Synthesis of bio-based supramolecular gelators to act as thickeners in industrial applications

Project background (identification of the problem and its importance and relevance to sustainability)

Following a recent increase in social and environmental pressures, along with new regulations to control microplastic release into the environment; industry has put a huge focus on ensuring formulations are made from readily biodegradable, sustainable materials.

Thickeners are a key component of many formulations however they are often formed of high molecular weight polymers, such as poly (acrylic acid), which are favoured for their ability to form gels at a very low weight percent. Unfortunately, these high molecular weight polymers have poor biodegradability, and are often sourced from petrochemicals, whilst bio-based polymer alternatives, such as hydroxyethyl cellulose, are costly and require heavy extraction.

Thus, the challenge arises to create an alternative to high molecular weight polymers, that are bio-degradable, designed with consideration of sustainability, and that perform equally at a similar weight percentage.


Proposed solution and methodology

It is proposed that by designing low molecular weight structures (<2000Da) with the ability to self-assemble though supramolecular, non-covalent interactions, gels can be formed with similar properties to the polymer-based systems.

When a low molecular weight gelator (LMWG) is mixed with a solvent and a stimulus is applied, non-covalent interactions (such as hydrogen-bonds, pi-pi stacking or van-der-waals forces) can lead to the formation of fibrils, which entangle together and entrap solvent molecules within the matrix forming a gel. Since the backbone of these fibrils are non-covalent, they can be broken by applying another physical or chemical stimulus, which could be tailored to conditions in waste-treatment.

One of the main challenges is to design LMWG's that can form gels in polar solvents such as water and propylene glycol, as the preferred solvents in personal-care formulations. Solvent effects are complex within these systems and therefore the behaviour of gelators in different solvent systems is difficult to predict. A key part of the project will focus on expanding an existing structure-property database to improve machine learning and prediction.

The project will begin with the synthesis of literature-reported gelators, aiming to obtain these structures via 'green' synthetic pathways. Using the chemistry acquired from the previous study, the project will then move toward the design of LMWGs from bio-based, waste, feedstocks such as terpenes, vanillin and macroalgae.

Extensive testing of the properties of each gelator in different solvent systems and formulations will be carried out, comparing to polymer-based formulations. Rheological screening, spectroscopic imagery and toxicology studies will all be key components of this work.

This CDT will deliver impact aligned to the following agendas:

People
A2P will provide over 60 PhD graduates with the skill sets required to deliver innovative sustainable products and processes into the UK chemicals manufacturing industry. A2P will inspire and develop leaders who will:
- understand the needs of industrial end-users;
- embed sustainability across a range of sectors; and
- catalyse the transition to a more productive and resilient UK economy.

Economy
A2P will promote a step change towards a circular economy that embraces resilience and efficiency in terms of atoms and energy. The benefits of adopting more sustainable design principles and smarter production are clear. For example, the global production of active pharmaceutical ingredients (APIs) has been estimated at 65,000-100,000 tonnes per annum. The scale of associated waste is > 10 million tonnes per annum with a disposal cost of more than £15 billion. Consequently, even a modest efficiency increase by applying new, more sustainable chemical processes would deliver substantial economic savings and environmental wins. A2P will seek and deliver systematic gains across all sectors of the chemicals manufacturing industry. Our goals of providing cross-scale training in chemical sciences with economic and life- cycle awareness will drive uptake of sustainable best practice in UK industry, leading to improved economic competitiveness.

Knowledge
This CDT will deliver significant new knowledge in the development of more sustainable processes and products. It will integrate the philosophy of sustainability with catalysis, synthetic methodology, process engineering, and scale-up. Critical concepts such as energy/resource efficiency, life cycle analysis, recycling, and sustainability metrics will become seamlessly joined to what is considered a 'normal' approach to new molecular products. This knowledge and experience will be shared through publications, conferences and other engagement activities. A2P partners will provide efficient routes to market ensuring the efficient translation and transferal of new technologies is realised, ensuring impact is achieved.

Society
The chemistry-using industries manufacture a rich portfolio of products that are critical in maintaining a high quality of life in the UK. A2P will provide highly trained people and new knowledge to develop smarter, better products, whilst increasing the efficiency and sustainability of chemicals manufacture.
To amplify the impacts of our CDT, effective public engagement and technology transfer will become crucially important. As a general comment, 'sustainability' styled research is often regarded in a positive light by society, however, the science that underpins its effective implementation is often poorly appreciated. The University of Nottingham has developed an effective communication portfolio (with dedicated outreach staff) to tackle this issue. In addition to more traditional routes of scientific communication and dissemination, A2P will develop a portfolio of engagement and outreach activities including blogs, webpages, public outreach events, and contribution of material to our award-winning YouTube channel, www.periodicvideos.com.

A2P will build on our successful Sustainable Chemicals and Processes Industry Forum (SCIF), which will provide entry to networks with a wide range of chemical science end-users (spanning multinationals through to speciality SMEs), policy makers and regulators. We will share new scientific developments and best practice with leaders in these areas, to help realise the full impact of our CDT. Annual showcase events will provide a forum where knowledge may be disseminated to partners, we will broaden these events to include participants from thematically linked CDTs from across the UK, we will build on our track record of delivering hi-impact inter-CDT events with complementary centres hosted by the Universities of Bath and Bristol.