Published on: Mar 3, 2016
Transcripts - Nanocomposites
Inorganic and Organic
synthesis of nanocomposites
“ A Nanocomposite is a composite material, in which one
of the components has at least one dimension that is
around 10-9 m.
“ A Nanocomposite is a multiphase solid material where
one of the phases has one, two or three dimensions of
less than 100 nm, or structure having nano-scale
repeat distance between the different phases that
make up the material.
DIFFERENT TYPES OF NANOCOMPOSITES
• Ceramic-matrix nanocomposites
• Polymer-matrix nanocomposites
• Polymer-silicate nanocomposites
• Elastomeric nanocomposites
• In this group of composites, main part of volume is occupied
by a ceramic i.e a compound of oxides, bromides,nitrides and
• In most cases these encompass a metal as second component
• Ideally both components, metallic one and ceramic one, are
finely dispersed in each other in order to elicit particular
• Nanocomposite from these combinations demonstrated in
improving their optical, electrical and magnetic properties as
well as tribiological, corrosion resistance and other protective
• An appropriately adding nanoparticulates to a polymer
matrix can enhance its performance, often in very dramatic
degree, by simply capitalizing on the nature and properties
of the nanoscale filler.
• These materials are better described by the term
nanofilled polymer composites.
• This strategy is particularly effective in yielding high
performance composites, when good dispersion of the filler
is achieved and the properties of the nanoscale filler are
substantially different or better than those of the matrix,
for example, reinforcing a polymer matrix by much stiffer
nanoparticles of ceramics, clays, or carbon nanotubes.
• Polymer – silicate nanocomposites are hybrid organic
inorganic materials, in which mixing of the filler phase is
achieved at the nanometer level, so that at least one
dimension of the filler phase is less than 100 nm.
• The fillers generally used for such composites are
layered aluminosilicates, and most commonly
montmorillonites ( MMT s) from the family of
Elastomeric Nanocomposites are further divided into
• Clay-polymer (nano-)composites
• Dendrimer Nanocomposites
• The Clay minerals are aluminosilicates with a 2:1-layer
structure i.e. a central alumina octahedral sheet is
sandwiched between two silica tetrahedral sheets.
• Examples are : muscovite, phlogopite, smectites.
• The aluminosilicate layers are held together by cations
(usually alkali or earth alkali metals) in the interlayer.
• The thickness of one such layer is approximately 1 nm.
• The surface cations as well as the interlayer cationsin
smectites can be exchanged against organic cations(e.g.
• This offers the possibility to modify the silicate surfaces and
hence tune the filler matrix interaction.
• Dendrimer composite nanoparticles are nanosized organic
inorganic hybrid particles made from dendrimer templates
that contain small clusters of inorganic nanomaterials of
interest entrapped in the network of the macromolecular
• The method of reactive encapsulation involves
preorganization of an appropriate reactant by the active
interior sites of a dendrimer molecule, followed by
immobilization of the product with respect to the host.
• Combination of inorganic guests and dendritic building
blocks into multiple structures such as chains, films and
covalent clusters in solvents and solid matrices afford a
wide repertoire of nanosized building blocks and
architectures for more complex nanocomposite structures.
• Bionanocomposites form a fascinating interdisciplinary area
that brings together biology, materials science, and
• Bionanocomposites add a new dimension to enhance the
properties in that they are biocompatible and/or
• These nanocomposites are of immense interest to
biomedical technologies such as tissue engineering, bone
replacement/repair, dental applications, and controlled
PROPERTIES OF NANOCOMPOSITES
Nanocomposites can dramatically improve properties like:
• Mechanical properties including strength, modulus and
• Electrical conductivity
• Decreased gas, water and hydrocarbon permeability
• Flame retardancy
• Thermal stability
• Chemical resistance
• Surface appearance
• Optical clarity
PROCESS OF SELF-ASSEMBLY
• The process of self-assembly occurs by two mechanisms:-
• First, the organic matrix serves as template on
which to form a specific mineral.
• Second, inorganic materials usually appear in cells at the
protoplasmic surface boundary layer. Therefore, the
arrangement of the biominerals is controlled by the surface
tension between the cells, the vesicles, and the growing
NANOCOMPOSITES BY SELF-ASSEMBLY
• Self-assembling biomolecules act as the
organic matrix templates to direct and
facilitate the formation of different kinds of
structured organic/inorganic composite
• The biomolecules are either natural or
synthetic, including proteins, peptides, DNA,
RNA, and polysaccharides.
ADVANTAGES OF BIOMOLECULES
• Production of materials under mild reaction
conditions(neutral pH, room temperature,etc).
• Control over size, shape, chemistry and crystal structure of
• Materials formed are highly specific and can perform
• The use of these molecules are non toxic and hence are a
green process and environmentally benign.
BIOMOLECULES USED FOR SYNTHESIS
Different types of biomolecules used in bio-inspired synthesis
can be broadly categorized into four categories:
• Nucleic acids
PROTEIN MEDIATED SYNTHESIS
• Proteins provide functional building blocks for the
development of multi-functional materials . The self-
assembly property of proteins would allow controlled
organization of the organic/inorganic interface based on
molecular recognition, resulting in hierarchical organization
with desirable properties at multiple length scales.
• Proteins have superior specificity for target binding with
complex molecular recognition mechanism . Through their
unique and specific interactions with other
macromolecules and inorganics, they process the ability to
control structures and functions of biological hard and soft
tissues in organisms
Protein mediated hydroxyapatite
• Collagen and some proteins are used in Hap formation.
Collagen consists of bone which have 70% minerals (Ca,P)
and 30% organics (glycoproteins,collagens). Calcium
phosphates, notably HAp [Ca10(PO4)6(OH)2 ], are found in
hierarchical structures of bones. Mineralized collagen fibrils
are the basic building block for bone formation.
• Collagens serve as extracellular matrix molecules for many
other soft and hard tissues, such as cartilage, tendons, and
HAp FORMATION CONTINUED....
• A nanocomposite of collagen and HAp was prepared in a
continuous flow system, mimicking the situation in vivo, and
resulted in a direct nucleation of HAp on the self-assembled
collagen matrix. The biomineralization process of collagen and
the self-organization mechanism were also analyzed. The
inorganic crystals formed along the collagen fiber have similar a
Ca-P ratio, crystalline degree, and carbonation extent to that
observed in bone. When Osteonectin was added into the
collagen solution, results indicated that spindle-like nano-HAp
could be deposited on collagen I/osteonectin and pure
osteonectin (control) groups, but not on collagen II/osteonectin
. This helps in understanding the biomineralization process in
HAp FORMATION CONTINUED....
• Collagen templated HAp nanocomposite showed equal or better
biocompatibility than HAp ceramics, which was known to have
excellent biocompatibility. HAp/collagen composite can be potentially
used as an artificial bone material in medical and dental fields.
• Proteins other than collagen are also used in bioinspired HAp
synthesis. A novel human hair proteins and HAp composite was
synthesized for using as a biomineral-scaffolding material. The human
hair protein was soaked to a CaCl2 solution for fabrication into flat
films. The flat films mainly consisted of α-keratin, which could bind 3
Ca2+ ions per 1 keratin molecule. The composite of the human hair
protein and calcium phosphate was prepared via alternate soaking
processes using CaCl2 and Na2 HPO4 solutions. The diameters of
deposited calcium phosphate particles were about 2–4 μm. The human
hair proteins were not soluble and degraded during the soaking
processes. Synthetic proteins have also been developed as templates
for bioinspired synthesis.
PROTEIN MEDIATED MAGNETIC
• Nano sized magnetic particles similar to those in
magnetotactic bacteria were prepared in vitro by chemical
synthesis of magnetite in the presence of the protein
• Recombinant Mms6 facilitated the formation of magnetite
nanocrystals with uniform size (about 30 nm) in aqueous
solution, which was verified by using TEM analysis and
magnetization measurements. A polymeric gel was used to
mimic the conditions at which magnetite nanocrystals were
formed in magnetotactic bacteria and slow down the
diffusion rates of the reagents. The nanocrystals formed in
the presence of other proteins, did not exhibit the uniform
sizes and shapes.
PROTEIN MEDIATED MAGNETIC
MATERIALS FORMATION CONTD....
•Some inorganic magnetic materials which do
not appear in living organisms, for example,
cobalt ferrite (CoFe2O4) nanoparticles, were
also synthesized in vitro by using Mms6 protein
as a template. The recombinant full-length
Mms6 protein or a synthetic C-terminal domain
of Mms6 protein was covalently attached to
self-assembling polymers (Pluronic F127) in
order to template hierarchical growth of
CoFe2O4 nanostructures, as shown in Fig.3.
This new synthesis route enabled facile room-
temperature shape-specific synthesis of
complex magnetic crystalline nanomaterials
with particle sizes of 40–100 nm, which were
difficult to produce using conventional
PROTEIN MEDIATED SILICA
• Silica proteins, were found to be enzymes (structural and
catalytic proteins) that promote biosilica formation in nature .
The silicateins exhibit catalytic activity at neutral pH and low
temperature and are used as templates to direct the growth
of silica particles along the axial protein filament.
• Silicatein filaments also demonstrated the ability to form
titanium dioxide, gallium oxohydroxide (GaOOH) and gamma-
gallium oxide (gamma-Ga2O3) in vitro, which are three
inorganic semiconductors that biological species have never
naturally produced . An enzymatic biocatalyst from the
marine sponge Tethya aurantia, was used to catalyze and
template the hydrolysis and condensation of the molecular
precursor BaTiF6 at low temperature to form nanocrystalline
PROTEIN MEDIATED SILICA
Amorphous silica (or silica glass) is widely used in
different applications, such as
membranes, columns, heat-proof materials,
optical communication fibers, and catalysts in
organic synthesis . Silicatein from the freshwater
sponge Cauxi catalyzed the polymerization of this
type of silica in vitro. Briefly, the sponge shot the
axial protein filament in the desired growth
direction, and then silicatein polymerized a thin
silica layer around the filament. However, this
silica deposition inhibited the transport of the
siliceous acid to the axial filament, and a new set
of silicatein were shot onto the newly synthesized
silica deposition. This shooting process continued
until the final diameter of spicules was reached.
The process is shown by Fig.5.
PEPTIDE MEDIATED BIOINSPIRED
• Peptides consist of short amino acid sequences that have
less intricate functionality than proteins. Although peptides
may not perform highly specialized functions compared to
proteins, they can be synthesized more easily with desired
amino acid sequences by well established chemical and
genetic engineering techniques.
• Therefore, they are widely used in the applications ranging
from controlled gene and drug release, nanofabrication,
biomineralization, and membrane protein stabilization to
three-dimensional (3D) cell culture and tissue engineering.
Peptides are designed to be folded in desired
PEPTIDE MEDIATED BIOINSPIRED
• A 12-residue peptide (NPYHPTIPQSVH-GGGK-biotin: CLP12 peptide) has been
identified for HAp biomineralization using phage display. The sequence
responsible for the mineralizing activity resembled the tripeptide repeat (Gly-
Pro-Hyp) of type I collagen. This peptide was capable of binding to single
crystal HAp and templating the nucleation and growth of crystalline HAp
mineral in a sequence- and composition-dependent manner. In another study,
polylysine and polyleucine based block copolypeptides (K170L30) were found
to form gels at very low concentrations in aqueous media. The block
copolypeptides have been used as templates for forming self-assembled
calcium phosphate nanocomposites. The synthesis method allowed for
simultaneous formation of the selfassembled block copolypeptide gel and of
the inorganic phase. The inorganic contents accounted for over 50 wt% in the
nanocomposite, approaching the inorganic content in bone . Thermoreversibly
gelling block copolymers (Pluronic F127) conjugated to hydroxyapatite-
nucleating peptides (DSKSDSSKSESDSS) were used to template the growth of
inorganic calcium phosphate in aqueous solutions. The inorganic phase in the
organic/inorganic nanocomposite was confirmed to be HAp. This work offered
a route for the development of novel, self-assembling, injectable
nanocomposite biomaterials for potential orthopedic applications .
• A slow but increasing interest has been developing to explore
the role of polysaccharides in biomineralization, despite the
fact that they have been prevalent since the early stages of
evolution. Single types of polysaccharides are typically not
associated with biominerals. Only hydroxylated, carboxylated,
or sulfated polysaccharides, or those containing a mixture of
these functional moieties, are found in biominerals . Chitin is
the second most abundant natural polymer after cellulose on
earth. It is a linear polysaccharide of β-(1-4)-2-acetamido-2-
deoxy-d-glucose. The chemical structure of chitin is very
similar to that of cellulose, with a hydroxyl group replaced by
an acetamido group. Pure chitin with 100% acetylation does
not exist in nature. Chitin tends to form a co-polymer with its
N-deacetylated derivative, chitosan. Chitosan is a polymer of
BIOINSPIRED SYNTHESIS CNTD...
• Chitosan composite materials have attracted much
research interest in bone tissue engineering due to their
minimal foreign body reactions, intrinsic antibacterial
nature, biocompatibility, biodegradability, and ability to be
molded into various geometries and forms.
• Chitosan was also used as organic template to form HAp
nanocrystals. Spindle shaped HAp with 30- 40 nm length
and 7- 8 nm width was synthesized through the biomimetic
method with chitosan as template. The spindle shaped
nano HAp grew in a 0.5wt% chitosan solution for 7 days.
The crystallinity of samples increased with the aging time.
The HAp powders synthesized with chitosan as templates
had good thermal stability up to 800 °C
• Electro catalyst in batteries for energy
• Light weight materials for less fuel
• In artificial joints, economically
beneficial carbon nanotubes most
widely speaking nanomaterial which
can be made as nanocomposite fibers.
• Abrasion and wear Applications
• Marine Application
• Food packaging
• Fuel tanks
• Environmental protection
• Flame ability reaction
• Erosion and corrosion Applications
• Nanocomposites are upcoming
materials which shows great changes
in all the industrial fields and it is also
going to be an economical barrier for
developing countries as a tool of