Critical need for absolute molecular weight determination on size exclusion chromatography system

尺寸排阻色谱系统绝对分子量测定的迫切需求

• 批准号: RTI-2023-00316
• 负责人: Tran, Helen
• 金额: $ 10.93万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748370
• 关键词: Critical; need; absolute; molecular; weight

The size, or molecular weight, of a polymer is one of the most important factors in determining physical properties. Viscosity, degree of crystallinity, stiffness, bioavailability, conductivity, and other properties are all intimately associated with molecular weight. For example, for a given identical repeat unit of ethylene, polypropylene with a low molecular weight may be used as a plastic bag but polypropylene with ultrahigh high molecular weight may be used as anti-stab vests. Size exclusion chromatography (SEC) is a ubiquitous equipment to determine the molecular weight. The molecular weight is estimated by the time it takes for the polymer to elute from the column: the smaller the polymer, the more it interacts with the stationary solid phase of the column, the longer it takes to elute. Notably, typical methods widespread in the polymer research community and also at UofT inaccurately determine the molecular weight. Most researchers use a set of standard polymer samples with known molecular weight to create a calibration curve to correlate the time it takes for a polymer to elute and its known molecular weight. However, the time it takes to elute is intimately related to the identity of the polymer. For the same molecular weight, a polymer that is tightly coiled in a select solvent will elute at a different time that a polymer that is loosely coiled. Thus, the identity of the standard polymer samples used to create the calibration curve must match the identity of the polymer to be characterized. Since there are limited standards, often poly(styrene) or poly(methyl methacrylate) is used as a standard. Thus, the molecular weights determined by SEC calibrated against a standard is only a good estimated if the unknown polymer behaves like the standards. As new polymers are being developed at UofT, we are discovering that this estimation is no longer appropriate, where there are very large discrepancies. The requested SEC system coupled with a multi-angle light scattering technique, the first of its type at UofT and surrounding institutions to our knowledge, will enable the local polymer research community to determine absolute molecular weight. Moreover, the selected solvent system of chloroform is missing from UofT, which is the only solvent which solubilizes the new conjugated polymers developed by some of the UofT researchers. Also, it uses a quick analysis procedure and 85% less solvent per run than any system that is available on the market. The five co-PIs include Tran, Khan, Seferos, Winnik, and Bender, with more than 50 highly qualified personnel as potential users at the onset.

聚合物的大小或分子量是确定物理特性的最重要因素之一。粘度，结晶度，刚度，生物利用度，电导率和其他特性都与分子量密切相关。例如，对于给定相同的乙烯重复单位，具有低分子量的聚丙烯可以用作塑料袋，但超高分子量的聚丙烯可以用作抗稳定背心。尺寸排除色谱（SEC）是确定分子量的无处不在的设备。分子量是根据聚合物从色谱柱洗脱的时间来估计的：聚合物越小，它与色谱柱的固定相互作用越多，洗脱所需的时间越长。值得注意的是，聚合物研究界的典型方法以及UOFT不准确的情况下确定了分子量。大多数研究人员使用一组具有已知分子量的标准聚合物样品来创建校准曲线，以将聚合物洗脱的时间与已知的分子量相关联。但是，洗脱的时间与聚合物的身份密切相关。对于相同的分子量，在精选溶剂中紧密盘绕的聚合物将在不同时期的聚合物松散盘绕的不同时间洗脱。因此，用于创建校准曲线的标准聚合物样品的身份必须与要表征的聚合物的身份相匹配。由于标准有限，因此通常将聚（苯乙烯）或聚甲基丙烯酸甲酯作为标准。因此，仅当未知聚合物与标准表现出类似于标准的情况下，由SEC确定的SEC确定的分子量是一个良好的估计。随着Uoft开发新聚合物的新聚合物，我们发现此估计不再适当，而存在很大的差异。请求的SEC系统加上多角度的光散射技术，这是UOFT及其周围机构的第一种类型，它将使本地聚合物研究界能够确定绝对的分子量。此外，Uoft缺少所选的氯仿系统，这是唯一溶解了一些UOFT研究人员开发的新的共轭聚合物的溶剂。此外，它使用快速分析程序，每次运行的溶剂少85％，而不是市场上可用的任何系统。这五个共同案件包括Tran，Khan，Seferos，Winnik和Bender，一开始，有50多名高素质的人员作为潜在用户。