The structure and dynamics of water confined in nanoscale pools: the dynamic crossover

The peculiar behaviour of liquid and supercooled water has been baffling science for at least 236 years and is still seen as a major challenge facing chemistry today (Whitesides & Deutch, Nature 469, 21 (2011)). It was suggested that such strange behaviour might be caused by thermodynamic transitions, possibly even a second critical point. This second critical point would terminate a coexistence line between low- and high-density amorphous phases of water. Unfortunately, this second critical point (if it exists) and the associated polyamorphic liquid-liquid transition is difficult to study as it is thought to lie below the homogeneous nucleation temperature in a region known as "no man's land" (Angell, Science 319, 582 (2008)).

In recent preliminary femtosecond optical Kerr-effect spectroscopy experiments, we have shown that water in concentrated eutectic solutions forms nanometre scale pools in which it retains many if not most of its bulk liquid characteristics. Most importantly, such solutions can be cooled to below 200 K without crystallisation (typically forming a glass at lower temperatures) allowing one to explore "no man's land" in detail for the first time. Preliminary experiments combining femtosecond spectroscopy with NMR diffusion measurements have shown that water in these pools undergoes a liquid-liquid transition as predicted for bulk water.

Hence, it is proposed to use such nanopools as nanometre scale laboratories for the study of liquid and glassy water. A wide-ranging international collaboration has been set up to be able to study different critical aspects of the structure and dynamics of water. This includes cryogenic viscosity measurements, large dynamic-range (femtosecond to millisecond) optical Kerr-effect experiments, pulsed field gradient NMR, dielectric relaxation spectroscopy, terahertz time-domain spectroscopy, infrared pump-probe spectroscopy, and two-dimensional infrared spectroscopy. To ensure maximum impact of the experimental work, it is critical to have strong ties with experts in the theory and simulation of water and its thermodynamic behaviour. We have arranged collaboration with two international theory groups covering different aspects of the proposed work.

Although the proposed research is relatively fundamental in nature, it will have impact as described in more detail elsewhere. The research addresses EPSRC priorities in nanoscience (supramolecular structures in liquids), energy (proton transport and liquid structuring in electrolytes for batteries and fuel cells), life sciences (the role of water in and on biomolecules), and the chemistry-chemical engineering interface (the role of the structuring of water in crystal nucleation). Our strong links with theory collaborators will ensure that fundamental insights will indeed propagate to the 'users' of such information. The close working relationship between the PI and CI has made Glasgow a centre of excellence in advanced femtosecond spectroscopy. This project exploits this expertise and international collaborations to immerse PDRAs and PGRSs in internationally leading research using state-of-the-art previously funded equipment.

Economy

This proposal concerns relatively fundamental physical-chemistry research. However, there are tangible routes to economic impact. The research addresses EPSRC priorities in nanoscience, energy, life sciences, and the chemistry-chemical engineering interface. Most relevant to the economy (e.g., pharmaceutical industry) are insights to be gained in the role of the structuring of water in crystal nucleation. The PI's membership in the CMAC-SPIRIT crystallisation science consortium (including GSK, NiTech, Pfizer, Astra Zeneca, Fujifilm, and others) facilitates the exploration of routes to impact. Our studies of transport phenomena in solutions will have a direct bearing on proton transport and liquid structuring in electrolytes for batteries and fuel cells addressing the EPSRC priority areas of energy and nanoscience. The salt solutions to be studied here are in many respects similar to room-temperature ionic liquids and show similar effects. One of the collaborators on the project (Seddon) is founder director of the Queen's University Ionic Liquid Laboratories (Quill) research centre, which has members from all sectors of the chemical industry including SHELL, Chevron, Eastman, Merck, and Procter and Gamble. Again, this will facilitate the exploration of routes to impact.

Knowledge

The knowledge generated by the proposed work will be communicated through standard routes: papers, conferences, etc. The team (PI + CI + collaborators) have had considerable impact in the past with numerous papers in high impact journals such as Nature, Science, PNAS, JACS, and PRL. The publication record of the applicants is strong and is expected to continue in this manner with targeting of the top tier journals such as Science and Nature with the collaborative work proposed here. In addition, the PI and CI are guest editors for a special issue of PCCP on Ultrafast Physical Chemistry and Chemical Physics to be published in 2012.

Other channels of knowledge transfer include the organisation of conferences in which the PI and CI have a strong track record. Two relevant conferences will be organised in Glasgow by the applicants during the proposed grant period. Furthermore, the PI is a member of a number of programme committees organising conferences in the area of the proposal.

People

The research proposal under consideration here is people centred and career development of the team members a key aim. A critical aspect of this is the ultrafast chemical physics collaboration between the PI at Glasgow University and the CI at Strathclyde University both in the City of Glasgow and separated only by a 10-minute journey. This local collaboration is a centre of excellence in advanced femtosecond spectroscopy. We host international researchers, organise a number of local meetings (see above), and provide a range of training opportunities for PDRAs and PGRSs.

Society

It will be attempted to communicate a flavour of the research enterprise and its results to the public. For this we will use modern channels of communication, such as video (through our YouTube channel 'ucpgroup'), Twitter (using our feed 'klaaswynne'), blog (the survival blog for scientists), and web. Finally, the PI is participating in the 'Capture a Chemist' crowd-sourced chemistry engagement arts project in conjunction with the International Year of Chemistry 2011 that brings the photographic and chemical communities together to share the stories of chemists across the world.