Puronic polyols

The commonly used polymer for preparing degradable hydrogels are PVA, PEG, PVP, puronic polyol, and some natural polymers including cellulose and alginate (80). 

Puronic polyols are block copolymers of PEG and poly(propylene oxide). Plutonic copolymers with 70% ethylene oxide and 30% propylene oxide, with an average molecular weight of 11,500, exhibits a reversible thermal gelation in aqueous solution at >20% concentration. The polymer solution at room temperature is liquid, but turns to a gel in the body. This gel has been used as a delivery system for several proteins (80). 

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