Abstract:

Temperature-sensitive hydrogels P(NIPA-co-DiAB) with aromatic group as hydrophobe was were prepared by free radical micellar crosslinking copolymerization with N-isopropyl acrylamide(NIPA) and N,N-dially benzylamine(DiAB) as comonomers, N,N-methylene-bis-acrylamide(BIS) as crosslinker, sodium dodecyl sulfate(SDS) as surfactant and ammonium persulfate(APS)tetramethylethylenediamine(TMEDA) as initiator system. The influence of DiAB content on the properties of the hydrogels was discussed. In the initial swelling stage, the swelling behavior of the four hydrogels changed from Fickian kinetics to nonFickian with increasing of molar fraction x(DiAB) from 0 to 3%. While x(DiAB) values were 0, 1%, 2% and 3%, the equilibrium swelling ratio SR0 of P(NIPA-co-DiAB) hydrogels were 63.6, 93.5, 141.6 and 167.4 in distilled water; 63.1, 71.0, 59.0 and 77.5 in a 0.01 mol/L SDS solution; 37.6, 42.2, 44.1 and 60.0 in a 0.01 mol/L CTAB solution; 30.9, 49.4, 68.5 and 88.3 in a 0.01 mol/L Triton X-100 solution respectively. It was found that the SR0 values of P(NIPA-co-DiAB) hydrogels were greater than that of PNIPA, and the SR0 values of the four hydrogels in distilled water were greater than those in 0.01 mol/L aqueous surfactant solution. The volume phase transition temperature or lower critical swelling temperature(LCST) of PNIPA hydrogel was enhanced from 32.5 ℃ in distilled water to 35.4 ℃, 45.6 ℃ or 80 ℃ in a 0.01 mol/L Triton X-100, CTAB or SDS solution, respectively. The LCST of P(NIPA-co-DiAB) hydrogels was increased from 32.0～32.5 ℃ in distilled water to 34.7～35.6 ℃, about 45.8~46.2 ℃ or 80 ℃ in a 0.01 mol/L Triton X-100, CTAB or SDS solution, respectively. It was shown that the LCST of P(NIPA-coDiAB) hydrogels was increased by adding surfactant. The high volume transition temperature was essentially independent of hydrophobic comonomer DiAB content.

Key words: N-isopropylacrylamide, N,N-diallybenzylamine, hydrophobicallymodifiedpolymers, intelligenthydrogel, surfactant