Mass polymerization & interfacial polymerization

A short introductory note on Mass Polymerization & Interfacial Polymerization

1. Mass Polymerization & Interfacial Polymerization

2. Contents What is mass polymerization Process of mass polymerization Advantages of mass polymerization Disadvantages of mass polymerization Examples

3. Mass or Bulk Polymerization Bulk polymerization  or  mass polymerization  is carried out by adding a soluble initiator to pure monomer in liquid state. The initiator should dissolve in the monomer. The reaction is initiated by heating or exposing to radiation. It is used for most step-growth polymers and many types of chain-growth polymers. Bulk polymerizations are also difficult to stir because of the high viscosity, associated with high-molecular-weight polymers.

4. Process This method involves only the monomer molecule, an initiator and a chain transfer agent. carried out by adding a soluble initiator to pure monomer ( in liquid state ). The mixture is constantly agitated & heated to polymerization temperature. Once the reaction starts, heating is stopped as the reaction is exothermic The heat generated is dissipated by circulating water jacket. Viscosity increases results difficulty in stirring.

5. Advantages The system is simple and requires thermal insulation. The polymer obtained is pure. Large castings may be prepared directly. Molecular weight distribution can be easily changed with the use of a chain transfer agent. The product obtained has high optical clarity.

6. Disadvantages Heat transfer and mixing become difficult as the viscosity of reaction mass increases. Heat removal is difficult. Hot spots may form and explosion may possible. Gel effect occurs. Removal of traces of unreacted monomer is difficult.

7. Examples   Methyl methacrylatestyrene , Polyurethanes polycaprolactam (Nylon 6) polycarbonates and polyester (PET) etc.

8. Interfacial Polymerization

9. CONTENTS What is interfacial polymerization Mechanism of interfacial polymerization Advantages of interfacial polymerization Disadvantages of interfacial polymerization Examples

10. Interfacial Polymerization Interfacial polymerization  is a type of step-growth polymerization in which polymerization occurs at the interface between two immiscible phases (generally two liquids), resulting in a polymer that is constrained to the interface. It was first discovered by Emerson L. Wittbecker and Paul W. Morgan in 1959 as an alternative to the typically high-temperature and low-pressure melt polymerization technique.

11. One phase is above the interface, and the other phase is below. Polymerization occurs where the two phases meet, at the interface

12. Mechanism The most commonly used interfacial polymerization methods fall into 3 broad types of interfaces: liquid-solid interfaces, liquid-liquid interfaces, and liquid-in-liquid emulsion Interfaces. In the liquid-liquid and liquid-in-liquid emulsion interfaces, either one or both liquid phases may contain monomers. There are also other interface categories, rarely used, including liquid-gas, solid-gas, and solid-solid. In a liquid-solid interface, polymerization begins at the interface, and results in a polymer attached to the surface of the solid phase.

13. In a liquid-liquid interface with monomer dissolved in one phase, polymerization occurs on only one side of the interface, whereas in liquid-in-liquid interfaces with monomer dissolved in both phases, polymerization occurs on both sides.

14. Schematic of the steps involved in the interfacial polymerization of water-in-oil microemulsion process.

15. Advantages Polymerization is rapid and occurs at low temperatures. High conversions are not necessarily required to obtain high molecular weight Unnecessary to start with stoichiometric quantifiers of reactants. Disadvantages Limited to highly reactive systems Need appropriate choice of solvent to dissolve reactants.

16. Examples polyaniline Polypyrrole Poly(3,4-ethylenedioxythiophene) Polythiophene

17. Mashrur Wasity Shovon