Reactionary resources are. Launching self-healing and self-healing programs The power of your own healing

Self-healing - the hidden reserves of our body – a topic of increasing interest to modern people. Read about the hidden mechanism of self-healing, what is needed to restore the body’s defenses, the reasons for blocking and ways to activate its hidden reserves.

What do you mean by self-healing?

Self-healing is the natural ability of all living beings to regenerate. In science, this ability is called homeostasis. According to this natural property, our body is capable of self-healing, self-defense, self-healing and even self-rejuvenation. In other words, the natural mechanism of homeostasis returns the body to a state of balance between effort and energy expenditure.

Self-healing mechanism

Scientists have not yet discovered the natural mechanism for triggering self-healing. But we ourselves are convinced of the unique ability of our body to heal itself.

Each of you has ever received small cuts to the skin. If you could see through a microscope what happens to the cut, you would be surprised at its miraculous transformation into a small scar. As a result of the formation of a clot of blood cells - platelets - at the site of the cut, the damaged vessels become clogged and the bleeding stops. Cell division along the edges of the wound occurs until it heals completely.

Similar healing and restoration of the functions of diseased organs occurs inside our body.

Reserve forces of the body

Nature has placed in us enormous reserve forces capable of restoring a damaged organ, growing new cells to replace the dead, supporting and restoring impaired body functions.

When we get sick, strange complex processes begin to happen inside us. Body temperature rises, cough, vomiting, and diarrhea appear. In this way, the body is cleansed of dead cells and foreign substances.

Those reserve sources of energy that heal the patient are opened.

What do we need to restore strength and reduce energy costs?

To understand this and help yourself recover, you need to believe that each of us is a particle (cell) of the Universe, and has unlimited capabilities. Our hidden internal capabilities usually manifest themselves in extreme situations and save our lives, and also tell us how to cope with the disease. This happens because a person is connected through the subconscious with the Universe and, through it, with all of humanity - this is a fact already proven by scientists.

Illness is a signal from our subconscious that some of our actions or thoughts, emotions come into conflict with the laws of the Universe. Thus, the body, when it gets sick, tells us about incorrect behavior and violation of the laws of the surrounding World. In order to recover from a disease, you need to correct thinking errors and bring your thoughts into line with the Universal laws.

But we are accustomed to believing only the obvious, material. Meanwhile, we have no idea what enormous resources are hidden within us. We have to learn to recognize them and manage them, then we will gain health, wisdom and strength.

Reasons for blocking the hidden reserves of our body

If a person lives in an ecologically clean environment, eats natural food, does not experience constant stress, does not have bad habits or burdened heredity, leads a moderately active lifestyle, lives with good intentions and thoughts, then all processes in his body proceed effectively, providing him state of complete health.

This means that his body has enough positive energy, his blood, lymph, intercellular space, liver, kidneys, intestines, etc. do not contain excess amounts of toxins and microorganisms. And the immune system is able to provide reliable protection to the body in the event of an excessive amount of pathogenic pathogens, that is, if necessary, hidden reserves are activated.

However, in the modern civilized world, the majority of people live in an environmentally unfavorable environment, eat foods full of harmful chemicals, experience constant stress, trying to earn more money, lead a sedentary lifestyle, think with envy, anger, and sometimes hatred.

Constant tension and slagging of the body with waste products disrupt the functions of many organs. Accumulating toxins and waste block the hidden forces of the body and do not allow the immune system to perform its cleansing function.

With age, when a person’s motor activity decreases, a negative attitude towards life increases, the blocking of hidden reserves intensifies, and not only functional, but also organic damage to internal organs appears in the form of chronic diseases. Under such conditions, the body's reserve forces cannot manifest themselves in full force.

Ways to activate our reserve forces

3 main ways

Enabling a process self-healing – the hidden reserves of our body, depends on many factors: the inheritance of upbringing stereotypes, knowledge about the structure and development of the human body, the life habits of the individual, the moral and intellectual skills of his thinking and behavior, as well as faith in health and the Higher Mind.

However, there are 3 main ways to activate the body’s reserve forces, acceptable for almost all of us:

Stop or limit your exposure to chemicals. Modern foods contain a lot of toxic chemicals. In everyday life and to care for our body and face, we also use products containing toxic chemicals. Accumulating in the body, chemicals interfere with the functioning of cells, pollute our body, disrupt the complex natural processes of homeostasis, and lead to chronic diseases, as a result of decreased self-defense.
Gradually switch to and. After all, the lack or absence of essential minerals, vitamins and other nutrients in food, as well as junk food (fast food, yeast baked goods, sweets, carbonated drinks, etc.) interfere with the natural process of self-healing and self-renewal of the body, polluting it with toxins and wastes, disrupting metabolism.
Recognize and begin the negative attitude that has the most aggressive destructive effect on the healing and cleansing forces of our body. To enable self-healing – the hidden reserves of our body, you need to bring your thinking and behavior into conformity with universal laws. Inner harmony will be translated into harmony outside. If you begin to change positively inside, you will be able to recover from the disease, create a beneficial space around yourself that will have a positive impact on your health, environment and prosperity.

A variety of techniques for turning on the body’s reserve capabilities

There is a lot of inclusion of our body's reserve capabilities. So, the power of thought, as our main hidden reserve, was proven by Roger Sperry, a leading neuropsychologist who received the Nobel Prize in 1981 (together with Thorsten Wiesel and David Hubel). Sperry proved that our thoughts are material and all events in life are a consequence of the thought forms of our inner mind.

Resentment, self-pity, anger, hatred, envy in the form of corresponding energy fall into the Universe filled with energy and return to us, forming illnesses, quarrels, poverty, disasters, etc.

But the purity of our thoughts and desires, a positive attitude enhances our life and shapes good events in life. Therefore, this is the most effective method of turning on our internal reserves.

Self-hypnosis Dagestan philosopher and psychologist Khasai Aliyev and professor of the Vienna clinic Zonald Veld (back in the mid-nineteenth century) are considered the strongest human reserve.

Research has proven that with self-hypnosis You can cause certain changes in the body: not only heal yourself, but also drive you into illnesses.

Moreover, scientists advise talking to your DNA cell, which stores all the information about us and our kind. If something doesn't suit you, you can make changes to your DNA.

Meanwhile, we cannot dispute one fact - each of us can use our reserves in everyday life and in difficult situations, if we are not lazy and believe in our hidden capabilities.

How to learn to feel and correctly use your hidden powers

Motivate yourself, that is, constantly support.
Correctly formulate your goals (get better, improve relationships with loved ones, discover your purpose in life, etc.).
Consistently and persistently work on your Self. Control your thoughts and emotions sent to the World.
Regularly study the necessary literature and the experience of researchers.
Help your healing powers: proper diet, weekly fasting, moderate physical activity, hardening, etc.
Let you be inspired by the examples of survival and healing presented in the video “Self-hypnosis, placebo effect, self-healing.”

I wish you health and perseverance in self-healing!

The liver has 500 functions. Imagine that invisible strings connect the liver and thyroid gland. One of these threads broke.

What does this mean?

The fact that the tiny connection between two organs in a certain function has disappeared and it needs to be restored, because a metabolic disorder has begun. Taking any medications is useless.

When you are diagnosed with metabolic disorders, you are told which of the many organ functions is impaired. No? So what are we treating?

Improper functioning of the thyroid gland disrupts the tone and motility of contraction of the gallbladder (1), leads to a pathogenic sphere (2), and causes pain in the stomach (3). Here you have three diseases just because the thin thread of the liver-gland was broken.

Is it possible to restore their activities?

Can. You just need to be attentive to your body. Help him and he himself restore what is necessary.

If the concentration of chlorine in the blood is not replenished, then the blood becomes viscous (varicose veins, thrombophlebitis, heart disease, tinnitus, headache, hypertension, hypotension, etc.). Sealing larger vessels – stroke, heart attack. Yes and much more.

The stomach produces 10 liters of gastric juice. 2 liters are used to digest food, the rest is absorbed into the blood (blood and sweat are salty).

The stomach produces hydrochloric acid and pepsins, which dissolve organic matter.

By 18 o'clock there is no hydrochloric acid in the stomach, there are no cells that produce it.

To prevent the cells in the stomach from dissolving (if there is no food, we dissolve what is in the stomach), it is necessary to eat something or have a snack every 2 hours.

Breakfast - proteins, fats. Lunch - soups. Dinner – porridge (carbohydrates). They will quickly leave the stomach, because carbohydrates are not digested by the stomach and will go into the intestines.

At 18:00 the kidneys turn on and begin filtering. To help the kidneys filter viscous blood, after 6 pm you can drink salted water: the body simply needs chlorine, it thins the blood. (Essentuki mineral water supply No. 4 or No. 17 is well suited).

It is necessary to take into account the fact that if you drink tea, coffee, water during meals, then you dilute the gastric juice, which leads to longer digestion of food, which is not good. Nowadays they constantly talk about taking no more than 2 liters of water per day. Some people find it good, but some people don’t want it. A person cannot drink this. Well, don't drink. Don't do as everyone else does, do as you need.

Check your thyroid gland (you can do it at home)
Meals: from 5 am to 6 pm (max)
Meals are split: every 2-2.5 hours. Portion - fits in the palms of your hands.
Do not drink before, during or after meals (40-60 minutes). This will give you a good chance to digest food. And then drink whatever you want. (Please note: the animal never drinks after eating).

What will you get in return from your body?

Ulcerative, liver, kidney, etc. pains go away. (Slowly your sores are going away.)
For three days you will feel some discomfort: the brain must understand and adapt to a new way.
Excess weight will begin (gradually) to disappear.
The healing of your internal organs will begin (the organs themselves will restore those threads that have broken), which leads to the body’s self-healing naturally.
If you have thrombophlebitis or varicose veins, use the method of wrapping with bandages for 1 hour with a solution of acetylsalicylic acid. It is necessary to dissolve the plaques.
You will stop taking pills and feel light in your body.

You may ask: what about salted water? Salt? Oh God.

But the body cannot live without sodium and chlorine. Nobody says: eat kilograms of salt, but if you really want it, the body gives a signal that it needs it.
Do you have calf muscle spasms? Rub them with salted water: there is not enough sodium.

And one more thing: to help the body undergo self-healing more smoothly, do an energetic cleansing of the body, remove not only physical, but also energetic dirt.

Materials Science

N.N. Sitnikov 1, 2, I.A. Khabibullina 1, V.I. Mashchenko 3

1 State Research Center Federal State Unitary Enterprise “Keldysh Center” (Russia, Moscow)

2 National Research Nuclear University “MEPhI” (Russia, Moscow)

3 Moscow State Regional University (Russia, Moscow)

Annotation. This review is devoted to the mechanisms for obtaining the effects of self-healing of the original properties or any characteristics in various artificially created materials, such as polymers, ceramics, metals, composite materials, etc. The chemical and physical processes that cause self-healing effects are briefly reviewed, and examples and experimental prototypes of self-healing materials are given.

Keywords: self-healing, self-healing, self-healing, polymers, ceramics, cements, concretes, metals, composite materials.

Self-healing materials: an overview of self-healing mechanisms and their applications

Abstract. This review is devoted to the mechanisms of obtaining self-healing effects of the original properties or any characteristics in various artificially created materials, such as: polymers, ceramics, metals, composite materials, etc. The chemical and physical processes causing effects of self-restoration are briefly considered. Examples and experimental prototypes of the self-repairing materials are given.

Key words:self-restoring, self-healing, polymers, ceramics, cements, concretes, metals, composite materials.

Release	Year
№1(9)	2018	Sitnikov N.N., Khabibullina I.A., Mashchenko IN AND. Self-healing materials: a review of self-healing mechanisms and their applications // Video science: network journal. 2018. No. 1(9). URL: (date of access: 04/01/2018).

Self-healing materials: a review of self-healing mechanisms and their applications

Introduction

Self-healing (“self-healing”) materials are artificially created substances or systems that are capable of automatically and autonomously partially or completely restoring their original characteristics after damage caused to them. Ideally, recovery processes should occur without any external intervention, especially human intervention. The most outstanding self-healing materials are biological materials that exhibit the ability to self-heal and regenerate their functions after receiving external mechanical damage, and it is in relation to them that the terms self-healing or self-healing materials are applied. In biological systems, self-healing can occur both at the level of single molecules (for example, DNA repair) and at the macro level: healing of broken bones, healing of damaged blood vessels, etc. These processes are familiar to everyone, but materials made by humans, in most cases, do not have a similar ability to self-heal (if only because they are not “living”). Artificial “self-healing” materials would open up enormous possibilities, especially in cases where the reliability of materials needs to be ensured for as long as possible in difficult-to-reach areas.

The ability of artificial materials to self-heal any properties can increase their service life, reduce the cost of maintaining them in working condition and repairs, and also increase the level of safety of the structure or product as a whole. For this reason, self-healing materials currently form the subject of one of the most researched areas of materials science.

Self-healing materials, depending on the mechanism for triggering self-healing processes, can be divided into two different classes: autonomous and non-autonomous. With autonomous self-healing, the impulse to trigger any recovery processes is the damage itself, and the material is able to partially or completely restore its original characteristics without any additional external influence. Non-autonomous self-healing mechanisms require external initiation, such as elevated temperature or light. The self-healing mechanisms of artificial materials are divided into “external” and “internal” according to the method of organizing the “self-healing” processes. “External” self-healing mechanisms are based on certain external restorative components specially embedded in the matrix of the base material, for example, microcapsules with healing substances, and “internal” self-healing mechanisms do not require the presence of any additional restorative compounds.

Self-healing materials represent a wide class of substances and can be divided into “pure” materials (polymers, ceramics, cements and metals) and composite materials and systems, which are presented in various combinations (reinforced materials, encapsulated materials, systems with hollow and filled fibers, vascular systems, layered materials, sandwich panels with liquid reagents, etc.).

The presented review examines the literature published on the problem of creating self-healing materials, the main mechanisms of self-healing and examples of their practical implementation.

2. Review and discussion of self-healing mechanisms of artificial materials

The concept of “self-healing” artificial materials appeared relatively recently, several decades ago, but thanks to the modern development of materials science technologies and the emerging prospects for the use of materials that can self-restore their original characteristics after damage, this area of materials science continues to attract the scientific community and is experiencing rapid development. The complex nature of the processes involved in the self-healing of the original characteristics of materials requires an understanding of multi-level molecular, microscopic and macroscopic processes. This review will consider the main mechanisms for obtaining self-healing effects in various substances, as well as their use to create prototypes of “self-healing” materials and composites based on them.

In the English-speaking scientific community, for materials that exhibit self-healing effects, the term “self-healing materials” is used to popularize them by analogy with biological objects, which in direct translation sounds like “self-healing” or “self-healing” materials and implies restoration of the original structure of the material. In direct translation, the terms “self-healing” or “self-healing” do not quite correctly reflect the essence of the phenomena occurring in “non-living” organic and inorganic materials, but they give a good three-dimensional (general) idea of the final macroscopic effect. In Russian-language scientific literature, in our opinion, it is more correct to use the term self-healing, but this term requires emphasizing the parameters or characteristics that were restored after destruction. Therefore, in this review, the authors will use the term “self-healing” when generally describing the relevant effects, and self-healing when specifically referring to the properties being restored.

2.1. Self-healing polymer materials

The requirements of modern materials science are such that self-healing in artificial materials, and in particular in polymers, is often most in demand in cases of mechanical damage of various scales:

in microcracks, in close proximity to the place where intermolecular bonds were damaged;

in macrocracks (conditions must be created for filling the crack with a “healing” substance);

in areas with disconnected surfaces (conditions are necessary for their connection).

From a macroscopic point of view, damage caused by mechanical impact at the microcrack level can lead to damage on a wider scale, so that “self-healing” of microcracks becomes a reliable protection against the formation of macrocracks and is the most pressing problem in polymer materials science.

Self-healing of mechanical damage in polymer systems can be achieved both through the use of covalent bonds and non-covalent interactions. In the first case, various cross-linking reactions, Diels-Alder and others, are used. Non-covalent healing can be achieved through the formation of hydrogen bonds and complexes, aromatic interactions (π-π interactions), ionic interactions, van der Waals forces and other non-covalent interactions. Various sol-gel processes can also be used for healing. Changes in viscosity with changes in shear flow rates of some oligomeric and polymeric materials can, under certain conditions, impart self-healing characteristics to them.

Cross-linking reactions can be self-initiated or caused by irradiation and mechanical action on specially introduced low-molecular compounds or on reactive groups associated with the main chain of the macromolecule.

An example of healing by covalent cross-linking is the use of reactions that lead to the formation of stable bonds between acylhydrazine groups at the ends of polyethylene oxide (PEO) macromolecules. Photographs illustrating the self-healing properties of the modified PEO gel are shown in Figure 1. Two gel samples were stained (one with carbon black, the other with rhodamine) and cut. Next, the carbon black-stained half of the sample was brought into contact with the rhodamine-stained half. After seven hours at room temperature, the two halves bonded into a single, fairly strong material. .

Figure 1. Photographs of self-healing PEO gel: (a, b) each of the samples is divided in half, (c, d) halves of differently colored samples were joined together, (e) an attempt to deform the sample with tweezers 7 hours after joining the halves.

Diels-Alder cycloaddition reactions can also be used to implement a self-healing mechanism in polymeric materials (Figure 2). Such reactions represent a concerted 4+2 addition occurring between a 1,3-diene and an unsaturated compound, a dienophile. Typically, a diene contains an electron-donating substituent, and a dienophile contains an electron-withdrawing group. A less common option is when the electron-rich compound is a dienophile. The Diels-Alder reaction is used in specially modified materials such as epoxy resins, polyacrylates and polyamides. The formation of bonds between the diene and the dienophile after their physical rupture can be stimulated by external radiation to the material or an increase in its temperature, however, an excessive increase in temperature can lead to the destruction of the formed bonds.

Figure 2. Schematic representation of the implementation of the self-healing mechanism through the cycloaddition reaction when the material is irradiated with ultraviolet radiation.

Figure 3 shows photographs illustrating how a cut polymer material, when heated or exposed to ultraviolet radiation, restores its integrity due to the occurrence of cycloaddition reactions in a copolymer of butyl methacrylate and oxydioalkylene, thereby realizing self-healing of the surface.

Figure 3. Photographs of self-healing of the polymer surface during the cycloaddition reaction: (a) initial cut, (b) heating to 140 °C for 2 minutes, (c) heating to 140 °C for 5 minutes - complete “healing” of the scratch.

In some polymers, where mechanical destruction occurs due to homolytic cleavage of bonds, automatic self-healing reactions can occur with the formation of free radicals. To do this, the disconnected ends of chains with reactive groups must move and react with each other before the resulting free radicals enter into other reactions. For effective self-healing properties of such materials, it is necessary to avoid the interaction of free radicals with oxygen. If free radicals interact with oxygen, they will not be able to interact with the other ends of the chains, and thus the material will not be able to “self-heal”. For example, the structure of the trithiocarbonate polymer complex allows for bond rearrangement through the resulting free radical intermediate. Restoration of broken bonds in trithiocarbonate occurs through mobile groups with free radicals and is stimulated by ultraviolet radiation.

Thermoplastic polymer materials that contain covalent bonds capable of reversible reactions can also exhibit “self-healing” properties. An example is polymers with grafted alkoxyamine groups (Figure 4). Although the reversibility and synchrony of these reactions, along with the hydrophobic interactions used in such thermoplastics, promote healing quite effectively, there is no guarantee that mechanical damage will not lead to the breaking of C–C bonds. Under such circumstances, these materials will not be able to show stable self-healing of connections.

Figure 4. Schematic representation of reversible bond scission in an alkoxyamine group.

Most polymers and polymer systems above the glass transition temperature have the ability to partially or completely self-heal when connecting separated surfaces. This self-healing mechanism is well stimulated by additional heat. Also, some materials operated below the glass transition temperature can be healed by heating the damaged area.

A striking example of such an autonomous self-healing polymer is materials based on borosiloxanes, which are non-Newtonian liquids in which oligomeric siloxane molecules are connected by coordination bonds capable of rapid recovery after rupture. After damage, you just need to press the fracture surfaces together, and the material will restore the broken bonds (Figure 5). Such materials are capable of “self-healing” the resulting punctures and cracks within a few minutes (Figure 5).

Figure 5. Photographs of two borosiloxane-based polymers: (a) two polymers in their original state; (b) disconnected polymers; (c) linked polymers; (d) polymer “healed” upon joining; (e) stretched and (f) torn “healed” polymer [VIDEO].

Supermolecular (supramolecular) interactions in most cases allow for faster bond restoration than covalent bonds. However, such materials usually do not have good mechanical properties, being quite soft and mobile, which limits their areas of application.

As mentioned above, self-healing materials, depending on the initiation mechanism used and the nature of the self-healing processes, are divided into two different classes: autonomous and non-autonomous. Autonomous self-healing processes in polymer materials in their pure form are observed in high-molecular systems, as well as when capsules or other structural elements (will be discussed later) with various “healing” reagents, such as epoxy resins, are introduced into the polymer matrix. To trigger non-autonomous self-healing processes in polymers, some external influences are required, for example, elevated temperature or optical radiation.

Among the non-autonomous self-healing mechanisms, five main ways of their implementation can be distinguished. The first of the self-healing mechanisms is based on reversible reactions. The most widely used process is based on Diels-Alder reactions. The second mechanism of non-autonomous self-healing is based on the inclusion of fusible thermoplastic additives in the matrix of the thermoset material. Heating allows the thermoplastic additives to be redistributed into microcracks, preventing their growth. The third and fourth mechanisms of non-autonomous self-healing are realized due to dynamic supramolecular bonds and ionomers. A fifth mechanism for achieving preferential internal self-healing is based on the molecular distribution of material by diffusion.

2.2. Self-healing ceramic materials

Self-healing effects in ceramic materials are not as extensive and pronounced as in polymers. In ceramics, in general, self-healing of only small defects is possible, the size of which is limited to hundreds of micrometers. Nevertheless, “self-healing” of microcracks caused by mechanical wear or thermal stress in ceramic materials can significantly improve their performance characteristics. Self-healing of microcracks in ceramic materials is based on the processes of oxidation of the constituent parts of the ceramic matrix at high temperatures. Such self-healing effects are observed in ceramic materials containing phases M n+1 AX n (MAX phase), where M is a transition metal, A is an element IIIA or IVA of the subgroup of the periodic system, X is carbon or nitrogen. Self-healing ceramic materials often use oxidation reactions, with the volume of oxide exceeding the volume of the starting material. As a result, microcracks are filled with oxides of the A-element, formed from the components of the MAX phase during exposure to high temperature in an oxygen-containing atmosphere. As a result, the products of these reactions, due to the increase in volume, can be used to fill small cracks.

For example, self-healing Ti 2 AlC ceramics uses the effect of filling a crack with α-Al 2 O 3 and TiO 2 compounds formed at high temperatures in air (Figure 6).

Figure 6. Image of a fully “healed” crack: (a) after exposure in an oven at 1200 °C for 100 hours, (b) enlarged image, (c) “mapping” by the elemental composition of compounds in the “healed” crack.

Another example of “self-healing” of ceramics is the self-healing oxidation of SiC ceramics. The active SiC filler embedded in the matrix is oxidized by penetrating oxygen, thereby the formed SiO 2 completely fills the crack.

2.3 Self-healing metalical materials

In metallic materials, due to their special properties, achieving the self-healing effect is more difficult than in most other classes of materials. One of the obstacles is the nature of the bonds between atoms and their low mobility at operating temperatures. Basically, defects in metals are “healed” by more fusible and plastic phases introduced into the main matrix of the material, or by the accelerated formation of agglomerates from phases that precipitate under certain conditions from the base material at the sites of defects. Melted or precipitated phases can fill the defect and stop further growth of destruction. The “self-healing” mechanism, which consists in the diffusion of precipitated substances from a supersaturated solid solution into defective areas, can prevent the formation of voids (Figure 7). The effectiveness of this self-healing mechanism depends on temperature, applied stress, location of the defect, its orientation in the stress field, and grain boundaries.

Figure 7. Illustration of the mechanism of cavity growth and the movement of sediment atoms into it from a supersaturated solid solution.

Experiments on damage healing by precipitation and cavity creep in steels have demonstrated dynamic precipitation of copper, boron nitride (BN) or gold on the surface of the creeping cavity. It has been demonstrated that autonomous repair of heat damage via precipitate creep can be achieved in iron containing small amounts of gold. At a temperature of 550 °C, precipitation of gold atoms on the free surface of the cavern leads to the filling of the pore and, as a result, to the autonomous repair of damage (Figure 8). Agglomerates from precipitated gold particles collect in the formed cavities (cavities) before the cavities can unite into microcracks along the grain boundaries. Grain boundaries and dislocations are fast routes for the transport of gold atoms dissolved in the iron matrix to the resulting cavity.

Figure 8. Images of the Fe-Au alloy after diffusion of gold atoms along grain boundaries at 550 °C and stress: (a, c) 117 MPa and (b, d) 80 MPa.

Some metallic materials also contain “innate self-healing” mechanisms due to surface passivation, which can indirectly be attributed to “self-healing”. For example, in such a chemically active metal as aluminum and most alloys based on it, the surface of the metal in the atmosphere quickly turns into an inactive, passive state associated with the formation of thin and, at the same time, durable surface layers of compounds that prevent corrosion. Thus, the resulting areas with a juvenile surface are “self-healing” with a protective film.

2.4. Self-healingcementingmaterials

Cementing materials have been around since the Roman era, and in the modern world, concrete and its constituent cement are among the most popular building materials. The process of cementation is the bonding of rock components (sand, limestone fragments, and other rocks) with dissolved minerals. These materials have an innate ability to self-heal, which was first reported back in 1836. Scientists have noticed that some materials containing mineral components have a natural ability to “self-heal” small cracks in the natural environment.

The main mechanisms of self-healing of cementitious materials are divided into three main types: natural or autogenous (hydration and carbonization reactions), bio-based and activation (“self-healing” with the help of chemical additives, reactions using fly ash, special expanding reagents, embedded GEO‑materials, etc.). d.)

Autogenous self-healing is the innate ability of cementitious materials to “self-heal” cracks. The main idea of such self-healing concrete is to add some mineral components to it, for example, those present in the shells of sea animals or other active substances. This ability is mainly justified by the further hydration of non-hydrated cement particles and the saturation of calcium hydroxide with carbon dioxide, access to which was revealed during the fault process. It is the mineral components that influence the tendency of concrete to regenerate when interacting with the external environment. Whether it is rain or artificial irrigation, concrete actively interacts with water, as well as with carbon dioxide, which is in excess in the Earth’s atmosphere, filling cracks with calcium carbonate and forming a kind of crust, the strength of which is not inferior to the strength of concrete before damage (Figure 9). Cementitious materials in freshwater systems can autogenously “heal” cracks up to 0.2 mm wide in 7 weeks.

Figure 9. Images illustrating the autonomous self-healing of a crack in mineral-filled concrete.

The self-healing ability of concrete can be improved by the introduction of bacteria, which can cause the formation of calcium carbonate through their metabolic activities. These formations can grow and contribute to faster bridging of the crack tip and effective “healing” of the defect.

It has been shown that one of the promising approaches to self-healing of concrete is the implantation of special microcapsules with bacteria that produce limestone into it (bio-based healing). For example, it has been demonstrated that alkaliphilic species of bacteria are implanted into the concrete material, the spores of which are sealed in special capsules along with the necessary nutrient (calcium lactic acid). Experimentally selected strains of bacteria (for example, Bacilli megaterium) are extremely tenacious and, while in concrete, can remain in a “dormant” state for years, beginning their active life only when oxygen or water enters the capsule, which, in fact, can happen inside concrete only in case of crack formation. The first laboratory experiments showed that bacteria are indeed capable of sealing cracks with calcite (Figure 10). In this case, both relatively large defects and microcracks about 0.2 mm in size disappear. Without “self-healing,” such microcracks can grow over time and lead to the destruction of the material as a whole.

Figure 10. Images illustrating biobased healing in concrete.

Additional self-healing of cementitious materials can be achieved through the reaction of certain chemicals (agents) introduced into the base matrix. To accommodate these agents, various schemes have been developed with the inclusion of special structural elements, such as capsules, hollow fibers and tubes, and other types of capillaries arranged like vascular systems. Capsules or capillaries, when damaged, release reaction agents that heal the defects. Various silicon-containing substances, such as alkali metal silicates, various forms of silicon oxide, etc., are used as reaction agents in such systems.

3. Review and discussion of self-healing composite materials

As noted earlier, a logical solution to improve the self-healing characteristics of various materials is to develop composite systems based on them, into which various fibers, materials with special properties or chemical components are introduced, allowing autonomously or non-autonomously to reduce the destruction of the original material and contribute to a faster and more complete “ healing" of the defect.

For example, some elastic fibers are introduced into the polymer matrix, which, after deformation, press the boundaries of the destroyed area of the polymer (Figure 11), the brought together surfaces then form bonds and the defect is “healed” according to previously described methods (autonomous action). Non-autonomous self-healing is realized by introducing into the matrix materials with special properties that are capable of exerting additional influence under external influence, for example, expanding and thereby reducing the size of the destroyed area. Such materials can be various entangled fibers and materials with a “shape memory effect” (SME), expanding or contracting with increasing temperature, as well as various substances, for example, gels, capable of increasing in size several times under a certain external influence.

Figure 11. Schematic illustration of a self-healing fiber material.

In the case of using materials with SME (polymers or alloys), they are first given a “memory” of the required initial shape, then they are introduced into the polymer matrix in their original or deformed form. Subsequently, after destruction or deformation of the resulting composite material, upon subsequent heating, the embedded materials with SME “remember” their original shape and press the boundaries of the destroyed region of the main matrix material, which are then “healed” according to previously described mechanisms.

The most used memory effect materials are alloys based on titanium nickelide (nitinol). There are also shape memory polymers, which return to their original shape after being exposed to temperature, light, electricity or a magnetic field. As an example of such a composite material, Figure 12 demonstrates the reinforcement of a polyurethane matrix with microfibers made from a shape memory alloy. This scheme of the composite material allows, when cracks appear due to mechanical deformation, by heating the material to activate the restoration of the shape of threads with SME, which compress cracks in the polymer matrix and bring their walls together, thereby allowing them to “heal”.

Figure 12. Diagram of a self-healing material with threads with SME: (a) crack initiation, (b) crack propagation deep into the material during loading, (c, d) “healing” of the crack upon heating.

A large number of works are devoted to the study of self-healing composite materials, in which thin-walled inert fragile capsules with a “healing” substance are introduced into the main matrix. When a defect occurs, such as a crack, the capsule breaks and the “healing” agent is released and spreads into the crack. In this case, it either interacts with the matrix or the external environment or is mixed with a catalyst - a hardener, previously introduced into the material (separate from the capsules), hardens and seals the crack (Figure 13).

Figure 13. Schematic of a self-healing composite material with healing capsules.

Such a scheme makes it possible to implement various options for the structure of the encapsulated composite material:

capsules with a liquid (viscous) “healing” substance without a catalyst in the volume of the matrix; when the “healing” substance interacts directly with the matrix material or external environmental factors, for example, the atmosphere in which the composite is used (Figure 14, a);
capsules with a liquid (viscous) “healing” substance of two types, which harden when mixed without an additional catalyst in the body of the matrix (Figure 14, b);
capsules with a liquid (viscous) “healing” substance and a catalyst distributed throughout the volume, which, upon contact with the “healing” substance, causes it to harden (Figure 14, c);
the catalyst causing hardening of the “healing” substance is located on the outside of the capsule shell; if the shell is damaged, the “healing” substance immediately interacts with the catalyst (Figure 14, d);
multilayer capsules with a “healing” substance in a protective shell, which also contains layers of hardener, catalyst, etc. (Figure 14, e, f).

Figure 14. Schematic representation of options for “self-healing” capsule composite material (a-e), schematic representation of a multilayer capsule with a “healing” substance (f).

Examples of such self-healing composite materials include a thermosetting epoxy polymer with microcapsules of dicyclopentadiene and a Grubbs catalyst introduced into the material or microcapsules with a polyester resin in a urea-formaldehyde resin shell.

Oligomers or monomers containing at least two epoxy or glycidyl groups in the molecule are well suited as “healing” liquid substances, the mixing of which causes curing for capsule technology. Such systems, when cross-linked, turn into polymers of a spatial structure with the common name - epoxy resins.

The main disadvantage of the process with external initiation of self-healing through the introduction of restorative capsule components is the possibility of only a one-time “regeneration”.

The development of capsule system technologies to eliminate the problem of one-time “healing” is aimed at embedding hollow fibers (capillaries) with liquid fillers into the matrix material instead of capsules. The basic principle of “healing” in such systems is similar to composites with capsules and is implemented in accordance with similar schemes (Figure 15). In addition to the implementation schemes, it is possible to include the possibility of various 2D and 3D weaving of capillaries to increase the self-healing ability of the composite.

Figure 15. Schematic illustration of self-healing capillary composite material.

Self-healing systems with hollow fibers also do not completely solve the problem of obtaining a reusable “self-healing” effect, associated with the fact that the components that ensure the healing of such a composite material are consumed and are not supplied repeatedly in the required quantities. Consequently, the further development of this technology is associated with ensuring the supply of the necessary components or their pumping (in the case of a two-component liquid circuit), which directly refers to the analogy of self-healing of biological tissues.

As an example demonstrating the complexity of self-healing of biological tissues, let us cite a skin wound. Our skin, thanks to its blood vessels, has a remarkable ability to heal and repair itself. The skin consists of two main parts - the outer layer (epidermis) and the inner, thicker layer (dermis), rich in blood vessels and nerve endings. After injury, a clot of fibrin (a protein that forms the basis of a blood clot during blood clotting and stopping bleeding) is formed, then the main stages of healing occur, partially overlapping in time - inflammation, the formation of temporary granulomatous tissue, tissue reconstruction; finally, the epidermis is restored (Figure 16).

Figure 16. Scheme of skin healing (a) and schematic representation of the “healing” of a composite material of a two-capillary network vascular system (b).

Currently, artificial systems are far from the skin and biological analogues, however, a similar healing scheme is already beginning to be used. By analogy with the vessels of a living organism, it is called the “vascular system”. Its main distinguishing feature from the above-considered scheme with fibers is that such a system requires the presence of pumps for pumping “healing” components through a network of “vessels”. 2D and 3D vascular systems and various weaves of “vessels” can also be used. Self-healing occurs with the simultaneous destruction of fibers (“vessels”) with various reagents, which, when mixed, harden like two-component epoxy resins (Figure 16, b). Such circuits are complex to make and use, but have been shown to achieve multiple healing effects.

Numerous experiments have shown that neither spherical capsule nor hollow structures are ideal for achieving high recovery efficiency. Much greater recovery efficiency can be achieved by using elongated capsules with an aspect ratio of 1:10. Further research on such self-healing systems based on capsules and hollow fibers has mainly focused on improving the quality of capsules and encapsulated reagents.

Layered composite materials (“sandwich” panels) containing a layer or several layers that have some kind of “self-healing” mechanism are considered a promising direction for creating self-healing systems. In such a scheme, each layer performs its specific function, and in the overall system, the layered composite material is able to minimize damage and restore its original macro-characteristics. An illustrative example is a sandwich type material with an internal healing layer of a chemically active liquid. The created self-healing “sandwich” panel is a system in which a chemically active liquid or viscous substance is located between two sheets of polymer materials. As long as the tributylborane-based active substance remains between the panels, it will not harden. However, as soon as the polymer plate is damaged by something from the outside, the active substance flows out of the resulting defect and polymerizes upon contact with atmospheric oxygen, after which it hardens almost instantly, sealing the resulting hole in just a few seconds (Figure 17). Thus, a strong plug is formed in the hole almost instantly. “Sandwich” panels can include various solid, viscous and liquid fillers, which, when a material defect occurs, react with each other, forming a solid phase. This self-healing pattern is not a property of any one material, but is a characteristic of the entire system.

Figure 17. Stage self-healing mechanism of a sandwich panel (a), a visual test of “self-healing”: (b) leakage of “healing” liquid after damage and (c) restored material.

In overwhelming cases, in such layered or encapsulated materials, “healing” is represented as filling the discontinuities that arise in the material with some other substance, different from the base material, sometimes with properties completely different from the matrix material. In fact, this does not involve the restoration of the original characteristics of the material, but the formation of a new material with a different structure and properties. However, self-healing in most cases implies the restoration of the volumetric or surface integrity of the product with the simultaneous partial or complete restoration of important performance properties, such as tightness, strength characteristics, electrical conductivity, exterior, etc.

The concept of self-healing layered composite materials is broad and can incorporate various self-healing mechanisms in a single system, allowing for unique “self-healing” effects that are not achievable in other materials.

CONCLUSION

The presented review briefly examined the main mechanisms of self-healing of damage in various materials and presented examples of their implementation. Materials that can autonomously detect and repair damage at the initial level have enormous potential and application possibilities, especially when in hard-to-reach areas it is necessary to ensure the reliability of materials for as long as possible. The creation of artificial “self-healing” materials is still at an early stage of development, however, modern technologies have already helped to increase the durability and resistance of materials, and the materials themselves have been developed and used mainly in various composite systems. Currently, polymeric and cementitious materials and their composite systems are the most studied category of materials in the context of self-healing ability. Based on the emerging prospects, a large number of academic and industrial research organizations are supporting work on the development of new self-healing materials and the study of the kinetics and stability of “self-healing” processes.

There is no doubt that with the development and reduction in cost of technologies for creating self-healing materials, they will increasingly be introduced into production in order to improve the properties and extend the service life of products and devices necessary for humans.

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Sitnikov Nikolay Nikolaevich

Candidate of Technical Sciences. Senior researcher (SSC FSUE "Keldysh Center"), leading engineer (NRNU "MEPhI"). Specialist in the field of nanotechnology and materials with shape memory effect.

Khabibullina Irina Aleksandrovna

Engineer at the State Scientific Center FSUE "Keldysh Center". Nanotechnology specialist

Mashchenko Vladimir Igorevich

Candidate of Chemical Sciences, Senior Researcher at Moscow State Regional University. Specialist in the field of nanotechnology.

Authors:

Sitnikov Nikolay Nikolaevich

Federal State Unitary Enterprise Keldysh Research Center; National Research Nuclear University MEPhI (Moscow Engineering Physics Institute).

Candidate of Technical sciences. Senior Research Fellow. Specialist in the field of nanotechnology and materials with shape memory effect

Khabibullina Irina Alexandrovna

Federal State Unitary Enterprise Keldysh Research Center.

Engineer 3 category. Specialist in the field of nanotechnology

Mashchenko Vladimir Igorevich

Moscow Region State University.

PhD in Chemical sciences. Senior Research Fellow. Specialist in the field of nanotechnology

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In the era of the heyday of insurance and paid medicine, it is naive to believe that someone else will take care of a person’s health other than himself. This troublesome task has long been transferred to the shoulders of the patients themselves, and insurance or cash serve only as crutches, on which many rely more than on their own strength.

At the same time, instead of the usual waste of energy, time and money, you can very thoughtfully engage in such an affordable activity as self-healing. The human self-healing system will simultaneously include disease prevention and treatment of existing ailments.

How to trigger the body's self-healing mechanism

Any human body has enormous potential, allowing it not only to survive, but also to live a quality life, independently preventing the development of pathological processes in the body. During transitional periods of life (early childhood, during hormonal changes or old age), a person’s protective mechanisms and self-healing resources weaken somewhat. Against the backdrop of poor nutrition, an irrational lifestyle, industrial hazards or environmental difficulties, the body also spends all its strength on simple survival, without having a margin of safety to restore problem areas. But synthetic drugs, artificial hormones and household antiseptics simply turn off the human self-healing function, switching the body to life in sterile conditions and breaking the immune self-defense.

In order to solve the problem, you need to adhere to six simple rules.

How to start recovery mechanisms:

Realize that external factors are a provocation of the disease, and the readiness for it lies in the person himself. Therefore, resistance to the disease or recovery from it is possible only with the right and conscious attitude.
It is necessary to start the day or any task during it with a smile, straighten your shoulders and straighten your back. Positive emotions are the key to successful self-healing of a person.
Rejoice at your even small achievements and praise yourself for them. Feeling grateful to yourself for taking care of your health can mobilize significant resources that a person did not even know about.
Master the practices of relaxation, relieve internal tension and muscle tightness, connect not only consciousness, but also subconscious attitudes to the body’s self-healing.
Master the skills of simple gymnastics, self-massage and use them regularly, accustoming the body to a clear routine for the functioning of all organs and systems.
Stick to the basics of good nutrition, avoiding overeating, an unbalanced diet or fasting.

Self-healing methods for the spine

The spine is the main support of the entire body, the health of which determines the mobility and flexibility of the body, the adequacy of cerebral blood flow and the normal functioning of internal organs. In the East, it is believed that the main flows of vital energy are distributed along the spinal column and, having learned to manage the health of the spine, you can control the entire body. And this can be achieved by simple actions that accelerate the process of human self-healing.

Spine health rules:

Monitor your posture and train your muscle corset, strengthening and stretching the ligaments. This allows you to reduce the load on the spine and prevent its premature wear, as well as injuries.
Timely relax the spine and massage to help the muscles around it receive enough oxygen and remove toxins.
Eat right, pushing back degenerative-dystrophic changes in the bone and cartilage tissue of the spine.
With psychological training, reinforce all physical achievements and form the correct attitudes that guide the self-healing of the spine.

Self-healing vision

The visual analyzer works fully only if all its parts are rationally loaded. Therefore, the basis for vision rehabilitation using the body’s own forces is the restoration of physiological loads on the muscular system of the eye. This allows the muscles to alternate contraction and relaxation in a balanced manner, sufficiently nourish all the tissues of the eye with blood, stimulate the optic nerve and the center in the occipital lobe of the brain. At the same time, visual tables are a way to monitor achievements, and eye gymnastics itself does not give brilliant results without the right psychological attitude and mobilization of a person’s mental and physical self-healing capabilities.

Liver self-healing

How to take care of your liver:

Avoid intoxication.
Do not abuse medications, adhering to the principles of self-healing.
Follow a diet balanced in fats, do not eat dry food.
Train the abdominal muscles and limbs so that sudden loads do not cause spasms of the bile ducts.
Maintain spinal health by ensuring normal functioning of the autonomic nervous system.

“An organism is a highly self-organizing and self-regulating system”

Russian physiologist I. Pavlov

“Do not rely on medicine, it cannot teach a person how to become healthy. Try not to be captured by doctors! To become healthy, you need your own efforts, constant and significant. Man, fortunately, is so perfect that he can almost always regain health.”

Academician, cardiac surgeon N.M. Amosov

Today, no one needs to be convinced that chemical drugs are unsafe for the body. Synthetic drugs are foreign to the body (xenobiotics). The concept that a person can be cured by a synthetic chemical is contrary to nature.

Modern medicine is based on relieving the symptoms of diseases, instead of eliminating the causes. Agree, you can endlessly bail water out of a leaky boat. Maybe it would be better to seal the hole?

Modern medicine's approaches to "treatment" are crude and violent. , antibiotics, antacids, hormonal, psychotropic drugs, non-steroidal anti-inflammatory drugs, surgeries and much more, unnecessarily and unnecessarily disrupt the delicate regulatory mechanisms and break the body's defense systems. While the human body is so wisely designed that it is capable of regenerating itself. The body’s ability to self-regulate, self-heal, and self-renew is worthy of admiration. From birth, a person has enormous compensatory capabilities and a huge potential for self-healing. All systems of our body always strive to defeat the disease and restore balance. The body always knows exactly how to repair itself. You just need to help him with this. Create favorable conditions for him and he will naturally and automatically heal himself.

But a person's physical and mental capabilities are limited. And health problems arise when a person balances at the limit of his capabilities. And the “margin of safety” of the body depends on the supply of nutrients necessary for normal functioning.

Biochemical processes occur in the body constantly, every second. All substances that enter the body with food are converted into body tissue. Self-renewal of cells, tissues and organs is a natural process. Obsolete, damaged cells are destroyed, and new ones are formed instead - young and healthy.

On average, half of all tissue proteins change in a person every 80 days. Every 120 days - red blood cells, 10 days - skin, 2-3 days - the mucous membrane of the stomach and intestines. In a maximum of a year, the body is completely renewed. And it is very important that the “building materials” for renewing body tissues are of high quality.

Be healthy!