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

Abstract

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 (C₉P₁E_n and C₉B₁E_n) 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 C₉P₁E_n and C₉B₁E_n exhibited lower γ_CMC values compared to the isononanol polyether surfactant (C₉E_n), 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.