Structural studies of future materials are carried out at JINR

NUST MISIS researchers together with scientists of the Laboratory of Neutron Physics of JINR conducted studies of biocompatible polymer materials used in endoprostheses, as well as advanced carbon composites, at the Xeuss 3.0 X-ray scattering station. The carbon fiber composite is known for its applications in aviation, but it also finds application in the creation of exoprostheses – what is commonly called prostheses. Within the framework of these works, JINR is part of the collaboration of the Laboratory of Accelerated Particles (LUCH), which is being created at NUST MISIS.

 

Xeuss 3.0 serves NUST MISIS specialists to analyze the crystalline and molecular structure of the new materials being developed. According to the head of the Department of Physical Chemistry of NUST MISIS, Deputy Head of the Luch Laboratory, Ph.D. n. Alexey Salimon, for the study of polymeric materials, small-angle scattering is best suited.

 

To provide the necessary set of properties of the created material, it is necessary to form its structure correctly. This is followed by a testing phase, in particular in the case of implantology, special biological tests. “This is always a labor-intensive process of moving in a circle “structural research – testing properties – application”, in which you have to circulate for a long time in order to refine the problem and improve the properties of the material,” the scientist said.

 

“Xeuss is a unique tool specifically for structural studies,” he said, explaining that his research team was attracted to work on Xeuss by such an advantage as a small spot of illumination, i.e., the studied region of interest in the volume of matter. “This is a very sharp-focused instrument, where the size of the light spot on the sample is no more than 100-150 microns. On most laboratory X-ray sources, you will not get such resolution, ”the scientist added. A sharp focus is important because, for example, it allows one to study the subtleties of stress distribution, in particular, when loading complex layered structures of carbon composites.

 

As is known, synchrotrons produce the most sharply focused X-rays, but these instruments are of a very high class and cost, and there are not many of them in the world. “Modern laboratory instruments of the Xeuss class are approaching synchrotrons in a number of properties. This is a good opportunity to fill the gap between ultra-expensive mega-science instruments and traditional laboratory instruments,” Alexey Salimon said.

To simulate the mechanical loads of carbon composite samples, a special frame test device was created. A small beam cut from a carbon composite is fixed in the device between two stops and, having installed Xeuss in the working chamber, is loaded by shifting the stops towards each other. As a result, in real time, you can track exactly how the gap occurs, what effort needs to be applied for this and how it is related to the internal structure.

 

An innovative material for endoprostheses based on ultra-high molecular weight polyethylene (UHMWPE) combines three layers: solid, imitating slippery and smooth cartilage, porous UHMWPE, imitating spongy bone tissue and porous collagen. It is very difficult to accurately reproduce the complex tissues of the human body, so composite, hybrid materials in bioengineering are the most common solution.

 

“Our hip and knee materials are in pre-clinical testing. The unique property of polymers is used in the hip joint – low coefficient of friction and high wear resistance,” said Alexey Salimon. He said that the developed material allows both the creation of artificial joints and the reconstruction of directly supporting bones. In case of oncological diseases, in order to save the limb, it is possible to replace large fragments of the femur or tibia of the leg, ulna, humerus of the arm and other large bones. The Scientific and Educational Center “Bioengineering” at MISiS showed this in veterinary medicine, in operations on pets – it is much easier for animals to obtain permission for use during surgery:

 

Ultrahigh molecular weight polyethylene has been used in surgery for a long time. “We are expanding and improving the standard grades of these polymers and giving them special properties. In particular, for the cup of the hip joint, NUST MISiS was able to significantly reduce the coefficient of friction and increase wear resistance through the use of carbon nanotubes,” the scientist said.

In addition to small-angle X-ray scattering on Xeuss, MISiS scientists also use other methods of structural analysis: voids, discontinuities, defects are monitored using tomography at the Academician O. V. Roman Institute of Powder Metallurgy , the chemical states of atoms in a sample are refined with high accuracy by the EXAFS Extended X method -ray Absorption Fine Structure (fine structure of the absorption edge of various elements).

 

Biocompatibility and other interesting properties of materials of the future are actively used in maxillofacial surgery. MISiS partners from the Research Institute of Emergency Pediatric Surgery and Traumatology use such materials in the tasks of reconstructing the cranial vault after operations to treat traumatic brain injuries. “In the modern era, if cerebral edema begins after a traumatic brain injury, surgeons need to remove from a third to a half of the area of ​​the patient’s skull, which then has to be closed. And one of the solutions here is the use of a complex titanium-polymer construction, where the polymer is the one that we are developing,” said Alexey Salimon.

 

The work done was commented by Senior Researcher of FLNP JINR, Candidate of Physics and Mathematics. n. Yulia Gorshkova: “In 2022, the MISiS team and I conducted zeroing experiments on biocompatible polymer materials and advanced carbon composites using Xeuss 3.0. In fact, these were commissioning works at the installation. At this stage, it was important for us to determine the limiting capabilities of the device ourselves. However, the results obtained were impressive, which allowed them to be included in a joint publication ¹“. Yulia Gorshkova said that on February 15, the Xeuss 3.0 station was officially put into operation. “Already today we have plans to further develop mutually beneficial cooperation with the team of Professor Alexander Korsunsky on a regular basis. This is exactly the case when we have something to offer, and there is something to learn from our colleagues,” she said.

 

Reference

Xeuss 3.0 implements the method of small-angle (SAXS) and wide-angle (WAXS) X-ray scattering and makes it possible to carry them out in one pass, saving time for research. Liquids and amorphous bodies, polycrystalline and porous substances, alloys, powders can also be studied by the WAXS (Wide-Angle X-Ray Scattering) method. On the device, it is possible to study in real time the structure of materials and nanomaterials from the atomic to the nanoscale scale.

Among other participants of the LUCH collaboration are Skoltech, the Institute of Powder Metallurgy named after Academician O. V. Roman (Belarus), the Department of Electromagnetic Processes and Interaction of Atomic Nuclei of the Research Institute of Nuclear Physics of the Moscow State University named after Skobeltsyn, the Technological Institute of Superhard and New Carbon Materials (TISNUM) and the Laboratory of X-ray Optics of the A. N. Lebedev Institute of X-ray Optics of the FIAN.

Literature

Eugene S. Statnik, Alexey I. Salimon, Yulia E. Gorshkova, Natallia S. Kaladzinskaya, Ludmila V. Markova and Alexander M. Korsunsky. Stress relaxation analysis in bulk and porous Ultra-High Molecular Weight Polyethylene (UHMWPE). Polymers 2022, 14, 5374. IF 4.967, Q1 (SRJ 0.73) https://doi.org/10.3390/polym14245374

Source: JINR