Epoxy-acrylic core-shell particles by seeded emulsion polymerization

Delicate and Independent Manipulation of Dynamic Fluorescence Behavior of Polymer Nanoparticles Based on a Core-Shell Strategy

Fluorescent polymer nanomaterials with dynamic fluorescence properties hold great potential in many advanced applications, including but not limited to information encryption, adaptive camouflage, and biosensors. The key to improving the application value of materials is to establish an accurate control strategy for dynamic fluorescence behavior. Herein, we develop a core-shell engineering strategy to precisely and independently manipulate the dynamic fluorescence behavior through the shell polymeric matrix. The core-shell fluorescent polymer nanoparticles (CS-FPNPs) are constructed through a sequential process of miniemulsion polymerization and seeded emulsion polymerization. Taking advantage of the core-shell structure, the rigid core matrix ensures the strong initial emission of AIE units, while the photoisomerization behavior of spiropyrane (SP) units is delicately and independently regulated by the rigidness of the shell matrix. Thereby, CS-FPNPs exhibit bright time-dependent reversible dynamic fluorescence behavior under alternating UV/vis irradiation. Benefited from the excellent processability and film formation ability, we have successfully applied CS-FPNPs to dynamic decorative painting, warning labels, and dynamic QR code security. Impressively, the fluorescence manipulation strategy based on core-shell engineering allows the independent regulation of specific luminescent units in complicated emission systems to accurately embody designed emission behavior.

Synthesis and Application of Reactive Acrylic Latexes: Effect of Particle Morphology

The aim of the study is the synthesis and characterization of epoxy functional reactive polyacrylic latexes, e.g., poly (BA-co-MMA-co-AN-co-GMA) with core/shell and non-structured (random) particle morphologies. Additionally, their performance as binders and coating ability in leather finishing were studied. The epoxy functional polymers were synthesized via the seeded emulsion polymerization technique and the obtained latexes were characterized by means of particle size, zeta potential, FTIR, TEM, DSC, DMTA, and TGA. The results showed that the particle size and zeta potential values were very similar for both latexes, except core/shell latex had slightly higher particle size. DSC, TEM, and DMTA studies verified the successful synthesis of core/shell latex morphology. The copolymer films were elastic in nature and had low T_g values (-13 and -20 °C). The performance results showed some different behavior for core/shell and random copolymer coatings. The abrasion resistance of the leather finish with random copolymer as binder exhibited slightly better values, especially in wet conditions. On the other hand, the leathers finished with core/shell binder showed better performance in flexing endurance and the water spotting test.

Preparation of Polypropylene-Composite Particles by Dispersion Polymerization

Polypropylene (PP)/poly(benzyl methacrylate) (PBzMA) composite particles were prepared by dispersion polymerization of benzyl methacrylate (BzMA) in the presence of PP particles without a conventional dispersant. The polymerization process yielded a stable emulsion of composite particles with a "currant bun"-like morphology consisting of a PBzMA core and PP bumps, indicating that the PP particles operate as colloidal stabilizers. Conversely, when BzMA was replaced with styrene as the monomer, dispersion polymerization yielded a large amount of aggregates. Finally, a stable emulsion was formed by copolymerizing a small amount of methyl methacrylate (MMA) with styrene. This result suggested that PP must interact with a second polymer to prepare stable composite particles. The surfaces of the PP particles, which are highly hydrophilic due to their carboxyl groups, were involved in the attachment and stabilization of the polymer precipitated in the medium. A film prepared from the obtained PP/PBzMA composite particles was highly hydrophobic and strongly adhesive to a PP sheet.

Well Defined Poly(Methyl Methacrylate)-Fe3O4/Poly(Vinyl Pivalate) Core-Shell Superparamagnetic Nanoparticles: Design and Evaluation of In Vitro Cytotoxicity Activity Against Cancer Cells

The objective of this work is to develop and characterize polymeric nanoparticles with core-shell morphology through miniemulsion polymerization combined with seeded emulsion polymerization, aiming at the application in the treatment of vascular tumors via intravascular embolization. The synthesis of the core-shell nanocomposites was divided into two main steps: (i) Formation of the core structure, consisting of poly(methyl methacrylate)/magnetic oxide coated with oleic acid (OM-OA) via miniemulsion and (ii) shell structure produced through seeded emulsion polymerization of vinyl pivalate. Nanocomposites containing about 8 wt.% of OM-OA showed high colloidal stability, mean diameter of 216.8 nm, spherical morphology, saturation magnetization (Ms) of 4.65 emu·g-1 (57.41 emu·g-1 of Fe3O4), preserved superparamagnetic behavior and glass transition temperature (Tg) of 111.8 °C. TEM micrographs confirmed the obtaining of uniformly dispersed magnetic nanoparticles in the PMMA and that the core-shell structure was obtained by seeded emulsion with Ms of 1.35 emu·g-1 (56.25 emu·g-1 of Fe3O4) and Tg of 114.7 °C. In vitro cytotoxicity assays against murine tumor of melanoma (B16F10) and human Keratinocytes (HaCaT) cell lines were carried out showing that the core-shell magnetic polymeric materials (a core, consisting of poly(methyl methacrylate)/Fe3O4 and, a shell, formed by poly(vinyl pivalate)) presented high cell viabilities for both murine melanoma tumor cell lines, B16F10, and human keratinocyte cells, HaCaT.

New Fluorescent Nanoparticles for Ultrasensitive Detection of Nucleic Acids by Optical Methods

For decades the detection of nucleic acids and their interactions at low abundances has been a challenging task that has thus far been solved by enzymatic target amplification. In this work we aimed at developing efficient tools for amplification-free nucleic acid detection, which resulted in the synthesis of new fluorescent nanoparticles. Here, the fluorescent nanoparticles were made by simple and inexpensive radical emulsion polymerization of butyl acrylate in the presence of fluorescent dyes and additional functionalization reagents. This provided ultra-bright macrofluorophores of 9-84 nm mean diameter, modified with additional alkyne and amino groups for bioconjugation. By using click and NHS chemistries, the new nanoparticles were attached to target-specific DNA probes that were used in fluorimetry and fluorescence microscopy. Overall, these fluorescent nanoparticles and their oligonucleotide derivatives have higher photostability, brighter fluorescence and hence dramatically lower limits of target detection than the individual organic dyes. These properties make them useful in approaches directed towards ultrasensitive detection of nucleic acids, in particular for imaging and in vitro diagnostics of DNA.