**3. Conclusions**

Throughout the past two decades N-heterocyclic carbenes (NHCs), have well stood as a true organocatalyst for the production of many industrial polymers. Owing to their rich structural modularity, NHCs can afford highly selective polymerization reaction pathways. A deep awareness of NHC's catalytic activity potential was gained through understanding their activation reaction mechanism that opens pathways for the production of commercial polymers. They have been extensively involved as transesterification agents in the ROP. Also, they showed a tremendous impact on step-growth reactions for the production of high molecular weight polymers (polycarbonates, polyesters, polybenzoins). Besides, their role of accelerating polymerization and their temperature range extends, they have the ability to introduce functionality to polymers. Due to their sensitivity to air and moisture, NHCs were in-situ generated using affordable and air-stable precursors, imidazolium chloride salt as starting source. As the catalyst design field progresses, opportunities for NHC polymerization catalysis can move beyond its current niche to compete in a field currently dominated by heterogeneous metal catalysis.

*N-Heterocyclic Carbenes: A Powerful Catalyst for Polymerization DOI: http://dx.doi.org/10.5772/intechopen.102466*
