second research thrust focuses on biomorphs that form in silicate-barium solutions under the influx of carbon dioxide. These 10-100 micrometer large structures have life-like morphologies such as cardioidal sheets and helices and consist of highly ordered aggregates of barium carbonate nanorods. To elucidate their growth mechanism and nano-to-macro architecture, the research team develops mean-field reaction-transport models. The modeling and simulation efforts are based on experiments aiming to identify mechanistic details from flow and electric-field induced perturbations.