The Dow Chemical Company, Analytical Sciences, Collegeville, PA 19426, USA.
The Dow Chemical Company, Home and Personal Care, Collegeville, PA 19426, USA.
J Chromatogr A. 2018 Jul 27;1560:55-62. doi: 10.1016/j.chroma.2018.05.033. Epub 2018 May 16.
Hydrophobically modified ethylene oxide urethane (HEUR) rheology modifiers are polymers used widely in waterborne coatings and other consumer products. The incorporation of hydrophobic end-groups significantly affects the thickening performance of HEURs. Therefore, understanding the degree of incorporation of hydrophobic end-groups on the polymer chain can help gain important insights on the structure/property relationship for HEUR rheology modifiers. A comprehensive two-dimensional liquid chromatography (2D-LC) method was developed for separating polymeric HEUR rheology modifiers based on the number of hydrophobic end-groups incorporated on the polymer chain. Our 2D-LC method uses a size exclusion chromatography (SEC) separation in the first dimension (D) using an ultra-high performance Advance Polymer Chromatography (APC) column and a gradient reversed-phase liquid chromatography (RPLC) separation in the second dimension (D). A low flow rate was used in the first dimension SEC separation to minimize the strong organic eluent transferred to the second dimension LC column. A small inner diameter (ID) LC column was used for the second dimension to reduce the total solvent consumption for routine analysis of process samples. The D flow rate, D transfer volume and gradient profile were all optimized to avoid polymer breakthrough and to achieve optimal separation of the polymer chains based on end-groups. Three types of polymer chains with 0, 1, and 2 terminal hydrophobes were successfully separated using this method. The total run time was further reduced by implementing flow programing in the first dimension separation. The 2D-LC method was applied to study how the polymerization process recipes affected hydrophobe incorporation and how the hydrophobe incorporation correlated with thickening efficiency. The method was also used to separate HEUR rheology modifier with branched polymer architecture.
疏水改性氧化乙烯基聚氨酯（HEUR）流变改性剂是广泛应用于水性涂料和其他消费产品的聚合物。疏水端基的引入显著影响 HEUR 的增稠性能。因此，了解聚合物链上疏水端基的引入程度有助于深入了解 HEUR 流变改性剂的结构-性能关系。本文开发了一种全面的二维液相色谱（2D-LC）方法，用于根据聚合物链上引入的疏水端基数量分离聚合型 HEUR 流变改性剂。我们的 2D-LC 方法在第一维（D）中使用超高效 Advance Polymer Chromatography（APC）柱进行尺寸排阻色谱（SEC）分离，在第二维（D）中使用梯度反相液相色谱（RPLC）分离。在第一维 SEC 分离中使用低流速，以最大程度减少转移到第二维 LC 柱的强有机溶剂。在第二维中使用小内径（ID）LC 柱，以减少常规过程样品分析的总溶剂消耗。D 流速、D 转移体积和梯度轮廓均经过优化，以避免聚合物穿透，并根据端基实现聚合物链的最佳分离。该方法成功分离了具有 0、1 和 2 个末端疏水性的三种聚合物链。通过在第一维分离中实施流程序，进一步缩短了总运行时间。该 2D-LC 方法用于研究聚合过程配方如何影响疏水性引入，以及疏水性引入如何与增稠效率相关。该方法还用于分离具有支化聚合物结构的 HEUR 流变改性剂。
