Polymers and its applications
- 1. POLYMERS by s. kavya m.pharmacy (pharmaceutics) i-year srmc & ri
- 2. Polymer” word is derived from Greek roots “Poly” meaning many and “Meros” meaning parts. Definition : Polymers are long chain organic molecules assembled from many smaller molecules called as monomers. The term was coined in 1833 by Jons Jacob Brezelius Polymers represent an important constituent of pharmaceutical dosage forms
- 8. Types of polymer Since the structural and physicochemical characteristics of the polymer are decisive in the drug release mechanism, some will be more suitable than others, depending on the aim pursued and the drug desired . Hydrophilic polymers a) Cellulosic · Methylcellulose · Hydroxypropylmethylcellulose (Hypromellose, HPMC) b)Non-cellulosic · Sodium alginate · Xanthan gum · Carrageenan Hydrophobic polymers · Ethylcellulose · Hypromellose acetate succinate · Cellulose acetate
- 9. density molecular weight. degree of polymerization. molar volume. crystallinity of material. Specific gravity. Water absorption. Water vapor permeability. Contact Angle. Rheology. Viscosity. Melt processing characteristics. Melting point. Cloud point. Pour point ( transfer point). Oil absorption of pigments.
- 10. The degree of polymerization (DP)n in a polymer molecule is defined as the number of repeating units in the polymer chain. For example: Note : In the case of polymers we talk about the average values of molecular weights
- 12. The ratio of the weight-average molecular weights to the number-average molecular weights is called polydispersity index (PDI) or heterogeneity index, which measures the polydispersity of the polymer mixture. Note : The dispersity measures heterogeneity of sizes of molecules or particles in the mixture. The mixture is called monodisperse if the molecules have the same size, shape, or mass.
- 13. polymer characteristics uses Methylcellulose (MC) Water soluble, Viscosity range 10-15,000 MPa for 2% aqueous solution Tablet coating and granulation Ethylcellulose (EC) Insoluble in water Soluble in chloroform, THF Microencapsulation Sustained release tablet coating Hydroxypropylcellulose (HPC) Soluble in cold water and polar organic solvents, insoluble in hot water and hydrocarbons Controlled release matrix Hydroxyethylcellulose (HEC) Soluble in hot or cold water Insoluble in organic solvents Ophthalmic formulations Topical formulations Thickener Hydroxypropylmethylcellulose Hygroscopic Soluble in cold water, mixture of water and alcohol, insoluble in ethanol, ether Viscosity increasing agent Stabilising agent Hydroxyethylmethyl cellulose Viscosity = 100-70,000 MPa for 2% aqueous solution Suspending and a thickening agent
- 14. Polymer Characteristics Uses Poly (butyl methacrylate, (2-dimethyl aminoethyl) methylacrylate) Cationic polymer. Soluble in gastric juices and weakly acidic buffer solutions pH~5. Film coatings. Poly(methacrylic acid, methacrylate) Anionic copolymers. Soluble in neutral to weakly alkaline solutions (pH~6-7) and form salts with alkali. Soluble in intestinal pH. Enteric coatings; resistant to gastric juices. Poly(ethyl acrylate, methylmethacrylate, trimethylaminoethyl methacrylate chloride) Water insoluble copolymer. Water insoluble, used as film coats for sustained release
- 15. Polymer Properties Poly(D-Lactide) (D-PLA) Semi-crystalline Poly(L-Lactide) (L-PLA) Semi-crystalline ; Soluble in MeCl2, CHCl3 Poly(DL-Lactide) (DL-PLA) Amorphous ; Soluble in MeCl2, THF, EtOAc, CHCl3 Poly(ε-caprolactone) (PCL) Semi-crystalline; Soluble in MeCl2, C3H6O, CHCl3 Polyglycolide (PGA) Semi-crystalline ; Soluble in hexafluoro- isopropanol
- 16. Chemical Properties Uses Cationic polyamine Drug delivery (cationic nature allows the formation of complexes with the drug/excipient molecules) Reactive hydroxyl and amino group Adsorption enhancer for hydrophilic drugs High charge density at pH<6.5 Controlled drug release (gel forming ability in low pH media, has a high charge density at pH<6.5)