Intermolecular Interactions and Self-Assembly in Aqueous Solution of a Mixture of Anionic-Neutral and Cationic-Neutral Block Copolymers
Intermolecular Interactions and Self-Assembly in Aqueous Solution of a Mixture of Anionic-Neutral and Cationic-Neutral Block Copolymers
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DOI：
10.1021/acs.macromol.5b01368
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发表时间：
2015-10-13
期刊：
影响因子：
5.5
通讯作者：
Yusa, Shin-ichi
中科院分区：
文献类型：
--
作者：
Takahashi, Rintaro;Sato, Takahiro;Yusa, Shin-ichi
通过直接观察、光学显微镜和电子显微镜以及小角X射线散射等手段，研究了阴离子-中性嵌段共聚物（AP）和阳离子-中性嵌段共聚物（MP）混合物在稀水溶液中的自组装行为。带电与中性嵌段链长度的比率为约1.5。10.,并且AP和MP的总共聚物浓度和混合比（MP电荷单元在总电荷单元中的摩尔分数）分别固定为0.005g/cm（3）和0.6。随着C-S从2 M降低到0 M，我们发现在AP-MP混合物的水溶液中的可重入单相、两相、单相转变。在C-S类似于0.5 M的两相到单相的转变是由宏观相变和胶束化之间的竞争引起的，这是在稀嵌段共聚物溶液中首次观察到的。此外，我们还发现了从双层囊泡到圆柱形胶束的胶束形态转变，C-S从0.5 M进一步降低到低于0.05 M。
We have investigated the self-assembly in dilute aqueous solutions of a mixture of an anionic-neutral block copolymer (AP) and a cationic-neutral block copolymer (MP) by changing the added sodium chloride (NaCl) concentration C-S or electrostatic interactions among oppositely charged blocks, by direct observation, optical and electron microscopies, and small-angle X-ray scattering. The ratio of the charged to neutral block chain lengths was ca. 10., and the total copolymer concentration and the mixing ratio (the mole fraction of the MP charge unit in the total charge units) of AP and MP were fixed to be 0.005 g/cm(3) and 0.6, respectively. With decreasing C-S from 2 to 0 M, we have found reentrant one-phase, two-phase, one-phase transitions in the aqueous solution of the AP-MP mixture. The two-phase to one-phase transition at C-S similar to 0.5 M arises from the competition between the macroscopic phase transition and micellization, which is the first observation in dilute block copolymer solutions. Moreover, we have found a micelle morphology transition from the bilayer vesicle to the cylindrical micelle with further decreasing C-S from 0.5 M to lower than 0.05 M.