Polymeric Reaction - Polymerization and their Type
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Polymeric Reaction : Definition and their various types, Polymerization, Biochemistry - biomolecules reaction
![Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 5
IV. Classification based upon polymerization
1. Addition Polymerization
(a) Addition polymers are those in which addition reaction takes place
(b) If monomer is ethylene, then addition polymer may be either linear polymer of branched
chain polymer.
Examples are Polystyrene, Polytetrafluoroethylene, Polyacrylonitrile etc.
(c) If monomer is 1,3–butadiene or 2–substituted-1, 3–butadiene [CH2=CG-CH=CH2], then
polymer is always branched chain polymer.
(d) Addition polymers are also known as chain growth polymers.
MONOMER POLYMER
(a) G = H : 1,3-Butadiene (i) Polybutadiene
(b) G-CH3 : 2-Methyl-1, 3-butadiene or
isoprene
(ii) Polyisoprene (Neoprene)
(c) G=Cl; 2-Chloro-1, 3-butadiene or
chloroprene
(iii) Polychloroprene](https://image.slidesharecdn.com/1-250810083810-85f23e6e/85/Polymeric-Reaction-Polymerization-and-their-Type-5-320.jpg)
Polymeric Reaction - Polymerization and their Type
- 1. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 1 POLYMERIC REACTION POLYMER Poly = many ; Mer = unit -> polymer Polymers can be found in almost every environment. From our DNA strand, this is a naturally occurring biopolymer, to polypropylene, which is utilized as a plastic all over the world. Polymers can be found naturally in plants and animals (natural polymers) or they can be created artificially (synthetic polymers). Polymers contain a variety of physical and chemical qualities that allow them to be used in everyday life. On the basis of their molecular weight, polymers are divided into two parts: Micromolecules: Low molecular weight molecules (<1000kDa) is called Micromolecules. E.g., Amino acids, Vitamins, Minerals, Monosaccharide, Disaccharides, Nitrogenous bases, Fats, Sulphate and Phosphate etc. Macromolecules: High molecular weight molecules (>1000kDa) is called Macromolecules. E.g., Polysaccharides, Proteins, Nucleic acid, Hemoglobin, Chlorophyll etc. Monomer Monomer is the molecule that forms the basic unit for Polymer. E.g., Propene, Styrene, Vinyl chloride etc. Polymer A polymer is defined as a high molecular weight compound formed by combination of large number of one or more type of small molecules of low molecular weight molecules. This process of forming polymer from monomer is called Polymerization. Natural, semisynthetic and synthetic compounds consisting of number of molecules (monomers) called Polymer. E.g., Polypropene, Polystyrene, PVC, Nylon-6 etc.
- 2. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 2 Degree of Polymerization The number of monomers which are joined together in a polymer constitutes the degree of polymerization. The number of repeating units in a polymer is known as Degree of Polymerization. • If n =Low, Mol.Wt = 500 – 5000 Dalton units, it is Oligo polymer. • If n = High, Mol.Wt = 10,000 – 2,00,000 Dalton units, it is High polymer. Monomer-Based Classification Homopolymer: There is only one sort of monomer unit in this category. Heteropolymer or co-polymer: It is made up of a variety of monomer units. Polymers in which repeating units are derived from two or more types of monomers units are called Copolymers. E.g. Nylon-6,6; Buna-S; Buna-N; Polyesters. I. Classification Based upon Source (1) Natural polymers They are found in both plants and animals and exist naturally. To round things off, there are biopolymers, which are biodegradable polymers. E.g. Starch, Cellulose, Natural rubber, Silk, Proteins, Nucleic acid. etc.
- 3. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 3 (2) Semisynthetic polymers They are made from naturally existing polymers that have been chemically modified. Most of the semisynthetic polymers are prepared from cellulose. E.g. Cellulose acetate, Cellulose nitrate, Cellulose xanthate and Rayon. (3) Synthetic polymers The polymer are synthesized in the laboratory are known as synthetic polymers. Man-made polymers are known as synthetic polymer. It’s used in a variety of industries and dairy products. E.g. PVC, Polyethylene, Polystyrene, Nylon-6, Nylon-6,6; Nylon-6,10; Terylene, Synthetic rubbers etc. II. Classification Based upon Structure 1. Linear polymers Monomers are joined together to form long straight chains. The various linear polymeric chains are stacked over one another to give a well packed structure close packed in nature, having high densities, high melting point and high tensile (pulling) strength. Linear polymers may be condensation as well as addition polymers. Examples are cellulose, polypeptide, nucleic acid, nylon, terylene etc. Note: All fibers are linear polymers. Eg. cellulose, silk, nylon, terylene etc. 2. Branched chain polymers Polymers in which the monomeric units constitute a branched chain. Branched chain polymers have lower melting point low densities and tensile strength as compared to linear polymers. Examples are amylopectin, glycogen, low density polyethylene and all vulcanized rubbers. 3. Cross linked or Three-Dimensional network polymers
- 4. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 4 When linear polymeric chains are joined together to form a three dimensional network structure. These polymers are hard, rigid and brittle. Cross linked polymers are always condensation polymers. Resins are cross linked polymers. E.g., Bakelite, Peptidoglycan layer, etc. III. Classification Based upon Molecular Force 1. Elastomers Polymers in which the intermolecular forces of attraction between the polymers chains are the weakest (weak vander Waals forces of attraction) these polymers consist of randomly coiled molecular chains of irregular shape having a few cross links. E.g., Natural rubber, Buna-S, Buna-N etc. 2. Fibers Those polymers in which the intermolecular forces of attraction are the strongest are called fibers. These polymers held together by H-bonding or dipole-dipole interaction. Fibers have high tensile strength, least elasticity having high melting point and low solubility. 3. Thermoplastics In thermoplastics intermolecular forces of attraction are in between those of elastomers and fibers. Thermoplastics become soft and viscous on heating and rigid on cooling. E.g., Polythene, Nylon-6, Nylon-6,6 etc. 4. Thermosetting polymers These polymers have low molecular masses and are semi-fluid substances. These polymers are hard and infusible. E.g., Melamine-formaldehyde, Bakelite (phenol-formaldehyde) etc.
- 5. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 5 IV. Classification based upon polymerization 1. Addition Polymerization (a) Addition polymers are those in which addition reaction takes place (b) If monomer is ethylene, then addition polymer may be either linear polymer of branched chain polymer. Examples are Polystyrene, Polytetrafluoroethylene, Polyacrylonitrile etc. (c) If monomer is 1,3–butadiene or 2–substituted-1, 3–butadiene [CH2=CG-CH=CH2], then polymer is always branched chain polymer. (d) Addition polymers are also known as chain growth polymers. MONOMER POLYMER (a) G = H : 1,3-Butadiene (i) Polybutadiene (b) G-CH3 : 2-Methyl-1, 3-butadiene or isoprene (ii) Polyisoprene (Neoprene) (c) G=Cl; 2-Chloro-1, 3-butadiene or chloroprene (iii) Polychloroprene
- 6. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 6 2. Condensation Polymerization (a) They are formed due to condensation reactions. (b) Condensation polymerization is also known as step growth polymerization. (c) For condensation polymerization, maybe monomers ought to have at least two functional groups. (Functional groups may be same or different). For example, (d) During condensation elimination of small molecules like ammonia, alcohol, water, HCl takes place. (e) Monomer having three functional groups always gives cross linked polymer. Examples: Urea formaldehyde resin, Phenol-formaldehyde resin.
- 7. Dr. Divya Sharma, Assistant Professor / Biochemistry – Polymeric Reaction Page 7 Conclusion Biomolecules are involved in the metabolic process of living organisms. Biomolecules play an important role in life by preventing various diseases. Ranging from small molecules like hormones to larger molecules like nucleic acids, biomolecules are present. Depending on the characteristics various types of biomolecules are defined such as Carbohydrates, proteins, nucleic acids and lipids.