09:00 to 09:30 Registration 09:30 to 09:40 Welcome from Christie Marr (INI Deputy Director) 09:40 to 10:20 Randall Kamien (University of Pennsylvania)Packing Liquid Crystal Domains Focal conic domains are complex, geometric configurations found in cholesteric and smectic liquid crystals: they are not topologically protected but are very low energy states. How do they pack on finite geometries? Come and listen! INI 1 10:20 to 10:40 Thomas Machon (University of Bristol)Contact Topology and the Cholesteric Landscape Cholesterics, chiral liquid crystals, typically exhibit a large number of metastable states for a given geometry. This is both a blessing and a curse, it affords great potential for the creation of new devices but can also mean that tight control of a structure can be difficult to achieve. In this talk we will discuss why it is that the tendency of cholesterics to twist means that they have a complex energy landscape. Our principle tools will be drawn from the field of contact topology. By describing cholesterics as contact structures we will show that non-vanishing twist implies conservation of the layer structure in cholesteric liquid crystals. This characterises the morphological richness of these systems, leads to a number of additional topological invariants for cholesteric textures that are not captured by traditional descriptions, and gives a geometric characterisation of cholesteric dynamics in any context, including active systems, those in confined geometries or under the influence of an external field. INI 1 10:40 to 11:10 Morning Coffee 11:10 to 11:50 Margarida Telo da Gama (Universidade de Lisboa)Self-organization of patchy colloidal particles: 2 & 3DSession: A part of the celebration of Women in Materials Science (WMS) We investigate the self-organization of patchy colloidal particles deposited on flat substrates in three (2+1) and two (1+1) spatial dimensions. We propose and use a simple stochastic model for the interaction between the particles, which allows the simulation of very large systems, to probe the long time and large-scale structure of the deposited films. The latter exhibit well defined surface, liquid and interfacial regions except when the growth is dominated by the formation of chains, which occurs for systems with an effective valence close to two. We also investigate the interfacial roughening in (1+1) systems and compare our results with those obtained experimentally for evaporating droplets. We find, in line with the experiments, that when the film growth is dominated by chains the generic Kardar-Parisi-Zhang (KPZ) interfacial roughening is replaced by quenched KPZ. We discuss this somewhat surprising result. INI 1 11:50 to 12:30 Anja Schlömerkemper (Julius-Maximilians-Universität Würzburg)Evolution of magneto-viscoelastic materialsSession: A part of the celebration of Women in Materials Science (WMS) In this talk I will survey our recent approach to the modeling of magneto-viscoelastic materials. Our system of partial differential equations consists of the Navier-Stokes equations, the Landau-Lifshitz-Gilbert equation and an evolution equation for the deformation gradient. I will address modeling aspects, analytical results and potential applications. INI 1 12:30 to 13:30 Lunch at Westminster College 13:30 to 14:10 Hillel Aharoni (Weizmann Institute of Science)Making Faces: Universal Inverse Design of Thin Nematic Elastomer Surfaces Thin nematic elastomer sheets can be programmed, via the nematic director field embedded into them, to take different shapes in different environments. Recent experiments from various groups demonstrate excellent control over the director field, thus opening a door for achieving accurate and versatile designs of shape-shifting surfaces. At the crux of any effort to implement this design mechanism lies the inverse design problem -- given an arbitrary surface geometry, constructing the director field that would induce it. In this talk I describe several aspects of this inverse problem. I present a numerical algorithm for finding global approximate solutions for any 2D geometry. I also show that many exact solutions always exist locally and can be readily integrated, and classify the set of all director fields that deform into an arbitrary given geometry. These results allow optimizing the resultant director fields for different purposes, e.g. maximizing the domain of a global solution, increasing its robustness, reducing residual stresses, or controlling the entire shape-shifting path. INI 1 14:10 to 14:50 Ard Louis (University of Oxford); (University of Oxford)Simplicity bias in random design The design of a soft-matter system can be recast as an input-output map, where the inputs are the parameters that fix the components and their interactions, and the outputs describe the outcome of a self-assembly process. By extending the coding theory from algorithmic information theory, we have recently shown [K Dingle, C. Camargo and AAL, Nat Comm. 9, 761 (2018)] that for many computable maps, the a priori probability P(x) that randomly sampled inputs generate a particular output x decays exponentially with the approximate Kolmogorov complexity $\tilde{K}(x)$ of that output. While Kolmogorov complexity is technically uncomputable, we show how to make approximations that work in practice, allowing for a tight upper bound on P(x). For soft matter systems, simplicity bias implies that randomly sampling design inputs will naturally lead to outputs that have low descriptional complexity. Since high symmetry structures typically have low descriptional complexity, simplicity bias implies that randomly picking design patterns can lead to the spontaneous emergence of highly symmetric self-assembled structure. We provide evidence for these trends for self-assembled RNA and protein structures. INI 1 14:50 to 15:20 Afternoon Tea 15:20 to 16:00 Gareth Alexander (University of Warwick)Geometric Topology of Liquid Crystal Textures: Chirality and Bend The textures and phases of liquid crystals are replete with geometric motifs, and the geometric approach to elasticity underpins a large portion of nonlinear theories. Despite this, the basic characterisation of topology comes from the homotopy theory without particular attention to geometric features. I will describe our recent work developing geometric approaches to liquid crystal topology, describing cholesteric point defects and topological chirality, and the geometric features of bend distortions, illustrated by applications to the twist-bend nematic phase. INI 1 16:00 to 16:40 Alex Travesset (Iowa State University)Soft Skyrmions and Programmable Self-Assembly of Superlattices Materials whose fundamental units are nanocrystals (NC)s, instead of atoms or molecules, are gradually emerging as major candidates to solve many of the technological challenges of our century. Those materials display unique structural, dynamical and thermodynamical properties, often reflecting deep underlying geometric, packing and topological constraints. In this talk, I will discuss the rational design of NC materials by programmable self-assembly. I will present the Orbifold Topological Model (OTM), which successfully describes the structure of crystal or quasicrystal arrangements of NCs (superlattices) by considering capping ligands as Skyrmion textures, which determine the bonding very much like atomic orbitals in lattices of simple atoms. I will show that the OTM describes “atomic orbitals” as consisting of vortices, which enable the generation of a spontaneous valence and reveal the universal tendency of these systems towards icosahedral order, allowing to describe them as quasi-Frank-Kasper phases.  These results will be confirmed by numerical simulations. I will elaborate on the success of the OTM in describing all existing experimental structural data on single component and binary superlattices obtained by solvent evaporation and present new candidate phases. INI 1 16:40 to 17:00 Shayandev Sinha (Harvard University)Thermally actuated portable microvalves using elastomeric focusing Thermally actuated controlled shape changes in soft materials is a challenge as the material shows non-linear expansion characteristics. CTE of many materials is not properly available. In order to focus the expansion of the soft solid into large displacements a confined geometry is created to amplify the shape changes. Here we use an elastomer (PDMS sheet) confined between two rigid layers, which when locally heated using resistive heating expands into the micromolded channels, resulting into a massive relative displacement compared to the case of an unconfined geometry. This principle is used to make microfluidic valves which are electrically controlled (using a 3.3V-5V cellphone battery) and close in less than 100 ms. They operate within a power range of 140-160 mW generated by the specifically designed resistive heating element (in-house made ink) screen printed on the chip. We investigate the parameters of the heating element design, height dimensions and flow conditions through the valves. This technique helps us to make multiple valves along the fluidic pathway with arbitrary positioning. The size of these really help to make the devices portable as one does not need a separate controller for the actuating the valves. INI 1 17:00 to 18:00 Welcome Drinks Reception and poster session at INI