School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.
Langmuir. 2010 Sep 21;26(18):14502-8. doi: 10.1021/la102539v.
Polydimethylsiloxane-graft-poly(ethylene oxide) (PDMS-g-PEO) copolymers form micelles in water with PDMS as the core and PEO as the corona. The introduction of poly(acrylic acid)-block-polyacrylonitrile (PAA-b-PAN) block copolymers in water leads to the formation of micellar complexes due to the hydrogen bonding between carboxyl groups and ether oxygens among the PAA and PEO chains in the corona of the micelles. The effects of pH, molar ratios (r) of PAA/PEO, and the standing time on the directly mixing these two micelles in water have been investigated using laser light scattering (LLS) and transmission electron microscopy (TEM). Our results showed that the complexation between PAA and PEO in the corona was greatly enhanced at a pH below 3.5. For a fixed pH value, the interactions between these two micelles in water were governed by the value of r. At r < ∼0.6, mixing the two micelles in water resulted in a large floccule because the smaller PAA-b-PAN micelles act as physical cross-links, which are absorbed onto one PDMS-g-PEO micelle and simultaneously bonded to PEO chains on the other micelles, forming bridges and causing flocculation. At ∼0.6 < r < ∼1.2, the mixing led to stable micellar complexes with a layer of PAA-b-PAN micelles absorbed onto the initial PDMS-g-PEO micelles. At r > ∼1.2, the resultant micellar complexes first remained stable, but they precipitated from solution after a long time standing.
聚二甲基硅氧烷接枝聚（环氧乙烷）（PDMS-g-PEO）共聚物在水中形成胶束，其中 PDMS 为核，PEO 为冠。在水中引入聚丙烯酸嵌段-聚丙烯腈（PAA-b-PAN）嵌段共聚物，由于胶束冠层中 PAA 和 PEO 链之间的羧基和醚氧之间的氢键作用，导致形成胶束复合物。使用激光光散射（LLS）和透射电子显微镜（TEM）研究了 pH 值、PAA/PEO 的摩尔比（r）和静置时间对这两种胶束在水中直接混合的影响。我们的结果表明，在 pH 值低于 3.5 时，胶束冠层中 PAA 和 PEO 之间的络合作用大大增强。对于固定的 pH 值，水相中这两种胶束之间的相互作用由 r 值决定。在 r < ∼0.6 时，将两种胶束在水中混合会导致大絮状物，因为较小的 PAA-b-PAN 胶束充当物理交联剂，其被吸收到一个 PDMS-g-PEO 胶束上，并同时与另一个胶束上的 PEO 链键合，形成桥并引起絮凝。在 ∼0.6 < r < ∼1.2 时，混合导致稳定的胶束复合物，其中一层 PAA-b-PAN 胶束被吸收到初始 PDMS-g-PEO 胶束上。在 r > ∼1.2 时，所得的胶束复合物首先保持稳定，但在长时间静置后会从溶液中沉淀出来。
