Invited Speakers

Abstract

The physical properties of polymers depend on a range of both structural and chemical parameters. Apparently trivial changes in polymer topology, such as joining the two chain ends to form a ring, can profoundly affect molecular conformation and dynamics, and therefore have a great impact on polymer properties. The focus of the talk is on cyclic polymers which are the simplest model system where reptation is completely suppressed.

Compared to linear chains, experimental work using neutron scattering has been limited due to lack of well-characterized ring samples, and deuterated analogues. However, small angle neutron scattering (SANS) data are now available on a range of polymer systems. Our conformational study of linear and cyclic poly(dimethyl siloxane) (PDMS) is consistent with more recent work on other polymers.

Most of the literature deals with the long-range dynamics of high molecular weight cyclics where the reptation model comes into play. However, the absence of chains ends has a wider impact on the motion of rings, even on a local scale, as shown by our work on linear and cyclic PDMS using quasi-elastic neutron scattering and covering a wide range of molar masses. This work, supported by theoretical predictions and computations, is discussed in the context of the broader literature.

Bio

Valeria graduated in Pure Chemistry from the University of Padova, and received her PhD in Polymer Science in 1992 from Imperial College London. Following a postdoctoral fellowship also at Imperial, she joined the faculty at Heriot-Watt University, Edinburgh, in 1996. Her research focuses on the molecular-level study of polymer structure and dynamics, employing extensive neutron scattering and spectroscopy methods. Her group elucidates physical properties such as conformation, topology and orientational order in model polymer nanocomposites and membranes for water purification, and establishes fundamental correlations with material performance.

Abstract

The prediction of the adsorption and dynamic properties of polymers at solid and soft interfaces is an important technological and biological problem. Solid interfaces are indeed present in all polymer composites (where particles are dispersed into a polymeric matrix with the aim of improving its mechanical and rheological properties) but also relevant for many applications such as for coating. Polymers adsorb also at liquid interfaces in many industrial processes, such as liquid/liquid extractions, solvent displacement methods, or emulsifications, and also when used for biological applications, such as drug nanocarriers, biocompatibilizers, or protective coatings.

In this talk we will show how multiscale modelling can help in predicting the adsorption properties of polymers at solid surfaces (specifically carbon black) and soft interfaces (liquid/liquid). We will clarify the thermodynamic of adsorption and how the properties of the interface as well as of the bulk polymer change upon adsorption.

Bio

Paola obtained her PhD in Materials Science in 2004, followed by a postdoc at the University of Bologna, and a Humboldt Foundation fellowship at the Technical University of Darmstadt. She was awarded an RCUK fellowship and joined the University of Manchester in 2008. Paola’s research focuses on soft matter simulations, and her group specialises in developing new multiscale coupling procedures to link different modelling techniques from quantum mechanics to dissipative particle dynamics. Currently active research areas are: electrolyte/graphene interfaces, polymer composites for industrial applications and surfactant solutions. 

Abstract

It is well understood that under confinement, typically for length scales on the order of a nanometer to tens of nanometers, polymers exhibit physical properties that manifest the influence of entropic affects and of interactions between polymer chain segments and external interfaces. Physical properties, including glass transition temperatures (Tg), chain dynamics, physical aging rates, mechanical moduli, thermal conductivities and charge carrier mobilities are well documented to exhibit film thickness (h) dependent behavior. Three topics will be discussed in this presentation. (1) The origins of the film thickness dependencies of these different physical properties will be briefly explained.  (2) Macromolecular architecture, linear chain or multi arm star-shaped, strongly influences the magnitudes of the thickness dependencies of the Tgs and the physical aging rates of polymers.  The transitions from linear-chain, to star-like, to colloidal-like behavior will be explained. (3) Different experimental techniques -incoherent neutron scattering, spectroscopic ellipsometry and broad band dielectric spectroscopy -are known to yield Tgs of different magnitudes and, in some cases different h-dependent trends, for the same polymer thin film/substrate systems. While these techniques rely on different observables that denote the transition, the origins of these discrepancies  remain a matter of debate. It will be shown how insights based on the first quantitative measurements of the strengths and length-scales of the interactions at the buried interfaces between different polymers and a substrate, using kelvin force microscopy, provide a pathway to reconcile these apparent discrepancies.

Bio

Peter graduated from Hunter College and obtained his MS and PhD from Cornel University (1985). He joined Sandia National Laboratories, and then the faculty at the University of Texas at Austin (1996), later moving to the University of Michigan in 2005 to chair the Department of Materials Science and Engineering. He became deputy laboratory director, Science and Technology, and chief research officer at the National Renewable Energy Laboratory (NREL) in 2016. Peter is the recipient of numerous awards and fellowships (APS, AAAS, MRS etc.), and was the inaugural editor in chief of MRS Communications.  He is a former President of the Materials Research Society.

His research is devoted to developing a fundamental understanding of, and controlling, the structure and properties of "soft" materials for applications that include: energy conversion, active and passive coatings, membranes, sensors and organic electronic and electrorheology.

Phase transitions in polyelectrolyte gels
Matt Hennessy, University of Bristol, UK

Abstract:

When a polyelectrolyte gel is placed in an ionic solution, slight alterations in the environmental parameters can trigger enormous changes in the gel volume.  In some cases, the gel volume will change discontinuously, resulting in a volume phase transition.  Many studies of the volume phase transition focus on the equilibrium and electrically neutral states of the gel.  In this talk, I will discuss how a novel phase-field model can be used to explore the evolution of the gel structure during the volume phase transition.  Numerical simulations reveal that the volume phase transition can occur via two routes.  In the first case, a swelling/deswelling front propagates into the gel from its free surface.  In the second case, spinodal decomposition occurs alongside front propagation.  I will then re-visit the assumption of electroneutrality by studying the electric double layer at the gel surface.  Phase separation within the electric double layer can trigger the self-assembly of electrically charged phases throughout the entire gel.  I will conclude by discussing how the breakdown of electroneutrality can provide an alternative interpretation of the volume phase transition.

Bio

Matt completed a DPhil in Applied Mathematics at the University of Oxford in 2014.  Afterwards, he held a postdoctoral fellowship at Imperial College London, a Marie Skłodowska-Curie Fellowship at the Centre de Recerca Matemàtica in Barcelona, and a Hooke Research Fellowship at the University of Oxford.  In 2021, he joined the University of Bristol as a Lecturer in Engineering Mathematics.  His research focuses on the continuum modelling of complex materials.  He is especially interested in instability-driven pattern formation in polymeric systems and its application to functional materials.

Abstract

“Plastic is fantastic…” We live in a plastic world, and it’s impossible to imagine a world where plastic isn’t the dominant material for applications from construction to electronics, from textiles to packaging. But we are increasingly aware of how our misuse of plastics, especially after their working life is bringing growing environmental consequences… So what role can bio-derived and natural polymers do in helping society to maintain the efficiency and convenience gains brought about by plastics whilst mitigating their unintended environmental consequences…

Futamura has a foot in both camps. We are a world leader in regenerated cellulose technology, producing cellulose films, casings and non-wovens for applications ranging from packaging, to sausage-skins and wet-wipes, with production in Japan, UK and USA. In Japan we also produce conventional plastic products. This gives us a uniquely balanced view of the plastic versus bio-derived polymers debate.

The fact is that from an industrial perspective, the odds are actually quite firmly (and I’d argue unfairly) stacked against bio-derived materials. There is no lack of amazing innovation going on at an academic and R&D level. The challenge is converting that into production at scale.

This presentation will cover those challenges and set out where biomaterials have the greatest chance of success. It will illustrate where they can make the greatest positive contribution to a more sustainable materials world and what the future could and should look like. And it will highlight where academia and research can play a key role in making this work to best effect for both industry and society

Bio

Andy Sweetman is a sustainable packaging market expert, and currently chairs the UK’s Biobased and Biodegradable Industries Association. He is also a past Chairman of the board of European Bioplastics (2009-2013). Following a degree in Modern Languages, and further studies in Packaging Technology, Andy occupied several roles at Innovia, and is currently a director at Futamura UK. He has extensive experience in the flexible packaging industry, with a focus on sustainability and cellulose and bioplastic films.

Abstract

TBC

Bio

Jan studied Chemical Engineering at KU Leuven, Belgium, obtaining his PhD in 1996, and was a postdoctoral fellow of Elf Aquitaine and the Fund for Scientific Research – Vlaanderen. He joined the faculty at KU Leuven in 2000, and ETH Zürich in 2014. He is the recipient of numerous awards, including the Onsager professorship and Onsager medal, and 2019 Weissenberg Award of the European Society of Rheology. His research focuses on the rheology and applications of complex fluid-​fluid interfaces, colloidal suspensions and the development of novel experimental methods and soft matter applications.