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Effects of ethylene oxide chain length on crystallization of polysorbate 80 and its related compounds

DOI: 10.1016/j.jcis.2021.01.065 DOI Help

Authors: Tania K. Lind (Malmö University) , Emelie J. Nilsson (Malmö University) , Benjamin Wyler (Lonza AG) , Dieter Scherer (Lonza AG) , Tatyana Skansberger (Malmö University) , Maxim Morin (Malmö University) , Vitaly Kocherbitov (Malmö University) , Johan Engblom (Malmö University)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Journal Of Colloid And Interface Science , VOL 592 , PAGES 468 - 484

State: Published (Approved)
Published: June 2021
Diamond Proposal Number(s): 22299

Open Access Open Access

Abstract: 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.

Journal Keywords: Polysorbate 80; Thermotropic behavior; Liquid chromatography; Differential scanning calorimetry; Ethylene oxide chains; Crystallization

Subject Areas: Chemistry

Instruments: I22-Small angle scattering & Diffraction


Discipline Tags:

Organic Chemistry Chemistry

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS) Wide Angle X-ray Scattering (WAXS)