Biomedical Sciences, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden; Biofilms - Research Center for Biointerfaces, Malmö University, SE-205 06 Malmö, Sweden.
Biomedical Sciences, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden; Biofilms - Research Center for Biointerfaces, Malmö University, SE-205 06 Malmö, Sweden.
J Colloid Interface Sci. 2021 Jun 15;592:468-484. doi: 10.1016/j.jcis.2021.01.065. Epub 2021 Jan 26.
As a result of the synthesis protocol polyoxyethylene sorbitan monooleate (polysorbate 80, PS80) is a highly complex mixture of compounds. PS80 was therefore separated into its main constituents, e.g. polyoxyethylene isosorbide esters and polyoxyethylene esters, as well as mono- di- and polyesters using preparative high-performance liquid chromatography. In this comprehensive study the individual components and their ethoxylation level were verified by matrix assisted laser desorption/ionization time-of-flight and their thermotropic behavior was analyzed using differential scanning calorimetry and X-ray diffraction. A distinct correlation was found between the average length of the ethylene oxide (EO) chains in the headgroup and the individual compounds' ability to crystallize. Importantly, a critical number of EO units required for crystallization of the headgroup was determined (6 EO units per chain or 24 per molecule). The investigation also revealed that the hydrocarbon tails only crystallize for polyoxyethylene sorbitan esters if saturated. PS80 is synthesized by reacting with approximately 20 mol of EO per mole of sorbitol, however, the number of EO units in the sorbitan ester in commercial PS80 products is higher than the expected 20 (5 EO units per chain). The complex behavior of all tested compounds revealed that if the amount of several of the linear by-products is reduced, the number of EO units in the chains will stay below the critical number and the product will not be able to crystallize by the EO chains.
由于合成方案，聚氧乙烯山梨糖醇单油酸酯（聚山梨酯 80，PS80）是一种高度复杂的化合物混合物。因此，PS80 使用制备高效液相色谱法分离成其主要成分，例如聚氧乙烯异山梨醇酯和聚氧乙烯酯，以及单、二和聚酯。在这项综合研究中，使用基质辅助激光解吸/电离飞行时间和差示扫描量热法和 X 射线衍射法验证了各个成分及其乙氧基化水平。发现头基中乙氧基（EO）链的平均长度与各个化合物的结晶能力之间存在明显的相关性。重要的是，确定了结晶头基所需的 EO 单元的临界数量（每个链 6 个 EO 单元或每个分子 24 个 EO 单元）。研究还表明，只有当聚氧乙烯山梨醇酯的烃尾链饱和时才会结晶。PS80 是通过与山梨糖醇反应合成的，每摩尔山梨糖醇约有 20 摩尔的 EO，但商业 PS80 产品中山梨醇酯中的 EO 单元数高于预期的 20（每个链 5 个 EO 单元）。所有测试化合物的复杂行为表明，如果几种线性副产物的数量减少，链中的 EO 单元数量将低于临界数量，并且产品将无法通过 EO 链结晶。
