Community Research and Development Information Service - CORDIS

FP7

ESMI Report Summary

Project reference: 262348
Funded under: FP7-INFRASTRUCTURES

Final Report Summary - ESMI (European Soft Matter Infrastructure)

Executive Summary:
Objective: Soft materials and soft nanotechnology are generally considered as a field that will have a major impact on technological developments in the near future. Therefore, in 2011, ESMI set out to create a top-level interdisciplinary research infrastructure to serve the needs of a broad community of European soft materials researchers. By combining the most important techniques for the synthesis and investigation of soft matter with cutting edge scientific expertise through a sophisticated networking programme, the ESMI consortium intended to create a world class distributed infrastructure for transnational access, which would provide soft matter scientists with a broad choice of techniques to address their scientific objectives. Joint research activities were designed to further improve the existing infrastructure.
During its runtime, from January 2011 to December 2015, ESMI was active in three fields, as detailed below:

Transnational Access: ESMI succeeded in establishing a unique infrastructure, which allowed European researchers to synthesize novel soft matter materials, investigate them with the most advanced techniques and to explore their properties by computer simulations. About 2700 days of access to facilities and more than 120,000 Tflop-hours of computing time was distributed to the users, corresponding to almost full utilization of the planned capacity. About five percent of the resources were used by industrial projects, which is a significantly higher fraction than usually observed for large scale research infrastructures. The high acceptance by both academic and industrial researchers demonstrates the success of ESMI and the need for a distributed infrastructure to serve the European soft matter research community.

Joint Research Activities: Common efforts of the consortium partners were dedicated to develop new infrastructure and to improve the existing one in three categories.
New synthesis and purification routes were developed to broaden the range of available soft matter systems. Groundbreaking work led to the production of completely novel materials and in parallel the quality and availability of systems known beforehand were largely improved in terms of quantity and purity.
Research on the enhancement of inspection techniques resulted in novel instruments which allow the investigation of aspects of soft matter physics which were not accessible before. Advancement of sample environments for existing instruments improves their versatility by allowing for the inspection of samples with the same technique under a variety of different external conditions.
Theoretical and simulation research generated methods for the prediction of material properties which could not be captured previously, either by analytical theory or by computer simulations.

Networking activities: Through its networking activities, ESMI achieved the integration of the European key facilities for soft matter research. Dissemination of knowledge and the spreading of excellence were accomplished by organizing and supporting a variety of workshops and conferences, presenting events independent of ESMI and by publishing in scientific journals. By organizing and supporting themed workshops, schools and laboratory courses ESMI contributed to the continued education and training of soft matter researchers, thereby strengthening European competitiveness in soft matter research and soft nanotechnology. Particular effort was taken to maximize industry awareness, resulting in industrial participation in all ESMI activities at a level between 5 - 7%.

Project Context and Objectives:
Despite the fact that soft matter is ubiquitous in daily life and plays a fundamental role in biology, research on soft matter used to be fragmented into a variety of fields. These were separated along the lines of different materials such as polymers, colloids, surfactants, liquid crystals etc., and dispersed over various disciplines such as physics, chemistry, simulation sciences, chemical engineering and biology. In this unsatisfactory situation, the EU-funded Network of Excellence SoftComp was established by a number of leading soft matter groups in Europe with the aim to foster the integration of European soft matter science.

Based on the experience of the NoE SoftComp, the ESMI consortium set out to build a distributed infrastructure which would provide transnational access to all European soft matter scientists, offering them opportunities of synthetic, experimental and computational research far beyond their own laboratory capabilities. ESMI started up in January 2011 and was supported by the EU for five years. The transnational access (TNA) activities of the infrastructure was complemented by a wide-ranging networking programme for the integration of the soft matter community, the dissemination of knowledge, the education of young scientists and the training of TNA users. ESMI’s activities were completed by an ambitious joint research programme dedicated to establishing new infrastructures and improving existing ones.

Transnational access activities:
The TNA activities were organized in three work packages: experimental, synthesis and computational infrastructures. The access to all these installations was offered through a peer-review system of submitted proposals which was operated online-only at the single entry point of the ESMI web portal.

WP3 ESMI Experimental infrastructure: The objective of this WP was providing access to the ESMI experimental infrastructure, which consists of state-of-the-art instruments available for cutting-edge soft matter research. The ESMI experimental infrastructure comprises light, neutron, synchrotron scattering instruments, rheometers, dielectric and NMR spectrometers, electron and optical microscopes, together with a variety of ancillary equipment and sample environments. The ESMI infrastructure is located in eight European laboratories.
The ESMI experimental infrastructure received 187 successful proposals to which 1900.33 days of access were allocated, which corresponds to 93 % usage of the planned capacity.
WP4 ESMI Synthesis infrastructure: The objectives of this WP were devoted to accessing the ESMI synthesis infrastructure, which consists of state-of-the-art synthesis capabilities comprising world leading polymer and nanoparticle synthesis laboratories located in three European countries.
The ESMI synthesis infrastructure received 31 successful proposals to which 789 days of access were allocated corresponding to 93 % usage of the planned capacity.

WP5 ESMI Supercomputing infrastructure: The objective of this WP was to provide access to the ESMI supercomputing infrastructure, which consists of the JUROPA machine, available at Forschungszentrum Jülich. This infrastructure provides a powerful tool for the prediction of soft matter properties using computer simulations.
The ESMI computation infrastructure received 20 successful proposals to which more than 129000 Tflophours of computing time were distributed, which corresponds to 88 % usage of the planned capacity.

Joint research activities:
The ESMI joint research activities, dedicated to improving existing infrastructure and developing new ones was organized in four work packages, i. e. new theoretical and computational tools, new experimental methods, new sample environments and novel synthesis routes.

WP6 Computational tools to support the design and interpretation of experiments on soft matter: The objective is to further develop and combine existing simulation techniques of flowing soft matter into hybrid methods, which are able to describe a wide range of soft matter systems, including those with internal hard or flexible interfaces. Rheological protocols to disentangle and identify different time scales will be tested and new ones will be devised. Analytical methods will be developed to describe heterogeneous flow properties in bulk, near walls and in microfluidic devices.
Progress towards the objectives was achieved by tackling the following specific tasks.
• Development of hybrid simulation techniques for soft matter systems with hard and flexible interfaces
• Creation of computational tools to support the interpretation of rheological experiments.
• Design of rheology measurement protocols for very slow systems

WP7 Novel experimental technique development: There are two emerging trends and areas of interest in soft matter research: the study of increasingly complex systems with structural and temporal responses over a wide range of scales and investigating their responses under the effect of various external fields. Therefore, the objective of this work package was to develop new experimental techniques that will allow in-depth characterization of a wide range of complex soft matter systems and their response to external fields and associated far-from-equilibrium phenomena. Industrial partners were involved in joint technique development to help ensure that new techniques are user-friendly and robust so that they can eventually be easily utilised by the wider soft-matter community.
In particular the following experimental methods and instruments were newly developed:
• Fourier transform dynamic Raman scattering
• Ultra-small-angle dynamic and static light scattering
• Optimized transmission electron microscopy for soft matter
• Nano dielectric spectroscopy
• Experimental set-ups for advanced interfacial rheology
• Real time analysis confocal microscopy data
• Laser tweezers set-ups for thick samples
• High frequency rheology

WP8 Development of sample environment: This work package aimed at building up novel sample environments on existing infrastructures. The topics have been chosen to allow for a wider range of users to successfully exploit the techniques already available and to develop user interfaces that enhance the capabilities of existing equipment in the consortium to address a wider range of scientific and technological challenges and to further stimulate user access in the future.
A range of sample environments was developed that open up the capabilities of the experimental platform to new types of samples or new types of problems to be studied, which are in detail:
• Universal magnetic field sample environment for time-resolved small-angle scattering experiments
• Sample cells enabling the study of wall and confinement effects on the rheology of colloidal dispersions
• User-friendly environments for dynamic light scattering on non-ergodic samples at rest and under shear
• Microfluidic sample environments for local scale microstructure measurements
• Thermal diffusion cell in combination with confocal microscopy

WP9 Synthesis of tailored systems: This work package aimed to strengthen the basis for new materials used in the soft matter field. The new synthesis methods developed in this work package shall be taken up in the TNA activities in order to facilitate the access to new soft matter samples.
Specifically, the following three research areas were addressed:
• Development of surface modification methods for nanoparticles in order to make them compatible with matrices such as polymers.
• Synthesis of novel polymer bio hybrids by combining polypeptides and polycopeptides with synthetic polymers to combine the properties of peptides and synthetic polymers
• Production of polymers with special architectures such as ring or branched polymers in larger quantities and of a higher structural quality.

Networking activities:

ESMI networking activities were dedicated to the integration of the European key facilities for soft matter research, the dissemination of knowledge and spreading of excellence, providing continued education and training of soft matter researchers, and maximizing industrial participation in all ESMI activities. The work was organized in two work packages, for dissemination, education and training, and for industrial liaison, respectively.

WP1 Networking, Dissemination, Education and Communication: This WP had multiple objectives. First of all, it ensured the successful dissemination of ESMI-related information. Secondly, it provided a coherent programme for the continued education and research training of young and industrial researchers and facilities’ users in the various areas of soft matter. Thirdly, an effective communication programme ensured Europe-wide awareness of the opportunities offered by the ESMI project.

In particular, ESMI
• co-financed and organized dissemination events, such as workshops and conferences on soft matter topics
• co-financed and organized schools and laboratory courses dedicated to training on soft matter subjects
• operated a web site and regularly issued newsletters and mailings to provide the soft matter community with updated information.

WP2 Liaison to industry and related initiatives: The objective of this WP was to develop a roadmap for establishing links to the industry by addressing technological needs and to enhance industrial involvement in ESMI activities.
To accomplish these tasks:
• an industrial user group was established to coordinate ESMI industry relations and to advertise ESMI to external companies
• a road show was produced, which ESMI leading scientists used to introduce the options ESMI was offering to industrial users
This resulted in an industrial participation in all ESMI activities of about 5%.


Project Results:
ESMI research activities were organized in four work packages and resulted in a variety of improvements to existing facilities and the development of new methods and techniques. These are described in detail in the ESMI periodic reports. Here we will highlight the most important and prominent outcome of the ESMI JRA. Please note that in many cases this report is linked to graphs and images, which are not displayed in the online version. For a more comprehensive presentation the reader is referred to the attached PDF-version.

WP6 Computational tools to support the design and interpretation of experiments on soft matter:
Task 6.1: Development of hybrid simulation techniques for soft matter systems with hard and flexible interfaces:
• The properties of MPCD fluids were studied in detail and the influence of hydrodynamic correlations on the dynamics of polymers was fully elucidated. The RaPiD model was extended to better describe shear thinning and elongation rheology. The link between atomistic detail and RaPiD parameters was established. A hybrid model combining MPCD and RaPiD particles was established.
• We developed a method to perform MPCD simulations near complicated geometries which was validated by studying the sedimentation of red blood cells. A dissipative particle dynamics (DPD) simulation approach describing the appearance and growth of flexible interfaces by self-assembly in amphiphilic systems has been developed and successfully applied. We developed a model to simulate hard lath-like particles and studied their gel transition. Smoothed particle hydrodynamics (SPH), originally invented for astrophysical calculations, was adapted for use in complex liquids exhibiting shear-banding, in close proximity to walls.

Task 6.2: Computational tools to support the interpretation of rheological experiments Design of rheology measurement protocols for very slow systems
• The RaPiD algorithm was applied to simulate rheological properties. In particular we investigated core-shell particles under melt conditions and validated the simulation results against experimental data from a star polymer melt of moderate functionality and low molecular weight. Experimental collaborators provided rheological data for comparison with start-up and cessation protocols
• We developed an analytical theory for shear gradient coupling instability in glassy systems. Using a combination of Brownian Dynamics simulations and computational fluid dynamics, we found that hard spheres band with one of the bands being jammed.

WP7 Novel experimental technique development:
Task 7.1: Fourier Transform Dynamic Raman Scattering
Dynamic light scattering (DLS) is a convenient and widely used technique for the investigation of particle diffusion and particle size characterization. An extension to Raman scattering that is able to distinguish chemically different species could open up a wide field of promising new applications. In mixtures, the diffusion coefficients for different components could be resolved without special labelling, and an analysis of cross correlation of different Raman lines would contain the information if different species diffuse together and are thus attached to the same particle. While a simple implementation where DLS is performed on a single Raman line is clearly out of reach due to the low Raman intensities, a Fourier transform approach (e.g. in Fourier transform infrared (FTIR) spectroscopy), based on the interferometer, results in a sufficiently high intensity at the detector since all Raman lines, as well as the Rayleigh scattering, contribute to the signal.
In this project we have developed a new Dynamic Light Scattering (DLS) instrument that detects and analyses chromatic scattered light using Fast Fourier Transform (FFT) techniques. The instrument permits the measurement of particle diffusion coefficients as a function of the wavelength of the incident light. If the wavelength of scattered light is correlated to the chemistry of the scatterer, one could distinguish the dynamics of chemically different particles. We have successfully tested our new method first using the Rayleigh component of the scattered light, which results in quantitative agreement with the results obtained using classical correlation techniques on a commercial DLS spectrometer. While the main objective of using Raman lines in order to extract diffusion coefficients of colloidal particles with chemical specificity could not be achieved due to fundamental limits in the nature of the Raman light, there remain other, highly interesting potential applications for such an instrument. It could, for example, be applied in investigations of the dynamics of photonic colloidal crystals, where the ability to resolve correlation functions for different colours of the scattered (diffracted) light would result in an extremely efficient way of measuring dynamics for different crystallite orientations and crystal structures.

Task 7.2: Ultra-small-angle dynamic and static light scattering
At the start of the project, small-angle light scattering was already widely implemented in a number of commercial instruments designed to characterize colloidal particles with sizes typically larger than 100 nm. However, these instruments allowed for static measurements only. This was quite in contrast to trends in soft matter research, where in particular in the investigation of complex fluids exhibiting slow dynamics, dynamical arrest, phase transitions of gel and glass transition access to dynamic light scattering at low and ultra low angles becomes important. Several research groups had pioneered such studies, but no commercial instrument was available. Moreover, the software used to obtain, for example, correlation functions using multi-speckle correlation techniques was generally far from being user- friendly, which is an essential requirement for its use in a TNA programme or for successful commercialization. We therefore planned to develop a CCD camera-based light scattering set-up for static and dynamic experiments at low and ultra-low angles, combined with user-friendly software.
A new SALS design was developed, which is sketched in Figure 7.2.a. The set-up is optimized for use with the latest generation of optical and electro-optical components (cameras, lasers, optical elements). Care was also taken to allow the integration of anticipated developments in the future. The software structure and layout was concluded. Functionality requirements for a commercial product were identified. Programming of drivers for key components and communication interfaces were concluded. A first prototype was assembled and feasibility tests conducted. A webpage was established at
http://www.lsinstruments.ch/technology/small_angle_light_scattering
to introduce and explain SALS and USALS to scientist unaware of the technology.

Task 7.3: Optimization of Electron Microscopy for Soft Matter
Since the start of the project, significant progress has been made concerning the optimization of soft matter imaging using transmission electron microscopy. The most important steps in the optimization correspond to the reduction of beam damage during sample preparation as well as during imaging in the microscope. Further, special attention was paid to the 3D investigation of soft matter and self assembly by electron tomography.
a) Minimization of beam damage:
In order to reduce the effects of beam damage during characterization by electron microscopy, we evaluated the use of so-called “high angle annular dark field scanning transmission electron microscopy” (HAADF-STEM), an advanced electron microscopy technique. HAADF-STEM is commonly used in the field of "hard matter", but its application for soft matter materials is currently limited. HAADF-STEM uses a focused beam rather than a parallel beam and scans across an area of interest. Even though a relatively high current is used, the technique can be considered as a low-dose imaging technique because of the extremely small dwell times that are used at each scanning position. We have successfully used HAADF-STEM in the study of insulin fibrils, colloidal nanoparticles, porous materials and polymer systems.
Another approach we investigated to minimize the effect of beam damage is the use of low acceleration voltages. Working at acceleration voltages as low as 80kV reduces knock-on damage caused by the electron beam, but will also reduce the spatial resolution. We have demonstrated that the use of aberration-corrected transmission electron microscopy yields images that still show atomic resolution, even at 80kV. As an example, we successfully imaged glycogen-based nanoprobes that were investigated in collaboration with Dr. Sergey Fillipov (Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic) in the framework of a transnational ESMI project. From this and other studies, it could be concluded that the current of the electron beam is the most crucial factor and should be lower than 40pA. We consider this as the tolerance level for these materials.
Although use of low acceleration voltages in TEM (80 kV, 60 kV or even lower) limits knock-on damage to sensitive materials, ionization damage, caused by local heating of the sample, is increased in low-voltage TEM. To counteract this local sample heating, recent experiments on sensitive metal-organic framework samples (MOFs) were carried out at 80 kV acceleration voltage, under cryo-conditions. This approach greatly increases the framework stability. Using these cold imaging conditions, we were able to image the in-tact pore structure of delicate MOF-5 crystals for the first time in a TEM.
b) Optimization of sample preparation:
Soft matter samples such as polymer systems are often prepared for TEM investigation using an ultra microtome. However, cutting artefacts can be present when using this technique. In addition, the samples are often still too thick to enable the use of advanced TEM techniques. Furthermore, ion beam milling has been tested in the study of carbon-based materials as well as anodized aluminium oxide membranes. Although these trial studies resulted in useful TEM samples, their preparation must be carried out with great care and is very time-consuming. Another disadvantage is the fact that both the ultra microtome and the ion mill are not site-specific. The use of focused ion beam milling (FIB) has as a major advantage that it is indeed site specific. Until recently, FIB was only used for hard matter compounds. The FIB installed at the University of Antwerp can be used at flexible acceleration voltages as well as a broad range of ion beam currents. In this manner, a protocol has been developed in which the initial rough milling is carried out at high voltages and at high currents. This initial approach is followed by sequential steps at lower voltages and currents. The final milling steps, resulting in lamellae with a thickness of approximately of 80 nm or less are carried out at an acceleration voltage as low as 1kV and a beam current of 75 pA. Using this approach, a broad range of samples has been prepared with great success including polymers, porous membranes and biological cell tissue. Also needle-shaped samples for electron tomography can nowadays be prepared successfully.
For cryo-microscopy, we have implemented the use of a plunge freezing device (Vitrobot Mark IV). This technique can be used to form a thin layer of amorphous ice in which the sample is embedded. We came to the conclusion that it is of great importance to first make the TEM grids hydrophilic using a plasma. Using this approach we can study samples in their native conditions (e.g. during an ESMI TNA project concerning assemblies of nano-dumb-bells) Furthermore, cryo-microscopy can greatly reduce electron beam damage as explained above.
c) Evaluation of the Recording Medium:
The use of HAADF-STEM enables imaging of soft matter with sufficient contrast using the newest generation of HAADF detectors. By optimizing the collection angle of the detector, the contrast can be optimized for each specific sample. We also demonstrated that the use of ADF-TEM is very useful in this respect. A major advantage of the ADF-TEM technique is the absence of scanning noise and, perhaps more importantly, the easy insertion of an ADF-TEM aperture in a TEM configuration using a CCD camera, whereas ADF-STEM requires a dedicated system that includes an annular dark field detector. These findings might favour the use of ADF-TEM to image soft materials.
Recently, we have tested the use of a so-called Super-X system, which consists of 4 windowless energy-dispersive X-ray spectroscopy (EDX) detectors symmetrically arranged between the pole pieces of the objective lens at a short distance from the sample. As a consequence, a high X-ray count rate is obtained and the detection efficiency for light elements is increased with a factor of 20-50. The successful use of this detector was demonstrated during an ESMI TNA project
d) Optimization of Statistical Treatment and Software:
An efficient way to interpret images with low signal-to-noise ratio in a quantitative way is by using statistical parameter estimation theory. In this theory, use is made of a model which is parametric in a set of unknown structure parameters, including, for example, the object size, orientation, shape, and location. These parameters can then be measured by fitting this model to an experimental image. Therefore, a criterion of best fit is employed, which quantifies the similarity between the images and the model. This methodology makes optimal use of the available measurements, which is of critical importance since electron microscopy experiments are more and more limited by the maximal allowable dose. In order to further improve its performance, a new method was developed to explore the optimal experimental settings to detect light atoms from scanning transmission electron microscopy (STEM) images. Since light elements are important in soft matter, great efforts were made to optimize the STEM technique in order to detect these elements. Therefore, classical performance criteria, such as contrast or signal-to-noise ratio (SNR) are often discussed here in order to improve the direct visual interpretability. However, when images are interpreted quantitatively, one needs an alternative criterion, which we derive based on statistical detection theory. Using realistic simulations, we demonstrate the benefits of the proposed method and compare the results with existing approaches.
e) 3D investigation of self-assembly by electron tomography
For the characterization of nano-assemblies, electron tomography is nowadays a standard technique, yielding a 3D description of the morphology and inner structure. However, 3D reconstructions based on classical algorithms, suffer from a number of restrictions. Most importantly, for soft samples degradation due to the electron dose often occurs. As a consequence, the projections were mostly acquired with tilt increments of 1°-5°, yielding an under-sampling of the higher frequencies and a consequent degradation of the resolution with a blurring of the sharper features. We therefore developed a novel approach at the University of Antwerp that enables us to determine the coordinates of each nanoparticle in an assembly, even when the assembly consists of up to 10,000 (spherical) particles. This technique has a major impact as it enables a straightforward quantification of inter-particle distances and 3D symmetry of the stacking. Furthermore, the outcome of these measurements can be used as an input for modelling studies that predict the final 3D structure as a function of the parameters used during the synthesis.

Task 7.4: Nano Dielectric Spectroscopy
A new experimental approach for the characterization of molecular dynamics at the nanoscale by broad band dielectric spectroscopy has been implemented on a commercial AFM. We have developed the experimental protocol and a user friendly interface for nano-dielectric spectroscopy experiments using LabView (see Figure 7.4.a). In this way this innovative approach has become available to non-expert external users in the ESMI TNA programme. Furthermore, a detailed numerical model and a semi-quantitative analytical equation connecting the measured signal and the complex local permittivity have been established.
Finally, we have explored the suitability of this experimental method in various soft matter research lines.

Task 7.5: Experimental Setups for Advanced Interfacial Rheology
A quantitative description of the material properties and the rheological material functions of highly elastic interface layers represent the basis to understand not only the functioning of biological systems (such as breathing mechanism of lung alveoli), but also to optimize and improve industrial processes that involve multiphase systems like foam and emulsions.
It has been proved in the past that the use of a rectangular Langmuir trough especially for highly elastic systems introduces a complex 2D state of stress; in fact in this kind of geometry the interfacial stress is determined by both dilatation and shear response of the interface. In order to obtain a proper quantitative characterization of the response of these systems to a uniform dilatational deformation where no shear contributions are induced, an advanced version of radial trough apparatus has been designed, which is shown in Figure 7.5.a.
Thanks to a precise driving mechanism, twelve aluminium fingers pull simultaneously on an elastic band in a coordinated way, creating approximately a circular shape. Each finger is placed on a slide rail and connected to a linear stage motor by an ultra high molecular weight polyethylene wire. An accurate calibration procedure previous to each experiment ensures a precise and reproducible initial position of the elastic band. Additionally, this apparatus is equipped with an advanced optical system that allows visualization of the interface to characterize the applied dilatational flow field and perform particle tracking. A wide range of interfaces can be studied, including recently characterized polymer multilayer systems directly assembled in situ using a sub-phase exchange system.
The material properties that can be determined with the radial trough apparatus are surface pressure-area isotherms and pure dilatational rheological parameters. Standard for a radial geometry, surface pressure is measured using a platinum rod connected to a Wilhelmy balance. Although this technique respects the radial symmetry, this widely used technique has numerous disadvantages: evaporation and buoyancy effects, distortion of the interfacial stress profile around the probe and limited frequency range of oscillatory rheological measurements. With the goal of overcoming these restraints and at the same time increasing the sensitivity, a miniaturized set-up for tensiometry measurements has been developed and tested, based on an idea by Zell et al (Z.A. Zell et al., Appl. Phys. Lett. 97 (2010) 133505). This set-up consists of a microtensiometer made out of a semi-flexible polymer structure placed at the interface. The gradient in surface pressure between the in- and outside of the tensiometer will cause the device to be compressed through flexible millimetre-scale springs. Using the previously mentioned optical set-up, the deflection and hence the related surface pressure can be determined.
Proof-of-principle oscillatory measurements showed a remarkable agreement between the values of surface pressure independently detected by the Wilhelmy balance and by tensiometer deflection. Furthermore, the instantaneous response of the tensiometer set-up allows for high frequency measurements, up to frequencies in a range much higher than currently reported in the literature. The whole system is now operational, validated and ready for use in TNA experiments.

Task 7.6: Advanced Confocal Microscopy
State-of-the-art confocal microscopy systems enable users to acquire high quality images at very high speeds generating vast amounts of data. However, the only instantaneous information available to the experimentalist is (some of) the raw image data, which often is not enough to ascertain that experimental parameters have been optimised and may considerably limit the efficiency of experiments. Therefore, the usability of the existing rheo-imaging set-up at the University of Edinburgh, which relies on a fast confocal microscope, was drastically increased by implementing real-time image analysis.
Real-time availability of image data is achieved by streaming individual image frames (together with some of the relevant meta-data) to a SSD RAID array as soon as they are captured (Figure 7.6.a).
A user-friendly software package was devised that analyses these temporary image files ‘on the fly’ and also optimizes the hardware design in order to deliver a ‘confocal microscopy based flow visualization device’. This integrated system was tested and fully commissioned for access by external users.
The rheo-imaging set-up consists of a commercial rheometer (Physica MCR 301, Anton Paar) which is mounted on top of a confocal research microscope (Nikon TE300 with the upgraded VT-Eye confocal). The microstructure of the sheared sample can be imaged through the custom glass bottom plate of the sample stage. One of the basic analysis steps consists of checking the flow profile of the sample, as this can easily identify experimental artefacts such as wall slip.
To perform this analysis ‘on the fly’, the software package needs to
1. Monitor the directory receiving the temporary image files for the arrival of new image files (once the acquisition has started)
2. For each new file read the image data and extract its time stamp and position data
3. Process this new data to quantify the flow in the system
4. Present the results to the user as they become available
The software package was implemented in MATLAB, which provides acceptable performance with a fairly straightforward programming environment. The core analysis step consists of calculating the Pearson correlation of two successive images at the same z position (height) within the sample. The shift leading to the highest correlation is then estimated with sub-pixel resolution. From this the average shear rate at a given height can be determined and by analysing a confocal stack, the complete shear profile of the imaged sample volume is calculated.
For relatively small image sizes and slow frame rates (256x256 pixels, 15 fps) the full analysis can be performed in real time. For larger images sizes and/or faster frame rates the GUI includes options to reduce the image size by binning or the frame rate by the skipping of frames, and can thus still allow real-time feedback. The analysis results are also saved to disk to facilitate more detailed off-line analysis.
Although the software is primarily designed for “on the fly” processing of image data generated by the VT-Eye confocal system, it can also be used to analyse pre-recorded data, such as the OME-Tiff stacks saved by the Visitech confocal software or avi files recorded by our camera-based epi-fluorescence rheo-imaging set-up.
The software development was complemented by improvements to the overall design of the system, for example by inclusion of a temperature control for our custom rheo-imaging base plate. The system is now operational, and was used in TNA experiments.

Task 7.7: Advanced laser tweezers set-ups for thick samples
Optical tweezers are a very versatile tool for studying soft matter, with applications ranging from simple manipulation of microscopic particles to highly quantitative measurements such as characterization of the interaction potentials between colloids and micro-rheology measurements. However, most implementations used for quantitative measurements require good optical access to the sample from both sides, severely restricting the types of samples that can be used. We added a new measurement modality to the existing dual-trap optical tweezers (OT) set-up, where the positions of the trapped particles are monitored with a high performance digital camera. The images are analysed to track the particle positions and deduce interaction potentials and rheological data.
a) Quantitative force measurements
‘Traditional’ set-ups for force measurements need good optical access to the sample from both bottom and top. In this implementation, determining the deflection of the transmitted light of the laser beams used to trap them monitors the positions of two trapped particles. As this implementation uses simple semiconductor detectors (quadrant photo diodes) relatively high sampling rates (10s of kHz) can be achieved routinely and it is straightforward to convert the voltage signals from the detectors into position information with resolution better than 10nm.
However, often such high bandwidth is not required, making it feasible to implement quantitative force measurement set-ups using fast cameras. In this case, good optical access to the sample is only required from one side, allowing for measurements in thick samples
We successfully tested several locally available cameras camera (Pulnix TM6740, Mikrotron MC1362 and Orca Flash 4.0) for recording movies of trapped particles. The Pulnix camera was sufficiently fast for most applications and was therefore chosen for the default configuration. We wrote custom software code in Labview (as well as Matlab) to track the particle positions with sub-pixel accuracy and extract the viscoelastic properties of the suspending medium. A second modality that we implemented is the use of two alternating traps to perform wideband microrheology to measure the viscoelastic properties of complex fluids. In this scenario, two nearby traps are modulated in an alternating fashion, forcing a single probe particle to move between the two trap positions.
b) Combining confocal imaging with optical tweezers
Confocal microscopy and optical tweezers can in principle be combined using the same objective for both systems. However, in this configuration neither system is independent. For instance, it would be impossible to hold a particle in an optical trap and simultaneously scan the regions above and below this particle without moving the particle in the process. This obstacle can be overcome by using independent objective lenses either side of the sample. This enables the operation of both systems to be entirely independent, but requires good optical access from both sides of the sample, thereby preventing experiments on very thick samples.
In our implementation we combine confocal microscopy and optical tweezers through the same objective but use a remote focusing technique to make them independent. Remote focusing is a relatively new technique which allows focusing to be carried out externally without introducing severe optical aberrations. It does not require the main objective (or sample) to move in order to acquire a confocal stack. The axial position of the optical tweezers trap within the sample can thus be controlled independently, namely by adjusting the separation of sample and main objective.
We have combined a user friendly optical tweezers system with a commercial confocal microscope (Biorad Radiance 2000MP attached to a Nikon TE-2000 inverted microscope). We used a dual-objective focusing rig to improve the optical efficiency. We engineered a coupling of the confocal microscope to the tweezers set-up that is stable enough for routine use and enclosed the optical path in critical locations for user safety. The set-up is operational, as shown by the z-stack displayed in Figure 7.7.a and was fully commissioned for user access by July 2015.

Task 7.8: High Frequency Rheology
High-frequency rheology provides insight into the microstructure, interactions and local dynamics of complex fluids. Conventional rheometers are limited in frequency to about 10 Hz due to inertial contributions. Since time-temperature superposition is not suitable for many complex fluids, a homebuilt rheometer was developed to enable rheological measurements at higher frequencies. We have shown how resonator devices could achieve high sensitivity, but their functioning is limited to rather low viscosity materials. Therefore we investigated whether another technology could be of use and developed a piezo shear high frequency device, capable of measuring materials with higher viscosities/moduli.
The rheometer (Figure 7.8.a) makes use of two stacks of piezo-elements, operated in shear mode and mirrored against each other, with one element acting as attenuator and the other as detector. This results in a pure shear motion with a continuous frequency range from 10 − 3000 Hz, up to the first resonance frequency. At an operating gap of 100 μm, 10 μL of sample volume is required. A high-performance lock-in amplifier is used both for generating a sinusoidal shear motion and detecting the output signal. Alignment is carried out by a combination of piezo-screws and inductive proximity sensors, offering a sensitivity < 100 nm. In Figure 7.8.b the raw value of the complex modulus G* of PDMS (5000 cSt), measured by the novel high-frequency rheometer, is shown. The un-calibrated data agrees reasonably well with moduli obtained with a commercial stress-controlled rheometer (TA Instruments, Discovery Hybrid Rheometer 3) and an earlier developed piezo-rheometer (Roth et al., 2010).



WP8 Development of sample environment
Task 8.1 Universal magnetic field sample environment for time-resolved small-angle scattering experiments
This task concerns the development of a flexible sample environment for measurements in both static and dynamic magnetic fields where the local magnetic field can be correlated with the results from different small-angle scattering techniques to investigate time-dependent structural properties such as local viscoelastic properties in complex soft matter
We have constructed a final version of a Helmholtz coil sample environment, which allows for time-resolved small-angle scattering measurements, for the investigation of field-induced structures and anisotropic diffusion as well as for field-driven rotational motion of anisotropic magnetic particles. The strength, direction and rotation frequency can be selected remotely, and when using it in combination with light scattering, the resulting field-induced structures can then be recorded in a time-resolved fashion either using transmission measurements with crossed polarizers, or using a fast CCD camera as a two-dimensional detector for small-angle static and dynamic light scattering. The coil set-up is designed for working with a variable sample holder that can use commercial Hellma quartz cells with different thicknesses, and is thus also suitable for SANS experiments. We have also adapted the coil system such that it can be used together with one of the light scattering goniometer systems available at the University of Lund in order to perform dynamic light scattering of anisotropic diffusion of magnetic particles in external fields

Task 8.2: Sample cells enabling the study of wall and confinement effects on the rheology of colloidal dispersions
In this task, sample cells for probing the phenomena occurring near walls are developed using two approaches. On the one hand, techniques which are sensitive to the structure and dynamics near walls such as total internal fluorescence microscopy and evanescent wave dynamic light scattering will be adapted and equipped with sample environments in which viscometric flows can be applied. On the other hand, a home-built high resolution fluorescence microscope will be incorporated in a commercial rheometer. To study the effect of confinement, a transparent plate-plate shear cell with distance tuneable on a micron scale and combined with microscopy techniques will be built.
a) Wall slip measurements with flexure-based rheometer
A flexure-based rheometer (FMR) at KU-Leuven as the reference tool for slip measurements has further been improved with a redesigned nanopositioning system to minimize compliance in the system and to enable shearing surface parallelism < 1 μrad. This had proven to be necessary in order to accommodate for the expected shear stress range of the fluids to be tested during the validation measurements of the set-ups developed at FORTH and FJZ. Furthermore, to study the effects of surface roughness under confinement and to control slip of the confined particle suspension shearing surfaces were developed with defined roughnesses of 0.1, 15 and 50 um while maintaining the required flatness of the shearing surfaces of lambda/10 in order to set apparent gaps smaller than the actual surface roughness.
The improvements of the set-up have been validated with a model system of soft deformable particles in the form of the cross-linked poly(acrylamide) microgel particle system Carbopol. Initial investigations determined the true particle shape and dimensions in a swollen state using confocal microscopy on stained gel particles, in order to assess in situ the critical overlap concentration at which the swollen gel particles become space filling (Fig. 3a)
b) Near-wall dynamics under shear
At Forschungszentrum Jülich, a sample cell for near-wall velocimetry was constructed based on a plate-plate geometry applying an air bearing rotation device, used to rotate the bottom. The top plate, which is fixed, carries a semi-spherical lens, allowing for the creation of an evanescent wave and the measurement of correlation functions of the scattered intensity. Due to the symmetry of the above-mentioned lens, it is possible to change scattering vector components parallel and normal to the reflecting interface, independently of each other. It is therefore possible to study the particles’s near-wall dynamics normal and parallel to the wall, which however comes at the cost of the top part having to be fixed and consequently the rheological response of the sample cannot be measured online.
c) Combination of rheology and evanescent wave DLS
A near-field velocimetry based on EWDLS set-up was implemented on a stress controlled rheometer (Rheometrics DSR) in FORTH. This model was chosen as it is specially adapted to rheo-optical measurements, having a very accessible and changeable bottom plate. Particular attention was given to the design of a special mount that allows the attachment of a semi-cylindrical lens together with a glass plate on the rheometer, where the glass serves as the bottom plate of the rheometric shear cell.
In the measured correlation functions, an oscillating signal is visible which can be attributed to the motion of tracer particles within the evanescent wave. From this signal, the near wall particle velocities and the local shear rate can be determined. Results from a feasibility test on a Silica sample in a water glycerol mixture are shown in Figure 8.2.a.

Task 8.3 User-friendly environments for dynamic light scattering on non-ergodic samples at rest and under shear
The aim of this task was to develop user-friendly software to open access to the so-called multi-speckle dynamic light scattering technique, where a 2D CCD camera enables averaging over a large number of independent speckles and thus the determination of the ensemble averaged correlation function representative of the dynamics of the sample. Multi-speckle set-ups for both single and multiple scattering samples in a well-thermostated environment shall be adapted for use on a commercial rheometer to enable simultaneous high quality DLS/DWS and rheological measurements for samples under steady and oscillatory shear.
The work towards building user-friendly MSDLS software has been undertaken along two lines. We have upgraded the software to allow for fast and reliable acquisition of multi-speckle DLS or DWS data both at rest and under shear. Secondly we have implemented image analysis within a commercial software (Igor +) that enables fast and automated fitting of the MSDLS time correlation functions as a function of waiting times. This part of the software, including acquisition and storage of data, analysis of data and calculation of the time correlation function and automatic plot of correlation functions, mean relaxation times and stretching exponents as a function of waiting times, is available for TNA users. The second and more ambitious step towards new software for calculating correlation functions in a much less time-consuming manner (or even possibly in real time) with the use of graphical processing units is still under way.
Extensive testing of the LS-echo and multi-speckle DLS (MSDLS) and rheometer combination built on an Anton-Paar MCR 501 stress-controlled rheometer and an ARES/TA strain- controlled rheometer demonstrated the feasibility of the technique. We have thoroughly discussed the technique and its capabilities with the industrial ESMI partner Malvern and investigated the option of the joint commercialization of the set-up. We have agreed on a project plan whereby FORTH will build a laboratory prototype of the set-up on a Malvern rheometer.

Task 8.4 Microfluidic sample environments for local scale microstructure measurements
Microfluidics offers unique opportunities to study the structure, dynamics, and kinetics of liquids, suspensions, and colloids. In particular when studying the response to concentration, solvent, or time lag, it is mandatory that all corroborative measurements be taken from the same sample volume at the same time. Microfluidic approaches have shown to be very powerful and promising in this respect. A microfluidic system will be developed, which allows the remote-controlled flow and mixture of liquids in a sample container for concurrent small-angle X-ray scattering and UV-VIS spectroscopy.
A prototype device was developed at PSI which is suitable for X ray scattering experiments in the momentum transfer range between 0.02/nm and 20/nm and which allows UV/Vis spectra to be acquired close to the position at which X ray measurements take place. Consistent with design parameters, overall sample consumption for such a combined measurement was determined to be in the order of 30µl. Beyond the original specifications of the device, the importance of accurate temperature control was recognized. Consequently, temperature control was added to the device’s capabilities.
Whereas basic functionality could be demonstrated, the prototype requires further modification to be suitable for standard TNA user operation. In its current form, the design requires too much device-specific expertise to be used by non-experts and has not been deemed fully suitable for regular user operation at the cSAXS beamline. However, parts of the device are used regularly for offline measurements, complementary to X-ray spectroscopy experiments at the PHOENIX beamline at SLS, e.g., surveying CaCO3 nanoparticle precipitation. Thus expertise gained, for instance, in regard to more user-friendly connectivity and window sealing, can be incorporated at a later point in a second version, which should be more amenable to use at the cSAXS and PHOENIX beamlines as originally envisioned.
Various microfluidic devices were developed for use with confocal microscopy, of which one proved particularly useful. This can be used in confocal microscopy and at the same time it is possible to use it for thermal diffusion measurements. The details of these results will be discussed in Task 8.5.

Task 8.5: Thermal diffusion cell in combination with confocal microscopy
Temperature-gradient induced mass transport in complex soft matter systems is a still largely unexplored. Therefore this task was dedicated to develop a thermal-gradient cell that can be used in combination with a confocal microscope. The combination of a thermal cell and microscopy is very useful for soft matter systems, since the diffusing entities are in the micrometer range. The use of existing set-ups is often complicated either due to strong scattering or due to rather long equilibration times in the order of days. The challenge here is to build a very thin cell (20-50 micron) in order to limit equilibration times and to apply an accurately controllable temperature gradient (temperature differences of the order 0.001 K).
Various dimensions and production methods were tested to manufacture microfluidic cells. The general design concept of the cell, which eventually proved useful, is sketched in Figure 8.5.a
For the quantitative description of the temperature gradient in the working channel, a calibration method based on fluorescence lifetime microscopy (FLIM) was developed. Using this cell in a confocal microscope it is now possible to measure the thermal diffusion properties of micron-sized colloidal objects.

WP9 Synthesis of tailored systems
Task 9.1: Surface modification and compatibilization
Various types of nanocrystals as well as combinations of these were capped with aminofunctional-ized poly(isoprene)-diethylenetriamine. While the diethylenetriamine binds to the nanocrystal surface, the hydrophobic poly(isoprene) block is especially suited to be integrated in other hydrophobic polymers or block copolymers. The capped nanocrystals were then integrated in functional polymers and block copolymers via a micelle approach and seeded emulsion polymerization. As a demonstration system, an encapsulation in poly(isoprene)-block-poly(ethylene glycol) diblock copolymer (PI-b-PEG) was employed, which results in excellent water solubility and bioinertness of the nanocrystals. The encapsulation was performed via self-assembly processes of the amphiphilic diblock copolymers in water leading to micelle structures, in which the PI moiety is subsequently cross-linked by a radical polymerization using azobisisobutyronitrile (AIBN) as the initiator. Additionally, seeded emulsion polymerization with styrene/divinylbenzene can be used to further increase the stability and provide new functionalities. The system is extremely versatile. Instead of QDs, superparamagnetic iron oxide nanocrystals (SPIOs) and gold nanocrystals (Au), as well as arbitrary combinations of these, can be encapsulated. Moreover the PI-b-PEG can be functionalized and functional derivatives of styrene/divinylbenzene may be used in the seeded emulsion polymerization. This allows for the modification of the properties of the resulting composite, including polarity, solubility, zeta potential and stability under diverse conditions. Finally, the nanocrystals were incorporated in poly(isoprene). SPIOs (diameter 12 nm) were dissolved in a solution of poly(isoprene) in toluene. After removal of the solvent, a homogenous nanocomposite was obtained.

Task 9.2: New polymer-bio hybrids
The synthesis of new hybrid miktoarm star materials of the type (PBd)2PBLG, where PBd is polybutadiene and PBLG is poly(γ-benzyl-L-glutamate), involved first the preparation of in-chain polybutadiene functionalized with an amine group, followed by the ROP of γ-benzyl-L-glutamete N-carboxy anhydride to produce the hybrid miktoarm copolymer. All manipulations were performed under high vacuum in glass reactors, equipped with break-seals, glass-covered magnets, and constrictions, for the addition of reagents and removal of the intermediate products following well-established high vacuum techniques. The polymer characterization was carried out at each step of the synthesis using 1H-NMR and multi-detector size exclusion chromatography.

Task 9.3: New Production processes for polymers with architecture
Among the non-linear polymers, cyclic polymers were taken as an example. At the beginning of the work, a method was established to synthesize cyclic polyethylene glycol from the linear precursor material. Classical high dilution techniques were used. The raw product contained large quantities of higher molecular weight linear and cyclic by-products, together with linear precursor. The higher molecular weight structures could be removed by classical fractionation using a solvent/non–solvent pair. The linear precursor could be removed by oxidizing the alcoholic end groups to carboxylic acid groups. This method allowed separating the residual linear material by ion exchange chromatography. Sample quantities of 10g could be obtained. Meanwhile, the molecular weight range was extended to 20.000 g/mol. The removal of the oxidized linear precursor gets more difficult with increasing target molecular weight. Therefore the selection of the right ion exchange resin is of crucial importance for the complete removal of the linear material. It was found that especially the use of resins with particle sizes in the micrometer range improves the purification efficiency.

Potential Impact:
The major achievement of ESMI is the true integration of European soft matter science in three directions: building networks across scientific disciplines, connecting different research methodologies and bridging academia with industry. This will continue to have a significant synergy effect on soft matter research and so strengthen Europe’s position in a field which, in the light of developing soft nano-technology and biophysical applications, will become more and more important in the future.
The high involvement of industry, both of ESMI partners and companies external to ESMI, in all activities will increase the level of basic understanding of soft matter properties among industrial researchers. This will enhance the options for knowledge-based rational design of materials and products and consequently result in a more effective use of resources and increased environmental sustainability.

Transnational access activities
The ESMI transnational access activities offered synthesis as well as experimental and computational possibilities, which were unattainable or even unknown to individual scientists or even to entire communities. With the support of the facilities’ local contacts, also non-expert users were enabled to acquire, thoroughly analyse, and interpret data at a specialist level. Due to the network nature of this distributed infrastructure with its variety of facilities, researchers could design interdependent and mutually supplemental approaches to tackle a scientific problem, which is significant added value compared with a single sited infrastructure. All these aspects add up to a competitive advantage for European soft matter scientists helping to consolidate the ERA’s leadership in the development and investigation of new soft matter materials.
The broad spectrum of methods and techniques offered by ESMI or a potential follow up research infrastructure could attract new user communities. A plethora of biophysical problems could be tackled with the aid of ESMI facilities which provides European scientists with unprecedented research options in a highly competitive field. An increased usage of ESMI facilities by industrial researchers will in the short term help to enhance their capabilities for rational product design. In the medium and long term, this will increase the innovation potential of European industries, such as those producing food or personal care products, and enable them to hold on to or improve their position in the global market.
A sizable fraction of the access granted under ESMI was allocated to researchers from south-eastern European countries. With this, ESMI will add to a strengthening of the research landscape in these countries, which will contribute to the economical harmonization of these regions with northern Europe

Joint research activities
ESMI JRAs contributes to the integration and harmonization of the scientific endeavour of leading European groups. This bundles together expertise, reduces internal competition and avoids duplication of work. This ensures a more efficient use of resources and faster results. Additionally, co-operation across disciplines leads to a mutual fertilization of research fields and together with high industry involvement, this enables fast knowledge transfer and improves innovation potential.
By nature, the main impact of JRAs will be scientific. The efforts to explore new routes for the synthesis of soft matter systems will provide the community with a wealth of systems and materials which may have novel features, ranging from inorganic particulate materials providing completely new options to tune optical material properties, to polymer/protein hybrid materials which combine the availability of large quantities of synthetic polymers with biological functions.
The development of new experimental methods, sample environments and simulation algorithms will expand the range of techniques which are nowadays available to a significant extent, which will lead to unimagined research techniques. An example of this would be the work performed for the optimization of transmission electron microscopy to investigate soft matter. At the beginning of ESMI, 3D reconstructions of soft matter material from tomographic TEM observation were unknown. Through the ESMI JRA, they are now available, and have the potential to revolutionise the imaging of biological material.

Networking activities
The ESMI networking activities can be coarsely grouped into training and education efforts on the one hand and dissemination and communication activities on the other.
The continued education of young scientists and training of users has been provided through a series of themed workshops and laboratory courses as well as by user training at the hosting TNA facility. Participants will benefit from these activities by increasing employability and improved career options. Academic and industrial employers will find a group of well trained researchers with specialized experience in soft matter science. This will help the European research area to take a leading role in the field of soft matter. The participation of industrial partners ensures the consideration of the industrial dimension of research and training. Therefore, ESMI training and education activities help to bridge the industry-academia gap in a field where a high level of innovation is expected in the coming years. Through ESMI’s efforts to train researchers already in employment or young scientists trained through ESMI activities, European industry has access to a number of highly-skilled scientists equipped to lead the way to further innovations.
The results and foreground obtained from ESMI research activities were and will be disseminated in over hundred sixty publications in peer reviewed scientific journals, presentations and posters at international scientific conferences, seminars, colloquia and in university lectures in the long term. By this, ESMI will contribute to making the Innovation Union a reality, which is a central part of the Europe 2020 strategy [1,2]. Dissemination of research results is an important basic for innovation, thus ESMI will help to strengthen European leadership in a key field important for a plethora of applications.
[1] Europe 2020: “A strategy for smart, sustainable and inclusive growth", COM(2010) 2020, Brussels, 03/03/2010.
[2] Europe 2020: “Flagship Initiative Innovation Union", COM(2010) 546, Brussels, 03/03/2010.

Gender Support activities
ESMI set-up a gender support programme with the aim of increasing the participation of women in natural sciences. Apart from promoting equal opportunities for women in general, this activity will also lead to a more efficient employment of human resources. This contributes to reducing the European skills shortage in the natural sciences and in technical fields by increasing the participation of women in science.

List of Websites:
ESMI web site URL: www.esmi-fp7.net

Scientific coordinator: Prof. Jan Dhont, e-mail: j.k.dhont@fz-juelich.de
Project manager: Dr. Peter Lang, e-mail: p.lang@fz-juelich.de

Related information

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Riese, Gelinde (Administrative Officer)
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Fax: +49 2461 61 2118
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Record Number: 187833 / Last updated on: 2016-08-18