Substitution of Alkylphenol Polyoxyethylene Ethers with Bio-Based Surfactants: Their Synthesis, Properties, and Performance Evaluation

The growing demand for sustainable, biodegradable, and low-toxicity products has accelerated innovations in bioderived chemicals and materials. Since the restriction of alkylphenol polyoxyethylene ethers, substituting these surfactants with safer, greener, and more eco-friendly chemicals has been a goal for researchers to strive. Herein, we report three biobased nonionic surfactants (PAHA-EO, PAOA-EO, and PAIA-EO) derived from the esterification of renewable biomass phloretic acid and straight- or branched-chain fatty alcohols followed by alkoxylation. The chemical structures of PAHA-EO, PAOA-EO, and PAIA-EO were confirmed by ¹HNMR and FT-IR spectra. A comprehensive characterization of their physicochemical properties, including surface activity, aggregation behavior, and adsorption parameters, was performed. Surface tension measurements revealed critical micelle concentration (CMC) values of 0.51 mmol/L, 0.31 mmol/L, and 0.42 mmol/L for PAHA-EO, PAOA-EO, and PAIA-EO, respectively. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses demonstrated that these surfactants form spherical micelles in aqueous solutions at concentrations exceeding their CMC. The wetting properties of the three surfactants were evaluated through the measurement of the dynamic contact angle, with the resulting θ_t values for PAHA-EO, PAOA-EO, and PAIA-EO being 58.3°, 54.6°, and 55.4°, respectively. Finally, the emulsification capacity of these surfactants was evaluated, and the biobased surfactants showed excellent emulsion stability to emulsions prepared from hexadecane, olive oil, and soybean oil. Compared with traditional alkylphenol polyoxyethylene ethers (OP-10 and NP-10), these biobased surfactants exhibit comparable surface activity and wettability while surpassing them in emulsification efficiency, demonstrating promising potential as high-performance sustainable alternatives.