Synthesis and Properties of Isononyl-Extended Multibranched Alcohol Polyether Nonionic Surfactants

Isononanol, a branched aliphatic alcohol, is derived from isobutylene upgradation, encompassing dimerization and hydroformylation. Branched surfactants exhibit lower surface tension, superior wettability, and rapid defoaming compared to linear surfactants. Isononanol (C9–OH) with abundant methyl branching can serve as a hydrophobic tail of branched surfactants, suffering from insufficient lipophilicity due to its short effective chain length. This paper proposes a strategy to extend the hydrophobic tail by grafting one propylene oxide (P1) or butylene oxide (B1) to increase chain length and branching degree with the aim of synthesizing extended multibranched alcohols C9P1–OH and C9B1–OH with purities of 95.3 and 97.2%, respectively. Subsequently, a series of extended multibranched alcohol polyether nonionic surfactants (C9P1En and C9B1En) were synthesized by ethoxylation, with their structures confirmed by Fourier-transform infrared (FT-IR) and 1H NMR and their surfactant properties systematically investigated. The findings indicate that C9P1En and C9B1En exhibited lower γCMC values compared to the isononanol polyether surfactant (C9En), which allows for rapid wetting on a hydrophobic surface, especially C9B1E6 with an initial contact angle of only 54° compared to 80° for C9E6. Also remarkable is the rapid defoaming performance, with C9B1E6 having less than 0.1% of the initial foam volume but C9E6 having up to 50.1% foam volume after 30 s. These surfactant performances provide significant benefits for the potential application of branched nonionic surfactants in the industrial cleaning field.