“Smart” materials, in other words “smart” materials, are a class of materials that are different in chemical composition and state of aggregation , which combines the manifestation of one or more physical (optical, magnetic, electrical, mechanical) or physicochemical (rheological, etc. .) characteristics significantly (reversibly or irreversibly) changing under the influence of external influences: pressure, temperature, humidity, pH of the medium ., electric or magnetic fields, etc. Smart materials are often used to create y Noah clothes .
Content
Description
The “heterogeneous” materials of this group are made manifest by interdependent but different in nature properties (mechanical, electrical, magnetic, etc.), which allows them to be used as sensors that are sensitive to any external influence, or as “ actuators ”, causing artificially performed action when a control signal is applied. In both cases, the response function to the effect, as a rule, is nonlinear. Some of the “smart” materials can independently respond to external influences, such as bimetallic plates in the simplest temperature controllers.
Most often, “smart” materials include piezoelectrics ( alpha quartz , lead zirconate titanate ), which act as “sensors” or “actuators”. Recently, they also include thermoelectrics , multiferroics , magnetocaloric materials, materials with a giant magnetoresistance effect, magnetorheological, electrorheological liquids, materials with a shape memory effect ( nitinol , etc.), thermo- and photosensitive polymers. “Smart” materials include polymer gels that can change their volume hundreds of times ( gel collapse ) with a small change in external conditions (temperature, solvent composition, pH of the medium). Various polymer coatings, which significantly change their conductive, optical, and other properties during the sorption of certain substances, are used in sensors of devices for environmental monitoring, in particular, for determining the concentration of toxic substances.
Not all “smart” materials are directly related to the category of nanomaterials , but they often find application in the field of nanotechnology. So, ferroelectrics (piezoelectrics) are used to create high-precision positioning devices (in particular, for scanning probe microscopy), highly dispersed magnetic particles ( nanoparticles ) are used in magnetorheological liquids. A number of nanodevices were created on the basis of piezoelectrics ( nanoscale , one-dimensional nanostructures of barium titanate or zinc oxide, used to generate electricity, etc.).
See also
- Smart composites
Literature
- Multiferroic nanofibres // Nanometer, 2008
- Smart clothes will charge batteries // Nanometer, 2008
- Nano-alphabet: atomic force microscopy // Nanometer, 2007
- (English) Official site of the journal “Smart Materials and Structures”
- (English) Kuznetsov AA, Shlyakhtin OA, Brusentsov NA, Kuznetsov OA “Smart” Mediators For Self-Controlled Inductive Heating // European Cells and Materials - No. 3. Suppl. 2, 2002 - pp. 75-77