High Performance Polymers in Ionic Liquids: A Review on Prospects for Green Polymer Chemistry. Part I: Polyamides

The introduction of cleaner technologies has become a major concern worldwide and therefore, the search for alternatives to the unsafe volatile solvents has become the greatest priority throughout the academy and industry. Due to enforcement of policies in protecting the environment, "green chemistry" has received much attention since 1990's which it is still progressing. Green chemistry is understood to be a superior, innovative chemistry which is cost-effective and has minimum deleterious impact on environment. Highly polar conventional solvents such as N,N'-dimethylformamide, N,N'-dimethylacetamide, pyridine, N-methylpyrrolidone and chlorinated solvents which are used in polycondensation polymerizations are volatile and most of them are flammable, toxic, quite hazardous and harmful compared to ionic liquids (ILs). Hence, there is a basic obligation for the advancement of new methodologies of polymerizations by using environmentally benign media which could replace the conventional solvents and enhance adequate solubility for polymerization processes. Ionic liquids have great potential as a non-volatile organic medium for polymerization and polymer processing due to their near-zero vapour pressure, nonflammability, low cost and ease of production. However, implementation of ILs as solvents for polymerization processes has afforded some marked advantages such as increased molecular weight and narrower polydispersity in comparison to organic solvents. Owing to their higher performance and characteristics, the demand for high-performance polymers is growing steadily. Hence, the synthesis and properties of high-performance polyamides in the green media using ILs are reviewed to develop a methodology for "green polymer chemistry".