Nanocomposites are combinations of two or more dissimilar constituents or phases which have dissimilar physical and chemical properties and are separated by a different interface. The constituents which are generally present in more quantities are called the matrix. The mechanical properties of nanocomposites increase by inserting the constituent into the matrix material called reinforcement. Abalone shell and bone these nanocomposites are found in nature. The reinforcing material can be made up of particles like minerals, Carbon nanotubes and sheets as exfoliated clay stacks, graphene or fibres as Electrospun nanofibers. Reinforcement is usually in the form of nanosized filler materials. The term nanocomposite is extensively used to describe an incredibly expensive range of materials, where one of the dimensions is in nano range.
Types of Nanocomposites:
Nanocomposites are categorised according to the types of reinforcement materials and matrix materials used in their construction, and these are generally classified into following three classes
- Ceramic Matrix Nanocomposites
Ceramic matrix nanocomposites, having a wide range of applications in industry, and out of two phases one phase having nano size dimension. The microstructure of nanoceramic composites results in greatest electrical and mechanical properties. Several methods have been used in ceramic matrix nanocomposites preparation. Generally, the common methods used in microcomposites fabrications are conventional powder method, polymer precursor route, spray pyrolysis, and sol-gel process as chemical method, colloidal and precipitation methods and template synthesis.
- Metal Matrix Nanocomposites
Metal matrix nanocomposites are materials reinforced by nanoparticles consisting of ductile metal Science and uses of alloy matrix in which nanoparticle reinforcement is embedded. These type composites consist of a metal/alloy matrix filled with nanoparticles, displaying physical, chemical and mechanical properties totally differ from those of matrix material. The nanoparticles are generally used to improve wear resistance, mechanical properties and damping characteristics. Metal matrix nanocomposites are being investigated by researchers recently, due to their superior properties because of nanoparticle embedment, are finding applications in structural components
- Polymer Matrix Nanocomposite
For the fabrication of Polymer matrix nanocomposites either chemical or mechanical process is used. The major problem in polymer nanocomposite fabrication is uniform and homogeneous scattering of nanoparticles in the polymer matrix. Nanofillers have a tendency to formulate the micron size filler cluster after aggregates, and filler clusters limit the distribution of nanoparticles in the polymer matrix thus deteriorating the properties of nanocomposites. In polymer matrix nanofillers disperse uniformly by chemical reactions, surface modification of filler material or complicated polymerisation reactions.
Advantages
- Polymer nanocomposites having greater mechanical properties [modulus and strength].
- Nanocomposites having good structural and thermal stability.
- It has promising electrical conductivity and has low permeability of fluid.
- Improving the properties of matrix material in nanocomposites requires a limited amount of nanofiller material as compared to conventional composites.
- Due to the addition of a small percentage of nanofiller materials, nanocomposites are much lighter in weight compared to conventional composites.
- Size dependent properties of nanomaterial increases thermal, chemical, mechanical, optical, magnetic and electrical properties to a much greater extent than conventional composites.
Technique in Preparation of Nanocomposites
1) Intercalation Method
The intercalation method mostly involves the distribution of nanoplatelet types of nanomaterials into the polymer matrix. The bulk properties such as stiffness, shrinkage and flammability are increased due to addition of clays (nanomaterial). Intercalation is a best approach and requires surface modification of nanoplatelets for homogeneous scattering of plate-like nanofillers in the polymer matrix. Intercalated morphology occurs when diffuse the polymer chains into the gallery space of layered structure. The techniques used for the homogenous dispersion of nanoplatelets are as follows:
a) Chemical Technique: In this technique polymerisation reactions yield when nanoparticles are distributed in monomer, and nanoplatelets are distributed into polymer followed by an additional polymerisation process. Due to the polymerisation method, nanoplatelets are enlarged in monomer solution and between the intercalated sheets, polymer formation occurs.
b) Mechanical Technique: In this technique polymer with nanoplatelets direct intercalation occurs through mixing of solution. The dissolution of polymer in a co-solvent, nanoplatelets sheets are enlarged in the solvent and both solutions are mixed together, and the polymer chains insert into the nanoplatelets layers and move the solvent.
2) In Situ Polymerisation Method
In situ polymerisation comprises the swelling of the nanofillers in monomer solution subsequently the low-molecular weight monomer solution can easily leak in between layers producing swelling. The resultant mixture is polymerised either using radiation, heat, initiator diffusion or by organic initiator. The resultant mixture of monomers is then polymerised between interlayers thus forming either intercalated or exfoliated nanocomposites.
Situ template synthesis is an equivalent method, in which the clay layers are synthesised in the presence of polymer chains. Polymer matrix and clay layers both are softened in an aqueous solution and gel is usually refluxed at high temperature. The polymer chains are enclosed inside the clay layers and nucleation, thus development of clay layers proceeds on the polymer chains at high temperature. In this process decomposition of polymers occurs due to high temperature.
3) Sol- gel Method
Sol- gel method is a bottommost approach and follows totally an opposite principle than previous methods. The term sol-gel is related to two relations steps, sol and gel. The colloidal suspension of solid nanoparticles forms in monomer solution called as sol and 3D interrelating network formed between phases called as gel. In this method, colloidal suspension of solid nanoparticles is formed due to distribution of solid nanoparticles in monomer solution is (sol), and formation of interconnecting networks between phases by polymerisation reactions followed by the hydrolysis process is (gel). The polymer nanoparticle 3D network is involved throughout the liquid. The polymer encourages the growth of layered crystals and serves as a nucleating agent. When crystals are grown, the polymer is leaked between layers and thus nanocomposite is formed.
4) Direct Mixing of Polymer and Nanofillers
Direct mixing of a polymer matrix and nanofillers is an uppermost approach of nanocomposite production and based on the disruption of the aggregated nanofillers throughout the mixing process. This fabricating method of polymer matrix nanocomposites has two methods of mixing the polymer and nanofillers.
a) Melt Compounding
In this method, the shear stress (hydrodynamics force) is incorporated in the polymer melt by viscus drag, and due to shear stress nanofiller masses collapse and it forms uniform nanofiller dispersion in the polymer matrix.
b) Solvent Method
In this method, nanoparticles are dispersed in the solvent and the polymer is dissolved in a co-solvent. The resultant nanocomposites are recovered through solvent evaporation method. This method required lowered shear stress. By sonication process, nanofillers are pre-dispersed in the solvent and the nanofiller aggregates are broken down.
Conclusion
These are the different techniques used in the preparation of nanocomposites. These methods are widely used in the beauty industry to develop futuristic cosmetic and skincare products. Pursuing a B.Sc. in Beauty Cosmetology can help you further understand the role of nanocomposites in the beauty industry. This is a future-proof branch of study that can lead to global career opportunities with leading brands in the cosmetic industry.