polymer science

Views:
 
Category: Education
     
 

Presentation Description

Polymer, Classification of Polymer, synthesis, Physical Characterization, Thermodynamic of polymer, Applications

Comments

By: usbagul (7 month(s) ago)

Dear, its really nice presentation being made by you. Can you pls send me a copy of the same Thanks

By: deepscpn (6 month(s) ago)

Nice to see your request but quote ur mail ID and other details including institutional and academics

 

By: sweetybuch (9 month(s) ago)

this is very nice presentation could u plz send me copy of that via mail on sweetumodibuch@gmail.com

Presentation Transcript

Polymer Science : 

Polymer Science Dipak Gadade Dept. of Pharmaceutics, Shri Bhagwan College of Pharmacy, Aurangabad 1

Why it is necessary to study polymers? : 

Why it is necessary to study polymers?

Slide 3: 

What is polymer? Poly- Many & Meros- parts Large molecule build from smaller molecules Linear, branched, crosslinked or network Mechanical Strength Small molecules- Monomer Polymer Size of molecule defined by mass or no. of repeat units (degree of polymerization) 3

Classification of PolymersA) Depending on response to heat : 

Classification of PolymersA) Depending on response to heat Themoplastics: linear or slightly branched Solid Melt Solid Resolidification Weak attractive forces hence, can be remoulded Eg. PE, PP, PVC, etc. 4

Classification of PolymersA) Depending on response to heat : 

Classification of PolymersA) Depending on response to heat Themosets: Extensive crosslinking covalently Solid Decomposed solid Chains can not be easily broken Eg. Epoxy resin, polyurathane 5

Classification of PolymersB) Based on chemical Reaction : 

Classification of PolymersB) Based on chemical Reaction Condensation Polymers Reaction monomers occurs with loss of water molecules usually e.g. Polyester formation nHO-R-OH + n HOOC-R’COOH HO[-R-COO-R’COO-]n+(n-1)H2O Addition Polymers Addition of unsaturated monomers e.g. PVC formation nCH2=CH-Cl [-CH2-CHCl-]n 6

Classification of Polymersc) Based on type of repeating unit : 

Classification of Polymersc) Based on type of repeating unit Homopolymer: Same repeating monomer units PE,PS,PVC - [A – A – A – A – A] - Copolymer: Different repeating monomer units Alternating copolymer - [A – B – A – B – A – B – A – B] - Random copolymer - [A – B – A – A – B – A – B– B] - Bolck coplymer - [A – B – B – B – A – B– B – B] - Graft coplymer - [A – B – B – B – A – B– B – B] – A C 7

Classification of Polymersc) Based on origin of polymer : 

Classification of Polymersc) Based on origin of polymer Natural eg. Gelatin, Xanthan gum, sodium alginate, etc. Semisynthetic eg. Methyl cellulose, HPC, HPMC, CAP, etc. Synthetic eg. Carbopol, PVA, PVP, PEG,PEO, etc. 8

Classification of Polymersc) Based on degradation properties : 

Classification of Polymersc) Based on degradation properties Non-biodegradable eg. Ethyl cellulose, PVC Biodegradable a) Bulk eroding polymers eg. PLGA, PLA b) Surface eroding polymers eg. Polyanhydrides 9

Biodegradable Polymer: Erosion : 

Biodegradable Polymer: Erosion

Biodegradable polymers: break down : 

Biodegradable polymers: break down Enzymatic: eg. Degradation of pectin in colon Hydrolysis

Characteristics of ideal polymer : 

Characteristics of ideal polymer Inert and compatible with the environment. Non-toxic. Should be easily administered. Should be easy and inexpensive to fabricate. Good mechanical strength.

Synthesis of polymers : 

Synthesis of polymers Methods of synthesis Addition homopolymerization (Free radical homopolymerization) Free radical copolymerization Step polymerization (Condensation polymerization) Ring opening polymerization 13

Synthesis of polymers1. Addition homopolymerization : 

Synthesis of polymers1. Addition homopolymerization 4 simultaneous reactions occurs Initiation I 2Rc* eg. P-N=N-P 2P-N* Rc* + M R1* eg. R1 = Kpc [Rc*] [M] 14

Slide 15: 

Synthesis of polymers1. Addition homopolymerization b) Propogation R1*+ M  Rr+1* eg. Rate of propogation (polymer formation) 15

Slide 16: 

Synthesis of polymers1. Addition homopolymerization c) Chain Transfer Reaction Rr*+ M Pr +R1* 16 Rate of chain transfer to monomer

Synthesis of polymers1. Addition homopolymerization : 

Synthesis of polymers1. Addition homopolymerization X= S/I/A/P S = solvent I = initiator A = transfer agent P = polymer 17 Rr* + S/I/A/P Pr + S*/I*/A*/P* Rfx = Kfx [Rr*] [X]

Synthesis of polymers1. Addition homopolymerization : 

Synthesis of polymers1. Addition homopolymerization d)Termination (Bimolecular coupling) Combination Disappropriation

Slide 19: 

Synthesis of polymers1. Addition homopolymerization

Synthesis of polymers2. Free radical copolymerization : 

Synthesis of polymers2. Free radical copolymerization Initiation

Synthesis of polymers2. Free radical copolymerization : 

Synthesis of polymers2. Free radical copolymerization Propogation

Synthesis of polymers2. Free radical copolymerization : 

Synthesis of polymers2. Free radical copolymerization Termination

Synthesis of polymers2. Free radical copolymerization : 

Synthesis of polymers2. Free radical copolymerization

Synthesis of polymers3. Step (condensation) polymerization : 

Synthesis of polymers3. Step (condensation) polymerization Two monomer involved in reaction A monomer has 2 functional groups Susceptible to linkage (bio)breakdown General reaction nA-A + nB-B  -[-AABB-]n- eg

Synthesis of polymers3. Step (condensation) polymerization : 

Synthesis of polymers3. Step (condensation) polymerization Acid catalyzed esterfiction

Synthesis of polymers3. Step (condensation) polymerization : 

Synthesis of polymers3. Step (condensation) polymerization

Synthesis of polymers3. Step (condensation) polymerization : 

Synthesis of polymers3. Step (condensation) polymerization Self catalyzed condensation

Synthesis of polymers4. Ring opening polymerization : 

Synthesis of polymers4. Ring opening polymerization

Synthesis of polymers4. Ring opening polymerization : 

Synthesis of polymers4. Ring opening polymerization

Slide 30: 

Physical Properties And Thermodynamics of Polymer

Molecular Weight : 

Molecular Weight Monodisperse- All molecule posses same mol. wt eg. Sucrose, albumin Heterodisperse- Ave. mol. wt. differs with polymer chain length Average Mol. Wt. :

How Mol Wt. & M.W. Distn of polymer expressed? : 

How Mol Wt. & M.W. Distn of polymer expressed? Simple substance and Polymer MW Ave. Mol. Wt. of polymers Mol. Wt distribution

Molecular Weight : 

Molecular Weight General Equation for mol. wt. Where, Wi = weight fraction Mi = Mol. Wt. Ni = No. of moles

Molecular Weight : 

Molecular Weight Number Average mol. wt. Weight Average Mol. Wt.

Molecular Weight : 

Molecular Weight Z-average Mol. Wt. Viscosity Ave. Mol. Wt.

Molecular Weight : 

Molecular Weight Width of mol. wt. distribution Polydispersity index = Mw/Mn If ratio is 1 polymer is monodisperse Commercial polymers 2 <PDI< 20 Highly branched polymers PDI>20 Eg.Molecular Weight calculation.doc

Why to define diff. distributions/averages? : 

Why to define diff. distributions/averages? Number distribution Mn -analysis of polymerization reactions. Many physical properties depend more strongly on Mw than Mn. Light scattering from dilute solution is related to the z average (technique for measuring the size of molecules)

DSC : 

DSC

What is heat capacity? : 

What is heat capacity?

Transition Temperatures : 

Transition Temperatures

What is Glass Transition Temperature? : 

What is Glass Transition Temperature? Rigid (Glass) >>>Leathery>>> Rubbery

What is Polymer Crystallization? : 

What is Polymer Crystallization? Ordered molecular arrangement

What is Polymer Melting? : 

What is Polymer Melting? Solid (ordered) >>> Viscous (Highly Random)

What is Polymer Crystallinity? : 

What is Polymer Crystallinity? Polymers can form crystal structures Around crystallite get amorphous region Faster cooling Linear polymer- more crystalline Copolymers- less crystalline

DSC Thermogram : 

DSC Thermogram

What is tacticity? : 

What is tacticity? Sterioisomeric property of polymers with asymmetric carbon atom due to which they produce optical activity Different configuration produce different physical properties

Tacticity : 

Tacticity Isotactic- dddd/llll Syndiotactic – dldldldl Atactic- dddldllll

Thermodynamics of Polymer solution : 

Thermodynamics of Polymer solution Free energy of Polymer solution is ∆Gm = ∆Hm – T∆Sm ∆Gm= Negative for dissolution ∆Hm(-) or ∆Sm (+)* Secondary valence forces holding chains together in lattice must be overcome Volume fraction (Φ) instead of Mole fraction (X)

Thermodynamics of Polymer solution : 

Thermodynamics of Polymer solution Heat of mixing: Disso. is endothermic In terms of sol. Parameter ∆Hm = V12 (δ1- δ2)2 Φ1 Φ2 where V12 is vol. of mixture Flory- Huggin’s - ∆Hm (+ve) & expessed in van Laar eqn. ∆Hm= χRTn1 Φ2 Where χ- Flory-Huggin’s interaction parameter

Thermodynamics of Polymer solution : 

Thermodynamics of Polymer solution Entropy of mixing: Fig. deriverd form Boltzmann’s relations ∆S = -R (n1 ln Φ1 + n2 ln Φ2) where Φ2 = N n2 / n1 + N n2 n1=Moles of solvent, n2=Moles of polymer, N=DP

Thermodynamics of Polymer solution : 

Thermodynamics of Polymer solution Overall equation for free energy of per mole lattice site/solvent- ∆Gm = -R (n1 ln Φ1 + n2 ln Φ2+χn1 Φ2)

Characterization of Polymer : 

Characterization of Polymer Molecular wt. Determination Vibrational spectroscopy Nuclear Magnetic Spectroscopy Microscopy Thermal Analysis X-Ray diffraction Mechanical & Rheological Analysis

Applications of Polymer : 

Applications of Polymer Tablets : Binders, Glidants, Coating materials, etc. Liquids : Viscosity modifiers, For controlling the flow Semisolids : Gelling agents, waxes, etc.

Applications of Polymer : 

Applications of Polymer Biodegradable polymers PLA, PLGA, Dextran, etc Mucoadhesive polymers Polyacrylates, Chitosans, Polyglucan, etc. Proteins and peptides Gelatin, Albumin, Collagen, etc. In transdermal Patches Rate controlling polymer (EVA), adhesive (Silicone) Hydrogels Eg. Orabase (NaCMC, pectin, gelatin, PMMA,carbopol)

Applications of Polymer : 

Applications of Polymer

Thank you. : 

Thank you. 56