Mechanics of seed-grown planar chemical gardens
type: CreativeWork
description: In the 17th century, perhaps by accident, the German alchemist Glauber introduced solid crystals of iron(III) chloride into an aqueous solution of potassium silicate. He noted the formation of some strange, plant-like structures, which he recorded in his 1646 book Furni Novi Philosophici as "philosophical trees". Glauber would not have guessed that, three centuries later, his discovery opened up a whole new field of study. The structures he reported are known as "chemical gardens" -- self-assembled semi-permeable precipitates. They are considered laboratory analogues of hydrothermal vents that are thought to be where biological life on Earth self-assembled and originated. In this thesis, in Chapter 1, a review of chemical gardens studied in confined geometries -- Hele-Shaw cells and microfluidic chips -- is presented. Studies in these geometries have been classified into three approaches: seed-growth in Hele-Shaw cells, injection-growth in Hele-Shaw cells, and co-injection-growth in microfluidic chips. Over the past decade, these setups have seen a growing popularity due to lower complexity and easier analysis. Chapters 2-4 focus on the dynamics of seed-grown chemical gardens in Hele-Shaw cells. In Chapter 2, the growth behaviour of chemical garden walls in a horizontal Hele-Shaw cell has been investigated. The experiments have been conducted with pellets of either solid cobalt(II) or manganese(II) chloride contained in aqueous sodium silicate solutions. It is found that the growth of the chemical garden walls can be well described by a simple, diffusion-controlled dynamical model until their eventual osmotic fracture at a reproducible time. Chapter 3 investigates the behaviour of chemical gardens grown in a vertical Hele-Shaw cell. Instead of cobalt chloride, magnesium chloride pellets were used as seeds in aqueous sodium silicate solutions. The chemical gardens exhibited non-isotropic radial growth -- fastest at the bottom and slowest at the top. In each direction…
abstract: In the 17th century, perhaps by accident, the German alchemist Glauber introduced solid crystals of iron(III) chloride into an aqueous solution of potassium silicate. He noted the formation of some strange, plant-like structures, which he recorded in his 1646 book Furni Novi Philosophici as "philosophical trees". Glauber would not have guessed that, three centuries later, his discovery opened up a whole new field of study. The structures he reported are known as "chemical gardens" -- self-assembled semi-permeable precipitates. They are considered laboratory analogues of hydrothermal vents that are thought to be where biological life on Earth self-assembled and originated. In this thesis, in Chapter 1, a review of chemical gardens studied in confined geometries -- Hele-Shaw cells and microfluidic chips -- is presented. Studies in these geometries have been classified into three approaches: seed-growth in Hele-Shaw cells, injection-growth in Hele-Shaw cells, and co-injection-growth in microfluidic chips. Over the past decade, these setups have seen a growing popularity due to lower complexity and easier analysis. Chapters 2-4 focus on the dynamics of seed-grown chemical gardens in Hele-Shaw cells. In Chapter 2, the growth behaviour of chemical garden walls in a horizontal Hele-Shaw cell has been investigated. The experiments have been conducted with pellets of either solid cobalt(II) or manganese(II) chloride contained in aqueous sodium silicate solutions. It is found that the growth of the chemical garden walls can be well described by a simple, diffusion-controlled dynamical model until their eventual osmotic fracture at a reproducible time. Chapter 3 investigates the behaviour of chemical gardens grown in a vertical Hele-Shaw cell. Instead of cobalt chloride, magnesium chloride pellets were used as seeds in aqueous sodium silicate solutions. The chemical gardens exhibited non-isotropic radial growth -- fastest at the bottom and slowest at the top. In each direction…
author: Zheng, Mingchuan
language: eng
keywords: chemical garden, chemobrionics, Hele-Shaw cell, hydrothermal vent, origin of life, self-assembly
license: https://www.repository.cam.ac.uk/bitstreams/fadecb75-4506-4a8e-bba0-80710200cdec/download
license: https://creativecommons.org/licenses/by/4.0/
date published: 2025-09-25
date modified: 2026-07-22T22:23:57Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.124988