Mechanochemistry is the coupling of the mechanical and the chemical phenomena on a molecular

Molecule

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...

 scale and includes mechanical breakage, chemical behaviour of mechanically-stressed

Stress (physics)

In continuum mechanics, stress is a measure of the internal forces acting within a deformable body. Quantitatively, it is a measure of the average force per unit area of a surface within the body on which internal forces act. These internal forces are a reaction to external forces applied on the body...

 solids (e.g., stress-corrosion cracking), tribology

Tribology

Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear...

, polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

 degradation under shear

Shear stress

A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...

, cavitation

Cavitation

Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...

-related phenomena (e.g., sonochemistry

Sonochemistry

In chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems. The chemical effects of ultrasound do not come from adirect interaction with molecular species...

 and sonoluminescence

Sonoluminescence

Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound.-History:The effect was first discovered at the University of Cologne in 1934 as a result of work on sonar. H. Frenzel and H. Schultes put an ultrasound transducer in a tank of...

), shock wave

Shock wave

A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...

 chemistry and physics, and even the burgeoning field of molecular machine

Molecular machine

A molecular machine, or nanomachine, is any discrete number of molecular components that produce quasi-mechanical movements in response to specific stimuli . The expression is often more generally applied to molecules that simply mimic functions that occur at the macroscopic level...

s. Mechanochemistry can be seen as an interface between chemistry

Chemistry

Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 and mechanical engineering

Mechanical engineering

Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the...

. It is possible to synthetize chemical products by using only mechanical action. A method was proposed, in order to measure the energy involved during mechanical transformations.

The term mechanochemistry is also sometimes used in molecular nanotechnology

Molecular nanotechnology

Molecular nanotechnology is a technology based on the ability to build structures to complex, atomic specifications by means of mechanosynthesis. This is distinct from nanoscale materials...

 as a synonym for mechanosynthesis

Mechanosynthesis

Mechanosynthesis is any chemical synthesis in which reaction outcomes are determined by the use of mechanical constraints to direct reactive molecules to specific molecular sites.-Introduction:...

, the hypothetical process by which molecular assembler

Molecular assembler

A molecular assembler, as defined by K. Eric Drexler, is a "proposed device able to guide chemical reactions by positioning reactive molecules with atomic precision". Some biological molecules such as ribosomes fit this definition. This is because they receive instructions from messenger RNA and...

s would operate. Also called "positional synthesis" or "positional assembly", it is a technique for forming chemical bond

Chemical bond

A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

s by direct computer control of the position of molecules.

Mechanochemical phenomena have been utilized since time immemorial

Time immemorial

Time immemorial is a phrase meaning time extending beyond the reach of memory, record, or tradition, indefinitely ancient, "ancient beyond memory or record"...

, for example in making fire

Making fire

Fire was an essential tool in early human cultural development and still important today. Many different techniques for making fire exist...

. The oldest method of making fire is to rub pieces of wood against each other, creating friction and hence heat, allowing the wood to undergo combustion at a high temperature. Another method involves the use of flint and steel, during which a spark

Ember

Embers are the glowing, hot coals made of greatly heated wood, coal, or other carbon-based material that remain after, or sometimes precede a fire. Embers can glow very hot, sometimes as hot as the fire which created them...

 (a small particle of pyrophoric metal) spontaneously combusts in air, starting fire instantaneously.