Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, 700 13 Heraklion Crete, Greece.
Soft Matter. 2017 May 24;13(20):3777-3782. doi: 10.1039/c7sm00365j.
Well-defined poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) has been modified at low degrees of quaternization of the tertiary amine groups using alkyl halides with long alkyl chains as the quaternization agents. The resulting PDMAEMA-co-PQDMAEMA copolymers were studied in aqueous solution using potentiometric titrations, turbidimetry, surface tensiometry, dynamic light scattering and zeta potential measurements. An increase of the hydrophilicity of the precursor polymer, leading to an increase or even elimination of the lower critical solution temperature (LCST) for the quaternized copolymers was found; this extended the temperature range of the stable polymer solution. At the same time, it was shown that the hydrophobic character of the polymer increases upon quaternization, leading to higher surface activity compared to the precursor PDMAEMA homopolymer, and, thus, to more effective polymeric surfactants. This contradiction in the copolymer behavior was attributed to the interplay between the polymer self-assembly in the aqueous medium and the polymer adsorption at the air/water interface, which dominate the cloud point and the surface properties, respectively.
已使用长链烷基卤化物作为季铵化试剂，在低程度季铵化叔胺基团的情况下对明确定义的聚（2-二甲氨基乙基甲基丙烯酸酯）（PDMAEMA）进行了修饰。使用电位滴定法、浊度法、表面张力法、动态光散射和zeta 电位测量法研究了水溶液中的所得 PDMAEMA-co-PQDMAEMA 共聚物。发现前体聚合物的亲水性增加，导致季化共聚物的低临界溶液温度（LCST）增加甚至消除；这扩展了稳定聚合物溶液的温度范围。同时，表明聚合物的疏水性在季铵化后增加，与前体 PDMAEMA 均聚物相比具有更高的表面活性，因此是更有效的聚合物表面活性剂。这种共聚物行为的矛盾归因于聚合物在水介质中的自组装和聚合物在空气/水界面上的吸附之间的相互作用，分别主导浊点和表面性质。
