polymer science ppt


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CONTENT: Introduction Types of Polymer Classification Polymerization Molecular weight determination Thermal characterization Pharmaceutical Applications Bio degradable polymers Application of biodegradable polymers References. 2


INTRODUCTION Definition : A polymer is a large molecule (macromolecule) composed of repeating structural unit connected by covalent chemical bonds. - The word is derived from the Greek words (poly), meaning "many"; and (meros), meaning "part" Example:- Butadiene, poly-vinyl-chloride etc. - They are complex and giant molecules and are different from low molecular weight compounds. -`Macro-molecules’ are made up of much smaller molecules. 3

Types Of Linking In Polymers : 

Types Of Linking In Polymers Linear Polymers: A polymer in which the molecules form long chains without branches or cross-linked structures. examples: nylon, polyester, PVC etc. 4

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Branched Polymer: A polymer chain having branch points that connect three or more chain segments. Examples: polythene, glycogen, starch etc 5

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Cross linked Polymer: Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. Examples: malamine formaldehyde resin etc Linear & Branched Polymers are know as thermoplastic materials. Cross linked Polymer are know as thermosetting materials. 6

Classification of Polymers (According to their properties & characteristics.) : 

Classification of Polymers (According to their properties & characteristics.) 1) Natural and Synthetic Polymers. 2)Organic and Inorganic Polymers. 3)Thermoplastic and Thermosetting Polymers. 4)Plastics, Elastomers, Fibers, and Liquid Resins 7

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Natural and Synthetic Polymers: Natural Polymers Synthetic Polymer -Cotton -Polyethylene -silk -PVC -wool -Nylon -rubber 8

2) Organic and Inorganic Polymers: : 

2) Organic and Inorganic Polymers: A Polymer whose backbone chain is essentially made of carbon atoms is termed an Organic polymer. Examples- cellulose, proteins, polyethylene, nylons. A Polymer which does not have carbon atom in their backbone chain is termed as Inorganic polymer. Examples- Glass and silicone rubber 9

3) Thermoplastic and Thermosetting Polymer: : 

3) Thermoplastic and Thermosetting Polymer: Some polymer are soften on heating and can be converted into any shape that they can retain on cooling. Such polymer that soften on heating and stiffen on cooling are termed as `thermoplastic’ polymers. Ex. Polyethylene, PVC, nylon, sealing wax. Polymer that become an infusible and insoluble mass on heating are called ‘thermosetting’ polymers. 10

4)Plastic, Elastomers, Fibers and Liquid Resins: : 

4)Plastic, Elastomers, Fibers and Liquid Resins: A polymer is shaped into hard and tough utility articles by application of heat and pressure, it is used as ‘plastic’ e.g. PVC When vulcanized into rubbery products exhibiting good strength and elongation, polymers are used as ‘Elastomers’ e.g. Natural rubber 11

polymerization : 

polymerization Polymerization is a process of bonding monomer, or “single units” together through a variety of reaction mechanisms to form longer chains named Polymer As important as polymers are, they exist with monomers, which are small, single molecules such as hydrocarbons and amino acids These monomers bond together to form polymers. The process by which these monomers bond is called polymerization 12

Types of polymerization : 

Types of polymerization Addition polymerization Condensation polymerization 13

Addition polymerization : 

Addition polymerization A carbon – carbon double bond is needed in the monomer A monomer is the small molecule that makes up the polymer. 14

Addition polymerisation : 

Addition polymerisation The polymer is the only product. Involves the opening out of a double bond. The conditions of the reaction can alter the properties of the polymer. Reaction proceeds by a free radical mechanism. Conditions are high pressure and an oxygen initiator. Oxygen often used to provide the initial free radical. 15

Condensation Polymerisation : 

Condensation Polymerisation Involves 2 monomers that have different functional groups. They also involve the elimination of water or another small molecule. Hence the term condensation polymer. Monomer A + Monomer B  Polymer + small molecule (normally water). Common condensation polymers include polyesters (the ester linkage) and polyamides (the amide linkage as in proteins). 16

Condensation Polymeization : 

Condensation Polymeization The example here is terylene, a polymer of benzene-1,4-dicarboxylic acid and ethane-1,2-diol. hhhhhhhhhhhhhhhhhhh+ nH2O 17

Molecular weight determination : 

Molecular weight determination There are two ways to calculate the average molecular weight: 1. Number Average Molecular Weight 2. Weight Average Molecular Weight 18

Molecular weight determination : 

Molecular weight determination 1. Number Average Molecular Weight Molecular weight is determined by calculating the total molecular weight of monomer and total number of monomer. Mi- total molecular weight of monomer. Ni- number of monomer molecules. Mn- number average molecular weight. 19

Molecular weight determination : 

Molecular weight determination 2. Weight Average Molecular Weight M - weight average molecular weight. Mi- total molecular weight of monomer. Ni- number of monomer molecules. 20

Thermal characterization : 

Thermal characterization Thermal analysis of the polymers is the important phenomenon to study the stability and degradation of polymers. Method :- a) TGA b) DSC c) Thermo mechanical analysis 21


THERMOGRAVIMETRICAL ANALYSIS(TGA) This method provides indication for thermal stability and upper limit of thermal degradation where loss of sample begins. This method only measures loss of volatile content from the polymer. This method has limitation that it can not detect temperature at chain cleavage of chain takes place. 22

Differential Scanning Calorimetry (DSC) : 

Differential Scanning Calorimetry (DSC) parameters measured- Glass transition temperature (Tg) Crystalline melting point Heat of fusion Heat of crystallization It requires placing of Reference and test sample for the continuous monitoring in the heating chamber. 23

Differential Scanning Calorimetry (DSC) : 

Differential Scanning Calorimetry (DSC) 24 24 24

Thermo Mechanical Analysis(TMA) : 

Thermo Mechanical Analysis(TMA) This method is used for determination of deformation of polymer sample as a function of temperature placed on platform in contact with probe. It measures transition from glassy to a rubbery polymer and gives idea about softening temperature. 25

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APPLICATIONS IN PHARMACEUTICALS INDUSTRY Mainly used for drug delivery. As a coating material examples: Hydroxyl propyl methyl cellulose(HPMC), Methyl cellulose, Propylene glycol. As a binders in tabletting granulation examples: Acacia, Gelatin, Sodium alginate. As a disintegrants examples: starch,HPMC 27


APPLICATIONS As a thickening agent in suspension and ophthalmic preparations Example: methyl cellulose. To form bases in ointments. In hard and soft capsule gelatin is used. Gelatin also used as suppository base, as an emulsifying agent and suspending agent. 28


APPLICATIONS For microencapsulation polymers are used. Examples: Ethyl cellulose, Gelatin, Acacia, Polyvinylpyrrolidone etc. Biodegradable polymers are used nowadays in drug delivery. Examples: polyesters, proteins, carbohydrates. In packaging material polymers are widely used Examples: polyethylene, polyvinyl chloride, polyolefin etc. 29


BIO DEGRADABLE POLYMER Material progressively releasing dissolved or dispersed drug, with ability of functioning for a temporary period and subsequently degrade in the biological fluids under a controlled mechanism, in to product easily eliminated in body metabolism pathway. 30


BIO DEGRADABLE POLYMER Biodegradable polymers can be classified in two: Natural biodegradable polymer examples: xanthum gum, gaur gum, chitosan, chtin etc. Synthetic biodegradable polymer examples: Polyanhydrides, Poly(ß-Hydroxybutyric Acidc) etc. Synthetic biodegradable polymer are preferred more than the natural biodegradable polymer because they are free of immunogenicity & their physicochemical properties are more predictable &reproducible 31


ADVANTAGES OF BIODEGRADABLE POLYMERS IN DRUG DELEVERY Localized delivery of drug Sustained delivery of drug Stabilization of drug Decrease in dosing frequency Reduce side effects Improved patient compliance Controllable degradation rate 32


APPLICATIONS Wound management Sutures Orthopedic devices Rods Screws Staples Ligaments Pins Tissue engineering Dental applications Guided tissue regeneration Membrane Void filler following tooth extraction 33


REFERENCES Govariker V. R., Viswanathan N. V., Sreedhar J., “Polymer Science”, New age publications, 263 . Jain N.K., Controlled and novel drug delivery, CBS Publisher,New delhi, 27-49. Martin A., Swarbrick J., Commarata A., Physical pharmacy, K.M.varghese company, Bombay, 592-636. Biodegradable Polymer as drug delivery system; “Synthetic polysaccharides”; edited by-Mark Chasin, Robert Langer Vol- 45; Page No-43-49,71-90,121-160. http://en..wikipedia.org/wiki/Polymers. 34


REFERENCES Sinko P.J.,Physical pharmacy and pharmaceutical sciences, fifth edition, lippincot williams & wikins co., 585-627. 35

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