6 Materialchemie
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Healable materials could play an important role in reducing the environmental footprint of our modern technological society through extending the life cycles of consumer products and constructions. Future technologies require smart materials with advanced properties including responsiveness to external stimuli and particularly the ability to autonomously repair inflicted damage. The introduction of reversible connections in the polymer architecture, either in a non-covalent fashion, such as in supramolecular polymers, or by using dynamic covalent chemistry. One facile approach involves the implementation of reversible polymer networks as they offer high mechanical strength and thermal properties that are readily modified by the nature of the connecting dynamic bonds and the crosslinking density. In this context, small-angle scattering allows a detailed insight into the network structure of self-healing polymers either in bulk materials or in form of hydrogels. Here we report on how small-angle scattering can contribute to reveal the network structure. A first example is the conditional repair by locally switching the thermal healing capability of dynamic covalent polymers with light.
Typical experimental SAXS curves of a photo- and thermal switchable polymer are shown. The scattering pattern show three characteristics. Region 1 is dominated by a forward scattering interpreted as resultant from large scale inhomogeneities of the bulk polymers (characterized by a first correlation length). The second scattering contribution can be interpreted as resultant from the network and is characterized by its entanglement distance. The mesh size of this network can be described by a second correlation length. Region 3 of the scattering pattern is dominated by a broad peak. Taking all effects into account, we approximate the total scattering as a sum of the three scattering contributions. In particular, the Debye-Büche function is used for I1 the Ornstein-Zernike function for the crosslinking contribution I2 and a Lorentzian peak function.
We discussed this simple and more sophisticated approaches for revealing network structures. Examples of studies from hydrogel networks are provided as important materials with polymeric networks in life science applications. Finally, the determination of mesh size distributions as a function of temperature, time and healing efficiency is discussed in detail.
A brief perspective of BAM on nanocarriers is presented including examples with special emphasis on the characterization of such materials and underlying challenges. In this respect, also ongoing activities at BAM on different types of core/shell nanomaterials and related systems are briefly summarized.
This talk highlights a proof-of-concept that demonstrates the ability to calculate high-resolution Fourier transforms. These can be combined with multi-scale modeling to simulate scattering over a wide range, from small-angle scattering to XRD and PDF.
The preprint documenting this is available on the ArXiv here:
https://doi.org/10.48550/arXiv.2303.13435
The Jupyter notebook, VASP calculation details and MOUSE measured scattering patterns are available from this Zenodo repository: https://dx.doi.org/10.5281/zenodo.7764045
The present series of reports, the NanoDefine Methods Manual, has been developed within the NanoDefine project 'Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial'1 funded by the European Union's 7th Framework Programme, under grant agreement 604347.
In 2011 the European Commission (EC) published the recommendation (2011/696/EU) for a definition of the term 'nanomaterial'1, the EC NM Definition, as a reference to determine whether an unknown material can be considered as a 'nanomaterial' for regulatory purposes. One challenge is the development of methods that reliably identify, characterize and quantify nanomaterials (NM) both as substances and in various products and matrices.
The overall goal of NanoDefine was to support the implementation of the EC NM Definition. It can also support the implementation of any NM definition based on particle size. The project has developed an integrated approach, which allows identifying any material as a nano or non-nano material according to the EC NM Definition. NanoDefine explicitly supported the governance challenges associated with the implementation of legislation concerning nanomaterials by:
- addressing the issues on availability of suitable measuring techniques, reference materials, validated methods, acceptable to all - developing an integrated and interdisciplinary approach and a close international co-operation and networking with academia, commercial firms and standardization bodies.
Thus, the NanoDefine Methods Manual provides guidance on practical implementation of the EC NM Definition throughout the nanomaterial characterization process, and on the characterization techniques employed as well as their application range and limits. It assists the user in choosing the most appropriate measurement method(s) to identify any substance or mixture for a specific purpose, according to the EC NM Definition of a nanomaterial. The NanoDefine project also explored how to assess a material against the criteria of the definition through proxy solutions, i.e. by applying measurement techniques that indirectly determine the D50. Those findings were developed through empirically based scientific work and are included in Part 1 of this Manual. As they go beyond the text of the EC NM Definition, they may be used as practical approach to indicate whether a material is a nanomaterial or not, but keeping in mind that they should not be taken as recommendation for the implementation of the EC NM Definition in a regulatory context.
The NanoDefine Methods Manual consists of the following three parts:
Part 1: The NanoDefiner Framework and Tools
Part 2: Evaluation of Methods
Part 3: Standard Operating Procedures (SOPs)
Part 1 covers the NanoDefiner framework, general information on measurement methods and performance criteria and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool.
Part 2 discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size.
Part 3 presents the 23 Standard Operating Procedures developed within the NanoDefine project. The current document is part 3.
The present series of reports, the NanoDefine Methods Manual, has been developed within the NanoDefine project 'Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial', funded by the European Union's 7th Framework Programme, under grant agreement 604347.
In 2011 the European Commission (EC) published a recommendation for a definition of the term 'nanomaterial', the EC NM Definition, as a reference to determine whether an unknown material can be considered as a 'nanomaterial' for regulatory purposes1. One challenge is the development of methods that reliably identify, characterize and quantify nanomaterials (NM) both as substances and in various products and matrices.
The overall goal of NanoDefine was to support the implementation of the EC NM Definition. It can also support the implementation of any NM definition based on particle size. The project has developed an integrated approach, which allows identifying any material as a nano- or not a nanomaterial according to the EC NM Definition. NanoDefine explicitly supported the governance challenges associated with the implementation of legislation concerning nanomaterials by:
- addressing the issues on availability of suitable measuring techniques, reference materials, validated methods, acceptable to all stakeholders (authorities, policy makers, commercial firms),
- developing an integrated and interdisciplinary approach and a close international co-operation and networking with academia, commercial firms and standardization bodies.
Thus, the NanoDefine Methods Manual provides guidance on practical implementation of the EC NM Definition throughout the nanomaterial characterization process, and on the characterization techniques employed as well as their application range and limits. It assists the user in choosing the most appropriate measurement method(s) to identify any substance or mixture for a specific purpose, according to the EC NM Definition of a nanomaterial. The NanoDefine project also explored how to assess a material against the criteria of the definition through proxy solutions, i.e. by applying measurement techniques that indirectly determine the x50. Those findings were developed through empirically based scientific work and are included in Part 1 of this Manual. As they go beyond the text of the EC NM Definition, they may be used as practical approach to indicate whether a material is a nanomaterial or not, but keeping in mind that they should not be taken as recommendation for the implementation of the EC NM Definition in a regulatory context.
The NanoDefine Methods Manual consists of the following three parts:
Part 1: The NanoDefiner Framework and Tools
Part 2: Evaluation of Methods
Part 3: Standard Operating Procedures (SOPs)
Part 1 covers the NanoDefiner framework, general information on measurement methods and performance criteria and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool.
Part 2 discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size.
Part 3 presents the 23 Standard Operating Procedures developed within the NanoDefine project.
The current document is part 2.
The present series of reports, the NanoDefine Methods Manual, has been developed within the NanoDefine project 'Development of an integrated approach based on validated and standardized methods to support the implementation of the EC recommendation for a definition of nanomaterial', funded by the European Union's 7th Framework Programme, under grant agreement 604347.
In 2011 the European Commission (EC) published a recommendation for a definition of the term 'nanomaterial', the EC NM Definition, as a reference to determine whether an unknown material can be considered as a 'nanomaterial' for regulatory purposes1. One challenge is the development of methods that reliably identify, characterize and quantify nanomaterials (NM) both as substances and in various products and matrices.
The overall goal of NanoDefine was to support the implementation of the EC NM Definition. It can also support the implementation of any NM definition based on particle size. The project has developed an integrated approach, which allows identifying any material as a nano- or not a nanomaterial according to the EC NM Definition. NanoDefine explicitly supported the governance challenges associated with the implementation of legislation concerning nanomaterials by:
- addressing the issues on availability of suitable measuring techniques, reference materials, validated methods, acceptable to all stakeholders (authorities, policy makers, commercial firms),
- developing an integrated and interdisciplinary approach and a close international co-operation and networking with academia, commercial firms and standardization bodies.
Thus, the NanoDefine Methods Manual provides guidance on practical implementation of the EC NM Definition throughout the nanomaterial characterization process, and on the characterization techniques employed as well as their application range and limits. It assists the user in choosing the most appropriate measurement method(s) to identify any substance or mixture for a specific purpose, according to the EC NM Definition of a nanomaterial. The NanoDefine project also explored how to assess a material against the criteria of the definition through proxy solutions, i.e. by applying measurement techniques that indirectly determine the x50. Those findings were developed through empirically based scientific work and are included in Part 1 of this Manual. As they go beyond the text of the EC NM Definition, they may be used as practical approach to indicate whether a material is a nanomaterial or not, but keeping in mind that they should not be taken as recommendation for the implementation of the EC NM Definition in a regulatory context.
The NanoDefine Methods Manual consists of the following three parts:
Part 1: The NanoDefiner Framework and Tools
Part 2: Evaluation of Methods
Part 3: Standard Operating Procedures (SOPs)
Part 1 covers the NanoDefiner framework, general information on measurement methods and performance criteria and tools developed by NanoDefine such as a materials categorisation system, a decision support flow scheme and an e-tool.
Part 2 discusses the outcome of the evaluation of the nanomaterials characterisation methods for measuring size.
Part 3 presents the 23 Standard Operating Procedures developed within the NanoDefine project.
The current document is part 1.
The EC Recommendation on the definition of nanomaterial1, based solely on size of the constituent particles, foresees development of harmonised measurement methods ensuring ‘consistent results across materials and over time’. The EU/FP7 large research project NanoDefine (http://www.nanodefine.eu) has been exclusively dedicated to support the implementation of this EC Recommendation for the European Union’s legislation. For the first time, measurement techniques able to determine the size of nanoparticles have been evaluated systematically on a well-defined set of quality control materials (spherical, monodisperse) as well as industrial materials of complex shapes and considerable polydispersity. Particularly based on the analytical performance of the measurement techniques as tested on the challenging real-world particulate materials, it was possible to formulate recommendations for use of a new tiered approach consisting of screening and confirmatory techniques. Thus, a consistent framework of guidance for nanomaterial identification according to the EC Definition has been issued in form of the NanoDefiner e-tool (https://labs.inf.fh-dortmund.de/NanoDefiner), with a transparent decision flow scheme and an extensive user manual. Selected examples of analysis and classification as nano-/non-nanomaterials will be given, highlighting the limits of applicability of the available measurement techniques in dependence on sample properties. On some recent relevant developments in sample preparation – as a crucial part for an accurate analysis - will be also reported.
The EC Recommendation on the definition of nanomaterial, based solely on size of the constituent particles, foresees development of harmonised measurement methods ensuring ‘consistent results across materials and over time’. The EU/FP7 research project NanoDefine has been exclusively dedicated to support the implementation of this EC Recommendation for the European Union’s legislation. For the first time, measurement techniques able to determine the size of nanoparticles have been evaluated systematically on a well-defined set of quality control materials (spherical, monodisperse) as well as industrial materials of complex shapes and considerable polydispersity.
Particularly based on the analytical performance of the measurement techniques as tested on the challenging real-world particulate materials, it was possible to formulate recommendations for use of a new tiered approach consisting of screening and confirmatory techniques. Thus, a consistent framework of guidance for nanomaterial identification according to the EC Definition has been issued in form of the NanoDefiner e-tool, with a transparent decision flow scheme and an extensive user manual. Selected examples of analysis and classification as nano-/non-nanomaterials will be given, highlighting the limits of applicability of the available measurement techniques in dependence on sample properties. On some recent relevant developments in sample preparation – as a crucial part for an accurate analysis - will be also reported. Further, ISO/TC 229 ‘Nanotechnologies’ activities aiming at establishing accurate TEM and SEM measurement of NP size and shape as robust, traceable, standard procedures are highlighted. With participation of BAM, study groups have been organizing inter-laboratory comparisons on well-selected NP systems according to the market needs, such as aggregated or shape-controlled titania nano-powder for which size and shape distribution of primary particles must be measured accurately.
Many techniques are available for measuring particle size distribution. For ideal materials (spherical particles, well dispersed) it is possible to evaluate the Performance of These methods. The performance of the analytical instrumentation for the purpose of classifying materials according to EC Definition is unknown. In this work the performance of commercially available particle sizing techniques on representative NanoDefine set of real-world testing materials (RTM) and quality control materials (QCM) for the implementation of the Definition is evaluated.