Nanomaterials: Surface Functionalization …
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nanomaterials, nanoceramics, and self-assembled materials. Soft materials are classified in the following categories: synthetic and biological. Synthetic soft materials
are synthesized or made by mankind using different chemical methods or fabrication
process, whereas biological soft materials graft from nature.
2.1 Synthetic
For the development of synthetic soft materials at the nanoscale polymers, surfactants, lipids, colloids, and liquid crystals are the major building blocks. For the
development of nanotechnology, nano-struc-tures play a vital role, and that could
be graft by microphase separation of block copolymers. Surfactants contain surfaceactive agents are used for nanomaterials fabrication. These surface-active agents
have amphiphilic molecules with both hydrophilic and hydrophobic parts that preferentially segregate on the surface of the nanoparticles or nanomaterials and become
active. Detergent is the best example of a surfactant. Also, lipids, which are biological
amphiphiles having self-assembling building blocks collectively gather together in
water and aggregate into different nanostructures consequently, the contact between
the hydrophobic part of the amphiphiles with water molecules reduces and micelles
and vesicles forms. These micelles shapes vary that could be spherical or cylindrical and form hydrophobic cores and hydrophilic coronas in water. On the other
hand, vesicles form a hollow spherical shape where the outer surface of the sphere is
composed of layers of surfactant molecules. Colloids are the microscopic substance
that is dispersed evenly throughout another substance with dimensions in between
the range of 1 nm to 1 μm. Colloidal systems have two separate phases, and they are
heterogeneous. When the dispersed phase of molecules comes into contact and mixes
with continuous medium, it results in the self-organization of molecules. Aerosols,
foams, emulsions are few of the examples of colloids. Liquid crystals also come in the
soft materials category composed of moderate-sized organic molecules with molecular order intermediate between a liquid and a crystal. Liquid crystals present in the
mesogen phase. These mesogen phases consist of two-phase one is the thermotropic
phase, and the other is the lyotropic phase. Both the phase thermotropic phase as well
as lyotropic phase forms in different medium and condition. Organic molecules form
thermotropic phases in the absence of solvent, whereas amphiphiles form lyotropic
phases in a solution. Figure 1 illustrates the liquid crystal phase orientations, such as
the nematic phase and the smectic (layered) phase. Figure 1a illustrates the nematic
phase where the positional order of the molecules is short-range, and orientation is in
an average direction whereas Fig. 1b illustrates the translational order and the longrange orientations of molecules that form the smectic (layered) phase. This smectic
phase contains a high viscosity.
409
nanomaterials, nanoceramics, and self-assembled materials. Soft materials are classified in the following categories: synthetic and biological. Synthetic soft materials
are synthesized or made by mankind using different chemical methods or fabrication
process, whereas biological soft materials graft from nature.
2.1 Synthetic
For the development of synthetic soft materials at the nanoscale polymers, surfactants, lipids, colloids, and liquid crystals are the major building blocks. For the
development of nanotechnology, nano-struc-tures play a vital role, and that could
be graft by microphase separation of block copolymers. Surfactants contain surfaceactive agents are used for nanomaterials fabrication. These surface-active agents
have amphiphilic molecules with both hydrophilic and hydrophobic parts that preferentially segregate on the surface of the nanoparticles or nanomaterials and become
active. Detergent is the best example of a surfactant. Also, lipids, which are biological
amphiphiles having self-assembling building blocks collectively gather together in
water and aggregate into different nanostructures consequently, the contact between
the hydrophobic part of the amphiphiles with water molecules reduces and micelles
and vesicles forms. These micelles shapes vary that could be spherical or cylindrical and form hydrophobic cores and hydrophilic coronas in water. On the other
hand, vesicles form a hollow spherical shape where the outer surface of the sphere is
composed of layers of surfactant molecules. Colloids are the microscopic substance
that is dispersed evenly throughout another substance with dimensions in between
the range of 1 nm to 1 μm. Colloidal systems have two separate phases, and they are
heterogeneous. When the dispersed phase of molecules comes into contact and mixes
with continuous medium, it results in the self-organization of molecules. Aerosols,
foams, emulsions are few of the examples of colloids. Liquid crystals also come in the
soft materials category composed of moderate-sized organic molecules with molecular order intermediate between a liquid and a crystal. Liquid crystals present in the
mesogen phase. These mesogen phases consist of two-phase one is the thermotropic
phase, and the other is the lyotropic phase. Both the phase thermotropic phase as well
as lyotropic phase forms in different medium and condition. Organic molecules form
thermotropic phases in the absence of solvent, whereas amphiphiles form lyotropic
phases in a solution. Figure 1 illustrates the liquid crystal phase orientations, such as
the nematic phase and the smectic (layered) phase. Figure 1a illustrates the nematic
phase where the positional order of the molecules is short-range, and orientation is in
an average direction whereas Fig. 1b illustrates the translational order and the longrange orientations of molecules that form the smectic (layered) phase. This smectic
phase contains a high viscosity.