Dual thermo- and ion-responsive cross-linked poly(N-isopropylacrylamide) hydrogels incorporated with crown ether receptors
Dual thermo- and ion-responsive cross-linked poly(N-isopropylacrylamide-co-benzo-18- crown-6-acrylamide) (P(NIPAM-co-BCAm)) hydrogel was successfully prepared via thermally-initiated free-radical cross-linking copolymerization. Both the structures and stimuli-sensitive properties of the prepared hydrogel were characterized. The results indicated that the incorporation of crown ether groups into the poly(N-isopropylacrylamide) chains produced a smart hydrogel that responded to both temperature and ion stimuli. When the crown ether units captured Ba 2+ ions in their cavities and formed stable BCAm/Ba 2+ complexes, the lower critical solution temperature (LCST) of the hydrogel increased due to the repulsion among charged BCAm/Ba 2+ complex groups and osmotic pressure within the hydrogel resulted from a Donnan potential that arose from mobile counter ions to the crown ether bound Ba 2+ . Whereas crown ethers captured Cs + ions, the LCST shifted to a lower temperature because of the formation of 2:1 sandwich complexes. Unexpectedly, the LCST of the cross-linked P(NIPAM-co-BCAm) hydrogel in K + solution did not shift to a higher temperature, which was definitely different from the previously reported linear P(NIPAM-co-BCAm) copolymer in K + solution. The reason may be due to the following: if the copolymer chains were cross-linked, the cavities of crown ethers were close to each other; because the stability constant of BCAm/K + complex is not high enough, therefore the electrostatic repulsion among K + ions affected the formation of stable BCAm/K + complexes inside the cross-linked P(NIPAM-co-BCAm) hydrogel. The results of this work provide valuable information for development of dual thermo- and ion-responsive hydrogels which have potential applications in drug controlled-release systems or biomedical fields.
hydrogel ion-responsive N-isopropylacrylamide benzo-18-crown-6-acrylamide
Xiao-Jie Ju Liang-Yin Chu Li Liu Peng Mi Ming-Yu Zhou Shi-Bo Zhang
School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, China;Institute for Nan
国际会议
第四届中日化工学术研讨会(The 4th Joint China/Japan Chemical Engineering Symposium)(CJCES)
成都
英文
2007-12-19（万方平台首次上网日期，不代表论文的发表时间）