Block copolymer-enabled mesopore sensing

Lead Research Organisation: University College London
Department Name: Chemical Engineering

Abstract

Material architectures with pores on the 5 - 50 nm length scale offer distinct opportunities for chemo- and biosensing applications. Capillary condensation, i.e. the filling of pores with condensed liquid from the vapour phase, is highly dependent on the pore size and relative humidity. Efficient trapping of target analytes relates to a combination of adequate surface interaction and control over spatial confinement.

The aim of this research proposal is to build porous materials with unprecedented functioning in humidity and biomedical sensing through the structural control offered by the use of block copolymer (BCP) co-assembly. BCPs are macromolecules that are composed of chemically dissimilar building blocks, which are linked by covalent bonds. Solvent evaporation leads to phase separation into nanoscale morphologies, which can be controlled by the molecular design of the BCPs. In a co-assembly approach, BCPs are used as sacrificial host to structure direct inorganic guest material. After structure formation, the organic material is removed to reveal a porous inorganic network. Conceptually, this approach allows to systematically vary and control key parameters of porous thin films, such as porosity, pore size and dispersity as well as the pore architecture, by modifications to the molecular building blocks and processing conditions.

In the course of the proposed study, parameters that govern the pore size and dispersity will be elucidated and general effectiveness of BCP-derived porous materials evaluated on two different sensing platforms, namely humidity and biomedical sensing.

In humidity sensing, the fabrication of transparent material architectures will be pursued that allow accurate determination over the full humidity range via capacitative means, offering an integrated route to responsive glazing components for automotive and building applications. Findings will be implemented in a windscreen prototype with responsive anti-fogging control. In the light of the gradual extinction of the internal combustion engine towards electrified mobility where heat is no longer abundant and thus a significant burden to the energy consumption, such technology will offer widespread impact.

For biomedical sensing, the trapping of target analytes in porous networks will be studied for a number of candidates whose quantification is important in therapy, e.g. viruses, therapeutic antibodies, exosomes or microRNA. Applicability of effective trapping and the envisioned superior pore size control will be implemented in novel types of biosensors that allow detection by changes in electrochemical currents associated to a blockage of the pores. Successful proof-of-principle will stimulate the development of low-cost handheld diagnostic devices in point-of-care applications to improve therapeutic outcomes at minimal side-effects.

Planned Impact

Stimulation of Industry
The identified mesopore sensing opportunities offer potential for disruptive technologies in for the UK relevant multi-bn GBP markets, i.e. automotive, glazing and medical technology. Two partners with proven track record on innovation support this proposal, namely the solution-based coating team of Simon Hurst at Pilkington NSG and Prof. Nicolas H. Voelcker at Monash University.
The automotive glass market currently values at around USD 15bn with Pilkington NSG being one of the top 3 suppliers. Ever since the invention of the float glass process in the 1950s, UK research developments innovated the industry, e.g. low-k coatings, self-cleaning glass, conductive substrates and switchable coatings. As float glass meanwhile is a commodity material with overcapacities worldwide, the industry faces significant pressure towards innovation and added functionality. The proposed concept of a transparent humidity sensor offers an integrated route to responsive components for efficient energy management, e.g. in automotive windscreens. Especially in the light of the gradual extinction of the internal combustion engine towards electrified mobility where heat is no longer abundant and thus a significant burden to the energy consumption, this may become a transformative technology.
Medical technology is a key sector in the UK a growth forecast of 7.3% p.a. and an overall value of GBP 9.1bn by 2018, representing the sixth largest market worldwide and third largest in Europe. Currently 3,000 UK based companies operate in this sector with a total number of 71,000 employees. Personalised health care that takes into account individual pharmacodynamics and pharmacokinetics for more efficient therapy with reduced side effects is a major topic for European Research & Development with more than EUR 2bn being invested by the European Union within the Horizon 2020 framework, which is likely to trigger further stimulus for the UK Technology Sector. Close ties exist with UCL Business, with whom the applicant is already filing IP and developing prototypes for clinical validation on other point-of-care related concepts.


Training of Future Engineers and Scientists
The project provides a postdoctoral research associate position with close ties to industry through the partnership with Pilkington NSG, offering both academic stimulation to industry and industrial stimulation to the academic community. The add-on PhD studentship represents a second full time position with significant training and qualification opportunities linked to this proposal. Further leverage potential exists through five EPSRC Centres for Doctoral Training with related topics at UCL. The applicant engages with undergraduate students through summer internships (EPSRC vacation bursary) and research-influenced teaching, both of which will benefit from the proposed research.


Engaging with the General Public
The research group of the applicant recently established its own channel on YouTube with tutorials for research
techniques. This project further provides a multitude of examples to illustrate the relevance of engineering and natural sciences for prospective university students with whom the applicant engages through a number of internship and career advice schemes (In2Science and Future Frontiers). Further engagement is planned in outreach activities, such as the All Academic Festival and the Spark Festival. The research on mesopore
humidity sensing is particularly well suited for public demonstration of nano-effects through hands-on
demonstrators.

Publications

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Alvarez-Fernandez A (2020) Structural Characterization of Mesoporous Thin Film Architectures: A Tutorial Overview. in ACS applied materials & interfaces

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Reid B (2019) Tuning Pore Dimensions of Mesoporous Inorganic Films by Homopolymer Swelling. in Langmuir : the ACS journal of surfaces and colloids