Transcript Linear Polymer

Monomer is a small molecule
Polymer is a long chain of monomers
The process by which monomers combine is called polymerization
Repeating units are a simplified method of drawing a polymer
Polymers consist of repeating molecular units which usually are joined by covalent bonds
A pendant group on a polymer is a small
group of atoms (even a small chain
sometimes) that hangs off of the main
chain (that is, the backbone of the
polymer).
Here are some examples of pendant groups circled in red:
polypropylene
polyvinylalcohol
polystyrene
Polymers can be classified into several ways:
•
•
Based on Structure of Polymers
i) Linear polymers (ii) Branched chain polymers
(iii) Cross linked polymers
Based on the Origin of the Polymer
i) Natural polymers (ii) Semi-synthetic polymers
(iii) Synthetic polymers
•
Based on Types of Monomers
i) Homopolymer (ii) Copolymer
•
Based on Tacticity (Configuration)
i) Isotactic polymer (ii) Syndiotactic polymer
•
•
Based on Synthesis
i) Addition polymers
(iii) Atactic polymer
(ii) Condensation polymers
Based on Thermal Processing Behaviour
i) Thermoplastic Polymers (ii) Thermosetting Polymer
Linear Polymers:
Appearance of real linear polymer chains as recorded using an
atomic force microscope on surface under liquid medium. Chain
contour length for this polymer is ~204 nm; thickness is ~0.4 nm.
(The contour length of a polymer chain is its length at maximum
physically possible extension).
Linear Polymer:
Branched Polymer:
Linear Polymer:
Cross-linked Polymer:
Star Polymer:
Dendrimers:
Natural Polymers: Polymers in Plants
Cellulose
Cellulose, a linear polymer of D-glucose units (two are shown) linked by
β(1→4)-glycosidic bonds.
Starch
Natural Rubber
Natural rubber is a polymer of isoprene
Charles
GOODYEAR
discovered
vulcanization in
1839
Natural Polymers: Polymers in Animals
Protein
Functions of Proteins
• All enzymes are proteins.
• Structural: e.g. collagen in teehth and bone; keratin in skin, hair
and nails.
• Contractile proteins: actin and myosin in muscles allow contraction
and therefore movement.
• Hormones: many hormones have a protein structure (e.g. insulin,
glucagon, growth hormone).
• Transport: for example, haemoglobin facilitates the transport of
oxygen around the body
• Defence: immunoglobulins (antibodies) protect the body against
foreign invaders; fibrinogen in the blood is vital for the clotting
process.
Chitin
the exoskeletons of crabs,
lobsters and shrimps
(polymer of the N-Acetylglucosamine units)
Semi-synthetic Polymers: Cellulose nitrate and cellulose acetate
obtained from natural polymers by subjecting them to some chemical processes
Cellulose nitrate
Cellulose triacetate
Synthetic Polymers
1950s Black
Bakelite Telephone
Bakelite Sockets & Switches
Bakelite (1909)
Blue Bakelite Handle
Poly(methyl methacrylate) (PMMA) (1935)
PMMA sheet (organic glass)
Plexiglass aquarium
Polystyrene (1937)
Styrofoam - a brand of polystyrene foam
rigid polystyrene case, weight 2.6 Kg
Nylon 6,6 (1938)
A 1949 advertisement in Life
Magazine sings the praises of
nylon products.
Natural animal bristles were replaced by
synthetic fibers, usually nylon, by DuPont
in 1938.
Polyesters (1950)
Recycled PET Fabric
Poly(ethylene terephthalate)-PET bottles
Polycarbonates (1957)
GE Lexan® face shield
Lexan MR-10 windshields