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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - MULTIMAT (A multiscale approach towards mesostructured porous material design)

Teaser

Summary

\"Our contemporary society is endangered by upcoming challenges such as drinking water shortages, deprivation of oil reserves and climate change. Advanced materials will form a major contribution towards addressing these issues as they can provide e.g. efficient filters for desalination, catalysts for efficient conversion of resources, affordable CO2 capturing devices, optimised insulating materials and more efficient fuel cells. Unfortunately, most current materials at hand for these applications are either elaborate and based on fossil-fuel or energy-intense raw materials and processes, or lack the combination of a highly defined and large porosity together with required (mechanical, chemical, thermal) robustness.

MULTIMAT addresses (1) the industrial and societal need for affordable materials that have a highly defined and large porosity together with the required (mechanical, chemical and/or thermal) robustness for application in thermal insulation, catalysts, fuel cells and oil spill remediation and (2) the scientific need to better understand the mechanisms underlying the assembly of small building blocks into larger structures that are ordered hierarchically across multiple scales (\"\"multiscale assembly\"\"). Together this will contribute to achieving MULTIMAT\'s future aim: understanding and ultimately steering the bottom-up construction of materials with complex hierarchical structures.

MULTIMATâ€™s overall objectives are to:
- Generate objects with well-defined shapes from organic and inorganic components and use their colloidal self-organisation to produce hierarchical porous materials (BUILDING-BLOCK DESIGN)
- Control the assembly of building blocks into novel high-performance mesostructured porous materials using directional forces and templates (DIRECTING COLLOIDAL ASSEMBLY), modelling approaches (MULTISCALE MODELLING) and advanced in situ analysis methods (IN-SITU ANALYSIS)
- Provide a good understanding on mesoscopic structure-property relationships, with a focus on applications that require a combination of good mechanical properties and high porosity (PROPERTIES & FUNCTION).
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Work performed

The program is divided into 5 interconnected work packages (WP): 1) Building Block Design 2) Directing Colloidal Assembly 3) Properties & Function 4) Multiscale Modelling 5) In-situ Analysis.

In WP1, different building blocks have been designed and utilised to template the growth of silica. These include block copolymer assemblies and nanocellulose fibers and crystals. Surface modification of the building block templates has led to increased affinity for the silica and has produced hybrid materials with better thermal, mechanical and flame retardancy properties. Moreover, by designing the size and internal pore dimensions of porous bicontinuous block copolymer nanospheres, silica networks with pre-determinable dimensions can be obtained.

The objective of WP2 is to direct the colloidal assembly of the building blocks obtained in WP1. Organised assemblies of the silicified building blocks has so far been achieved by using ultracentrifugation and freeze-casting as external forces, or by adjusting the surface charge of the building blocks. In both cases, porosity has been achieved by removal of the organic template to leave a silica network. By controlling the surface properties, silicified surface-modified cellulose membranes have been obtained with optimised anti-biofouling properties.

WP3 works towards testing the mechanical, thermoconductive, surface and separation properties of the colloidal assemblies in WP2, and to understand the structure-property relations. Thus far, hybrid materials with improved mechanical, thermal and anti-fouling properties have been achieved.

WP4 utilises multiscale modelling to obtain a better fundamental understanding of the building block formation and their subsequent assembly into larger structures. This will then inform the design of the desired materials. Models have been developed for the formation of the block copolymer building blocks, their subsequent silicification, and the colloidal assembly of building blocks, which are in good agreement with the experimental observations.

The objective of WP5 is to develop liquid phase electron microscopy for its application to the in-situ dynamic multiscale analysis of building block formation and colloidal assembly. So far, new insights into block copolymer (organic) self-assembly processes and the beam tolerance of zeolites (inorganic) in base environments have been obtained by using quantitative image analysis. Moreover, by developing new low electron dose imaging protocols, it has been possible to obtain the optimal resolution with the minimum electron dose to preserve the integrity of the electron beam-sensitive materials.

Final results

The far-reaching aim of MULTIMAT is to understand and ultimately steer the bottom-up construction of materials with complex hierarchical structures. The industrial partnerships within the consortium drive the socio-economic impact of the work performed herein.

In this program we have already begun to develop novel materials and building blocks, and the subsequent assemblies are materials that exhibit superior thermal and anti-fouling properties. The exploitable results include the reliable coarse-grained models for polymeric self-assembly in solvent mixtures (already achieved), new electron microscopy hardware for controlling experimental conditions during in-situ analysis; and the development of new porous materials for novel separation technologies is currently underway.

Building block formation and the subsequent assembly has been achieved by combining experiment with modelling and in-situ analysis to inform and direct the materials\' design (i.e. surface modification, polymer assembly in solution). This bottom-up approach has enabled the formation of porous silica-based materials with highly defined and large porosity for important societal and industrial needs, such as improved thermal insulation and anti-biofouling and mechanical properties. By the end of the project, this will be extended to applications in fuel cells, anti-reflective coatings and catalysis. We foresee that these design and methodology principles will be directly applicable to other material types with various different physical properties (e.g. magnetic, optical and electrical materials).