Škorňa Adam, Selianitis Dimitrios, Pispas Stergios, Štěpánek Miroslav
Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic.
Theoretical & Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Avenue, 11635 Athens, Greece.
Polymers (Basel). 2024 Jul 24;16(15):2102. doi: 10.3390/polym16152102.
Aqueous solutions of a thermoresponsive diblock copolymer poly(di-[ethylene glycol] methyl ether methacrylate)--poly(2-[diisopropylamino] ethyl methacrylate) (PDEGMA--PDIPAEMA) were studied by static, dynamic and electrophoretic light scattering, small-angle X-ray scattering and differential scanning calorimetry. Thermoresponsive behavior of PDEGMA--PDIPAEMA was investigated at two pH values, pH = 2, at which the terminal carboxylic group of the PDEGMA chain and the PDIPAEMA block are protonated, and pH = 7, where the carboxyl terminal group is ionized while the PDIPAEMA block is partially deprotonated and more hydrophobic. Both at pH = 2 and 7, PDEGMA--PDIPAEMA copolymer underwent extensive association (the size of the aggregates was between 100 and 300 nm), indicating strong interchain interactions. While the measurements confirmed thermoresponsive behavior of PDEGMA--PDIPAEMA at pH = 7, no changes in the association with temperature were observed at pH 2 as the thermoresponsivity of PDEGMA was suppressed by hydrogen bonding between carboxylic groups and PDEGMA segments, as well as due to the increased hydrophilicity of the PDIPAEMA block. Fluorescence measurements with pyrene as a fluorescent probe showed that both at pH = 2 and pH = 7 the associates were able to solubilize hydrophobic substances.
通过静态、动态和电泳光散射、小角X射线散射以及差示扫描量热法研究了热响应性二嵌段共聚物聚（二乙二醇甲基醚甲基丙烯酸酯）-聚（2-二异丙基氨基乙基甲基丙烯酸酯）（PDEGMA-PDIPAEMA）的水溶液。在两个pH值下研究了PDEGMA-PDIPAEMA的热响应行为，pH = 2时，PDEGMA链的末端羧基和PDIPAEMA嵌段被质子化；pH = 7时，羧基末端基团被电离，而PDIPAEMA嵌段部分去质子化且疏水性更强。在pH = 2和7时，PDEGMA-PDIPAEMA共聚物都发生了广泛的缔合（聚集体尺寸在100至300nm之间），表明存在强链间相互作用。虽然测量结果证实了PDEGMA-PDIPAEMA在pH = 7时的热响应行为，但在pH 2时未观察到缔合随温度的变化，因为羧基与PDEGMA链段之间的氢键作用以及PDIPAEMA嵌段亲水性的增加抑制了PDEGMA的热响应性。以芘作为荧光探针的荧光测量表明，在pH = 2和pH = 7时，缔合体都能够溶解疏水性物质。
