Molecular Dynamics Simulations of Supramolecular Polymers within Nanoconfinements for Enhanced Oil Recovery

Supramolecular polymers offer promising potential for enhanced oil recovery (EOR) advancing techniques. Current instrumental analyses face limitations in capturing instantaneous intracomplex motions due to temporal and spatial constraints. The molecular mechanism of supramolecular polymer transport behavior within nanoconfinement is not yet fully understood. Therefore, the self-assembly mechanism of β-cyclodextrin (β-CD) and adamantane (ADA)-modified supramolecular polymers (p-AA-β-CD-ADA) was delved into in this work. Further exploration focuses on the translocation dynamics of p-AA-β-CD-ADA within nanoconfinement under external driving forces. Results suggest that β-CD and ADA in p-AA-β-CD-ADA were assembled into nodes in the form of a host and a guest, combining with a "node-rebar-cement" interaction model encapsulating the formation mechanism of these supramolecular polymers. The heightened density of the hydrate layers at the nanoscale pore throats acts as a constraining factor, resulting in restricted mobility and altered dynamics of the supramolecular polymers. During passage through nanopore throats, host-guest molecules within the supramolecular polymer experience noncovalent dissociation. Notably, these supramolecular polymers exhibit remarkable self-healing capabilities, reinstating their assembly state upon traversing pore throats. This work provides a molecular-level comprehension of the potential utility of supramolecular polymers in EOR processes, offering valuable information for the molecular design of polymers employed for EOR in low-permeability reservoirs.

Study on the Effect of Polymer-Modified Magnetic Nanoparticles on Viscosity Reduction of Heavy Oil Emulsion

To overcome the problems of large dosage, fast sedimentation, and the unsatisfactory emulsification effect of traditional magnetic nanoparticles, polymer-modified magnetic nanoparticle Co3O4@HPAM was synthesized as an emulsifier for heavy oil O/W emulsion by modifying the surface of Co3O4. The composition of Co3O4@HPAM was characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. Then, the effects of the mass fraction of magnetic nanoparticles before and after modification on the stability and rheology of the emulsion were compared and analyzed. The experiments show that the degree of reduction of the water-separation rate under the action of Co3O4@HPAM was 13 times higher than that under the action of Co3O4 at the same mass fraction. By using Co3O4@HPAM, the water separation of the emulsion was only 6.74% at 4 h, while the viscosity reduction was greater than 97% at a mass fraction of 0.04%. Finally, combined with the test results of zeta potential, interfacial tension, contact angle, and oil droplet distribution, the effect mechanism of Co3O4@HPAM on the viscosity reduction of heavy oil emulsification was investigated. It is found that the polymer-modified magnetic nanoparticles have stronger negative electricity, a larger contact angle, and smaller interfacial tension, while the oil droplets under their action have a smaller radius and a more homogeneous distribution. The research in this paper provides a theoretical basis for the application of magnetic nanoparticles in heavy oil emulsification and viscosity reduction technology.

Advances of supramolecular interaction systems for improved oil recovery (IOR)

Improved oil recovery (IOR) includes enhanced oil recovery (EOR) and other technologies (i.e. fracturing, water injection optimization, etc.), have become important methods to increase the oil/gas production in petroleum industry. However, conventional flooding systems always encounter the problems of low efficiency, high cost and complicated synthetic procedures for harsh reservoirs conditions. In recent decades, the supramolecular interactions are introduced into IOR processes to simplify the synthetic procedures, alter their structures and properties with bespoke functionalities and responsiveness suitable for different conditions. Herein, we primarily review the fundamentals of several supramolecular interactions, including hydrophobic association, hydrogen bond, electrostatic interaction, host-guest recognition, metal-ligand coordination and dynamic covalent bond from intrinsic principles and extrinsic functions. Then, the descriptions of supramolecular interactions in IOR processes from categories and advances are focused on the following variables: polymer, surfactant, surfactant/polymer (SP) complex for EOR and viscoelasticity surfactant (VES) for clean hydraulic fracturing aspects. Finally, the field applications, challenges and prospects for supramolecular interactions in IOR processes are involved and systematically addressed. The development of supramolecular interactions can open the way toward adaptive and evolutive IOR technology, a further step towards the cost-effective production of petroleum industry.

Enhanced Adhesion and Cohesion of Bioinspired Dry/Wet Pressure-Sensitive Adhesives

The byssus-mediated adhesion of marine mussels is a widely mimicked system for robust adhesion in both dry and wet conditions. Mussel holdfasts are fabricated from proteins that contain a significant amount of the unique catecholic amino acid dihydroxyphenylalanine, which plays a key role in enhancing interfacial adhesion to organic and inorganic marine surfaces and contributes to cohesive strength of the holdfast. In this work, pressure-sensitive adhesives (PSAs) were synthesized by copolymerization of dopamine methacrylamide (DMA) with common PSA monomers, butyl acrylate and acrylic acid, with careful attention paid to the effects of catechol on adhesive and cohesive properties. A combination of microscopic and macroscopic adhesion assays was used to study the effect of catechol on adhesion performance of acrylic PSAs. Addition of only 5% DMA to a conventional PSA copolymer containing butyl acrylate and acrylic acid resulted in 6-fold and 2.5-fold increases in work required to separate the PSA from silica and polystyrene, respectively, and a large increase in 180° peel adhesion against stainless steel after 24 h storage in both ambient and underwater conditions. Moreover, the holding power of the catechol PSAs on both steel and high-density polyethylene under shear load continuously increased as a function of catechol concentration, up to a maximum of 10% DMA. We also observed stark increases in shear and peel adhesion for the catecholic adhesives over PSAs with noncatecholic aromatic motifs, further underlining the benefits of catechols in PSAs. Overall, catechol PSAs perform extremely well on polar and metallic surfaces. The advantage of incorporating catechols in PSA formulations, however, is less straightforward for peel adhesion in nonpolar, organic substrates and tackiness of the PSAs.