Synthesis, physical and mechanical properties of amphiphilic hydrogels based on polycaprolactone and polyethylene glycol for bioapplications: A review

During the past decades, amphiphilic hydrogels found versatile applications in biomaterial field due to their suitable mechanical properties and control on releasement of hydrophobic substrates. Polyethylene glycol (PEG) and polycaprolactone (PCL) are FDA approved polymers that were used together in lots of research articles due to their complementary properties. This review focused on synthetic methods, physical, and mechanical properties as well as sol–gel-sol phase transition behavior of amphiphilic hydrogels based on polyethylene glycol (PEG) and polycaprolactone (PCL). Physical hydrogels were formed base on the hydrophobic interaction between copolymers of PCL and PEG or based on supramolecular chemistry. Also, chemical hydrogels synthesized via free radical crosslinking and chemical coupling reaction between functionalized prepolymers. Both types of physical and chemical hydrogels are biocompatible and biodegradable. Physical hydrogels are thermo-sensitive and were used as injectable hydrogels that can be sensitive to pH or other triggers. In addition, chemical hydrogels could be used as tissue scaffolds according to their mechanical properties.