pH and thermoresponsive comb-type grafted hydrogels based on polyethylene glycol diglycidyl ether and monoamino/diamino terminated jeffamines: synthesis, characterization and physicochemical properties

In the present study, the synthesis of thermo- and pH-sensitive comb-type grafted hydrogels based on polyetheramine was performed using polyethylene glycol diglycidyl ether [PEGDGE] as the activator. Monoamino terminated Jeffamine® M2005 was used as the polyether to incorporate the hydrophobic and thermo-sensitive character in the copolymer, while diamino terminated Jeffamine® ED600 was used as the crosslinker to initiate the amine-epoxy ring-opening reaction. These polyethylene glycol [PEG]-polypropylene glycol [PPG] hydrogels present pH responsive properties and thermo-sensitivity due to the presence of cationic functional groups and the Jeffamine moieties, respectively. Fourier-transform infrared [FTIR] spectroscopy and swelling behavior at different pH [2-10] and temperatures [4-50 °C] were applied to examine the physiochemical properties of the hydrogels. The volume-phase transition temperature [VPTT] of the hydrogels was determined based on PPG content and pH of solution. The physicochemical features of the hydrogels depended on the Jeffamine used and the ratio of Jeffamine units introduced. The maximum swelling capacity of the hydrogels as a function of time was determined at 4 °C and pH 5, while the optimum deswelling capacity was obtained at 40 °C and pH 7.4. Results showed that the dual responsive PEG-PPG based hydrogels may be suitable for potential application as drug delivery system sensors.