Synthesis And Characterization Of PH And Electrical Responsive Hydrogels

Novel pH and electrically responsive hydrogels were synthesized,which were based on acrylamide(AM)monomer.The smart polymer hydrgels were synthesized with the copolymerization,modification,change of system of polymerization.The properties of the polymers hydrogels were investigated in swelling capability,thermal properties,mechanical strength,and the response of pH and DC electric field.The copolymer hydrogel P(AM-co-MAA)was prepared with acrylamide(AM) and methacrylic acid under 80℃condition.The chemical structures were characterized with Fourier Transform Infrared(FTIR)spectroscopy.The swelling property of absorbing water and the swelling rate in different pH solution were investigated with different MAA content.The deswelling rate of sufficient swelling hydrogel in salty solution was evaluated.And the pH response was studied when transforming between pH=2 and pH=12.The morphology of hydrogel in acid and alkaline solution was observed using scanning electronic microscope(SEM).The results showed that the swelling ratio and rate either in water or different pH solution increased with the increase of MAA content.The deswelling rate in salty solution increased with the increase of ionic strength of solution,and the charge of cation affected the deswelling rate.The responsive time of swelling and deswelling were 75min and 230min respectively,when transforming between pH=2 and pH=12.And the stir could improve the responsive time.By sulfomethylation modification of P(AM-co-MAA)hydrogels,and the structures were characterized with Fourier Transform Infrared(FTIR)spectroscopy. There were differences in equilibrium swelling ratio of absorbing water,swelling rate, swelling behavior in different pH solution,pH responsive rate when transforming between pH=2 and pH=12,compared with P(AM-co-MAA)hydrogel.The results showed that the equilibrium swelling ratio of absorbing water was improved because of introducing -SO₃^- after sulfomethylation.When swelling in different pH solution, the swelling rate increased greatly after modification.The equilibrium swelling ratio was 5.5 times than that before modification in pH=2 solution.When transforming between different pH solution,the responsive time of deswelling increased,swelling time decreased.Poly(acrylamide-co-diallyldimethylammounium chloride)[P(AM-co-DADMAC)] hydrogel was synthesized in water and water-ionic liquid binary system respectively. The swelling behavior of the two type hydrogels in water and different pH solution were investigated.PVA was introduced into the hydrogel network to prepare semi-interpenetrating network hydrogels.The morphology of hydogels was obverved using scanning electronic microscope(SEM).The mechanical properties were test by Universal Material-Testing Machine.The thermo properties of hydrogels containing IL were characterized by differential scanning calorimetry(DSC).The results showed that the swelling ratio of hydrogel prepared in water-IL binary system was improved greatly.And the toughness of hydrogels containing IL and PVA was enhanced. Because of the IL,the thermo property was improved.Glass transition temperature(Tg)decreased with increase of IL content.The electrical response was test by self-made device.The factors which influenced the electrically responsive characteristics had been considered,including ionization group in the polymer chain of hydogels network,ionic strength of electrolyte,the type of counter ion,electric field strength.The results showed that the increase of strong ionization group increased the responsive rate at electric field.The radii of counter ion influenced the electrical response rate,in the same valence,the responsive rate increased with the increase of ion radii.With increasing of ionic strength of electrolyte,the responsive rate increased.When the ionic strength exceeded the critical value,the responsive rate decreased with the increasing of ionic strength.The responsive rate increased with the increasing of electric field strength. The P(AM-co-DADMAC)hydrogel synthesized in water and wter-IL binary system exhibited electricstration properties.And the hydrogel containing IL exhibited better deswelling response.With increasing of IL content,the responsive rate increased.