Applications

The NanoMoi instrument is designed to be used for a wide range of applications. On this page, you will find brief examples of measurements and experiments conducted using our instrument. If you are interested in a specific use-case, please feel free to contact us for more information. We will regularly update this page with the newest applications and results as there are numerous potential applications not yet covered in this list. If our examples have sparked your interest, don't hesitate to inquire about other possibilities.

Page Index

Introduction

Varnish Removal From Oil Paintings

Keywords: Art conservation, oil paintings, varnish, coatings, pigment, organic solvents, polymer, plasticization, cracking, evaporation, diffusion, solvent retention time, drying profile, time-trace, imaging

Paint Drying Profiles

Keywords: Coatings, paint, R&D, drying, curing, evaporation, humidity, film formation, drying profile, routine measurements, scratch test, drying time recorder, open time, touch-dry, hard-dry, time-trace, imaging

3D-Printing Layer Bonding 
Keywords: 3D-printing, FDM, additive manufacturing, extrusion, plastic, PLA, polymer, melting, solidification, imaging

Introduction

Broadly speaking, two types of nano-motion can be measured: phase-changes and local deformations. Phase-changes can be the classical melting, drying, or evaporation transitions, but also more subtle changes such as aggregation, crosslinking, phase-separation or (de)swelling that influence softness or rheological properties. Local deformations include  early crack detection, flow characterization, crystal growth and various other phenomena. 

The primary requirement to use the NanoMoi instrument is that your sample, material or object is non-transparent. And even if it is transparent, it might be feasible to add light-scattering tracer particles, enabling quantification of nanoscopic motion for your application. Therefore we can measure anything from small subsamples in a laboratory cuvette to applications in the field. 

With our software, multidimensional quantification of nanoscopic motions is performed in real-time. There are three ways to visualize the data, which can be performed in parallel:

• Imaging: For every pixel, the motion in the corresponding area is calculated and color coded to give an intuitive map of how the motion is distributed. The instrument has an additional brightfield color-camera so that events in the nano-motion can be related directly to visible changes in the same location. With imaging, local deformations can be detected, or the size or spread of inhomogeneities measured. 
• Time-trace: By tracking the amount of nanoscopic motion over time, a graph is constructed that shows the evolution of your material at a glance. Time-traces are an excellent tool to determine the timespan of phase-changes and evolutions in your material. By comparing multiple time-traces you can gain a deeper understanding of the effect of changing internal or external factors. 
• Spectrum: We can distinguish different speeds of nanoscopic motion by calculating the frequency spectrum, which measures an amplitude for each frequency. The spectrum gives detailed insights into the nature of the motion, including questions about characteristic movement speeds, the motion's nature (diffusion, flow, arrested, or even accelerated), and the timing of specific changes.

Varnish Removal From Oil Paintings

Keywords: Art conservation, oil paintings, varnish, coatings, pigment, organic solvents, polymer, plasticization, cracking, evaporation, diffusion, solvent retention time, drying profile, time-trace, imaging

The varnish layer on artistic oil paintings protects the centuries-old paintings and enhances the artworks colors. After a few decades, the varnish becomes brownish, and has to be renewed. The old varnish is dissolved and removed with organic solvents before a new layer is applied. However, penetration of the solvents into the paint layer has to be prevented as it can accelerate the chemical aging and localized swelling can induce cracking. 

As the solvent penetrates the paint layer, it plasticizes the polymers, increasing the freedom of movement of the pigment paticles. This increased naoscopic motion of the pigment particles is picked up by the NanoMoi instrument. By measuring the time-trace, the solvent retention time is determined from the drying profile. The importance of these measurements becomes clear from the drying profiles in the graph on the left. One minute of acetone cleaning can lead to more than an hour of accelerated aging.

Before removing varnish from the whole painting, the solvent retention time could be determined for several promising cleaning methods. Variations such as solvent type (acetone/ ethanol/ isopropanol/ mixtures), application method (cotton swab/microfiber/gel), or cleaning time can be objectively compared with the retention time. The conservator then chooses the best balance between the best cleaning result with the lowest solvent impact. From our tests, it has become clear that with the right choice of cleaning method, it is possible to remove a varnish layer with negligible solvent impact!

Additionally, it is also possible to visualize the spatial spread of solvent over the paint surface. Especially in the case of a cracked surface, the solvent can spread to areas where it was not originally applied by the conservator. This can be seen in the movie on the right ,played at 4x speed. 

Paint Drying Profiles

Keywords: Coatings, paint, R&D, drying, curing, evaporation, humidity, film formation, drying profile, routine measurements, scratch test, drying time recorder, open time, touch-dry, hard-dry, time-trace, imaging

The drying and curing of wet-applied coatings is key to achieve the best visual and protective quality in the final layer. At the same time, this drying time  determines the workability of the coating as it dictates how long after application mistakes can be corrected. With the development of health and environmentally-friendly water-borne coatings, manufacturers aim to keep the quality and workability of new formulations to high standards. 

Routine measurements by widespread drying time recorders employ the scratch test method, dragging a needle with a constant and slow speed through a wet coating. The moment at which the scratch mark vanishes is taken as the drying time for the whole surface. Although reproducible, this method has several disadvantages: 

• Scratch-test drying time recorders are often limited to glass substrate slides, which are not representative for the coatings target substrates. 
• With scratch-test drying time recorders, it is assumed that the drying is homogeneous through the whole surface area, while it is well-known that the edges dry faster than the central area.
• A scratch-test drying time recorder measurement is invasive as it leaves a big scratch in the coating, rendering the method useless for field-testing.

The drying profile graph below shows a NanoMoi drying profile for a consumer-grade water-based latex paint. After one hour the paint is touch-dry and the surface is non-stick. After roughly two hours, the paint is hard-dry throughout the whole layer. On the right a movie is shown of the drying front passing from right to left, just before two hours have passed.

The NanoMoi drying profiles show great potential for standardized drying time testing for new formulations and external factors. Our own tests show that small variations in the humidity doubled the drying time while the substrate porosity has an eightfold effect. We are able to identify multiple stages in the drying, including the open-time, touch-dry time and the hard-dry time. The imaging capabilities show the inhomogeneous drying from the edge to the center by means of the drying front. It also visualizes unwanted inhomogeneities like cracking, delamination, sissing and the orange peel effect. The NanoMoi drying profiles and imaging allow thorough testing of new and existing formulations, giving insights that allow targeted development and insure the best quality control.

3D-Printing Layer Bonding

Keywords: 3D-printing, FDM, additive manufacturing, extrusion, plastic, PLA, polymer, melting, solidification, imaging

During 3D-printing, molten plastic is extruded and deposited on previously printed material, a process that is crucial for the final print quality. The plastic has to be hot to liquifiy the plastic in the layers below to achieve good layer bonding and thus a strong final product. However, the plastic cannot be too hot as it will be liquid-like for too long, flowing away, and not producing the target shape. This balance between heating and cooling is nowadays studied with infrared (IR) imaging, which visualizes the plastic surface temperature. The NanoMoi instrument directly visualizes the polymer motion inside the plastic, directly visualizing the layer bonding process without assumptions. 

More information on this topic is available from a scientific publication in the Journal of Visualized Experiments (JoVE) that includes instructional videos on how the experiments were performed:

"Buijs, J. J., Fix, R., van der Kooij, H. M., Kodger, T. E. Real-Time Imaging of Bonding in 3D-Printed Layers. J. Vis. Exp. (199), e65415, doi:10.3791/65415 (2023)."

With this approach it becomes possible to study layer bonding during 3D-printing without knowing the exact plastic melting temperature trajectory. The NanoMoi instrument also measures deeper into the plastic than IR imaging, giving more reliable results. These insights can be used for the following applications: 

• Testing and benchmarking of newly developed filaments, to fine-tune recommended printing temperatures and speeds. A layer bonding 'hot-zone' of 5 layers (or 1mm) seems to give the best balance between layer bonding and surface quality. New filaments can be routinely tested with the NanoMoi instrument to obtain the technical specifications.
• Development of dynamic printing protocols that have better performance in challenging geometries. Certain geometries like bridges, corners, and overhangs are challenging to print. With the NanoMoi data, a better understanding of the polymer mobility is obtained, potentially giving hints on how to overcome these challenges with advanced slicing algorithms. For example, temporarily adjusting the printing temperatures, speeds, and cooling fan speeds: just like the first layer is generally printed slightly hotter than the rest of the build.