Kaniewska Klaudia, Kościelniak Patrycja, Karbarz Marcin
Faculty of Chemistry, Biological and Chemical Research Center, University of Warsaw, 1 Pasteura Str., PL-02-093 Warsaw, Poland.
Gels. 2023 May 29;9(6):447. doi: 10.3390/gels9060447.
Thermoresponsive gels based on -isopropylacrylamide functionalized with amino groups were modified with gallic acid, with gallate (3,4,5-trihydroxybenzoic) groups being introduced into the polymer network. We investigated how the properties of these gels were affected at varying pH, by the formation of complexes between the polymer network of the gels and Fe ions (which form stable complexes with gallic acid, exhibiting 1:1, 1:2, or 1:3 stoichiometry, depending on pH). The formation of complexes with varying stoichiometry within the gel was confirmed using UV-Vis spectroscopy, and the influence of such complexes on swelling behavior and volume phase transition temperature were investigated. In the appropriate temperature range, complex stoichiometry was found to strongly affect the swelling state. Changes in the pore structure and mechanical properties of the gel caused by the formation of complexes with varying stoichiometry were investigated using scanning electron microscopy and rheological measurements, respectively. The volume changes exhibited by p(NIPA-5%APMA)-Gal-Fe gel were found to be greatest at close to human body temperature (~38 °C). Modification of thermoresponsive pNIPA gel with gallic acid opens new opportunities for the development of pH- and thermosensitive gel materials.
基于用氨基官能化的N-异丙基丙烯酰胺的热响应凝胶用没食子酸进行了改性，从而将没食子酸盐（3,4,5-三羟基苯甲酸）基团引入到聚合物网络中。我们研究了在不同pH值下，这些凝胶的性质是如何受到影响的，这是通过凝胶的聚合物网络与铁离子之间形成络合物来实现的（铁离子与没食子酸形成稳定的络合物，根据pH值呈现1:1、1:2或1:3的化学计量比）。使用紫外可见光谱法确认了凝胶内不同化学计量比络合物的形成，并研究了此类络合物对溶胀行为和体积相变温度的影响。在合适的温度范围内，发现络合物化学计量比强烈影响溶胀状态。分别使用扫描电子显微镜和流变学测量方法，研究了不同化学计量比络合物的形成对凝胶孔结构和力学性能的影响。发现p（NIPA-5%APMA）-Gal-Fe凝胶在接近人体温度（约38°C）时表现出的体积变化最大。用没食子酸对热响应性pNIPA凝胶进行改性为开发pH和温度敏感凝胶材料开辟了新的机遇。
