EO/PO composition ratio analysis of EO-PO copolymer using JMS-S3000 "SpiralTOF™-plus3.0" and "msRepeatFinder"
Ethylene oxide-propylene oxide (EO-PO) copolymer is one of copolymer type nonionic surfactants (nonionic surfactants) that combines hydrophilic EO and hydrophobic PO. It is used in various fields such as lubricants, antifoaming agents, emulsifiers, solubilizers, detergents, and antistatic agents. The physical properties of EO-PO copolymers are controlled by the sequence of EO/PO, such as random copolymerization or block copolymerization, and the number of added moles. MALDI is one of the typical soft ionization methods, and since ions derived from polymers are mainly singly charged ions, the m/z on the mass spectrum is the mass of the polymer ions. The use of high-mass-resolution MALDI-TOFMS makes it possible to easily identify polymer series due to differences in the composition of repeating units and end groups, and to calculate the molecular weight distribution of each. Using the KMD method, it became possible to easily visualize polymer series contained in complex high-mass-resolution mass spectra. In MSTips No. 423, structural analysis of EO-PO random copolymers and block copolymers was performed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) and solution nuclear magnetic resonance (NMR), complementary. As a result, similar values for the EO and PO composition ratio can be obtained when comparing the quantitative analysis of MALDI-TOFMS and NMR. In this application note, the EO/PO composition ratio using MALDI-TOFMS were investigated for the EO-PO copolymers with six different molecular weight distributions and EO/PO compositions.