Branched polyoxyethylene surfactants with different hydrophilic head groups from fatty acid derivatives

Advances in surfactants for photolithography

The advancement of dense integrated circuits requires the miniaturization of feature sizes, which has driven continuous progress in photolithography. However, there are still some challenges in achieving a high patterning resolution for photolithography such as surface contaminants, defect formation, pattern collapse, etc. Surfactants have been extensively investigated for several decades as essential wet chemicals to resolve these issues due to their outstanding performance in reducing surface tension, enhancing wettability, and improving solubility. Recently, it has been revealed that surfactants with diverse chemical structures can exhibit distinct functionalities at various stages of the photolithography process, yet comprehensive discussions on their structures, performance, and mechanisms remain limited. In this review, we first address the structure-performance relationships for anionic, cationic, nonionic, and zwitterionic surfactants and then provide a general introduction to photolithography from a historical and technological perspective. Specifically, various surfactants used as additives in cleaners, developers, etchants, and strippers for photolithography are thoroughly summarized and discussed, where their key parameters, used concentrations, and underlying mechanisms have been introduced to provide a valuable guide for future research. Finally, we propose three strategic directions for the development of innovative surfactants to address emerging challenges and drive sustainable progress in photolithography: (1) high-performance surfactants, (2) switchable surfactants, and (3) bio-based surfactants.

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 θt 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.

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.

Ecofriendly Natural Surfactants in the Oil and Gas Industry: A Comprehensive Review

The use of different types of chemicals in upstream oilfield operations is critical for optimizing the different operations involved in hydrocarbon exploration and production. Surfactants are a type chemical that are applied in various upstream operations, such as drilling, fracturing, and enhanced oil recovery. However, due to their nonbiodegradability and toxicity, the use of synthetic surfactants has raised environmental concerns. Natural surfactants have emerged because of the hunt for sustainable and environmentally suitable substitutes. This Review discusses the role of natural surfactants in upstream operations as well as their benefits and drawbacks. The Review discusses the basic characteristics of surfactants, their classification, and the variables that affect their performance. Finally, the Review examines the possible applications of natural surfactants in the upstream oil sector and identifies areas that require further research.

Synthesis of a branched surfactant from the castor derivative and its surface properties

A new class of ricinoleic acid-derived branched surfactant with a Y-shaped structure (ethoxylated monohydroxy stearic acid methyl ester, 12-HMEE_n) was synthesized and characterized by introducing a polyoxyethylene head group in the hydroxyl position inside the molecule. The physicochemical properties and surface activities of 12-HMEE_n with different degrees of ethoxylation at various concentrations were studied. The typical Y-shaped structure of the molecule facilitates its adsorption at the interface, which provides an excellent surface activity and affects its surfactant properties significantly. The dynamic contact angle, wettability, foaming properties, and compatibility tests of 12-HMEE_n showed that it has good wetting performance, low foaming and fast defoaming properties, and good compatibility in formulation applications, indicating that the surfactant has potential application in industrial cleaning.