Effect of Dispersed Polymeric Nanoparticles on the Bulk Polymerization of Methyl Methacrylate

Emerging Structural and Interfacial Features of Particulate Polymers at the Nanoscale

Particulate polymers at the nanoscale are exceedingly promising for diversified functional applications ranging from biomedical and energy to sensing, labeling, and catalysis. Tailored structural features (i.e., size, shape, morphology, internal softness, interior cross-linking, etc.) determine polymer nanoparticles' impact on the cargo loading capacity and controlled/sustained release, possibility of endocytosis, degradability, and photostability. The designed interfacial features, however (i.e., stimuli-responsive surfaces, wrinkling, surface porosity, shell-layer swellability, layer-by-layer surface functionalization, surface charge, etc.), regulate nanoparticles' interfacial interactions, controlled assembly, movement and collision, and compatibility with the surroundings (e.g., solvent and biological environments). These features define nanoparticles' overall properties/functions on the basis of homogeneity, stability, interfacial tension, and minimization of the surface energy barrier. Lowering of the resultant outcomes is directly influenced by inhomogeneity in the structural and interfacial design through the structure-function relationship. Therefore, a key requirement is to produce well-defined polymer nanoparticles with controlled characteristics. Polymers are amorphous, flexible, and soft, and hence controlling their structural/interfacial features through the single-step process is a challenge. The microfluidics reaction strategy is very promising because of its wide range of advantages such as efficient reactant mixing and fast phase transfer. Overall, this feature article highlights the state-of-the-art synthetic features of polymer nanoparticles with perspectives on their advanced applications.

Effect of Graphene oxide or Functionalized Graphene Oxide on the Copolymerization Kinetics of Styrene/n-butyl Methacrylate

Nanocomposite materials based on copolymers of styrene and n-butyl methacrylate with either graphene oxide (GO) or functionalized graphene oxide (F-GO) were synthesized using the in-situ bulk radical copolymerization technique. Reaction kinetics was studied both experimentally and theoretically using a detailed kinetic model also taking into account the effect of diffusion-controlled phenomena on the reaction kinetic rate constants. It was found that the presence of GO results in lower polymerization rates accompanied by the synthesis of copolymers having higher average molecular weights. In contrast, the presence of F-GO did not seem to significantly alter the conversion vs time curves, whereas it results in slightly lower average molecular weights. The first observation was attributed to side reactions of the initiator primary radicals with the hydroxyl groups on the surface of GO, resulting in lower initiator efficiency, whereas the second to grafted structures formed from copolymer macromolecules on the F-GO surface. The copolymerization model predictions including MWD data were found to be in satisfactory agreement with the experimental data. At least four adjustable parameters were employed and their best-fit values were provided.

Effect of SiO₂ Nanoparticles on the Performance of PVdF-HFP/Ionic Liquid Separator for Lithium-Ion Batteries

Safety concerns related to the use of potentially explosive, liquid organic electrolytes in commercial high-power lithium-ion batteries are constantly rising. One promising alternative is to use thermally stable ionic liquids (ILs) as conductive media, which are however, limited by low ionic conductivity at room temperature. This can be improved by adding fillers, such as silica or alumina nanoparticles (NPs), in the polymer matrix that hosts the IL. To maximize the effect of such NPs, they have to be uniformly dispersed in the matrix while keeping their size as small as possible. In this work, starting from a water dispersion of silica NPs, we present a novel method to incorporate silica NPs at the nanoscale level (<200 nm) into PVdF-HFP polymer clusters, which are then blended with the IL solution and hot-pressed to form separators suitable for battery applications. The effect of different amounts of silica in the polymer matrix on the ionic conductivity and cyclability of the separator is investigated. A membrane containing 10 wt.% of silica (with respect to the polymer) was shown to maximize the performance of the separator, with a room temperature ionic conductivity of of 1.22 mS cm - 1 . The assembled half-coin cell with LiFePO 4 and Li as the cathode and the anode exhibited a capacity retention of more than 80% at a current density of 2C and 60 ∘ C.

Generation of Polymer Nanocomposites through Shear-Driven Aggregation of Binary Colloids

Design of polymer nanocomposites has been an intense research topic in recent decades because hybrid nanomaterials are widely used in many fields. Throughout their development, there has often been a challenging issue how one can uniformly distribute nanoparticles (NPs) in a polymer matrix, avoiding their agglomeration. In this short review, we first introduce the theory of colloidal aggregation/gelation purely based on intense shear forces. Then, we illustrate a methodology for preparing polymer nanocomposites where the NPs (as fillers) are uniformly and randomly distributed inside a matrix of polymer NPs, based on intense shear-driven aggregation of binary colloids, without using any additives. Its feasibility has been demonstrated using two stable binary colloids composed of (1) poly-methyl methacrylate fillers and polystyrene NPs, and (2) graphene oxide sheets (fillers) and poly-vinylidene fluoride NPs. The mechanism leading to capturing and distribution of the fillers inside the polymer NP matrix has been illustrated, and the advantages of the proposed methodology compared with the other common methods are also discussed.