Mahatma Gandhi Mission’sCollege of Engineering and Technology.

Noida, U.P., India

Seminar Reporton

“SELF HEALING MATERIALS”

aspart of B. Tech Curriculum

Submitted By:

Name: UDIT BHARDWAJSemester: 5th

Roll No:1009540039

Under the Guidance of:

“Ms. Manuja pandey ”

Submitted to: (Seminar Coordinator) HOD

Mechanical Engineering Department, ( S K Bharti ) MGM’s COET,

Noida

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Mahatma Gandhi Mission’sCollege of Engineering and Technology.

Noida, U.P., India

Department of Mechanical Engineering

CERTIFICATE

This is to certify that Mr. UDIT BHARDWAJ of B. Tech.

Mechanical Engineering , Class TT-ME Roll No 1009540039 has

delivered seminar on the topic SELF HEALING MATERIALS.

His seminar presentation and report during the academic year 2012-13

as the part of B. Tech Mechanical Engineering curriculum was

poor/fair/good/excellent.

(Seminar Coordinator) (Guide) (Head of the Department)

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ACKNOWLEDGEMENT

First of all I thank the almighty for providing me with the strength and courage to present

the seminar.

I avail this opportunity to express my sincere gratitude towards Mr. Sachin R Jambhale

head of mechanical engineering department, for permitting me to conduct the seminar. I

also at the outset thank and express my profound gratitude to my seminar guide Ms.

Manuja pandey for his inspiring assistance, encouragement and useful guidance.

I am also indebted to all the teaching and non- teaching staff of the department of

mechanical engineering for their cooperation and suggestions, which is the spirit behind

this report. Last but not the least, I wish to express my sincere thanks to all my friends for

their goodwill and constructive ideas.

UDIT BHARDWAJ

CLASS :- TT-ME

ROLL NO:- 1009540039

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ABSTRACT

Self-healing materials are a class of smart materials that have the structurally incorporated ability

to repair damage caused by mechanical usage over time. The inspiration comes from biological

systems, which have the ability to heal after being wounded. Initiation of cracks and other types

of damage on a microscopic level has been shown to change thermal, electrical, and

acoustical properties, and eventually lead to whole scale failure of the material. Usually, cracks

are mended by hand, which is difficult because cracks are often hard to detect. A material

(polymers, ceramics, etc.) that can intrinsically correct damage caused by normal usage could

lower production costs of a number of different industrial processes through longer part lifetime,

reduction of inefficiency over time caused by degradation, as well as prevent costs incurred by

material failure. For a material to be defined as self-healing, it is necessary that the healing

process occurs without human intervention.

Self-healing materials, when damaged, are designed to sense the failure and respond in an

autonomous fashion to restore structural function. Inspired by biological systems, synthetic self-

healing materials represent a new paradigm in the design of polymer based composites. This

overview article summarizes the different strategies and approaches to achieving self healing

functionality and discusses future directions in the nascent field. The strategies are broadly

classified into the following three categories: healing with an embedded liquid phase repair

agent, thermally activated solid phase healing, and healing of projectile puncture.

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ContentsAcknowledgement……………………………………………………………………………………………………………..……………3

Abstract…………………………………………………………………………………………………………………………..………………4

introduction…………………………………………………………………………………………………………………………………….6

Observation of self-healing materials…………………………………………………………………8

why self healing ? …………………………………………………………………………………...10

Self healing polymers…………………………………………………………………….………………………………………………13

Homolytic bond cleavage..................................................................................................................15

Heterolytic bond cleavage.................................................................................................................16

Reversible bond cleavage..................................................................................................................17

Supramolecular breakdown...............................................................................................................18

Covalently bonded system.................................................................................................................20

Hollow tube approach.......................................................................................................................26

Microcapsule healing.........................................................................................................................27

Liquid-based healing agents..............................................................................................................30

Solid-state healing agents..................................................................................................................30

Biomimetic design approaches..........................................................................................................31

Potential applications of self healing materials…………………………………………………………………….………..32

References……………………………………………………………………………………………………………………………………..34

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INTRODUCTION

The ability of materials to self-heal from mechanical and thermally induced damage is explored

in this report and has significance in the field of fracture and fatigue. The history and evolution of

several self-repair systems is examined including nano-beam healing elements, passive self-

healing, autonomic self-healing and ballistic self-repair. Self-healing mechanisms utilized in the

design of these unusual materials draw much information from the related field of polymer–

polymer interfaces and crack healing. The relationship of material damage to material healing is

examined in a manner to provide an understanding of the kinetics and damage reversal processes

necessary to impart self-healing characteristics. In self-healing systems, there are transitions

from hard-to-soft matter in ballistic impact and solvent bonding and conversely, soft-to-hard

matter transitions in high rate yielding materials and shear-thickening fluids. These transitions

are examined in terms of a new theory of the glass transition and yielding, viz., the twinkling

fractal theory of the hard-to-soft matter transition. Success in the design of self-healing materials

has important consequences for material safety, product performance and enhanced fatigue

lifetime.

Self-healing materials are a class of smart materials that have the structurally incorporated ability

to repair damage caused by mechanical usage over time. The inspiration comes from biological

systems, which have the ability to heal after being wounded. Initiation of cracks and other types

of damage on a microscopic level has been shown to change thermal, electrical, and

acoustical properties, and eventually lead to whole scale failure of the material. Usually, cracks

are mended by hand, which is difficult because cracks are often hard to detect. A material

(polymers, ceramics, etc.) that can intrinsically correct damage caused by normal usage could

lower production costs of a number of different industrial processes through longer part lifetime,

reduction of inefficiency over time caused by degradation, as well as prevent costs incurred by

material failure. For a material to be defined as self-healing, it is necessary that the healing

process occurs without human intervention.

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Self-healing materials are polymers, metals, ceramics and their composites that when damaged

through thermal, mechanical ,ballistic or other means have the ability to heal and restore the

material to its original set of properties. Few materials intrinsically possess this ability, and the

main topic of this review is the design for self-repair. This is a very valuable characteristic to

design into a material since it effectively expands the life time use of the product and has

desirable economic and human safety attributes.

In self-healing systems, there are transitions from hard-to-soft matter in ballistic impact and

solvent bonding and conversely, soft-to-hard matter transitions in high rate yielding materials

and shear-thickening fluids used in liquid armor. These transitions are examined in terms of a

new theory of the glass transition and yielding, viz., the twinkling fractal theory of the hard-to-

soft matter transition. It also gives an overview of the most recent advances in the self-healing

field, including the biomimetic microfluidic healing skins ,and provides some prospective for the

future design of self-healing materials. The biological analogy of self-healing materials would be

the modification of living tissue and organisms to promote immortality, and many would agree

that partial success in the form of expanded lifetime would be acceptable.

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Observation of self-healing materials

Materials such as polymers and composites experience damage and fatigue during their normal

utilization and the concept of eliminating this damage through a self-healing mechanism holds

the promise of enhanced lifetimes and enduring strength.

This is especially important in materials that are intended to perform in a designed manner for

significant times where repair is not possible. Our early attention to self-healing materials in

the1970sarose through the need to understand the constitutive properties of filled

elastomers ,such as those used in solid rocket propellants for applications in space exploration

(Apollo), Earth studies(Shuttle) and more recently, ballistic missile interdiction. These materials

consisted of ammonium perchlorate -filled hydroxyl terminated polybutadiene crosslinked with

diisocyanates. Itwas clear that mechanical action caused microscopic damage at the nano scale,

which could coalesce to form larger microscopic cracks, which in turn could propagate as

macroscopic cracks and cause catastrophic loss of the material and pay load. However, it became

readily apparent that much of this damage could self-heal and measures of damage through

modulus loss or mechanical stress–strain hysteresis were developed to quantify the damage and

healing processes

.

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Cyclic stress–strain curves of a HPP fiber with interveninghealing times from 10 to 1000 min at room

temperature.

An explicit example of a self-healing material was demonstrated with hard elastic polypropylene

(HPP).HPP is a stress-crystallized PP which has a morphology consisting of stacked lamella

perpendicular to the extrusion direction of the fibers or films. When stretched along the fiber

axis, the lamellae would splay apart permitting large reversible strains up to 500%.

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Why self healing ?

Traditional repairs are expensive

No matter how carefully you use your accessories in day to day life , by your fault or by

some others mistake sometime these things get damaged . Sometime the damage is at

very large scale and you have to replace the whole accessory and some time the damage

is at lower scale which could be repaired.

This low scale damage may be in the form of scratches or dents to the motor vehicles or

some other form of small damages. But due to the lack of time and due to working on the

repair of a single portion of accessory the repairs becomes very expansive.

Tradition repair process of leaving the car to garage and wait for the mechanic to remove

the dents is time consuming and expansive. Hence the concept of self healing comes into

picture for the small damages because it is fast and less expansive .

To design (never two the same)

it is never possible to design the new replacement with the same level of accuracy and

surface finish . Even after spending the money and time we did’ nt get the exact original

piece. But by self healing processes we need not to replace the original , because by

using self healing techniques we are providing the materials the power of healing itself

which minimizes the chances of replacement and the original is kept original with same

dimensional accuracy and quality.

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To implement (removal from service or in-situ repair)

in situ repairs are the repairs which are done to prevent the whole part to be replaced. If

this is not possible in the assembly then you have to replace the whole .And also in situ

repairs are very much expansive and also not that much precise and perfect . This

problem can be overcome by using self healing techniques , as this techniques the facility

of in situ repair by itself with very high level of accuracy.

To certify & monitor (additional inspection often required)

throughout remaining operational life.

Generally the repairs made to different materials requires expert monitoring and

certification .but by applying self healing techniques we need not to inspect or monitor

the repairs they are precisely done with self healing phenomenon.

Sense and respond to damage,restore performance without

affecting inherent properties.

Self healing sense and respond to damage ,restore performance and does not affect the

inherent properties of material. Usually self healing materials are used to repair the small

cracks in material when the self healing component is exposed to surroundings without

affecting inherent properties of the materials.

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No human intervention required.

For self healing process no human intervention is required . It decreases the chances of error

during the repair. In this process self healing of material starts without any human

interference .

Provide early means of detection of damage

It is like modeling and mimicking of the human body and other living systems which have

the ability to self heal. If the self healing inserts are used then the detection of damage is very

early and as soon as the damage is detected the healing repair starts. It prevent the material

from more damage .

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Self healing polymers

Research in the last decade has led to the development of self-healing polymeric materials that mimic some of these features found in biological systems .These self-healing polymers offer promise in significantly extending the life of polymeric components by autonomically healing microcracks whenever and wherever they develop. Potential applications for such materials are broad and include structural PMC for aerospace, prosthetics, civil infrastructure, and electronics. Though the potential benefits are quite high, there are several practical limitations (such as crack healing kinetics, stability of the healing functionality to environmental conditions, material costs, and virgin property reduction) that need to be overcome in order for the benefits to be realized.

There are several different strategies to impart self healing functionality that have been developed to various levels. The strategies, which are discussed in detail in the following headings, are broadly classified into three categories: healing with an embedded liquid phase repair agent, thermally activated solid phase healing, and healing of projectile puncture. Most of the work has been related to the liquid phase healing agent strategy, which will be described first.

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Polymer breakdown

From a molecular perspective, traditional polymers yield to mechanical stress though cleavage of sigma bonds. While newer polymers can yield in other ways, traditional polymers typically yield through homolytic or heterolytic bond cleavage. The factors that determine how a polymer will yield include: type of stress, chemical properties inherent to the polymer, level and type ofsolvation, and temperature.

From a macromolecular perspective, stress induced damage at the molecular level leads to larger scale damage called micro cracks. A micro crack is formed where neighboring polymer chains have been damaged in close proximity, ultimately leading to the weakening of the fiber as a whole.

Different types of polymer breakdown are -

Homolytic bond cleavage

Heterolytic bond cleavage

Reversible bond cleavage

Supramolecular breakdown

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Homolytic bond cleavage

Homolytic cleavage of   poly(methyl methacrylate)   (PMMA).

Polymers have been observed to undergo homolytic bond cleavage through the use of radical reporters such as DPPH (2,2-diphenyl-1-picrylhydrazyl) and PMNB (pentamethylnitrosobenzene.) When a bond is cleaved homolytically, two radical species are formed which can recombine to repair damage or can initiate other homolytic cleavages which can in turn lead to more damage.

Heterolytic bond cleavage15

  Heterolytic cleavage of   polyethylene glycol

Polymers have also been observed to undergo heterolytic bond cleavage through isotope labeling experiments. When a bond is cleaved heterolytically, cationic and anionic species are formed which can in turn recombine to repair damage, can be quenched by solvent, or can react destructively with nearby polymers.

Reversible bond cleavage

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Certain polymers yield to mechanical stress in an atypical, reversible manner. Diels-Alder-based polymers undergo a reversible cycloaddition, where mechanical stress cleaves two sigma bonds in a retro Diels-Alder reaction. This stress results in additional pi-bonded electrons as opposed to radical or charged moieties.

Supramolecular breakdown

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Supramolecular polymers are composed of monomers that interact non-covalently. Common interactions include hydrogen bonds, metal coordination], and van der Waals forces. Mechanical stress in supramolecular polymers causes the disruption of these specific non-covalent interactions, leading to monomer separation and polymer breakdown.

Reversible healing polymers

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Reversible systems are polymeric systems that can revert to the initial state whether it is monomeric, oligomeric, or non-cross-linked. Since the polymer is stable under normal condition, the reversible process usually requires an external stimulus for it to occur. For a reversible healing polymer, if the material is damaged by means such as heating and reverted to its constituents, it can be repaired or "healed" to its polymer form by applying the original condition used to polymerize it.

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Covalently bonded systemDiels-Alder and retro-Diels-Alder

Among the examples of reversible healing polymers, the Diels-Alder (DA) reaction and its retro-Diels-Alder (RDA) analogue seems to be very promising due to its thermal reversibility. In general, the monomer containing the functional groups such as furan or maleimide form two carbon-carbon bonds in a specific manner and construct the polymer through DA reaction. This polymer, upon heating, breaks down to its original monomeric units via RDA reaction and then reforms the polymer upon cooling or through any other conditions that were initially used to make the polymer. During the last few decades, two types of reversible polymers have been studied: (i) polymers where the pendant groups, such as furan or maleimide groups, cross-link through successive DA coupling reactions; (ii) polymers where the multifunctional monomers link to each other through successive DA coupling reactions.

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Cross-linked polymers

In this type of polymer, the polymer forms through the cross linking of the pendant groups from the linear thermoplastics. For example, figure have shown the reversible cross-linking of modified poly(N-acetylethyleneimine)s containing either maleimide or furancarbonyl pendant moideties. The reaction is shown in Scheme 3. They mixed the two complementary polymers to make a highly cross-linked material through DA reaction of furan and maleimide units at room temperature, as the cross-linked polymer is more thermodynamically stable than the individual starting materials. However, upon heating the polymer to 80 °C for two hours in a polar solvent, two monomers were regenerated via RDA reaction, indicating the breaking of polymers.[6] This was possible because the heating energy provided enough energy to go over the energy barrier and results in the two monomers. Cooling the two starting monomers, or damaged polymer, to room temperature for 7 days healed and reformed the polymer.

Scheme 3.   Reversible polymer cross-linking via   Diels-Alder   cycloaddition   reaction between

furan and maleimide.

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The reversible DA/RDA reaction is not limited to furan-meleimides based polymers as it is shown by the work of Schiraldi et al. They have shown the reversible cross-linking of polymers bearing pendent anthracene group with maleimides. However, the reversible reaction occurred only partially upon heating to 250 °C due to the competing decomposition reaction.

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Polymerization of multifunctional monomers

In this type of polymer, the DA reaction takes place in the backbone itself to construct the polymer, not as a link. For polymerization and healing processes of a DA-step-growth furan-maleimidebased polymer (3M4F) were demonstrated by subjecting it to heating/cooling cycles. Tris-maleimide (3M) and tetra-furan (4F) formed a polymer through DA reaction and, when heated to 120 °C, de-polymerized through RDA reaction, resulting in the starting materials. Subsequent heating to 90–120 °C and cooling to room temperature healed the polymer, partially restoring its mechanical properties through intervention. The reaction is shown in Scheme 4.

Scheme 4.   Reversible highly cross-linked furan-maleimide based polymer network.

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Thiol-based polymers

The thiol-based polymers have disulfide bonds that can be reversibly cross-linked through oxidation and reduction. Under reducing condition, the disulfide (SS) bridges in the polymer breaks and results in monomers, however, under oxidizing condition, the thiols (SH) of each monomer forms the disulfide bond, cross-linking the starting materials to form the polymer. Chujo et al. have shown the thiol-based reversible cross-linked polymer using poly(N-acetylethyleneimine).

Scheme 5.   Reversible polymer cross-linking by disulfide bridges

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Autonomic polymer healing

Self-healing polymers follow a three-step process very similar to that of a biological response. In the event of damage, the first response is triggering or actuation, which happens almost immediately after damage is sustained. The second response is transport of materials to the effected area, which also happens very quickly. The third response is the chemical repair process. This process differs depending on the type of healing mechanism that is in place. (e.g., polymerization, entanglement, reversible cross-linking). These self-healing materials can be classified in three different ways: capsule based, vascular, and intrinsic (which is listed as “Reversible healing polymers” above). While similar in some ways, these three ways differ in the ways that response is hidden or prevented until actual damage is sustained. Capsule based polymers sequester the healing agents in little capsules that only release the agents if they are ruptured. Vascular self-healing materials sequester the healing agent in capillary type hollow channels which can be interconnected one dimensionally, two dimensionally, or three dimensionally. After one of these capillaries is damaged, the network can be refilled by an outside source or another channel that was not damaged. Intrinsic self-healing materials, as you can see from above, do not have a sequestered healing agent but instead have a latent self-healing functionality that is triggered by damage or by an outside stimulus.

Thus far, all of the examples on this page require an external stimulus to initiate polymer healing (such as heat or light). Energy is introduced into the system to allow repolymerization to take place. This is not possible for all materials. Thermosetting polymers, for example, are not remoldable. Once they are polymerized (cured), decomposition occurs before the melt temperature is reached. Thus, adding heat to initiate healing in the polymer is not possible. Additionally, thermosetting polymers cannot be recycled, so it is even more important to extend the lifetime ofmaterials of this nature.

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Hollow tube approach

For the first method, fragile glass capillaries or fibers are imbedded within a composite material. The resulting porous network is filled with monomer. When damage occurs in the material from regular use, the tubes also crack and the monomer is released into the cracks. Other tubes containing a hardening agent also crack and mix with the monomer, causing the crack to be healed. There are many things to take into account when introducing hollow tubes into a crystalline structure. First to consider is that the created channels may compromise the load bearing ability of the material due to the removal of load bearing material. Also, the channel diameter, degree of branching, location of branch points, and channel orientation are some of the main things to consider when building up microchannels within a material. Materials that don’t need to withstand much mechanical strain, but want self-healing properties, can introduce more microchannels than materials that are meant to be load bearing. There are two types of hollow tubes: discrete channels, and interconnected channels.

Discrete channels

Discrete channels can be built independently of building the material and are placed in an array throughout the material. When creating these micro channels, one major factor to take into account is that the closer the tubes are together, the lower the strength will be, but the more efficient the recovery will be. A sandwich structure is a type of discrete channels that consists of tubes in the center of the material, and heals outwards from the middle. The stiffness of sandwich structures is high, making it an attractive option for pressurized chambers. For the most part in sandwich structures, the strength of the material is maintained as compared to vascular networks. Also, material shows almost full recovery from damage.

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Interconnected networks

Interconnected networks are more efficient than discrete channels, but are harder and more expensive to createThe most basic way to create these channels is to apply basic machining principles to create micro scale channel grooves. These techniques yield channels from 600–700 micrometers. This technique works great on the two-dimensional plane, but when trying to create a three-dimensional network, they are limited.

Direct Ink Writing

The Direct Ink Writing (DIW) technique is a controlled extrusion of viscoelastic inks to create three-dimensional interconnected networks. It works by first setting organic ink in a defined pattern. Then the structure is infiltrated with a material like an epoxy. This epoxy is then solidified, and the ink can be sucked out with a modest vacuum, creating the hollow tubes.

Microcapsule healing

This method is similar in design to the hollow tube approach. Monomer is encapsulated and embedded within the thermosetting polymer. When the crack reaches the microcapsule, the capsule breaks and the monomer bleeds into the crack, where it can polymerize and mend the crack

Figure 1.   Depiction of crack propagation through microcapsule-imbedded material.

Monomer microcapsules are represented by pink circles and catalyst is shown by purple

dots.

A good way to enable multiple healing events is to use living (or unterminated chain-ends) polymerization catalysts. If the walls of the capsule are created too thick, they may not fracture when the crack approaches, but if they are too thin, they may rupture prematurely.

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In order for this process to happen at room temperature, and for the reactants to remain in a monomeric state within the capsule, a catalyst is also imbedded into the thermoset. The catalyst lowers the energy barrier of the reaction and allows the monomer to polymerize without the addition of heat. The capsules (often made of wax) around the monomer and the catalyst are important maintain separation until the crack facilitates the reaction.

There are many challenges in designing this type of material. First, the reactivity of the catalyst must be maintained even after it is enclosed in wax. Additionally, the monomer must flow at a sufficient rate (have low enough viscosity) to cover the entire crack before it is polymerized, or full healing capacity will not be reached. Finally, the catalyst must quickly dissolve into monomer in order to react efficiently and prevent the crack from spreading further.

Scheme 6.   ROMP of DCPD via   Grubbs' catalyst

This process has been demonstrated with dicyclopentadiene (DCPD) and Grubbs' catalyst (benzylidene-bis(tricyclohexylphosphine)dichlororuthenium). Both DCPD and Grubbs' catalyst are imbedded in an epoxy resin. The monomer on its own is relatively unreactive and polymerization does not take place. When a microcrack reaches both the capsule containing DCPD and the catalyst, the monomer is released from the core-shell microcapsule and comes in contact with exposed catalyst, upon which the monomer undergoes ring opening metathesis polymerization (ROMP). The metathesis reaction of the monomer involves the severance of the two double bonds in favor of new bonds. The presence of the catalyst allows for the energy barrier (energy of activation) to be lowered, and the polymerization reaction can proceed at room

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temperature. The resulting polymer allows the epoxy composite material to regain 67% of its former strength.

Grubbs' catalyst is a good choice for this type of system because it is insensitive to air and water, thus robust enough to maintain reactivity within the material. Utilizing a live catalyst is important to promote multiple healing actions. The major drawback is the cost. It was shown that using more of the catalyst corresponded directly to higher degree of healing. Ruthenium is quite costly, which makes it impractical for commercial applications

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Liquid-based healing agents

Completely autonomous synthetic self-healing material was reported in 2001 on example of an epoxy system containing microcapsules.[21] These microcapsules were filled with a (liquid)monomer. If a microcrack occurs in this system, the microcapsule will rupture and the monomer will fill the crack. Subsequently it will polymerise, initiated by catalyst particles (Grubbs catalyst) that are also dispersed through the system. This model system of a self healing particle proved to work very well in pure polymers and polymer coatings.

A hollow glass fibre approach may be more appropriate for self-healing impact damage in fibre-reinforced polymer composite materials. Impact damage can cause a significant reduction in compressive strength with little damage obvious to the naked eye. Hollow glass fibres containing liquid healing agents (some fibres carrying a liquid epoxy monomer and some the corresponding liquid hardener) are embedded within a composite laminate. Studies have shown significant potential.

Solid-state healing agents

In addition to the sequestered healing agent strategies described above, research into "intrinsically" self-healing materials is also being performed. For example, supramolecular polymers are materials formed by reversibly connected non-covalent bonds (i.e. hydrogen bond), which will disassociate at elevated temperatures. Healing of these supramolecullary based materials is accomplished by heating them and allowing the non-covalent bonds to break. Upon cooling, new bonds will be formed and the material will potentially heal any damage. An advantage of this method is that no reactive chemicals or (toxic) catalysts are needed. However, these materials are not "autonomic" as they require the intervention of an outside agent to initiate a healing response.

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Biomimetic design approaches

Self-healing materials are widely encountered in natural systems, and inspiration can be drawn from these systems for design. There is evidence in the academic literature of these biomimetic design approaches being used in the development of self-healing systems for polymer composites. In biology, for the minimum power to pump fluid through vessels Murray's law applies. Deviation from Murray’s law is small however, increasing the diameter 10% only leads to an additional power requirement of 3%–5%. Murray’s law is followed in some mechanical vessels, and using Murray’s law can reduce the hydraulic resistance throughout the vessels.  The DIW structure from above can be used to essentially mimic the structure of skin. Toohey et al. did this with an epoxy substrate containing a grid of microchannels containing dicyclopentadiene (DCPD), and incorporated Grubbs' catalyst to the surface. This showed partial recovery of toughness after fracture, and could be repeated several times because of the ability to replenish the channels after use. The process is not repeatable forever, because the polymer in the crack plane from previous healings would build up over time.

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Potential Applications of Self Healing Materials

Scientists have recently developed a polyurethane coating that heals its own scratches

when exposed to sunlight.

The self-healing coating uses chitosan which is derived from chitin, the main component

of the exoskeleton of crustaceans .

When a scratch occurs on the outer coating, the chemical structure is damaged and the

chitosan responds to the UV component of sunlight.

Chemical chains are then formed with other materials in the coating, eventually filling the

scratch. 

Anything that cannot be reached for repair at the moment of damage!

Civil Structures (Engineered cementitious composite)

Tools (Nitinol)

Space applications

Self healing coatings for steel structure

Composite materials for:

Aerospace applications

High quality sporting equipment

Microelectronics

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Medical uses:

To detect a breach in a glove, gown, etc., using electrohydrodynamic technology

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References

www.Google.com

en.wikipedia.org/wiki/Self-healing_material

www.gizmag.com/self-healing-car-paint/11254

onlinelibrary.wiley.com

Self-Healing Polymers and Composites - Annual Review of Materials Research,

www.annualreviews.org

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