Project 1

TitleFormation and self-organization of nanoparticles with bicontinuous internal structure
Host InstitutionTU/e
Related Work PackagesWP1, WP2, WP4, WP5
Objectives: To form hierarchical hybrid and superporous mineral structures by the molecular self-assembly of bicontinuous polymer nanospheres (BPNs), their infiltration with mineral and their subsequent ordering into colloidal crystals, using LP-EM to monitor and help to direct all stages of the process.

Description: BPNs are colloidally and morphologically stable polymer nanoparticles with a bicontinuous internal structure, which will be formed by the assembly of PEO-b-PODMA. The internal pore network connects to the surrounding solution allowing infiltration with silica. Pore sizes can be tuned through the relative polymers block lengths by ATRP and particle size can be regulated from 50-250 nm through solution conditions during self-assembly (Sommerdijk et al Angew Chem 2015). As PEO catalyses silica deposition (Sommerdijk et al Adv Mater 2003) the PEO blocks will restrict silica deposition to the internal pores and the outer particle surface. LP-EM (with ESR12, INM) in combination with simulations (with ESR6, UM) will be used to study and optimise the mineral infiltration process. Extrusion, size exclusion chromatography and preparative ultracentrifugation (at UoK) will be used to prepare silicified particles with different degrees of polydispersity (typically 5-20 %). A library of particles with different sizes, size ranges and pore diameters will be used to explore the colloidal self-assembly of materials with different packing orders using entropically driven assembly, evaporation assisted assembly (at DSM) and gravitation (at UoK) (Cölfen et al Z. Naturf. 2013). The assembly process will be studied with LP-EM (with ESR2), and compared to simulations (with ESR6, UM). After assembly the polymers will be removed by calcination, and the preservation of meso-structure will be verified by STEM tomography. This will yield super-porous silica structures with a multimodal pore distributions of which the mechanical properties will be studied with indentation experiments and compared with modelling results of ESR6 (UM) and ESR9 (UU).

Expected Results: (i) a library of silicified block copolymer rods with controlled pore architecture; (ii) design principles for BNPs as building blocks with controllable diameter and pore structure; (iii) The controlled formation of organised assemblies of silicified BPBs; (iv) Increased understanding of the role of building block size and size distribution on the pore structure as well as on the mechanical and optical properties of the assemblies formed.

Planned secondment(s):

Project 2

Title Controlled pore architectures though co-assembly of silica and polymer-based nanoparticles
Host Institution TU/e
Related Work Packages WP1 – WP5
Objectives: To co-assemble inorganic (silica) and organic (peptide-based block copolymer micelles) objects to construct hierarchical materials with controllable internal structure and different mechanical properties.

Description: Different arrangements will be achieved 1. using different size combinations of silica particles and polymer assemblies, 2. by modulating interactions between the objects. Monodisperse block copolymer micelles can form ordered colloidal crystalline arrays (e.g. Förster Nature Mater 2007). The co-assembly of such building blocks with silica nanoparticles will provide a unique opportunity to build a variety of hybrid structures, due to the tunablility of sizes and chemical interactions between the organic and inorganic objects used. A library of monodisperse (PDI 1.01-1.001) random copolypeptides and their block copolymers will be prepared using automated synthesis (Sommerdijk et al. Soft Matter 2014). These can have a broad range of charges which are stable over a wide pH range due to internal buffering. Silica nanoparticles (20 - 200 nm) will be co-assembled with block copolypeptide micelles (20-50 nm) as well as with their vesicles (50-200nm) which will act as templates to achieve different degrees of organisation and different mechanical properties. After calcination silicates with predefined pore hierarchy will be obtained and tested for their mass transport-related characteristics (at AN). In addition, silica nanoparticles will be surface-functionalised by linking the random co-polypeptides. Co-assembly of different size batches of nanoparticles with different surface chemistries will be explored to achieve ordered hybrid structures. The development of structure and morphology will be monitored with cryoTEM and LP-EM (with ESR3) in combination with 3D FIB-SEM while mechanical properties will be analysed with indentation experiments. The structure-property relationship will be further developed by comparing with simulations (with ERS9, UU).

Expected Results: (i) Silicates and hybrid materials with controlled pore architecture, (ii) Improved understanding of the influence of size and ionic interactions on the assembly, pore architecture and mechanical properties (iii) Design parameters for mechanically robust porous silica based materials.

Planned secondment(s):

Project 3

Title Low dose LP-EM for multiscale imaging
Host Institution TU/e
Related Work Packages WP2 & WP5
Objectives: To evaluate resolution and contrast in low dose LP-EM we will use polymer, silica and hybrid nanoparticles with different sizes and different electron scattering power that are available within the consortium (with ESR1&2).

Description: Experimental data will be compared with calculations on resolution and contrast performed (with INM). LP-TEM and LP-STEM will be evaluated for imaging of different systems. Beam shift options in the low dose protocols in the existing imaging software will be used to set up imaging conditions (focus, beam diameter) remote from the imaging location, prior to starting the low dose imaging. As such protocols are not yet available for STEM, scripting will be used to develop these to control beam blanking and the “parking position” of the focused beam (with FEI). Beam damage in liquid phase electron diffraction (LP-ED) will be assessed by measuring the fading of diffraction spots upon sequential exposure of crystalline polymer building blocks (with ESR1, TUE and ESR13, INM). The developed protocols will be refined for practicality when imaging the colloidal self-organisation of the silica-based building blocks (with ESR1&2, TUE and ESR8 (UU)). Through modulation of the solution conditions and polymer composition the inter particle interactions will be tuned and the effect on the self-organisation studied with LP-EM. FFT analysis will be used to monitor and quantify the development of order during these processes.

Expected Results: (i) Understanding resolution and contrast under different imaging conditions, (ii) novel validated low dose protocols for the assessment of multiscale assembly using LP-TEM (thin layers) and LP-STEM (thick layers).

Planned secondment(s):

Project 4

Title Meso-structured and porous nanocellulose-silica hybrids for structural applications
Host Institution Stockholm Uni.
Related Work Packages WP1 – WP3
Objectives: To evaluate resolution and contrast in low dose LP-EM we will use polymer, silica and hybrid nanoparticles with different sizes and different electron scattering power that are available within the consortium (with ESR1&2).

Objectives: To understand and control nanocellulose assembly for the formation of silica-based mesostructured and porous materials for structural and functional applications. Description: We will prepare and surface-modify crystalline nanocellulose (CNC) from different sources, e.g. wood, cotton and bacterial cellulose. The purification, and surface modification will involve fractionation to control the aspects ratio of the CNC rods, and the generation of both cationic and anionic surface groups through controlled hydrolysis and enzymatic treatment (Bergstrom et al NPG Asia Materials, 2014). Controlled assembly will primarily rely on increasing the CNC concentration, e.g. by evaporation and ultracentrifugation (with UoK). Evaporation-driven self-assembly will be performed in confined droplets and also under the influence of external electrical fields. The structural evolution will be probed with advanced EM techniques (e.g. electron diffraction and electron tomography, with TUE), and small angle X-ray scattering (SAXS), in combination with rheology and polarisation microscopy. The experimental studies will be combined with modelling (with ESR 9, UU). The porous assemblies will be mineralised and both the structure (with ESR1, TUE) and the mechanical properties (with ESR2, TUE) of the resulting hybrids will be analysed. The applicability of the mesostructured, porous nanocellulose-based materials will be investigated (with UNIL).

Expected Results: (i) Strategies for preparation, fractionation and surface modification of well-defined cellulose nanocrystal building blocks; (ii) Reliable pathways to produce mesostructured and porous nanocellulose-based hybrid materials with a well-defined hierarchical structure; (iii) Mineralised porous nanocellulose-hybrids with optimised mechanical properties.

Planned secondment(s):

Project 5

Title Super-porous nanocomposite foams by directed assembly
Host Institution Stockholm Uni.
Related Work Packages WP2, WP3 & WP5
Objectives: To evaluate resolution and contrast in low dose LP-EM we will use polymer, silica and hybrid nanoparticles with different sizes and different electron scattering power that are available within the consortium (with ESR1&2).

Objectives: To co-assemble and structure nanosized carbon-based and inorganic nanoparticles building units from widely abundant renewable resources (i.e. nanocellulose, nanocarbons and clay) and construct hierarchically structured silicified foams with superinsulation properties. Description: Assembly and processing routes will developed to produce lightweight and mechanically super-insulating nanocomposite foams (e.g. Bergström et al Nature Nanotechnology 2015). An important aim is to understand how the degree of alignment of the nanoparticles in the walls and the dimensions and morphology of the tubular macropores can be controlled and relate that to the thermal conductivity and the mechanical strength. Versatile directed assembly and colloidal processing techniques known to produce foams with tailored structures will be investigated including e.g. freeze casting and particle stabilised emulsion/foam routes. The effect of composition and assembly method on the structural features (e.g. the pore size and degree of ordering) will be systematically investigated and related to the macroscopic thermal conductivity of the macroporous foams as well as to the local thermal conductivity in the mesoporous cell walls. The 3D structure and its evolution will be investigated in detail by a combination of SAXS experiments using both laboratory and synchrotron (at Max IV) instruments and electron microscopy, including LP-EM, 2D and 3D cryoTEM (with TUE). Silicification of the walls will be investigated to optimise the materials properties of the nanocomposite foams. This will be realised by careful tuning of the chemical compositions and interactions at given geometric constraints. The impact and effects of the surface modifica­tions on structures and material properties of the resulting hybrid materials will be studied (with AN).

Expected Results: (i) Design principles for superporous foams with controlled pore size and architecture; (ii) Understanding of the pore size and structure to thermal conductivity; (iii) Silicified foams with optimised mechanical and thermal properties.

Planned secondment(s):

Project 6

Title Modelling the formation of complex morphologies via block copolymer self-assembly
Host Institution Manchester Uni.
Related Work Packages WP1 & WP4
Objectives: To understand the self-assembly mechanism of semi-crystalline block copolymers in the presence of silica precursors (TEOS, TMOS).

Description: To this end, efficient coarse-grained (bead-and-spring) models (Patti et al., Langmuir, 2007), will be implemented to study the formation of self-assembled morphologies by Monte Carlo, MD and DPD simulations. Block copolymers with hydrophilic and hydrophobic segments of different lengths will be used to obatain aggregates of different shapes and sizes using PEO as the hydrophilic block. Starting point will be the modelling of PEO-PODMA block copolymers forming bicontinuous polymer nanospheres (BNPs, with ESR1, TUE) (Sommerdijk, Angew Chem 2015) The solvent will be implicitly modelled via an effective potential acting on polymer chains and silica precursor. This project will focus on synthesis conditions where the kinetics of silica condensation is sufficiently fast not to disturb significantly the polymeric template. Silica condensation will be incorporated in the simulations in year 3, once a complete understanding of the silica-polymer interactions will be available and the work by ESR7 (UM) validated. Powerful codes such as DL_POLY, DL_MONTE and DL_MESO will be used extensively. More specifically, the effect of the polymer-precursor interactions on the aggregation behaviour and morphology of the micellar clusters will be studied. Finally the colloidal self-organisation of the silicified BNPs will be studied in collaboration with ESR8 (UU). The output of the simulations will guide the improvement of the parametrisation of the model and the design of new block copolymers (TUE).

Expected Results: (i) A reliable model able to describe the self-assembly of semi-crystalline block copolymers. (ii) Understanding the effect of geometry (shape and size) and interactions of the block copolymer on aggregate morphology (pore size & architecture). (iii) Control over the formation of BNPs by controlling the polymer-precursor interactions. (iv) Design parameters for new block copolymers to assemble hybrid building blocks with predefined structural properties.

Planned secondment(s):

Project 7

Title Modelling the kinetics of silica growth in aggregates of semi-crystalline block copolymers
Host Institution Manchester Uni.
Related Work Packages WP1 & WP4
Objectives: Predicting and controlling the mechanism of silica growth in micellar phases and address the structural properties of the resulting bicontinuous silica building blocks.

Description: Atomistic and coarse-grained Monte Carlo and Molecular Dynamics simulations will be performed by using simulation software optimised for parallel computing (e.g. DL_POLY). Coarse-grained models, where the solvent is only implicitly modelled and polymer chains are represented as a sequence of beads connected by springs, will provide an insight in the evolving morphology of the hybrid structures, e.g. wall thickness, size distribution and connectivity of the pores (Patti, J Mater Chem 2009). To understand the role of the silica-polymer interactions, first simple PEO-based block copolymers (e.g. pluronics) will be studied. More complex blocks, such as PODMA, will be included in the third year. The simple copolymers forming micelles will be used as a benchmark for the more complex BNPs. To model the aggregation of silica represented by short range attractive interactions, an approach will be developed that limits the number of neighbours, similar to what is currently used in bond-order potentials. To investigate the formation of micropores, due to silica condensation in the hydrated hydrophilic domains of the assemblies, atomistic models based on reactive force fields will be employed. These models will be validated (at JM) by applying them to the multiscale assembly of of silica/metal oxide nanoparticles in solvents, for which for which experimental data are available. With ESR1 (TUE) experimental results (CryoTEM, LP-EM) on the polymer directed assembly of porous silica materials will be compared with simulation results and used for the optimisation of the model by a more precise parametrisation.

Expected Results: (i) Understanding the role of the silica-polymer interactions in the self-assembly of the BNPs; (ii) Understanding the kinetics of silica growth and addressing the potential existence of distinct growth regimes as a result of the copolymer-precursor interactions; (iii) Efficient model to describe the silicification of the polymer aggregates; (iv) Validation of the model with experimental measurements conducted at JM.

Planned secondment(s):

Project 8

Title Multiscale assembly of colloids using confinement and electric fields
Host Institution Utrecht Uni.
Related Work PackagesWP1, WP2 & WP5
Objectives: To organise colloidal particles through confinement in (microfluidic) emulsion droplets and to use the resulting so called ‘supraballs’ as building blocks in a next assembly step.

Description: Mixtures of colloids of both different size and shape will be probed inside an emulsion based platform (Dijkstra et al, Nature Mater 2015) In addition, the use of external electric fields will be investigated to manipulate the self-organisation in confinement and tune the properties of the resulting supraball assemblies. An important step is the production of monodisperse droplets by using microfluidics. The recent generation of single component supraballs from spherical particles indicate it is important to orchestrate parameter space of more complex assemblies (mixtures of spheres, rods, rods and spheres) by probing this parameter space with computer simulations (with ESR9, UU) and knowledge of self-organisation in bulk solution. We will first probe the assembly mechanisms experimentally by using larger (>200 nm) particles with different aspect ratios, applying 3D STED confocal microscopy and subsequently by using nanoparticles (< 200 nm) which will be characterised with electron tomography, as well as with LP-EM (with ESR3, TUE and ESR12, INM). The supraballs will be organised into even larger structures exploring the next level of structural complexity. The concept of supraball formation will be further investigated together with UNIL, evaluating their mechanical properties in particular the deformability of particles formed using external electric/shear fields.

Expected Results: (i) New microfluidic methodology towards a gram yield level of monodisperse supraparticles based on slow evaporation of emulsion droplets; (ii) mechanism of nucleation and growth of complex supraparticles from the SA of complex mixtures; (iii) design criteria for new structures of supraparticles build up from the SA of complex mixtures; (iv) Insight in the possibilities to manipulate the this SA process in confinement and the properties of the final supraballs by external (electric) fields.

Planned secondment(s):

Project 9

Title Predicting and designing colloidal self-organization from complex mixtures of building blocks
Host Institution Utrecht Uni.
Related Work PackagesWP1, WP2 & WP4
Objectives: To obtain via computer simulations a better fundamental understanding of the self-organisation of complex mixtures of building blocks into larger structures, and to predict and control the materials properties on the basis of that understanding.

Description: The effect of shape, effective interactions due to surface chemistry, and thermodynamic conditions on the spontaneous self-organisation of colloidal building blocks will be investigated using our efficient method to predict self-assembled structures with Monte Carlo and Molecular Dynamics simulations (Filion, L. et al. Phys. Rev. Lett., 2009). We will investigate the (co-)assembly spherical and rod-like building blocks, also using mixtures of populations with different shapes, sizes and surface chemistries. In collaboration with ESR 6 & 7(MU) effective interactions be refined, and the result of the simulations will be optimised with input from ESR 1 & 2 (TUE) and ESR5 (SU) and ESR8 (UU) from experiments on particle populations with different morphologies, surface interactions, and size distributions. In collaboration with ESR2 (TUE)we will use simulations to obtain insight in the mechanical properties of the different suprastructures. Moreover, the effect of tunable interaction potentials on the predicted mechanical properties of self-assemblies of semi-flexible fibers will be calculated in collaboration with UNIL.

Expected Results: (i) Understanding of the relationship between shape, size and thermodynamic conditions on the self-organised structures of anisotropic nanoparticles; (ii) understanding how mechanical properties emerge from these asemblies (iii) Predicting, designing, and controlling the structure and mechanical properties from well-defined building blocks on the basis on that fundamental understanding.

Planned secondment(s):

  • UM (Siperstein) – Modelling of the effective interactions of silica-based building blocks- 3 months (M31)
  • UNIL (Velikov) – Assembly of semi-flexible fibrils with tuneable interaction potential - 6 months (M19)

Project 10

Title Structural design of porous silica-based materials
Host Institution Akzo Nobel
Related Work PackagesWP1 & WP3
Objectives: to develop a toolbox for microstructural design of porous silica using a set of self-organizing silica particles as building blocks.

Description: Colloidal silica (silica sols) can easily form gels upon change of pH, temperature and ionic strength. Most gels suffer from very low mechanical strength and the challenge is to identify conditions under which relatively high mechanical strength can be combined with high total pore volume and surface area. In order to get a better control of the structures and morphologies specific particle-particle interactions will be generated by introduction of functional groups, to create weak interactions based on hydrogen bonding, coulomb or hydrophobic interactions etc. Further microstructural modifications will be conducted using linkers between the silica particles, phase separating polymers or organic particles acting as voids. Indirect Nanoplasmonic Sensing (INS) will be explored to monitor real time surface modification (with INSP), in addition to the analysis of surface groups and of their interaction with other molecules or nanoparticles. A standard test method for determination of bulk crush strength will be used to identify microstructures with enough mechanical strength. Mechanical properties of selected samples will be quantified (with ESR2, TUE) before and after removal of the organics by sintering. The resulting structure and its development during synthesis will be analysed using cryoTEM & tomography.

Expected Results: (i) Self-organising silica particles as building blocks in a 3D structure (ii) A tool box for the microstructural design of porous silica with a focus on sustainable processes possible to scale-up in industry; (iii) Indirect Nanoplasmonic Sensing established as a method to characterize surface modification and particle –particle interactions.

Planned secondment(s):

Project 11

Title Mesoporous hybrid materials with tuneable surface properties for mass transport and catalytic activity
Host Institution Chalmers Uni.
Related Work PackagesWP1 & WP2
Objectives: To develop methods to functionalise mesoporous hybrid materials allowing for tuning of their mass transport and chemical reactivity for improved performance in catalytic and fuel cell applications.

Description: Silica coatings can be used to increase the hydrophilicity or (electron and proton) conductivity of hydrophobic materials and to protect surfaces that are highly reactive to water. One major challenge in developing such coatings for different porous surfaces is to find conditions that provide the porous hybrid materials with the desired properties, while maintaining high total pore volume and surface area. The aim of this project is to understand how mass transport, chemical reactivity and conductivity are affected by surface-functionalisation and to develop efficient functionalisation methods to optimise these properties for catalysts and fuel cells.

Different silica precursors (e.g. alkoxides, and ion exchanged and differently aged water glass solutions) will be tested for the preparation of mesoporous hybrid materials with tuneable surface properties in which control over silica speciation, synthesis pH and relative concentrations of synthesis reagents will be important tools. Surface modification and characterisation methods will be optimised (with ESR10, AN). The evolution of structure will be analysed with ESI-MS, SAXS and with 2D and 3D cryoTEM (with ESR1, TUE). Properties of the resulting materials will be characterised using gas adsorption, diffusion NMR and EPR and correlated with their performance as support for immobilised enzymes in catalytic reduction of CO2 and in mesoporous carbon-based fuel cell electrode materials.

Expected Results: (i) Design principles for mesoporous hybrid materials with tuneable surface properties; (ii) Understanding on how to prepare mesoporous hybrid materials with tuneable mass transport and chemical reactivity; (iii) Improved characterisation methods for assessing silica speciation in synthesis solutions and mass transport in final mesoporous hybrid materials; (iv) Understanding the synthesis-structure-properties relationships of silica-functionalised mesoporous hybrids.

Planned secondment(s) Host, timing, length and purpose

Project 12

Title LP-EM of self-assembly processes
Host Institution Institute für Neue Materialien
Related Work PackagesWP1 & WP5
Objectives: To develop and demonstrate new technology to expand the application area of LP-EM to multiscale self-assembly.

Description: To this end, the LP-EM visualisation of the formation, mineralisation and self-organisation of bicontinuous polymer nanoparticles (BPN) will be studied (with ESR1, TUE) To investigate the mechanisms of formation and mineralisation, the geometry of holders/tips chips will be modified (with DENS) to allow reliable high resolution in-situ imaging. The studies will include the implementation of a new chip design that allows flow of a relatively large volume through a thin imaging segment (US Patent Application 13,299,241 (2011), as needed for high resolution imaging of low density materials, and for liquid mixing. The required chip technology will be developed in collaboration with DENS. With LP-TEM we aim to image the development of BPNs from PEO-POEGMA block copolymers, and visualise the effect of their interaction with silicification agents. Manipulation of the solution conditions will be used to observe in situ the effects on the assembly pathways. Movies of the block copolymer self-assembly will form input for the simulations of ESR6 and ESR7 (UoM) and for the optimisation of the block copolymer structure by ESR1 (TUE). The influence of the electron beam on the experiment will be considered particularly carefully by repeating experiments at different electron doses (with ESR3, TUE) and by determining the critical dose above which structural damage occurs.

Expected Results: (i) New chip designs for high resolution soft matter imaging ii) Insights in the mechanism of BPN formation and BPN mineralisation (iii) insight in critical dose and damage mechanisms.

Planned secondment(s):Host, timing, length and purpose

Project 13

Title Ultracentrifugation in Colloidal Crystallisation
Host Institution Nanolytics & TU/e
Related Work PackagesWP1 & WP2
Objectives: Develop and apply ultracentrifugation techniques for the formation and assembly of nanoparticles.

Description: The colloidal assembly of nanoparticles into regular, predicted structures requires control over the size and size distribution of the particles, as well as over the forces that drive their assembly. Ultracentrifugation (UC) can not only be used to analyse the size and composition of these particles, it can also help to drive their assembly making use of the concentration profile in the sedimentation gradient, and through sorting them by size. Structure and composition of the particles used for these studies will be characterized using cryoTEM in the first 10 month appointment at TUE. At Nanolytics (with UoK) analytical and preparative UC will be used to produce BPNs with improved monodisperse size distribution (with ESR1) by first fractionating the BPNs according to their density by preparative density gradient UC and subsequently by size using preparative UC. AUC will be used to investigate the efficiency of the mineralization process, distinguishing more or less mineralized particles of the same size based on their difference in sedimentation coefficient. Additionally, the crystallization of more disperse populations of mineralized BPNs will be investigated through making use of the sorting by size of similar sized particles in the gradient. Binary mixtures of nanoparticles will be studied (with ESR2) in a sedimentation gradient. This will lead to different concentration profiles of the two species, The resulting variation in stoichiometries will create colloidal crystals structures with different ratios of the constituting particles. These particle ratios will then guide the bulk crystallization experiments of ESR2 in the creation of porous materials with predefined porosity. The produced assemblies will be investigated with (cryo)electron tomography during secondment at TUE.

Expected Results: (i) procedures for the production and analysis of uniform hybrid NP building blocks (ii) procedures for the formation of colloidal crystals from non-monodispersed colloidal suspensions. (iii) guidelines for the formation of binary crystal systems with different crystal structures.

Planned secondment(s):