Microencapsulation

Deals with microencapsulation techniques and characterization

1. Microencapsulation: Techniques and Characteristics Dept. Textile and Apparel Designing College of Rural Home Science UAS, Dharwad Mrs. Shameembanu A. Byadgi Ph.D. Scholar

2. History The microencapsulation procedure was introduced by Bungen burg de Jon and Kan in the year 1931 The origin of microencapsulation lie in the pharmaceutical and paper industries of 1940s Textile industry started introducing encapsulated products in between 1980 and 1990 Pharmaceutical industry has long used microencapsulation for the preparation of capsules containing active ingredients During the past 10 years this approach has been explored widely by the agricultural, food, cosmetic and textile industries Introduction…….

3. What is MICROENCAPSULATION ……??? Micro-encapsulation is a process in which tiny particles or droplets are surrounded by a coating to give small capsules with useful properties Micro-encapsulation may also be defined as the process of surrounding or enveloping one substance within another substance on a very small scale, yielding capsules ranging from less than one micron to several hundred microns in size The potential size range of the microcapsules produced is enormous, with typical diameters being between 2 and 2000 µm Capsule walls are typically 0.5-150 µm thick The proportion of core material in the capsule is usually between 20 and 95% by mass

4. The substance that is encapsulated is called the core material, the active ingredient or agent, nucleus or internal phase The material encapsulating the core is referred to as coating, membrane, shell or wall material Microcapsules may have one wall or multiple shells arranged in of varying thickness around the core

5. Microcapsule with core and coat Can be liquid or solid in nature Liquid core can include dispersed and/or dissolved materials Solid core can be active constituents, stabilizers, diluents and release-rate retardants or accelerators Core materials Structure of a Microcapsule

6. Should be capable of forming a film that is cohesive with the core material Chemically compatible and nonreactive with the core material Provide the desired coating properties, such as strength, flexibility, impermeability , optical properties and stability The ideal characteristics of coating material are stabilization of core material inert toward active ingredients controlled release under specific conditions pliable, tasteless, stable and non-hygroscopic low viscosity soluble in an aqueous media or solvent should be flexible, brittle, hard, thin etc Coating materials

7. Non-biodegradable polymers Poly methyl methacrylate (PMMA), acrolein , glycidyl methacrylate epoxy polymers Biodegradable polymers Lactides , glycolides & their co polymers, poly alkyl cyanoacrylates , polyanhydrides Proteins Albumin, gelatin and collagen Carbohydrates Agarose, carrageenan, chitosan, starch, dextran, sucrose Chemically modified carbohydrates Poly dextran, poly starch Gums Gum arabic, sodium alginate, carragenan Celluloses Carboxymethylcellulose, methycellulose Lipids Bees wax, stearic acid, phospholipids Synthetic polymers Natural polymers

8. Skin moisturising agents, skin cooling agents, vitamins & pro-vitamins, essential oils, plant extracts, etc Natural polymer, semi-synthetic polymer, synthetic polymer Pressure, friction, diffusion, wall dissolution, biodegradation, etc A close view of Microcapsules…

9. MECHANISM …. How it Works…..??? Microencapsulation have two distinct objectives To block the substance within the microcapsule, necessarily rigid, when the diffusion of a product is not desired Progressive liberation of the active ingredient within the microcapsule. This is mostly used in the functional or active textiles

10. Type of Microcapsules Mononuclear (core-shell) microcapsules contain the shell around the core Polynuclear capsules have many cores enclosed within the shell Matrix encapsulation in which the core material is distributed homogeneously into the shell material

11. Physico -chemical processes Physico -mechanical processes Coacervation (2 – 1200 µm) Spray drying (5 – 5000 µm) Polymer-polymer incompatibility ( 0.5 – 1000 µm) Fluidized bed technology (20 – 1500 µm) Solvent evaporation (0.5 – 1000 µm) Pan coating (600 – 5000 µm) Encapsulation by supercritical fluid Spinning disc (5 – 1500 µm) Encapsulation by polyeletrolyte multilayer (0.02 – 20 µm) Co-extrusion (250 – 2500 µm) Phase inversion (0.5 – 5.0 µm) Interfacial polymerization (0.5 – 1000 µm) Hot melt (1 – 1000 µm) In situ polymerization (0.5 – 1100 µm) Microencapsulation processes with their relative particle size ranges Development of Microcapsules

12. Reagents Acacia powder : 5 g Water : 50 ml Core material (extract) : 25 ml Citric acid : 6% Sodium sulphate : 20% Microcapsules using magnetic stirrer

13. Characterization of Microcapsules Particle size analyzer Shape and surface morphology – SEM Atomic force microscopy

14. Techniques to apply on Textiles……. Injecting into the polymer / yarn Padding technique Coating Spraying Transfer print

15. APPLICATION IN TEXTILES …….

16. INTERESTING ASPECTS !!!! Claim to resist up to 25 wash cycles Shelf life between 3 – 5 years Colourless No visible effects when applied over coloured or printed fabrics Versatile technology for its controlled release properties