We have performed detailed molecular dynamics simulations to investigate the effects of solvation and confinement on the structure of polystyrene (PS) oligomers in four different environments, melt, concentrated solution, dilute solution and confined concentrated solution at 450 K and 1 bar, respectively. Local packing of the monomers and the solvent (toluene, good solvent) molecules were monitored by means of radial distribution functions (RDFs). We have also investigated bond, angle, and dihedral angle distributions of the monomers. End-to-end distances, radii of gyration and persistence lengths were calculated to characterize the static properties. The chain in the dilute solution was found to exhibit more stretched conformations. Dilution effect of the solvent was observed in the RDFs between the monomer centers. Only slight conformational changes in the polymers were observed by solvation. The effect of confinement was mainly seen in the density profiles, which showed an oscillatory behavior in the confined system.
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http://dx.doi.org/10.1039/c1cp21724k | DOI Listing |
Langmuir
January 2025
Research Center for Water Resources and Interface Science, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
The mechanism of the emulsion polymerization of styrene to polystyrene nanoparticles (PSNPs) remains a subject of debate. Herein, a series of reaction parameters with different surfactant concentrations, monomer contents, temperatures, and equilibration times were investigated to understand the formation mechanism of PSNPs, which demonstrate a correlation between the properties of PSNPs and the mesostructure of the premix. Cooling the model systems with self-emulsifying nanodroplets (SENDs) in the early reaction stages resulted in the hollow polystyrene spheres (H-PSSs), ruptured PSNPs, and dandelion-like PSNPs, further indicating that the oil nanodroplets are the key sites for the formation of PSNPs.
View Article and Find Full Text PDFChem Sci
January 2025
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University Changchun Jilin 130012 China
The chemical recycling of polystyrene (PS) waste to value-added aromatic compounds is an attractive but formidable challenge due to the inertness of the C-C bonds in the polymer backbone. Here we develop a light-driven, copper-catalyzed protocol to achieve aerobic oxidation of various alkylarenes or real-life PS waste to benzoic acid and oxidized styrene oligomers. The resulting oligomers can be further transformed under heating conditions, thus achieving benzoic acid in up to 65% total yield through an integrated one-pot two-step procedure.
View Article and Find Full Text PDFNanoscale
January 2025
Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
Waste Manag
January 2025
Plastic and Polymer Engineering, Department of Biological and Chemical Engineering, Aarhus University, Aabogade 40, DK-8200 Aarhus N., Denmark. Electronic address:
Plastic recycling is gaining traction to reduce the demand for fossil resources for plastic production. Poly(ethylene terephthalate) (PET), mainly used in the packaging and textile sectors, is often isolated in the sinking fraction during the density-based separation of mixed plastic waste streams. The heterogeneity of the sinking fraction makes direct mechanical recycling of PET impossible.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Univ. Bordeaux, CNRS, Bordeaux INP, ISM UMR 5255, F-33400, Talence, France.
Polystyrene (PS) is a commodity plastic recalcitrant to chemical recycling or upcycling processes. Approaches aimed at deconstructing PS by photocatalytic means struggle to generate high-energy species capable of cleaving the robust C-H and C-C bonds of PS. We show that 9-mesityl-10-methylacridinium perchlorate (MA) is capable of upcycling various grades of PS substrates into up to 40 % benzoic acid (BAc), formic acid (FA) and small proportions of acetophenone (ACP), under visible light (456 nm) or through solar radiation.
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