Department of Chemistry, Oklahoma State University, Stillwater, OK 74078, USA.
Department of Chemistry and Physics, 231 Natural Sciences Building, 111 Memorial Drive, Western Carolina University, Cullowhee, NC 28723, USA.
Molecules. 2020 Mar 19;25(6):1408. doi: 10.3390/molecules25061408.
Swellable polymers that respond to pH (including a portion of the physiological pH range) have been prepared from -isopropylacrylamide (NIPA) copolymerized with acrylic acid, methacrylic acid, ethacrylic acid or propacrylic acid by dispersion polymerization. When the swellable polymer particles are dispersed in a polyvinyl alcohol (PVA) hydrogel membrane, large changes occur in the turbidity of the membrane (which is measured using an absorbance spectrometer) as the pH of the buffer solution in contact with the hydrogel membrane is varied. The swelling of the NIPA copolymer is nonionic, as the ionic strength of the buffer solution in contact with the PVA membrane was increased from 0.1 to 1.0 M without a decrease in the swelling. For many of these NIPA copolymers, swelling was also reversible in both low- and high ionic strength pH-buffered media and at ambient and physiological temperatures. The composition of the formulation used to prepare these copolymers of NIPA can be correlated to the enthalpy and entropy of the pH-induced swelling.
可溶胀聚合物对 pH 值有响应（包括生理 pH 值范围的一部分），通过分散聚合由 - 异丙基丙烯酰胺（NIPA）与丙烯酸、甲基丙烯酸、乙基丙烯酸或丙基丙烯酸共聚制得。当可溶胀聚合物颗粒分散在聚乙烯醇（PVA）水凝胶膜中时，当与水凝胶膜接触的缓冲溶液的 pH 值发生变化时，膜的浊度会发生很大变化（通过吸光度光谱仪测量）。NIPA 共聚物的溶胀是非离子的，因为与 PVA 膜接触的缓冲溶液的离子强度从 0.1 增加到 1.0 M 而溶胀没有减少。对于许多这些 NIPA 共聚物，在低和高离子强度 pH 缓冲介质以及环境和生理温度下，溶胀也是可逆的。用于制备这些 NIPA 共聚物的配方的组成可以与 pH 诱导溶胀的焓和熵相关联。
