Solution polymerization
Solution polymerization is a method of industrial polymerization. In this procedure, a monomer is dissolved in a non-reactive solvent that contains a catalyst.
The reaction results in a polymer which is also soluble in the chosen solvent. Heat released by the reaction is absorbed by the solvent, and so the reaction rate is reduced. Moreover, the viscosity of the reaction mixture is reduced, not allowing autoacceleration at high monomer concentrations. Decrease of viscosity of reaction mixture by dilution also helps for the heat transfer, one of the major issues connected with polymer production as most of polymerizations are exothermic reactions. Once the maximum or desired conversion is reached, excess solvent has to be removed in order to obtain the pure polymer. Hence, solution polymerization is mainly used for applications where the presence of a solvent is desired anyway, as is the case for varnish and adhesives. Other application of polymer solutions is a manufacture of fibers by wet or dry spinning. It is not useful for the production of dry polymers because of the difficulty of complete solvent removal.
This process is one of two used in the production of sodium polyacrylate, a superabsorbent polymer used in disposable diapers.
Notable polymers produced using this method are polyacrylonitrile (PAN) and polyacrylic acid (PAA). The major disadvantage of the solution polymerization technique is that however inert the selected solvent may be, chain transfer to the solvent cannot be completely ruled out and, hence, it is difficult to get very high molecular weight product
See also
References
- Foundations of Materials Science and Engineering, fourth edition, William F. Smith & Javad Hashem
- Encyclopedia of Polymer Science and Technology, J.Wiley Sons, Interscience, Publ., New York, 4th edition, 1999-2012