Composites bring together the best aspects of their components in a single material. Typically made up of polymeric materials with a reinforcing agent, composites have diverse applications in transportation, sports, tissue engineering, and as energy storage devices. But understanding the manufacture and performance of these composites requires research at the intersection of chemistry, materials, and engineering.
The Polymer and Composite Engineering (PaCE) group, led by Alexander Bismarck, is doing just that by bringing together varied research expertise in interfaces and colloids, reinforcement materials, and polymers. The group is spread between two locations in Austria and the UK, and embraces interactions with other colleagues from across academia and industry including at Imperial College London, the Universities of Bristol, Manchester, and Exeter, as well as VTT, Aalto, Bordeaux, Fraunhofer in Europe, and Nanyang Technological University and City University Hong Kong in Asia. The work of the PaCE group and its collaborations are made possible through the continuous support of the UK Engineering and Physical Science Research Council (EPSRC), the European funding framework (FP7), the Austrian Research Councils (FWF and FFG), and various industry partners.
Among his other commitments, Alexander Bismarck is editor of the Elsevier journal Reactive and Functional Polymers.
Alexander Bismarck talked to Materials Today about his research and future plans…
How long has your team been running?
I founded the PaCE group in 2003, a year after I joined the Department of Chemical Engineering at Imperial College London following my move from industry back to academia. In September 2012, parts of the group moved with me to Vienna when I took up the Chair in Materials Chemistry in the Faculty of Chemistry at the University of Vienna. In 2013, we formed the foundations of the newly established Institute of Materials Chemistry and Research. Now the Institute consists of two groups: the PaCE group and the Christian Doppler Laboratory for Thermoelectricity headed by Peter Rogl.
How many staff makes up your team?
The PaCE group currently has 23 members – one senior researcher, nine postdocs, nine PhD students, three technicians, and a secretary. Moreover, we have quite a few Master's students completing projects within the group, alongside both visiting and bachelor students. The visiting students come from around the world (Brazil, Thailand, France, and the UK). The number of students in the group varies, depending on student interests and the attractiveness of our current projects. To appeal to young people and generate interest, we frequently host visiting professors.
What are the major themes of research in your lab?
We are interested in polymer and composite materials. Our work focuses on the development of innovative composites, both with structural and functional properties, porous polymers, polymer drag reduction, and green materials.
Our research is driven by real world challenges; for example, composites are strong and stiff materials but fail catastrophically without much prior warning. We, together with colleagues from Bristol and Imperial, are exploring approaches to create light, strong, and stiff composites that exhibit significant yielding prior to failure. Moreover, the limitations of current advanced composites, such as poor compression properties, can also be addressed by further reinforcing the polymer matrix with carbon nanotubes, for instance. We call such materials ‘hierarchical’ composites. We have shown that compression strength and toughness can be improved by the introduction of nanoscale reinforcements.
Besides composites made from synthetic constituents, we are also interested in one-dimensional renewable nanomaterials, such various nanocellulose forms and nanochitin, and their composites.
Another research theme aims to develop polymer materials for challenging environments, such as those encountered in oil and gas wells. To explore unconventional oil and gas reservoirs, information about the reservoir is required, which can be obtained by using tracer materials that are added to completion or fracking fluids. These completion fluids are complex formulations, containing various polymers and other additives, which need to be released at or carried to the zone of interest. We are working on polymers with the desired properties or functionality.
How and why did you come to work in these areas?
When I started studying chemistry, I wanted to do chemistry with a pair of pliers! But during the course of my studies at the Technical University Berlin, it was polymer science and engineering that interested me most. Afterwards, during my postdoc in the Surfactant & Colloid Group at the University of Hull, I got to know the challenging problems facing the oil and gas industry, which got me hooked. After my postdoc, I joined Sulzer Innotec in Winterthur, Switzerland, as an R&D engineer and was fortunate to learn how to produce thermoplastic composites. In industry, I developed composite materials but never had the chance to solve interesting problems, which was possible after joining Imperial.
My chemistry background, postdoc, and industry experience allowed me to explore the interface between chemistry, materials, and engineering where I feel most at home. Besides, I was fortunate to start at Imperial at roughly the same time as my colleagues Milo Shaffer and Emile Greenhalgh with whom I established great and fruitful collaborations.
What has been your highest impact/most influential work to date?
Our most influential work is probably the tool kit we developed for the synthesis of macroporous polymers by the polymerization of emulsion templates. High or medium internal phase (ratio) emulsions (HIPEs or MIPEs) with a continuous phase consisting of or containing monomers are used as templates for the preparation of interconnected macroporous polymers. Such polymers are called poly(merized)M/HIPEs, which are obtained after the removal of the internal emulsion phase. Besides academic interest, applications of polyHIPEs have remained limited to nappies and a few chromatography applications mainly because of their poor mechanical properties and low permeability. The challenge to be tackled is to improve both simultaneously.
We have now introduced a new class of macroporous polymers called poly-Pickering-M/HIPEs, produced by polymerization of particle-stabilized (Pickering) M/HIPEs. Using particulate emulsifiers provides a number of processing advantages: it removes the need for structurally parasitic surfactant and allows the preparation of macroporous polymers with much larger pores, as commonly observed in polyHIPEs made from surfactant stabilized emulsions. However, poly-Pickering-M/HIPEs are typically closed-cell but this new class of polyHIPEs with millimeter-sized pores can be opened up. Now we have a tool kit available to create novel polyM/HIPEs that, combined with different polymer chemistries, means we can produce a whole raft of new interconnected macroporous polymers for applications ranging from tissue engineering to energy harvesting and storage.
However, I guess the greatest real impact was made by our composite manufacturing line, which has been used by various industrial partners as a model system to test, redesign, and optimize industrial production lines for thermoplastic composites.
What facilities and equipment does your lab have?
We have facilities to manufacture materials at small scale, ranging from well-equipped chemistry laboratories, over mills, and extruders to a composite manufacturing line. We have standard polymer analytics and equipment to characterize morphology/topography as well as physical, thermal, and mechanical properties. In addition, we have a test facility for liquid flows in pipes at high Reynolds numbers. Within the Faculty of Chemistry, we have access to a mechanical and glass blowing workshop and elemental analysis, as well as X-ray diffraction, NMR, and mass spectrometry centers. If we need access to more specialized facilities, we work with our colleagues at the TU Wien, the University of Natural Resources and Life Sciences Vienna (BOKU), or TGM (die Schule der Technik).
Do you have a favourite piece of kit or equipment?
Our research requires quite a few pieces of equipment. However, my most favorite pieces of equipment are our kitchen appliances – mixers and blenders, which we use to produce interesting macroporous polymers and most of our nanocellulose. They are inexpensive, reliable, and easy to use. All we need are ideas to produce new materials. Usually these processes are scalable, which helps to create significant industrial interest in some of our material developments.
Another unique piece of equipment I like is our laboratory-scale composite production line, which we designed and built ourselves over a number of years. Subsequently, we added a fiber tow spreading unit and an atmospheric plasma treatment unit. Using our production facility, we can reliably produce unidirectional fiber-reinforced polymer composites using a relatively small amount of polymer matrix. This allowed us (in collaboration with Milo Shaffer and Emile Greenhalgh) to test the idea of further reinforcing the small matrix component in advanced composites with carbon nanotubes – resulting in hierarchical composites with improved mechanical properties and the added the benefit of electrical conductivity.
What is the key to running a successful lab?
I think the key is to recruit curious, skilled people interested in science and engineering that fit into our team and to maintain a ‘team spirit’ even if the group is split and works at two locations. We are a group and not a collection of individuals. We have lunch and/or coffee together and meet regularly even outside the workplace to maintain team spirit. The group has always been most productive the more people worked together, helped each other, and pushed ideas forward.
In addition, a crucial part of our success is to provide the group members with the freedom to explore their own ideas and make ‘mistakes’. Sometimes, those small mistakes resulted in great ideas, which we explore further.
How do you plan to develop your lab in the future?
After the move from Imperial College London to the University of Vienna, we started anew to design and build laboratories and reassemble a group. In the years to come, we want to take the opportunities available in Austria and continue to push forward with our ideas to create novel macroporous materials and explore routes to process them into interesting devices for applications such as energy harvesting and storage. In composites, we will continue to work with our collaborators to develop the next improved generation of composites that feature a significant degree of ductility or multifunctionality. These composites will be strong, stiff, yield, and have energy storage or shape memory capabilities.
- T.M. Herceg, M.S.Z. Abidin, E.S. Greenhalgh, M.S.P. Shaffer and A. Bismarck. Thermosetting hierarchical composites with high carbon nanotube loadings: en route to high performance. Composite Sci. Technol. 127 (2016) 134–141.
- C. Tridech, H.A. Maples, P. Robinson and A. Bismarck. High performance composites with active stiffness control. ACS Appl. Mater. Interfaces 5 (2013) 9111-9119.
- V.O. Ikem, A. Menner, T.S. Horozov and A. Bismarck. Highly permeable macroporous polymers synthesized from Pickering Medium and High Internal Phase Emulsion Templates. Adv. Mater. 22 (2010) 3588 - 3592.
- V.O. Ikem, A. Menner and A. Bismarck. High Internal Phase Emulsions stabilized solely by functionalized silica particles. Angew. Chem. Inter. Ed. 47 (2008) 8277 – 8279.
- M. Pommet, J. Juntaro, J.Y.Y. Heng, A. Mantalaris, A.F. Lee, K. Wilson, G. Kalinka, M.S.P. Shaffer and A. Bismarck. Surface modification of natural fibers using bacteria: Depositing bacterial cellulose onto natural fibers to create hierarchical fibre reinforced nanocomposites. Biomacromolecules 9 (2008) 1643–1651.
- K.K.C. Ho, A.F. Lee, and A. Bismarck. Fluorination of carbon fibres in atmospheric plasma. Carbon 45 (2007) 775–784.