Polymeric materials – Formation of polymer structure
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Polymeric materials are formed through polymerization reactions that link together small molecular units into long chains or networks. There are three main types of polymerization: condensation polymerization, step-growth polymerization, and ring-opening polymerization. Condensation polymerization involves monomers reacting to form larger units while releasing smaller molecules as byproducts. Step-growth polymerization proceeds through the formation of dimers, trimers, and eventually long chains. Ring-opening polymerization breaks cyclic monomers open to add them to the growing polymer chain. Examples provided include the condensation polymerization of polyethylene terephthalate and the ring-opening polymerization of nylon-6 from caprolactam.
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Polymers are high molecular weight compounds formed by linking together smaller molecules called monomers. There are several ways to classify polymers, including by source (natural, semi-synthetic, synthetic), method of polymerization (addition, condensation), and degradability (biodegradable, non-biodegradable). Biodegradable polymers are important for controlled drug delivery systems as they can release drugs through diffusion, swelling, or erosion over time. Common biodegradable polymers used in drug delivery include lactic acid, glycolic acid, polyanhydrides, and polycaprolactone.
The chemistry of_polymers.
This document discusses the chemistry of polymers, including:
- The process of polymerization where monomers react to form long chain molecules. Common types are addition polymerization and condensation polymerization.
- Sources of monomers from petrochemical and other raw materials. Examples of polymers produced from common monomers like ethylene, propylene, formaldehyde.
- Mechanisms of polymerization including free radical, ionic, coordinative, and step-wise condensation polymerization. Factors that control the polymerization process and properties of the resulting polymers.
- Common plastics and fibers produced including polyethylene, polypropylene, nylon, polyester, phenol formaldehyde, and their applications.
Polymer for engineering students
Polymers are large molecules formed by combining many small molecules called monomers. There are two main types of polymerization: addition and condensation. Addition polymers form without releasing any byproducts while condensation polymers form with the release of small molecules like water. Polymers can be classified based on their source, structure, and thermal properties. Common polymerization techniques include bulk, solution, suspension, and emulsion which depend on factors like physical state and reaction mechanism. Bulk polymerization involves only monomer and initiator while solution polymerization dissolves the monomer in a solvent.
Chapter 21.3 : Organic Reactions and Polymers
1. Organic reactions can be substitution, addition, condensation, or elimination reactions. Substitution reactions involve replacing atoms, addition increases saturation, condensation combines molecules removing a small molecule like water, and elimination forms a small molecule from carbon atoms.
2. Polymers are large molecules made of repeating small monomer units joined by organic reactions. Addition polymers form by monomers adding across double bonds, while condensation polymers form by monomers condensing and removing a molecule like water. Common examples are polyethylene, polyester, and vulcanized rubber.
polymer .pptx
Polymer is a large molecule made of repeating structural units called monomers. The process of linking monomers together to form polymers is called polymerization. There are several ways to classify polymers, including by their origin (natural, synthetic, semisynthetic), structure (linear, branched, cross-linked), and mode of polymerization (addition, condensation). Common polymers include polyethylene, nylon, polyester, bakelite, and natural rubber.
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- 1. Polymeric materials – Formation of polymer structure N J Maharajan Engg design dept
- 2. Introduction Polymer is a substance which has a molecular structure built up chiefly or completely from a large number of similar units bonded together. Polymers are classified into • Based on source Natural (Proteins, Enzymes) Synthetic(Plastics, Rubbers) • Based on application Thermosetting plastic(Bakelite, epoxy resin) Thermoplastic (polythene, polyvinyl chloride)
- 3. POLYMER STRUCTURE Most of the polymers are organic (Hydrogen and carbon) Hydrocarbon: • Each carbon atom has four electron that may participate in covalent bonding. • Similarly hydrogen has one electron that participate in covalent bonding Covalent bonding In methane(CH4) Saturated Ethylene Acetylene Unsaturated
- 4. Formation of polymer structures Polymerization Polymerization is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three- dimensional networks.
- 5. Condensation polymerization Small molecules react with each other to form larger structural units while releasing smaller molecules as a byproduct, such as water or methanol. A well-known example of a condensation reaction is the esterification of carboxylic acids with alcohols. + H2O
- 6. Polyethylene terephthalate(condensation polymerization) • Polyethylene terephthalate is produced from ethyleneglycol and dimethalterephthalate(DMT) (C6H4(CO2CH3)2) or terephthalic acid. • The former is a transesterification reaction, whereas the latter is an esterification reaction. The reactions are idealized as follows: First step C6H4(CO2CH3)2 + 2 HOCH2CH2OH → C6H4(CO2CH2CH2OH)2 + 2 CH3OH DMT + ethylene glycol terephthalic acid + methanol Second step n C6H4(CO2CH2CH2OH)2 → [(CO)C6H4(CO2CH2CH2O)]n + n HOCH2CH2OH terephthalic acid PET + ethylene glycol
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- 8. Polyether ether ketone(Step growth polymerization) PEEK polymers are obtained by step growth polymerization by the dialkylation of bisphenolate salts. Typical is the reaction of difluorobenzophenone with the disodium salt of hydroquinone which is generated in situation by deprotonation with sodium carbonate. The reaction is conducted around 300 °C in polar aprotic solvents - such as diphenyl sulphone. Difluorobenzophenone disodium PEEK hydroquinone
- 9. Ring opening polymerization • A ring-opening polymerization (ROP) is form of chain-growth polymerization in which the terminal end group of a polymer chain acts as a reactive center where further cyclic monomers can be added by ring-opening. • Typical cyclic monomers that can be polymerized via ROP are di-functional monomers that carry two different reactive groups like one amine or alcohol and one carboxylic acid that have undergone a cyclization reaction. Amide + Acid
- 10. Nylon-6 (ROP) • When caprolactam is heated at about 533K in an inert atmosphere of nitrogen for about 4-5 hours, the ring breaks and undergoes polymerization. • During polymerization, the amide bond within each caprolactam molecule is broken, with the active groups on each side re-forming two new bonds as the monomer becomes part of the polymer backbone. Caprolactam Nylon-6