Synthesis and phase behavior of double sensitive linear amphiphilic prepolymers before gelation

Abstract

A series of amphiphilic linear prepolymers for gelation, poly(poly(ethylene glycol) diglycidyl ether—monoethanolamine—poly(propylene glycol) diglycidyl ether), i.e. polyPEMPPs, were designed and synthesized by using poly(ethylene glycol) diglycidyl ether (PEGDGE), Poly(propylene glycol) diglycidyl ether (PPGDGE), and monoethanolamine (MEA) as main raw materials through nucleophilic addition/ring-opening reaction. The amphiphilic structure in the backbone of the prepolymers polyPEMPPs causes a phase transition in aqueous solution and has multiple stimuli responsiveness. The effects of hydrogen bonding and electrostatic interactions on phase transition behavior were discussed and analyzed structural reasons in detail. This has important guiding significance for further research on control sol–gel transition. The effects of polyPEMPPs concentration, content of PEGDGE and solution pH values on the phase transition temperature were examined. The experimental results show that increasing polyPEMPPs concentration promotes the phase transition, the transition temperature decreasing with increasing PEGDGE content. In the pH experiment, intra- and intermolecular association became difficult and the phase behavior will be inhibited, whether hydrochloric acid system or sodium hydroxide system. Moreover, we also experimented oscillatory phase transition, and the result exhibited a stably reversible phenomenon transition.