Pinprayoon Orawan, Saiani Alberto, Groves Robert, Saunders Brian R
Polymer Science and Technology Group, School of Materials, The University of Manchester, Grosvenor Street, M1 7HS, UK.
J Colloid Interface Sci. 2009 Aug 1;336(1):73-81. doi: 10.1016/j.jcis.2009.03.081. Epub 2009 Apr 8.
Polymers with properties that are governed by ionic interactions in discrete regions are termed ionomers. This work presents a comprehensive study of polymer films prepared from dispersions of crosslinked poly(butadiene/methacrylic acid) (poly(Bd/MAA)) particles in water. We showed recently [O. Pinprayoon, R. Groves, B.R. Saunders, J. Colloid Interface Sci. 321 (2008) 315-322] that poly(Bd/MAA) particles could be considered to have a core-shell structure with a MAA-rich shell. The poly(Bd/MAA) dispersions used here contained added ZnO particles which provided a source of Zn(2+). The films were investigated using AFM, FTIR, small-angle X-ray scattering (SAXS), dynamic mechanical thermal analysis (DMTA) and tensile stress vs. strain measurements. The films showed differences and similarities to conventional ionomers which are discussed. The FTIR data revealed that the Zn(2+) ions formed ionic crosslinks with the carboxylate groups (RCOO(-)). Mechanical property studies were conducted using DMTA and stress vs. strain measurements. The DMTA data revealed evidence of two main phases in the systems: a poly(Bd)-rich phase and a poly(MAA)-rich phase. A third phase was also found; which was ascribed to an interphase between the particle core and shell. The SAXS data showed that the films were composed of distinct poly(Bd/MAA) particles, implying that only partial coalescence occurred across the particle interfaces during formation of these particulate ionomer films. Ionic crosslinking of the particles was suggested to occur in the interfacial region (knit regions). The SAXS data also showed scattering from Zn(2+)(RCOO(-)) ionic-aggregates. These ionic aggregates had an average separation of 2.9 nm, which is much smaller than that for conventional ionomers. Interestingly, the concentration of these aggregates passed through a maximum and decreased as the degree of neutralisation of the MAA groups approached 100%. A conceptual model for the structure of these unconventional ionomers is discussed.
在离散区域中其性能受离子相互作用支配的聚合物被称为离聚物。这项工作对由交联聚（丁二烯/甲基丙烯酸）（聚（Bd/MAA））颗粒在水中的分散体制备的聚合物薄膜进行了全面研究。我们最近表明[O. Pinprayoon，R. Groves，B.R. Saunders，J. Colloid Interface Sci. 321 (2008) 315 - 322]，聚（Bd/MAA）颗粒可被认为具有富含MAA的壳的核壳结构。这里使用的聚（Bd/MAA）分散体含有添加的ZnO颗粒，其提供了Zn(2+)源。使用原子力显微镜（AFM）、傅里叶变换红外光谱（FTIR）、小角X射线散射（SAXS）、动态热机械分析（DMTA）以及拉伸应力与应变测量对薄膜进行了研究。这些薄膜与传统离聚物表现出异同，对此进行了讨论。FTIR数据表明Zn(2+)离子与羧酸根基团（RCOO(-)）形成了离子交联。使用DMTA以及应力与应变测量进行了力学性能研究。DMTA数据揭示了体系中两个主要相的证据：富含聚（Bd）的相和富含聚（MAA）的相。还发现了第三相；其归因于颗粒核与壳之间的界面相。SAXS数据表明薄膜由不同的聚（Bd/MAA）颗粒组成，这意味着在这些颗粒状离聚物薄膜形成过程中，仅在颗粒界面发生了部分聚结。颗粒的离子交联被认为发生在界面区域（编织区域）。SAXS数据还显示了来自Zn(2+)(RCOO(-))离子聚集体的散射。这些离子聚集体的平均间距为2.9 nm，这比传统离聚物的间距小得多。有趣的是，随着MAA基团的中和度接近100%，这些聚集体的浓度先达到最大值然后降低。讨论了这些非常规离聚物结构的概念模型。
