3. An important microstructural feature of a polymer is its
architecture, which relates to the way branch points lead to a
deviation from a simple linear chain.A branched polymer
molecule is composed of a main chain with one or more
substituent side chains or branches. Types of branched
polymers include star polymers, comb polymers, brush
polymers, dendronized polymers, ladders, and dendrimers.
A polymer's architecture affects many of its physical
properties including, but not limited to, solution viscosity,
melt viscosity, solubility in various solvents, glass transition
temperature and the size of individual polymer coils in
solution.
A variety of techniques may be employed for the synthesis
of a polymeric material with a range of architectures, for
example Living polymerization.
4. Brush polymers are a class of polymers that are adhered to a
solid surface.The polymer that is adhered to the solid
substrate must be dense enough so that there is crowding
among the polymers which then, forces the polymers to
stretch away from the surface to avoid overlapping.
6.
Brush polymers can be synthesized using any of the various
polymerization techniques available including: cationic, anionic ,
radical, ring-opening metathesis , photochemical, and
electrochemical polymerization. There have also been recent
advances using controlled radical polymerization (CRP)
techniques such as atom transfer radical polymerization (ATRP)
Brush polymers can be used in applications such as
prevention of flocculation of colloidal particles, new adhesive
materials, protein-resistant biosurfaces, chromatographic
devices, lubricants, polymer surfactants and polymer
compatabilizers.
8. Dendrimers are repetitively branched molecules.The name comes
from the Greek word "δένδρον" (pronounced dendron), which
translates to "tree". Synonymous terms for dendrimer include
arborols and cascade molecules.
9. Dendrimers and dendrons are monodisperse and usually highly
symmetric, spherical compounds. The field of dendritic
molecules can be roughly divided into low-molecular weight
and high-molecular weight species.
The properties of dendrimers are dominated by the functional
groups on the molecular surface as:water soluble, toxicity,
crystallinity, tecto-dendrimer formation, and chirality.
11. Click chemistry:
Dendrimers have been prepared via click chemistry, employing
Diels-Alder reactions,thiol-yne reactions and azide-alkyne
reactions. An example is the synthesis of certain polyphenylene
dendrimers.
13. Dendronized polymers (or dendronised polymers) are linear
polymers to every repeat unit of which dendrons are attached.
Dendrons are regularly branched, tree-like fragments and for
larger ones the polymer backbone is wrapped to give sausagelike, cylindrical molecular objects.
14. The two main approaches into this class of polymers are the
macromonomer route and the attach-to route.
15.
Depending on dendron generation, the polymers differ in
thickness. Neutral and charged dendronized polymers are
highly soluble in organic solvents and in water, respectively.
This is due to their low tendency to entangle.
Dendronized polymers have been investigated for/as bulk
structure control, responsivity to external stimuli, single
molecule chemistry, templates for nanoparticle formation,
catalysis, electro-optical devices, and bio-related
applications.
16.
Star polymers consist of several linear polymer chains
connected at one point.Star molecules prepared by anionic
polymerization had been examined prior to the development
of CRP.
Based on the chemical compositions of the arm species, star
polymers can be classified into two categories: homo-arm (or
regular) star polymers or mikto-arm (or heteroarm) star
copolymers.
