Periodic Reporting for period 2 - DYNAMOF (Electric Field Assisted Dynamic MOF alignment and Crystal Assembly)
Période du rapport: 2023-04-01 au 2024-09-30
Despite the staggering number of reports on Metal-Organic Frameworks (MOFs), we are still greatly limited in our ability to manipulate colloidal MOF particles and control MOF orientation. Reliable control of MOF crystal orientation is extremely important as the properties and functionality of most MOFs are highly dependent upon crystallographic direction due to
lattice anisotropy. We need tools to reliably control MOF crystals, to effectively utilize MOFs and realize their promise in many fields, such as in energy applications, electronic devices, optical materials, catalysis etc., all of which have significant implications for society. Based on the novel concept of exploiting MOF anisotropic ion mobility and polarizability, DYNAMOF aims to establish a
flexible toolbox of methods for both dynamic and static control over the orientation, alignment and deposition of MOF crystals, which can be integrated into other processing techniques, thus paving the way for major advancements in the performance of MOF materials, composites and devices.
The mechanisms of E-field alignment of MOF particles as well as colloidal interactions governing MOF plastic or liquid crystal assembly, non-classical crystal growth and oriented film formation will be studied to develop a comprehensive and revolutionary platform for orientational control of free-standing and supported MOF crystals. As a proof-of-concept, the implications of MOF alignment on the proton conduction of MOF composites will be tested to pave the way towards next generation MOF proton exchange membranes.
This ambitious project, which straddles the disciplines of materials science, chemistry and physics, is expected to break new ground by removing a key barrier in our ability to manipulate MOF particles. The wider goal of DYNAMOF is to establish the principles and working methods for colloidal manipulation across a wide materials spectrum, by using MOFs as a versatile platform for expanding our understanding of colloidal materials. Given the ubiquity and importance of colloids in materials science and daily life, the success of DYNAMOF will therefore have far reaching impact.
lattice anisotropy. We need tools to reliably control MOF crystals, to effectively utilize MOFs and realize their promise in many fields, such as in energy applications, electronic devices, optical materials, catalysis etc., all of which have significant implications for society. Based on the novel concept of exploiting MOF anisotropic ion mobility and polarizability, DYNAMOF aims to establish a
flexible toolbox of methods for both dynamic and static control over the orientation, alignment and deposition of MOF crystals, which can be integrated into other processing techniques, thus paving the way for major advancements in the performance of MOF materials, composites and devices.
The mechanisms of E-field alignment of MOF particles as well as colloidal interactions governing MOF plastic or liquid crystal assembly, non-classical crystal growth and oriented film formation will be studied to develop a comprehensive and revolutionary platform for orientational control of free-standing and supported MOF crystals. As a proof-of-concept, the implications of MOF alignment on the proton conduction of MOF composites will be tested to pave the way towards next generation MOF proton exchange membranes.
This ambitious project, which straddles the disciplines of materials science, chemistry and physics, is expected to break new ground by removing a key barrier in our ability to manipulate MOF particles. The wider goal of DYNAMOF is to establish the principles and working methods for colloidal manipulation across a wide materials spectrum, by using MOFs as a versatile platform for expanding our understanding of colloidal materials. Given the ubiquity and importance of colloids in materials science and daily life, the success of DYNAMOF will therefore have far reaching impact.
DYNAMOF is focused on the development of methods to manipulate colloidal materials, especially Metal-Organic Frameworks (MOFs), which serve as a platform which can be designed at the molecular level, to generate nano- and microcrystals, that can be further assembled into macroscopic structures. The ability to structure and control materials from the molecular, to the nano, micro and macroscopic length scales, is one of the biggest challenges in materials research. The selection and synthesis of target MOFs and their post-synthetic modification have been carried out to ensure their suitability for colloidal assembly. Methods to investigate the rate, extent and type of response to external electric fields have been developed and are being further studied. Knowledge from this has been used to effect control over MOF spatial arrangement, orientation and deposition, to generate assemblies with improved performances in converting chemical energy to motion (actuators) as well as in sensing applications.
Specifically, from the beginning of the project to the end of the covered period (30 months), the following works were performed:
- Design and replication of electric field alignment set-ups for MOF manipulation via electric fields.
- Development of a method to spatially control MOF deposition using interdigitated electrodes
- Investigation of the influences of guest molecules on MOF response to external fields, based on effect of MOF polarizability.
- Developed methods to generate MOF polymer composites with aligned MOF crystals
- Developed a method to generate highly oriented MOF assemblies rapidly (20 minutes instead of several days) by combining gravitational and electric field influences
Based on this work, the main results achieved so far include:
- Successful design of set-ups for MOF assemblies using E-fields, using horizontal and vertical E-fields in conjunction with gravity (sedimentation approach), to generate oriented and graded MOF
composites.
- Demonstrated for the first time the liquid crystalline assembly of MOF crystals, by exploiting the anisometry of the particles. We also demonstrated that by applying electric fields, that the
classical limitations of particle alignment to particles with high aspect ratios no longer applied. Particles with aspect ratios as low as 1.2 could rapidly form oriented macroscale assemblies.
- Obtained a method to precisely control MOF positioning with micrometer resolution which led to devices with 500 times conductivity increases, and improved performance for resistive and
capacitive sensing.
- Generation of graded MIL-88A MOF composites where anisotropy of the MOFs at the micrometric level is propagated to the macroscale by controlling MOF orientation. This led to humidity
responsive actuators with enhanced swelling responses.
Specifically, from the beginning of the project to the end of the covered period (30 months), the following works were performed:
- Design and replication of electric field alignment set-ups for MOF manipulation via electric fields.
- Development of a method to spatially control MOF deposition using interdigitated electrodes
- Investigation of the influences of guest molecules on MOF response to external fields, based on effect of MOF polarizability.
- Developed methods to generate MOF polymer composites with aligned MOF crystals
- Developed a method to generate highly oriented MOF assemblies rapidly (20 minutes instead of several days) by combining gravitational and electric field influences
Based on this work, the main results achieved so far include:
- Successful design of set-ups for MOF assemblies using E-fields, using horizontal and vertical E-fields in conjunction with gravity (sedimentation approach), to generate oriented and graded MOF
composites.
- Demonstrated for the first time the liquid crystalline assembly of MOF crystals, by exploiting the anisometry of the particles. We also demonstrated that by applying electric fields, that the
classical limitations of particle alignment to particles with high aspect ratios no longer applied. Particles with aspect ratios as low as 1.2 could rapidly form oriented macroscale assemblies.
- Obtained a method to precisely control MOF positioning with micrometer resolution which led to devices with 500 times conductivity increases, and improved performance for resistive and
capacitive sensing.
- Generation of graded MIL-88A MOF composites where anisotropy of the MOFs at the micrometric level is propagated to the macroscale by controlling MOF orientation. This led to humidity
responsive actuators with enhanced swelling responses.
Over 100,000 types of MOFs, a class of crystalline materials built up from inorganic nodes and organic multidentate ligands, have been reported in recent years. Their immense versatility, arising from the many permutations of metal-ligand combinations affords them great potential for many applications, such as for electronic or optical devices, fluorescence-based sensing, CO2 capture, and increasingly, for energy applications such as fuel cell membranes. Nevertheless, in spite of all their promise, there are very few commercialized MOF products hitting the market. A major reason for this is the glaring technological gap in our ability to control and process MOF materials.
The need to control orientation: The majority of MOFs possess very distinct physicochemical properties (and hence functionality) along different crystallographic directions due to their anisotropic lattices. Despite the dependence of MOF performance on the crystallographic direction, methods to control the orientation of MOF materials are extremely limited. As MOFs are generally synthesized as bulk powders, it is tempting to apply well-established processing methods to MOF materials, such as pressurized compaction or polymer blending and extrusion to form desired structures, but these do not address the problem of orientational control. Furthermore, directional functionality is not unique to MOFs, but is common to many classes of materials, ranging from biological composites like wood to inorganic materials like zeolites. The challenge of effectively exploiting such functional anisotropy arises when the materials of interest are loose nano or microcrystals, which are difficult to physically manipulate into user-directed orientations and positions.
Current approaches to achieve orientational control of MOFs focus on directional growth of MOFs on suitable substrates by carefully tailoring growth conditions. However, the laborious and time-consuming aspects of this approach have hindered its widespread adoption. Furthermore, such methods afford MOF crystals with a static orientation, preventing MOF reorientation under changing conditions and do not address the major question of how to manipulate and orientate free-standing MOF crystals. Therefore, the ability to precisely and dynamically control the orientation and motion of free-standing MOF crystals would represent a major step-change in our ability to manipulate MOF materials, which would be highly desirable for their integrated processing and for their incorporation into MOF devices.
The aim of DYNAMOF is to establish a toolbox of ground-breaking methods to control the orientation and alignment of free-standing and supported MOF crystals, in a manner that can be integrated into other processing techniques, thereby allowing major advancements in the performance of MOF materials, composites and devices.
Especially exciting is that MOFs are an ideal platform for understanding colloidal interactions and developing techniques for their manipulation, as they allow us unprecedented fine-tuning of particle size, shape, composition, surface functionality, density, zeta potential and dielectric constants and so forth, which are important parameters in colloidal assembly. The term ‘colloidal’ as used in this proposal describes particles of sizes ranging from one nanometre to several microns. The lessons learned herein will be important for controlling other colloidal materials such as covalent organic frameworks, hydrogen bonded frameworks, zeolites or carbon nanotubes, with applicability across different materials classes.
Furthermore, the control of materials across multiple length scales remains a significant scientific challenge. Although scientists are skilled at controlling molecular and macroscopic materials, as these clearly fit into traditional key disciplines of chemistry and materials science/engineering, many advancements remain to be made for mesoscale structural control and manipulation of materials, which falls into a highly interdisciplinary area, requiring insights from physics, chemistry, and engineering. Through this work, we aim to advance our ability to control nano and microscale materials, thereby helping to fill this key area.
The need to control orientation: The majority of MOFs possess very distinct physicochemical properties (and hence functionality) along different crystallographic directions due to their anisotropic lattices. Despite the dependence of MOF performance on the crystallographic direction, methods to control the orientation of MOF materials are extremely limited. As MOFs are generally synthesized as bulk powders, it is tempting to apply well-established processing methods to MOF materials, such as pressurized compaction or polymer blending and extrusion to form desired structures, but these do not address the problem of orientational control. Furthermore, directional functionality is not unique to MOFs, but is common to many classes of materials, ranging from biological composites like wood to inorganic materials like zeolites. The challenge of effectively exploiting such functional anisotropy arises when the materials of interest are loose nano or microcrystals, which are difficult to physically manipulate into user-directed orientations and positions.
Current approaches to achieve orientational control of MOFs focus on directional growth of MOFs on suitable substrates by carefully tailoring growth conditions. However, the laborious and time-consuming aspects of this approach have hindered its widespread adoption. Furthermore, such methods afford MOF crystals with a static orientation, preventing MOF reorientation under changing conditions and do not address the major question of how to manipulate and orientate free-standing MOF crystals. Therefore, the ability to precisely and dynamically control the orientation and motion of free-standing MOF crystals would represent a major step-change in our ability to manipulate MOF materials, which would be highly desirable for their integrated processing and for their incorporation into MOF devices.
The aim of DYNAMOF is to establish a toolbox of ground-breaking methods to control the orientation and alignment of free-standing and supported MOF crystals, in a manner that can be integrated into other processing techniques, thereby allowing major advancements in the performance of MOF materials, composites and devices.
Especially exciting is that MOFs are an ideal platform for understanding colloidal interactions and developing techniques for their manipulation, as they allow us unprecedented fine-tuning of particle size, shape, composition, surface functionality, density, zeta potential and dielectric constants and so forth, which are important parameters in colloidal assembly. The term ‘colloidal’ as used in this proposal describes particles of sizes ranging from one nanometre to several microns. The lessons learned herein will be important for controlling other colloidal materials such as covalent organic frameworks, hydrogen bonded frameworks, zeolites or carbon nanotubes, with applicability across different materials classes.
Furthermore, the control of materials across multiple length scales remains a significant scientific challenge. Although scientists are skilled at controlling molecular and macroscopic materials, as these clearly fit into traditional key disciplines of chemistry and materials science/engineering, many advancements remain to be made for mesoscale structural control and manipulation of materials, which falls into a highly interdisciplinary area, requiring insights from physics, chemistry, and engineering. Through this work, we aim to advance our ability to control nano and microscale materials, thereby helping to fill this key area.