Stable, polymer-directed and SPION-nucleated magnetic amphiphilic block copolymer nanoprecipitates with readily reversible assembly in magnetic fields

Self-assembly of amphiphilic poly(styrene-b-acrylic acid) on magnetic latex particles and their application as a reusable scale inhibitor

The deposition of scale on membranes or container and pipe surfaces (clogging the system) is a costly issue in water treatment processes or water-cooling systems. To effectively cope with this issue, magnetic polymeric nanoparticles (MPNPs) have been developed and applied as promising scale inhibitors, due to their high surface-area-to-volume ratio, surface modifiability, and magnetic separation ability. Carboxylated MPNPs, having a monodisperse size distribution (236 ± 26 nm) with a high magnetic content of 70 wt% and superparamagnetic properties, were fabricated by using a 2-step process: (i) formation of clusters of hydrophobic magnetic nanoparticles stabilized by oleic acid (OA-MNPs), and (ii) self-assembly of the amphiphilic block copolymer of poly(styrene₂₇-b-acrylic acid₁₂₀) (PS₂₇-b-PAA₁₂₀) onto the cluster surfaces. With application of ultrasonication to 12.0 wt% OA-MNPs, a three-dimensional network was formed by particle–particle interactions, suppressing coalescence, and then creating stable magnetic clusters. The cluster surfaces were then adsorbed by amphiphilic PS₂₇-b-PAA₁₂₀via the attractive force between hydrophobic PS blocks. This moves longer hydrophilic PAA blocks containing carboxylic acid groups into the water phase. The formulated MPNPs acted as a nanosorbent for calcium ion (Ca²⁺) removal with a removal efficiency of 92%. The MPNPs can be effectively reused for up to 4 cycles. Based on the electrostatic interactions between the negatively-charged polymer and the hydrated Ca²⁺, the resulting precipitation leads to the prevention of calcium carbonate scale formation. Insights into this mechanism open up a new perspective for magnetic-material applications as effective antiscalants.

Carboxylated magnetic polymeric nanoparticles, having a high magnetic content, and superparamagnetic properties were prepared and applied as effective antiscalants.

Evaluation of Self-Assembly Pathways to Control Crystallization-Driven Self-Assembly of a Semicrystalline P(VDF-co-HFP)-b-PEG-b-P(VDF-co-HFP) Triblock Copolymer

To date, amphiphilic block copolymers (BCPs) containing poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-co-HFP)) copolymers are rare. At moderate content of HFP, this fluorocopolymer remains semicrystalline and is able to crystallize. Amphiphilic BCPs, containing a P(VDF-co-HFP) segment could, thus be appealing for the preparation of self-assembled block copolymer morphologies through crystallization-driven self-assembly (CDSA) in selective solvents. Here the synthesis, characterization by 1H and 19F NMR spectroscopies, GPC, TGA, DSC, and XRD; and the self-assembly behavior of a P(VDF-co-HFP)-b-PEG-b-P(VDF-co-HFP) triblock copolymer were studied. The well-defined ABA amphiphilic fluorinated triblock copolymer was self-assembled into nano-objects by varying a series of key parameters such as the solvent and the non -solvent, the self-assembly protocols, and the temperature. A large range of morphologies such as spherical, square, rectangular, fiber-like, and platelet structures with sizes ranging from a few nanometers to micrometers was obtained depending on the self-assembly protocols and solvents systems used. The temperature-induced crystallization-driven self-assembly (TI-CDSA) protocol allowed some control over the shape and size of some of the morphologies.

Nanoformulation-by-design: an experimental and molecular dynamics study for polymer coated drug nanoparticles

The formulation of drug compounds into nanoparticles has many potential advantages in enhancing bioavailability and improving therapeutic efficacy. However, few drug molecules will assemble into stable, well-defined nanoparticulate structures. Amphiphilic polymer coatings are able to stabilise nanoparticles, imparting defined surface properties for many possible drug delivery applications. In the present article we explore, both experimentally and in silico, a potential methodology to coat drug nanoparticles with an amphiphilic co-polymer. Monomethoxy polyethylene glycol-polycaprolactone (mPEG-b-PCL) diblock copolymers with different mPEG lengths (M w 350, 550, 750 and 2000), designed to give different levels of colloidal stability, were used to coat the surface of indomethacin nanoparticles. Polymer coating was achieved by a flow nanoprecipitation method that demonstrated excellent batch-to-batch reproducibility and resulted in nanoparticles with high drug loadings (up to 78%). At the same time, in order to understand this modified nanoprecipitation method at an atomistic level, large-scale all-atom molecular dynamics simulations were performed in parallel using the GROMOS53a6 forcefield parameters. It was observed that the mPEG-b-PCL chains act synergistically with the acetone molecules to dissolve the indomethacin nanoparticle while after the removal of the acetone molecules (mimicking the evaporation of the organic solvent) a polymer-drug nanoparticle was formed (yield 99%). This work could facilitate the development of more efficient methodologies for producing nanoparticles of hydrophobic drugs coated with amphiphilic polymers. The atomistic insight from the MD simulations in tandem with the data from the drug encapsulation experiments thus leads the way to a nanoformulation-by-design approach for therapeutic nanoparticles.

Co-initiated hyperbranched-polydendron building blocks for the direct nanoprecipitation of dendron-directed patchy particles with heterogeneous surface functionality

A synthetic strategy branched polymer building blocks that allow the rapid construction of patchy nanoparticles is presented. Hyperbranched polydendrons with mixtures of PEG and thiol-functional dendrons nanoprecipitate to form isolated zones that are imaged with gold nanoparticles.

Environmental implications and applications of engineered nanoscale magnetite and its hybrid nanocomposites: A review of recent literature

This review focuses on environmental implications and applications of engineered magnetite (Fe3O4) nanoparticles (MNPs) as a single phase or a component of a hybrid nanocomposite that exhibits superparamagnetism and high surface area. MNPs are synthesized via co-precipitation, thermal decomposition and combustion, hydrothermal process, emulsion, microbial process, and green approaches. Aggregation/sedimentation and transport of MNPs depend on surface charge of MNPs and geochemical parameters such as pH, ionic strength, and organic matter. MNPs generally have low toxicity to humans and ecosystem. MNPs are used for constructing chemical/biosensors and for catalyzing a variety of chemical reactions. MNPs are used for air cleanup and carbon sequestration. MNP nanocomposites are designed as antimicrobial agents for water disinfection and flocculants for water treatment. Conjugated MNPs are widely used for adsorptive/separative removal of organics, dyes, oil, arsenic, phosphate, molybdate, fluoride, selenium, Cr(VI), heavy metal cations, radionuclides, and rare earth elements. MNPs can degrade organic/inorganic contaminants via chemical reduction or catalyze chemical oxidation in water, sediment, and soil. Future studies should further explore mechanisms of MNP interactions with other nanomaterials and contaminants, economic and green approaches of MNP synthesis, and field scale demonstration of MNP utilization.