Semi-interpenetrating network（semi-IPN） hydrogels composed of sodium carboxylmethylcellulose（NaCMC） and poly N-isopropylacrylamide（PNIPAm） were prepared by free radical polymerization of N-isopropyl acrylamide（...Semi-interpenetrating network（semi-IPN） hydrogels composed of sodium carboxylmethylcellulose（NaCMC） and poly N-isopropylacrylamide（PNIPAm） were prepared by free radical polymerization of N-isopropyl acrylamide（NIPAm） in dimethylsulfoxide（DMSO） in the presence of NaCMC. The structures of hydrogels were characterized by Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and differential scanning calorimetry（DSC）. SEM images show that the hydrogels present porous network structures. Most water in the hydrogels were free water and freezing water. The equilibrium swelling ratio（ESR） and swelling rate（SR） were quite different at various swelling temperature. ESR of the hydrogels ranged abruptly from 15.2 g/g to 1.56 g/g and the hydrogels changed from transparent into opaque with swelling temperature changing from 33 ℃ to 34 ℃, that is to say, the hydrogels exhibited the good temperature sensitivity at about 33 ℃ similar to low critical solution temperature（LCST） of pure PNIPAm, swelling rate were very different at below and above LCST due to hydrogel swelling with different swelling mechanism. Moreover, the semi-IPN hydrogels swelled much rapidly than pure PNIPAm hydrogels did at room temperature, the equillibrium swelling ratio（ESR） and swelling rate of the hydrogels increased with increasing of NaCMC content, i e. It is suggested that NaCMC could be potential for preparation of porous and rapid swelling hydrogels展开更多
用自由基聚合合成了具有两水亲性的异丙基丙烯酰胺与衣康酸共聚物 ,对它们水溶液及其水凝胶的 p H及温敏性进行了研究。结果表明 ,在一定的范围内 ,随衣康酸含量增加、水溶液浓度减少和 p H值增大 ,共聚物水溶液的低临界溶解温度随之升...用自由基聚合合成了具有两水亲性的异丙基丙烯酰胺与衣康酸共聚物 ,对它们水溶液及其水凝胶的 p H及温敏性进行了研究。结果表明 ,在一定的范围内 ,随衣康酸含量增加、水溶液浓度减少和 p H值增大 ,共聚物水溶液的低临界溶解温度随之升高。共聚物水凝胶的溶胀率随温度升高呈下降趋势 ,并且 p H值低时的溶胀率随温度的升高而下降的趋势比 p H高时的要快 ,而且表现出明显的溶胀 -退胀可逆过程。展开更多
A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carragee...A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carrageenan, kC, using ammonium persulfate （APS） as a free radical initiator in the presence of methylene bisacrylamide （MBA） as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy （SEM）. The effect of MBA concentration and AA/NIPAM weight ratio on the water absorbency capacity has been investigated. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The temperature- and pH-reversibility properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.展开更多
基金Funded by the National Natural Science Foundation of China(50973129)the Natural Science Found of Guangdong Province(07001781)+1 种基金the Open Project of Key Laboratory of Cellulose and Lignocellulosics ChemistryChinese Academy of Science(LCLC-2005-168)
文摘Semi-interpenetrating network（semi-IPN） hydrogels composed of sodium carboxylmethylcellulose（NaCMC） and poly N-isopropylacrylamide（PNIPAm） were prepared by free radical polymerization of N-isopropyl acrylamide（NIPAm） in dimethylsulfoxide（DMSO） in the presence of NaCMC. The structures of hydrogels were characterized by Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and differential scanning calorimetry（DSC）. SEM images show that the hydrogels present porous network structures. Most water in the hydrogels were free water and freezing water. The equilibrium swelling ratio（ESR） and swelling rate（SR） were quite different at various swelling temperature. ESR of the hydrogels ranged abruptly from 15.2 g/g to 1.56 g/g and the hydrogels changed from transparent into opaque with swelling temperature changing from 33 ℃ to 34 ℃, that is to say, the hydrogels exhibited the good temperature sensitivity at about 33 ℃ similar to low critical solution temperature（LCST） of pure PNIPAm, swelling rate were very different at below and above LCST due to hydrogel swelling with different swelling mechanism. Moreover, the semi-IPN hydrogels swelled much rapidly than pure PNIPAm hydrogels did at room temperature, the equillibrium swelling ratio（ESR） and swelling rate of the hydrogels increased with increasing of NaCMC content, i e. It is suggested that NaCMC could be potential for preparation of porous and rapid swelling hydrogels
文摘用自由基聚合合成了具有两水亲性的异丙基丙烯酰胺与衣康酸共聚物 ,对它们水溶液及其水凝胶的 p H及温敏性进行了研究。结果表明 ,在一定的范围内 ,随衣康酸含量增加、水溶液浓度减少和 p H值增大 ,共聚物水溶液的低临界溶解温度随之升高。共聚物水凝胶的溶胀率随温度升高呈下降趋势 ,并且 p H值低时的溶胀率随温度的升高而下降的趋势比 p H高时的要快 ,而且表现出明显的溶胀 -退胀可逆过程。
文摘A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carrageenan, kC, using ammonium persulfate （APS） as a free radical initiator in the presence of methylene bisacrylamide （MBA） as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy （SEM）. The effect of MBA concentration and AA/NIPAM weight ratio on the water absorbency capacity has been investigated. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The temperature- and pH-reversibility properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.
