Dynamic Control of Mineralisation

Información del proyecto

DYNAMIN

Identificador del acuerdo de subvención: 788968

DOI

10.3030/788968

Proyecto cerrado

Fecha de la firma de la CE 23 Abril 2018

Fecha de inicio 1 Septiembre 2018

Fecha de finalización 31 Agosto 2025

Financiado con arreglo a

• EXCELLENT SCIENCE - European Research Council (ERC)

Coste total

€ 2 632 375,00

Aportación de la UE

€ 2 632 375,00

Coordinado por

UNIVERSITY OF LEEDS
United Kingdom

Periodic Reporting for period 5 - DYNAMIN (Dynamic Control of Mineralisation)

Período documentado: 2024-09-01 hasta 2025-08-31

Resumen del contexto y de los objetivos generales del proyecto

Crystallisation underpins a vast range of processes as diverse as the production of nanomaterials, ceramics, and pharmaceuticals, the generation of biominerals such as bones and seashells, ice formation in our environment and the generation of scale in oil-wells. Understanding the mechanisms which govern crystallisation therefore promises the ability to inhibit or promote crystallisation as desired, and to tailor the properties of crystalline materials towards specific applications.

The overall goal of DYNAMIN was to use small volume systems – coupled to advanced analytical methods – to study and interact with crystallisation processes, and ultimately achieve control over crystal nucleation and growth by design. Biomineralisation, where nature achieves remarkable control over crystallisation, provides the inspiration for this strategy, where crystallisation occurs within confined volumes under temporal regulation of the environment.

This was achieved by using contrasting systems including static and flowing droplets, microfluidic devices and electron-transparent nanotubes as environments to study crystallisation in real time. These enabled precise control over nucleation and polymorph selection, and the ability to interact with crystallisation processes using additives, particulate nucleants and external stimuli. Together, this work supported the broader goal of establishing new tools and frameworks for controlling crystallisation with high spatial and temporal resolution, paving the way for advances in materials science, biomimetics, and functional material design.

Trabajo realizado desde el comienzo del proyecto hasta el final del período abarcado por el informe y los principales resultados hasta la fecha

This project delivered significant advances in the study and control of crystallisation, combining innovative experimental platforms with mechanistic insights.

A major achievement was the development of advanced droplet-based microfluidic and milli-fluidic platforms for in situ SAXS/WAXS analysis of crystallization. Key innovations included the Droplet-Microfluidic Coupled XRD (DMC-XRD) systems which enabled time-resolved, serial crystallography under controlled conditions (Fig 1). Further funding was also obtained to create Flow-Xl, a world-first facility that combines XRD and Raman spectroscopy with flow systems for time-resolved analysis of crystallization processes. This enables lab-based analysis previously limited to synchrotron facilities.

These droplet based systems were then exploited to interact with crystallisation processes using particulate nucleants, enabling us to identify effective nucleants for calcium carbonate and investigating mammalian hair as a potential universal nucleant. This work delivered new insight into the roles of surface charge, chemistry and topography in promoting nucleation.

A particular highlight is our work on calcium carbonate polymorphism, where we showed that both calcite and aragonite nucleate via amorphous calcium carbonate (ACC) composed of identical nanoparticulate subunits. It is the packing of these subunits into dense or loose aggregates that determines the final crystal polymorph (Fig 2). New insight into polymorph formation and interconversion was also gained from experiments using colloidal particles as model crystallisation systems, where these enable crystallisation to be studied at a single particle level.

A significant goal of DYNAMIN was to use small volume systems to explore crystallisation under biomimetic conditions. “Crystal Hotel” microfluidic devices were developed to create sophisticated biomimetic environments, and the production of highly oriented aragonite single crystals analogous to the tablets in nacre revealed how properties such as orientation and crystal quality can be defined in confinement (Fig 3). Gel droplets were also used to study the transformation of ACC, a key precursor to crystalline calcium carbonate in biomineralisation (Fig 4).

Offering smaller scales, titania nanotubes were used to study crystal growth in nanoscale compartments. Their electron transparency and mechanical stability enabled visualisation of calcium sulfate crystal formation within individual pores (Fig 5). It was found that single crystals derive from multiple nucleation events, with preferred orientation determined early, not by competitive growth—offering new insights into confinement effects relevant to natural mineral formation.

Finally, exceptional control over the crystallisation of amorphous precursors by independently triggering the nucleation and controlling the growth of ACC thin films. This approach generated sub-millimetre calcite single crystals with morphologies ranging from discs to serpentine patterns (Fig 6). Crucially, the magnesium content of the ACC was found to dictate the product mineral phase, enabling the transformation to be tuned to produce low- and high magnesium-calcite, pure aragonite and even dolomite.

These findings collectively offer powerful new tools and conceptual advances for designing functional crystalline materials.

Avances que van más allá del estado de la técnica e impacto potencial esperado (incluida la repercusión socioeconómica y las implicaciones sociales más amplias del proyecto hasta la fecha)

Polymorph Control
This project has delivered a major advance in our understanding of polymorph selection in calcium carbonate system, where its ability to form three distinct anhydrous polymorphs—calcite, aragonite, and vaterite—makes it an ideal system for studying inorganic crystallisation. A long-standing challenge has been the difficulty of precipitating aragonite at room temperature, despite its near-equivalent thermodynamic stability to calcite. Our work addressed this by developing a novel, additive-free method to selectively generate aragonite or calcite using flow conditions alone, enabling direct comparison of crystallisation pathways under identical solution conditions.
Using a suite of in situ scattering techniques (PDF, USAXS, SAXS, WAXS), we discovered that both polymorphs nucleate via amorphous calcium carbonate (ACC) precursors with similar short-range order. However, their hierarchical structures diverge dramatically: aragonite ACC comprises 2 nm nanoparticles forming fractal aggregates, while calcite ACC forms dense, smooth particles. SAXS and cryo-TEM confirmed both are built from the same nanoparticulate units, but their aggregation state—modulated by flow—determines the final polymorph. This revolutionises our understanding of polymorph formation in the calcium carbonate system and provides a unifying framework to explain how variables like stirring, additives, and temperature influence crystallisation—opening up new avenues for controlled material synthesis.

In Situ X-ray Analysis of Crystallisation in Droplet-Based Systems
This project significantly advanced crystallisation analysis through the development of advanced droplet-based microfluidic and milli-fluidic platforms for in situ SXAS/WAXS analysis of crystallisation. Key innovations included Droplet Microfluidics-Coupled X-ray Diffraction (DMC-XRD) and KRAIC-D systems, which enabled time-resolved, serial crystallography under controlled conditions, and the development of novel data processing pipelines. Building on these developments, further funding was also secured to establish Flow-Xl, a world-first lab-based facility that combines XRD and Raman spectroscopy with flow systems for time-resolved analysis of crystallisation processes. This enables lab-based analysis previously limited to synchrotron facilities.

Figure 3: (a) Schematic diagram of the “crystal hotel” systems. Each system contains 2 channels and

Figure 5: (a) Illustration of U-tube counter-diffusion apparatus used to precipitate calcium sulfate

Figure 6: Production of large single crystals of calcite, where nucleation was triggered at a single

Figure 4: (a) Injection into gel droplets. (b) Crystallisation in gel droplets, where droplets conta

Figure 2: (a) USAXS/SAXS and b) cryo-TEM of ACC form prior to the formation of aragonite and (c) cry

Figure 1: Microfluidic device for studying crystallization in flowing droplets using XRD