Mohanty P S, Dietsch H, Rubatat L, Stradner A, Matsumoto K, Matsuoka H, Schurtenberger P
Adolphe Merkle Institute, Fribourg Centre for Nanomaterials, Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland.
Langmuir. 2009 Feb 17;25(4):1940-8. doi: 10.1021/la803125v.
Amphiphilic diblock copolymers such as poly(styrene)-block-poly(styrene sulfonate) (PS-b-PSS) (Matsuoka, H.; Maeda, S.; Kaewsaiha, P.; Matsumoto, K. Langmuir 2004, 20, 7412), belong to a class of new polymeric surfactants that ionize strongly in aqueous media. We investigated their self-assembly behavior in aqueous solutions and used them as an emulsifier to prepare electrosterically stabilized colloidal particles of different diameters between 70 to 400 nm. We determined the size, size polydispersity, effective charge, total dissociable charge, structural ordering, and phase behavior using light scattering, transmission electron microscopy (TEM), small-angle neutron scattering (SANS), and potentiometric titration. These experiments clearly demonstrated that all of the synthesized particles were nearly monodisperse (polydispersity index<or=6%). The results of DLS and TEM clearly suggested the existence of hairy particles. The form factors obtained by SANS were well described by a polydisperse sphere model. The estimated total number of dissociable charges per particle was found to be larger than 10(4)e, whereas the effective charges per particle were found to be around 1000e. This significant difference suggested the confinement of charges inside the corona regions of the polyelectrolyte brush shell. Finally, these monodisperse particles were found to self-assemble into 3D ordered colloidal crystalline arrays at a low volume fraction (=0.00074) that diffract light in the visible region.
两亲性二嵌段共聚物，如聚（苯乙烯）-嵌段-聚（苯乙烯磺酸盐）（PS-b-PSS）（松冈，H；前田，S；凯赛哈，P；松本，K。《朗缪尔》2004年，20卷，7412页），属于一类在水性介质中强烈电离的新型聚合物表面活性剂。我们研究了它们在水溶液中的自组装行为，并将它们用作乳化剂来制备直径在70至400纳米之间的不同尺寸的静电稳定胶体颗粒。我们使用光散射、透射电子显微镜（TEM）、小角中子散射（SANS）和电位滴定法来确定颗粒尺寸、尺寸多分散性、有效电荷、总可解离电荷、结构有序性和相行为。这些实验清楚地表明，所有合成颗粒几乎都是单分散的（多分散指数≤6%）。动态光散射（DLS）和TEM的结果清楚地表明存在多毛颗粒。SANS获得的形状因子可以用多分散球体模型很好地描述。发现每个颗粒的估计总可解离电荷数大于10⁴e，而每个颗粒的有效电荷数约为1000e。这一显著差异表明电荷被限制在聚电解质刷壳的冠层区域内。最后，发现这些单分散颗粒在低体积分数（=0.00074）下自组装成三维有序胶体晶体阵列，在可见光区域产生光衍射。
