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Introduction: Dendrimers are a new class of
three-dimensional, man-made molecules produced by an
unusual synthetic route which incorporates repetitive
branching of molecules sequences to create a unique
novel architecture. “Dendrimers are perfect
mono-disperse macromolecules with regular and highly
branched 3-D architecture”. Dendrimers have often been
referred to as the “Polymers of the 21st century”. As
they are characterized by “branch upon branch”
architecture, they represent a novel class of polymers,
drastically different from that of traditional type
polymers.
Dendrimers were first described by Vogtle et al in 1978
as cascade molecule. The word derived from the ancient
word dendron meaning tree and from Greek suffix “mer”
meaning segment. Dendrimers therefore, are highly
branched like trees, with all the segments coming from a
central core. They are perfect mono disperse
macromolecules (polymers) with a regular and highly
branched 3 D architecture. Dendrimers have also been
known asarborals, cauliflowers and starburst polymers
and because of their nano size (1-100nm) and
mono-dispersity, as nanoscopic compound. Exceptional
features of the dendritic architecture include a high
degree of structural symmetry, a density gradient
displaying an intra-molecular minimum value and a well
defined number of terminal groups which may be
chemically different from the interior. The combination
of these features creates an environment within the
dendrimer molecule facilitates an avenue to developing
reliable and economical fabrication and manufacturing of
functional nanoscale materials that would have unique
properties (electronic, optical, opto-electronic,
magnetic, chemical, or biological) that could be the
basis of new nanoscale technology and devices.
Classification
Various classes of dendrimers reported in literature are
arbitrarily based upon their chemical structure and
physical characteristics as under.
Simple Dendrimers: They have simple monomer unit's e.g.
Poly (amidoamine) Dendrimers poly (propylene mine)
dendrimers, polyamino-phosphine dendrimers
a. Poly (amido) amino (PANAM) Dendrimers: These are
compound of poly (amidoamine) segments. E.g. star burst
Dendrimers.
b. Polypropyleneimine (POPAN) Dendrimers: These are
known as dendritic boxes.
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