What Are Smart Materials Their Examples and Applications

Non-Newtonian fluid:- A Non-Newtonian fluid is fluid whose flow properties are not described by a single constant value of viscosity. Many polymer solutions and molten polymers are non-newtonian fluids, as are many commonly found substances such as ketchup, starch suspensions, paint, blood, and shampoo. In a Newtonian fluid, the relation between the shear stress and the strain rate is linear, the constant of proportionality being the coefficient of viscosity. In a non-newtonian fluid, even be time-dependent. Therefore a constant coefficient of viscosity cannot be defined. A ratio between shear stress and rate of strain can be defined, this concept is more useful for fluids without time-dependent behavior. Although the concept of viscosity is commonly used to characterize a material, it can be adequate to describe the mechanical behavior of a substance, particularly non-newtonian fluids. They are best studied through several other rheological properties which relate to the relations between the stress and strain rate tensors under many different flow conditions, such as oscillatory shear, or extensional flow which are measured using different devices or rheometers. The properties are better studied using tensor-valued constitutive equations, which are common in the field of continuum mechanics.

Piezoelectricity:- Piezoelectricity is the ability of some materials to generate an electric field or electric potential in response to applied mechanical stress. The effect is closely related to a change of polarization density within the material's volume. If the material is not short-circuited, the applied stress induces a voltage across the material. The piezoelectric effect is reversible in that material exhibiting the direct piezoelectric effect also exhibits the reverse piezoelectric effects.

Temperature responsive polymer:- A temperature-responsive polymer is a polymer that undergoes a physical change when external thermal stimuli are presented. The ability to undergo such changes under easily controlled conditions makes this class of polymers fall into the category of smart materials. These physical changes can be exploited for many analytical techniques. After numerous investigations of poly (N-isopropyl acrylamide) (poly-NIPAAm), there was a sparked interest in the application of this and many other stimuli-responsive polymers. There has been extensive research in the applications of intelligent polymers for use as stationary phases, extraction compounds, surface modifiers, drug delivery, and gene delivery.

Ferrofluid:- A ferrofluid, is a liquid that becomes strongly polarized in the presence of a magnetic field. Ferrofluids are colloidal mixtures composed of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid, usually an organic solvent or water. The ferromagnetic nanoparticles are coated with a surfactant to prevent their agglomeration. Although the name may suggest otherwise, ferrofluids do not display ferromagnetism, since they do not retain magnetization in the absence of an externally applied field. In fact, ferrofluids display paramagnetism and are often described as superparamagnetic due to their large magnetic susceptibility. Permanently magnetized fluids are difficult to create at present.

Halochromic material:- A halochromic material is a material that changes color when a pH change occurs. The term chromic is defined as materials that can change color reversibly with the presence of a factor. In this case, the factor is pH. The pH indicators have this property. Halochromic substances are suited for use in environments where pH changes occur frequently or places where changes in pH are extreme. Halochromic substances detect alterations in the acidity of substances, like the detection of corrosion in metals. Halochromic substances may be used as indicators to determine the pH of solutions of unknown pH. The color obtained is compared with the color obtained when the indicator is mixed with solutions of known pH. The pH of the unknown solution can be estimated obvious disadvantages of this method include its dependency on the color sensitivity of the human eye, and that unknown solutions that are already colored cannot be used.