Rheology and microscopy analysis of polymer–surfactant complexes

Cleaning Oil-Based Drilling Cuttings with Synthetic Gemini Surfactants

The chemical cleaning method is the simplest approach for degreasing oil-based drilling cuttings (ODCs), with the effectiveness of the treatment relying mainly on the selection of the surfactant and the cleaning conditions. However, achieving the standard treatment of ODCs directly using conventional surfactants proves challenging. In light of this, this study introduces a synthesized and purified Gemini surfactant named DCY-1. The structure of DCY-1 was confirmed through Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analyses. The characterization in this article encompasses the use of an interface tension meter, nanoparticle size analysis, scanning electron microscopy, and infrared oil measurement. The critical micelle concentration (CMC) of DCY-1 was determined to be 3.37 × 10-3 mol/L, with a corresponding γcmc value of 37.97 mN/m. In comparison to conventional surfactants, DCY-1 exhibited a larger micelle size of 4.52 nm, approximately 24.52% larger than that of SDS. Moreover, the residual oil rate of 3.96% achieved by DCY-1 was the lowest among the chemical cleaning experimental results. Through a single-factor experiment, the optimal cleaning ability of DCY-1 for ODCs was determined as follows: a surfactant concentration of 3 mmol/L, a temperature of 60 °C, an ODC/liquid mass ratio of 1:4, a cleaning duration of 40 min, and a stirring speed of 1000 rad/min. Under these optimal conditions and after merely two cleaning procedures, the residual oil content of ODCs was reduced to 1.64%, accompanied by a smooth and loose surface structure.

Single core and multicore aggregates from a polymer mixture: A dissipative particle dynamics study

HYPOTHESIS

Multicore block copolymer aggregates correspond to self-assembly such that the polymer system spontaneously phase separates to multiple, droplet-like cores differing in the composition from the polymer surroundings. Such multiple core aggregates are highly useful capsules for different applications, e.g., drug transport, catalysis, controlled solvation, and chemical reactions platforms. We postulate that polymer system composition provides a direct means for designing polymer systems that self-assemble to such morphologies and controlling the assembly response.

SIMULATIONS

Using dissipative particle dynamics (DPD) simulations, we examine the self-assembly of a mixture of highly and weakly solvophobic homopolymers and an amphiphilic block copolymer in the presence of solvent. We map the multicore vs single core (core-shell particles) assembly response and aggregate structure in terms of block copolymer concentration, polymer component ratios, and chain length of the weakly solvophobic homopolymer.

FINDINGS

For fixed components and polymer chemistries, the amount of block copolymer is the key to controlling single core vs multicore aggregation. We find a polymer system dependent critical copolymer concentration for the multicore aggregation and that a minimum level of incompatibility between the solvent and the weakly solvophobic component is required for multicore assembly. We discuss the implications for polymer system design for multicore assemblies. In summary, the study presents guidelines to produce multicore aggregates and to tune the assembly from multicore aggregation to single core core-shell particles.

Non-Ionic Surfactant Effects on Innate Pluronic 188 Behavior: Interactions, and Physicochemical and Biocompatibility Studies

The aim of this research was to prepare novel block copolymer-surfactant hybrid nanosystems using the triblock copolymer Pluronic 188, along with surfactants of different hydrophilic to lipophilic balance (HLB ratio-which indicates the degree to which a surfactant is hydrophilic or hydrophobic) and thermotropic behavior. The surfactants used were of non-ionic nature, of which Tween 80® and Brij 58® were more hydrophilic, while Span 40® and Span 60® were more hydrophobic. Each surfactant has unique innate thermal properties and an affinity towards Pluronic 188. The nanosystems were formulated through mixing the pluronic with the surfactants at three different ratios, namely 90:10, 80:20, and 50:50, using the thin-film hydration technique and keeping the pluronic concentration constant. The physicochemical characteristics of the prepared nanosystems were evaluated using various light scattering techniques, while their thermotropic behavior was characterized via microDSC and high-resolution ultrasound spectroscopy. Microenvironmental parameters were attained through the use of fluorescence spectroscopy, while the cytotoxicity of the nanocarriers was studied in vitro. The results indicate that the combination of Pluronic 188 with the above surfactants was able to produce hybrid homogeneous nanoparticle populations of adequately small diameters. The different surfactants had a clear effect on physicochemical parameters such as the size, hydrodynamic diameter, and polydispersity index of the final formulation. The mixing of surfactants with the pluronic clearly changed its thermotropic behavior and thermal transition temperature (Tm) and highlighted the specific interactions that occurred between the different materials, as well as the effect of increasing the surfactant concentration on inherent polymer characteristics and behavior. The formulated nanosystems were found to be mostly of minimal toxicity. The obtained results demonstrate that the thin-film hydration method can be used for the formulation of pluronic-surfactant hybrid nanoparticles, which in turn exhibit favorable characteristics in terms of their possible use in drug delivery applications. This investigation can be used as a road map for the selection of an appropriate nanosystem as a novel vehicle for drug delivery.