Precise and smart nanoengineered surfaces: Impact resistance, icephobicity and dropwise condensation

Project Information

NICEDROPS

Grant agreement ID: 714712

DOI

10.3030/714712

Project closed

EC signature date 7 November 2016

Start date 1 March 2017

End date 28 February 2023

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 908 624,00

EU contribution

€ 1 908 624,00

Coordinated by

UNIVERSITY COLLEGE LONDON
United Kingdom

Periodic Reporting for period 4 - NICEDROPS (Precise and smart nanoengineered surfaces: Impact resistance, icephobicity and dropwise condensation)

Reporting period: 2021-09-01 to 2023-02-28

Summary of the context and overall objectives of the project

Phase change phenomena of water such as icing and condensation are ubiquitous and plays vital role societally and technologically to various applications from aerospace and maritime industries for transportation to household and industrial heat exchangers for heating, ventilation and air conditioning (HVAC) systems or energy production and harvesting. In NICEDROPS, we aimed to gain fundamental understanding on icing and dropwise condensation and to develop rational surface designs improving phase change heat transfer and energy efficiency. Thus, we have focused on studying metallic nanoengineered surfaces with a sustainable and scalable method, which are applicable to the industrial applications. We chose aluminium as the principal material considering its extensive usage on aircrafts and heat exchangers. Clearly the problem has strong social relevance and a potential to make deep positive impact.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project sought to
I. develop high precision nanotextured (<10 nm) surfaces with controlled nanomechanical properties
II. gain fundamental insights to how such nanoengineered surfaces can (i) delay ice formation and resist high-speed liquid impacts and (ii) protect against abrasion and corrosion.

A number of advances were made in order to deliver the three work packages (WPs) in the project.

First, we focussed on electrochemical anodization can achieve morphology control at the nanoscale, while using environment friendly electrolytes and etchants. This allowed us to investigate how safer chemicals can be used to achieve similar surface texture orecision as previously. The work was published as a journal article and a thorough book chapter.

Second, for further precision, surface grown metal-organic frameworks (MOFs) were introduced as sustainable, transparent, and amphiphobic (repels water as well as organic solvents) coatings. The approach enabled us to overcome issues such as avoiding use of per and polyfluoroalkyl substances (PFAS) which are known to have major health and environmental issues. These surfaces were also able to resist high-speed liquid impact (up to ∼35 m/s, typical of cars on a highway for example) and offered low ice adhesion (https://doi.org/10.1021/acs.nanolett.1c00157). Perhaps just as interestingly these surfaces offer a texture with hierarchy of nanoscale features. We call this nanohierarchical surfaces which have sub-nanometer scales pores. We also think that this surfaces may absorb pollutants directly from air. So far, we have demonstrated this by these surfaces absorbing water pollutants. The approach of highly precise nanoengineered surfaces was extended by using covalent organic frameworks (COFs), based coatings (https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202302466). These are chemical more stable and the precision allowed us to avoid ice formation down to -28C and scaling. We feel that these nano-precision, PFAS free surfaces should have fairly wide range of applications.

Third, we showed that by using flexible materials we can improve the robustness of liquid repellent surfaces. This is a principle that natural examples of liquid repellent surfaces such as butterfly wings or plant leaves inherently benefit from. The work was published in Nature Materials (https://doi.org/10.1038/s41563-018-0044-2) and we have now used it to make robust coatings with a wide variety of materials. This line of work led to an ERC Proof of Concept project around developing sustainable coatings for wind turbine blades. We are currently in the process of raising seed round to set-up a spin outcompany around sustainable, PFAS free coatings.

Fourth, we developed another nanocomposite which is simultaneously piezoelectric and piezocatalytic without requiring any poling step (i.e. self-poled). The films made of this material (https://doi.org/10.1016/j.nanoen.2020.105339) feature high power density (47.14 mW cm-3) subject to simple hand tapping and degrade harmful carcinogenic dyes (i.e. water pollutants with >90% within 20 min. This water remediation can happen in dark just with mechanical action, which is very different to light activated water remediation which relies on a source of light.

These innovations allowed us to team up with clinician to develop sensorised surgical gloves. These sensors are essentially similar to some of the nanocomposite coatings mentioned above. These are very inexpensive and we think they should enable safer surgeries. For example, we used such sensorised gloves to measure forces in real-time, during validated surgical tasks and other interventional applications. (10.1227/neu.0000000000002239). We are also investigating use of these sensors for helping to detect fetal orientation during labour (https://www.bbc.co.uk/programmes/w3ct31zn)

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project allowed us to gain and demonstrated a number of new insights.
I. Electrochemical anodization can achieve morphology control at the nanoscale, while using environment friendly electrolytes and etchants.
II. Surface grown metal-organic frameworks (MOFs) can be used as sustainable, transparent, and amphiphobic (repels water as well as organic solvents) coatings. The approach enabled us to overcome issues such as avoiding use of per and polyfluoroalkyl substances (PFAS) which are known to have major health and environmental issues. These surfaces were also able to resist high-speed liquid impact and, just as interestingly, offer a texture with hierarchy of nanoscale features. We call this nanohierarchical surfaces which have sub-nanometer scales pores. We also think that this surfaces may absorb pollutants directly from air. So far, we have demonstrated this by these surfaces absorbing water pollutants. The approach of highly precise nanoengineered surfaces was extended by using covalent organic frameworks (COFs), based coatings. These are chemical more stable and the precision allowed us to avoid ice formation down to -28C and scaling. We feel that these nano-precision, PFAS free surfaces should have fairly wide range of applications.
III. We showed that by using flexible materials we can improve the robustness of liquid repellent surfaces. This is a principle that natural examples of liquid repellent surfaces such as butterfly wings or plant leaves inherently benefit from. The work was published in Nature Materials and we have now used it to make robust coatings with a wide variety of materials.
IV. We developed another nanocomposite materials which is simultaneously piezoelectric and piezocatalytic without requiring any poling step (i.e. self-poled). The films made of this material produce produce power (47.14 mW cm-3) when subject to simple hand tapping and degrade harmful carcinogenic dyes (i.e. water pollutants with >90% within 20 min. This water remediation can happen in dark just with mechanical action.

Cover image from Nature Materials, durable and flexible liquid repellent coatings