Guo Yi, Wang Ruijin, Shang Yazhuo, Liu Honglai
Key Laboratory for Advanced Materials, School of Chemistry & Molecular Engineering, East China University of Science and Technology Shanghai 200237 China
RSC Adv. 2018 Feb 27;8(16):8699-8708. doi: 10.1039/c8ra00171e. eCollection 2018 Feb 23.
The gelation behavior and properties of sodium deoxycholate (NaDC) and l-aspartic acid (Asp) in aqueous solution were investigated in detail at 25 °C. The linear polymer poly(2-(2-methoxyethoxy)ethyl methacrylate--oligo-(ethylene glycol) methacrylate) (P(MEOMA--OEGMA)) and star-shaped polymer poly(2-(dimethylamino)ethyl methacrylate--2-(2-methoxyethoxy)ethyl methacrylate) (CDPDPM) were introduced in NaDC/Asp hydrogels for exploring the effects of polymers on the properties of NaDC/Asp hydrogels and the mechanism underlying gelation processes by polymers was proposed. The hydrogels were characterized by phase behavior observation, polarized optical microscopy (POM), cryogenic scanning electron microscopy (cryo-SEM), X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and rheological measurements. Moreover, the adsorption performances of hydrogels with and without polymers to methylene blue (MB) were studied using a UV-vis spectrometer. The results indicated that the transition from sol to gel state was observed with an increase in the Asp concentration in the system. Both linear and star-shaped polymers can participate in the formation of a gel network structure, so that the density of network structure and the mechanical strength of hydrogels increased. Furthermore, it was found that the viscoelasticity of the CDPDPM-containing hydrogel was much higher than that of the P(MEOMA--OEGMA)-containing hydrogel under the same condition, indicating that CDPDPM performed better in strengthening the network structure of the hydrogels than P(MEOMA--OEGMA) due to the special structure that provided more binding sites for hydrogen bonding and stronger hydrophobicity that inhibited the swelling and dissolution of hydrogels. On coming in contact with the MB solution, the CDPDPM-containing hydrogel can adsorb MB and maintain the hydrogel state for recycling. On the contrary, the NaDC/Asp hydrogel dissolved and P(MEOMA--OEGMA)-containing hydrogel collapsed in the MB solution. The properties of the hydrogels are expected to be tailored by introducing polymers with different properties, including the charge numbers, the number of available binding sites, and hydrophobic properties.
在25℃下详细研究了脱氧胆酸钠（NaDC）和L-天冬氨酸（Asp）在水溶液中的凝胶化行为和性质。将线性聚合物聚（甲基丙烯酸2-（2-甲氧基乙氧基）乙酯-寡聚（乙二醇）甲基丙烯酸酯）（P（MEOMA-OEGMA））和星形聚合物聚（甲基丙烯酸2-（二甲氨基）乙酯-甲基丙烯酸2-（2-甲氧基乙氧基）乙酯）（CDPDPM）引入NaDC/Asp水凝胶中，以探索聚合物对NaDC/Asp水凝胶性质的影响，并提出了聚合物引发凝胶化过程的机制。通过相行为观察、偏光显微镜（POM）、低温扫描电子显微镜（cryo-SEM）、X射线粉末衍射（XRD）、傅里叶变换红外（FT-IR）光谱和流变学测量对水凝胶进行了表征。此外，使用紫外可见光谱仪研究了含聚合物和不含聚合物的水凝胶对亚甲基蓝（MB）的吸附性能。结果表明，随着体系中Asp浓度的增加，观察到从溶胶状态到凝胶状态的转变。线性和星形聚合物都可以参与凝胶网络结构的形成，从而使网络结构密度和水凝胶的机械强度增加。此外，发现在相同条件下，含CDPDPM的水凝胶的粘弹性远高于含P（MEOMA-OEGMA）的水凝胶，这表明由于其特殊结构提供了更多的氢键结合位点以及更强的疏水性抑制了水凝胶的溶胀和溶解，CDPDPM在强化水凝胶网络结构方面比P（MEOMA-OEGMA）表现更好。与MB溶液接触时，含CDPDPM的水凝胶可以吸附MB并保持水凝胶状态以便循环使用。相反，NaDC/Asp水凝胶溶解，含P（MEOMA-OEGMA）的水凝胶在MB溶液中塌陷。预计通过引入具有不同性质的聚合物，包括电荷数、可用结合位点数量和疏水性质，可以调整水凝胶的性质。
