Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
J Colloid Interface Sci. 2010 Nov 1;351(1):88-95. doi: 10.1016/j.jcis.2010.07.027. Epub 2010 Jul 18.
The influence of mixing procedure on the properties of polyelectrolyte complexes (PECs) was investigated using two complexation techniques, polyelectrolyte titration and jet mixing, the latter being a new method for PEC preparation. For the low-molecular-weight polyelectrolytes polyacrylic acid (PAA) and polyallyl amine hydrochloride (PAH), shorter mixing times produced smaller PECs, whereas for higher molecular weights of the same polyelectrolytes, PEC size first decreased with decreasing mixing time to a certain level, after which it started increasing again. This pattern was likely due to the diffusion-controlled formation of "pre-complexes", which, in the case of low-molecular-weight polymers, occurs sufficiently quickly to form stable complexes; when polyelectrolytes are larger, however, non-equilibrium pre-complexes, more prone to aggregation, are formed. Comparing the techniques revealed that jet mixing produced smaller complexes, allowing PEC size to be controlled by mixing time, which was not the case with polyelectrolyte titration. Higher polyelectrolyte concentration during jet mixing led to the formation of larger PECs. It was also demonstrated that PEC size could be changed after preparation: increasing the pH of the PEC dispersion led to an irreversible increase in PEC size, whereas lowering the pH did not influence PEC size. The adsorption behavior of PECs formed from weak polyelectrolytes on model substrates was studied using QCM-D, SPAR, and AFM imaging; the results indicated that increasing the pH increased the amount of PECs adsorbed to model surfaces. However, the amount of PECs adsorbed to the model surfaces was low compared with other systems in all studied cases.
采用聚电解质滴定和射流混合两种复合技术研究了混合程序对聚电解质复合物（PEC）性能的影响，后者是一种新的 PEC 制备方法。对于低分子量聚电解质聚丙烯酸（PAA）和盐酸聚烯丙基胺（PAH），较短的混合时间会产生较小的 PEC，而对于相同聚电解质的较高分子量，PEC 尺寸首先随混合时间的减少而减小到一定水平，然后再次开始增加。这种模式可能是由于扩散控制形成的“预复合物”所致，对于低分子量聚合物，这种预复合物形成得足够快以形成稳定的复合物；然而，对于较大的聚电解质，形成的是更容易聚集的非平衡预复合物。比较这两种技术表明，射流混合产生的复合物较小，允许通过混合时间控制 PEC 尺寸，而聚电解质滴定则不行。在射流混合过程中增加聚电解质浓度会导致形成更大的 PEC。还证明可以在制备后改变 PEC 的尺寸：增加 PEC 分散体的 pH 值会导致 PEC 尺寸不可逆地增加，而降低 pH 值不会影响 PEC 尺寸。使用 QCM-D、SPAR 和 AFM 成像研究了弱聚电解质形成的 PEC 在模型基底上的吸附行为；结果表明，增加 pH 值会增加吸附到模型表面的 PEC 量。然而，与所有研究案例中的其他系统相比，吸附到模型表面的 PEC 量较低。
