Polymers: Introduction, definition, clasiification, properties and application Presentation.pptx
- 1. Presented By: Komal R. Chimkar M.Pharm First Year Department of Pharmaceutics Dr. Rajendra Gode College of Pharmacy, Malkapur Polymers: Introduction, Definition, Classification, Properties and Application
- 2. Content Introduction Definition Advantages Classification Properties Applications
- 3. Introduction The word poly means ‘many’ and meros means ‘units’ in Greek. Polymers are compounds with high molecular masses form by monomers, also referred to as macromolecules. Definition: Polymers are the macromolecules containing long chain buildup by the presence of monomeric units. Polymerization: The process of multiple arrangement of polymers is called polymerizations. The arrangement of monomers decides the type of polymers; i) Linear ii) Branched iii) Cross-linked iv) Network
- 4. Continue… Linear and branched polymers are also called Thermoplastic polymer and Cross-linked polymers are thermosetting polymers. All the polymeric chains are interconnected by cross linked covalent bonds and did not flow in presence of heat. Because of their unique properties, polymers are used in pharmaceuticals. Pharmaceutically these polymers are used as a binders in tablets, flow controlling agents in liquids, suspensions and emulsions, as film coating agents to mask unpleasant taste of drug, protective and stabilizing agent.
- 5. Advantages of polymers Polymers increase the stability of drug, minimize drug degradation and loss. Polymers are used to modify the exposure of drugs to the body by controlling dissolution, reducing plasma concentration, etc. Used as coating material and by this it can mask the taste and odour of drug. In the preparation of nanoparticles for targeted drug delivery of the drug. In the formulation of transdermal drug delivery system to control the release of the drug from dosage form. Act as permeation enhancer. Eg.Chitosan Improve patient compliance and drug utilization.
- 6. Polymer Classification The polymers are classified into various types based on different categories. They are: Classification of polymers Based on mode of polymerizat ion: -Addition -Condensation
- 7. Continue… Examples of polymers based on origin: a) Natural polymers: Chitosan, alginate, pectin, collagen, gelatin, gelatin. b) Synthetic polymers: Polyethylene, polyanhydrides, , polylactic acid, polyglycolic acid, aliphatic poly (ester)s, etc. c) Semi-synthetic polymers: Hydroxyl propyl cellulose, methyl cellulose, hydroxyl propyl methyl cellulose, sodium CMC, etc. Examples of polymers based on degradation: a) Biodegradable polymers: starch, cellulose, polylactide (PLA). b) Non-biodegradable polymers: Polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), etc.
- 8. Properties of polymer Chemical properties Physical properties Mechanical properties Molecular weight Crystalline and Amorphous form Glass transition temperature Viscoelastic properties Chemical properties: • The polymer is enable with hydrogen bonding and ionic bonding, results is better cross-linking strength. • Dipole-dipole bonding side chains enable the polymer for high flexibility. • Polymers with Van der Waals forces linking chains are known to be weak, but gives the polymer a low melting point.
- 9. Continue… • Structure of polymer identifies the pathway by which degradation will take place. Physical properties: • Polymers do not melt; they change state from crystalline to semi-crystalline. • Polymers can exist either in crystalline or in amorphous forms. • As chain length and cross-linking increases, the tensile strength of the polymer increases. • Water permeability and water solubility of polymer determines the rate with which hydrolysis proceed. Mechanical properties: • Depending on their structure, molecular weight and intermolecular forces, polymers resist differently when they are stressed. • They can resist against stretching (tensile strength), compression, bending, sudden strength (impact strength), and dynamic loading (fatigue).
- 10. Continue… Molecular weight: • The molecular weight of polymers are much larger than the small molecules usually encountered in pharmacy. • The molecular weight of polymer describe as average molecular weight. • The molecular wt. of polymers is important to describe the relation with other properties. • Very low mol.wt. has essentially no useful mechanical properties. • The increase in mol.wt. increases intrest in mechanical properties; increase in polystyrene mol.wt. shows increase in tensile strength.
- 11. Crystalline and amorphous form: • Presence of crystallinity has significant effect on polymer properties. • Crystallinity increases stiffness and toughen the polymer. • Amorphous structure is formed due to either rapid cooling of a polymer melt or due to lack of structural regularity in the polymer structure. Glass transition temperature: • At low enough temperature all amorphous polymers exist in Glassy state. • In glassy state, polymers are characterize for hardness, stiffness and brittleness. • As temperature is increased, polymer undergo transition known as glass transition temperature (Tg) or second order transition. • Transition is from glass to rubber elastomer or flexible plastic.
- 12. Viscoelastic properties: • Polymers are neither a pure elastic nor a pure fluid material. • They have the ability to store energy (elastic behavior) and to dissipate it (viscous behavior). • For this reason most of the polymers are viscoelastic material. • Examples: poly vinyl chloride has a glass transition temperature of about 100°C. This means, it behaves like solid at temp below its Tg and like a fluid at temp above its Tg.
- 13. Applications of polymers Diffusion controlled devices. Dissolution controlled devices. Osmotically controlled devices. Resin controlled devices. Chemically controlled devices. Chemically control system: • Polymers act as a carrier for the transport of drug. • The polymer-drug conjugate direct the complex towards targeted organ/tissue. • Another system consists of biodegradable or bio-degradable system. Drug release is based on erosion or degradation of polymer.
- 14. Solvent activation system: • It is controlled by swelling or osmosis. • Hydrophilic polymeric chains are able to absorb large amount of water without dissolving. • The water uptake allows the drug inside the system to diffuse outward. Osmotically controlled system: • This device contains semipermeable membrane. • As the solvent permeated inside the membrane, it interacts with osmotic agents. • This generate the pressure inside the system and drug comes out from orifice.
- 15. Magnetically controlled system • Magnetic nanoparticles combined with the polymeric components. • Due to magnetic properties and externally applied magnet, magnetic nanoparticles moves inside the body. • Specific force combine with hemodynamic force of bloodstream results in final motion force. • Materials with high magnetization at room temperature are used for delivery. • Examples: Iron, cobalt, nickel.
- 16. References S.P. Vyas and Roop K. Khar, Controlled Drug Delivery- concept and advantages, Vallabh Prakashan. Novel Drug Delivery System- Dr.K.Jesindha Beyatricks and Mrs. Ashwini Joshi by Nirali prakashan. N.K. Jain, Controlled and novel drug delivery, CBS Publisher and Distributors