2-Hydroxyethyl methacrylate based polymer microgels and their hybrids

2-Hydroxyethyl methacrylate (HEMA) based microgels have gained much attention in recent decades due to their potential applications in various fields. The existence in the form of free-flowing liquid, very low response time and easy fabrication with different morphologies are major advantages of microgels over macrogels of HEMA. These microgels, depending upon the nature of co-monomer, present quick and reversible swelling/deswelling behavior due to minute changes occurring in external stimuli like ionic strength, temperature and pH of the medium. HEMA-based microgels are biocompatible, degradable and less toxic. The presence of HEMA along with the thermosensitive monomers like N-isopropylacrylamide or N-isopropylmethacrylamide units in the polymeric structure of thermosensitive microgels affects their volume phase transition temperature (VPTT). Many researchers have reported applications of HEMA-based microgels in the domains of tissue engineering, drug delivery, bio-catalysis, catalysis and pollution control. A comprehensive review of synthesis, properties and applications of HEMA-based microgels and recent research progress in this discipline have been presented in this article.