Abstract: Hydrophobical monomer N,N-diallyl-N-hexadecylamine was synthesized by the reaction between diallyamine and 1-bromohexadecane. The monomer was characterized using FTIR, 1H NMR and element analysis. A series of hydrophobically modified pH sensitive intelligent hydrogels poly(2-hydroxylethyl-methacrylate/sodium acrylate/N,N-diallyl-N-hexadecylamine)[P(HEMA-NaAA-DiAC16)] was successfully prepared by radically micellar copolymerization with 2-hydroxylethyl methacrylate(HEMA), sodium acrylate(NaAA), and N,N-diallyl-N-hexadecylamine(DiAC16) as comonomers, sodium dodecyl sulfate(SDS) as the surfactant, N,N′-ethylenebisacrylamide(BIS) as crosslinking agent, ammonium persulfate [(NH4)2S2O8]-N,N,N′,N′-tetramethylethylenediamine(TMEDA) as initiating agent. The effects of hydrophobical monomer, NaAA, BIS contents and pH, ionic strength on swelling behaviors of P(HEMA-NaAA-DiAC16) had been studied. The results indicate that the equilibrium swelling ratio SR0 of the hydrogels decreases with increasing the amounts of DiAC16 or BIS, with decreasing of NaAA, which are 78.9～163.91 in distilled water. The n values are 0.5~1.0 and increase with the increase of DiAC16, NaAA or BIS. The diffusions of water into P(HEMA-NaAA-DiAC16) gels are found to be a non-Fickian mode and exothermic process. The ΔHm are -2.09～-3.64 kJ/mol, the modulus of ΔHm and affinity between the polymers and water increase with the increase of NaAA and BIS, and the decrease of DiAC16. The equilibrium swelling ratio decreases with the increase of ionic strength.

Key words: hydrophobically modified, intelligent hydrogels, swelling ratio, pH sensitivity, swelling dynamics