Encapsulation of clay by ad-miniemulsion polymerization: the influence of clay size and modifier reactivity on latex morphology and physical properties

Recent advances in colloidal nanocomposite designviaheterogeneous polymerization techniques

Recent advances in colloidal nanocomposite design by heterogeneous polymerization are reviewed, with a specific focus on encapsulation and particle-based stabilization for specific materials applications.

Laponite-Based Surfaces with Holistic Self-Cleaning Functionality by Combining Antistatics and Omniphobicity

In the present work, perfluoroalkylated laponite nanoparticles with a high degree of functionalization (60 wt %) have been prepared and a methodology to prepare transparent, antistatic, and omniphobic laponite-based films with holistic self-cleaning properties against liquids, solids and liquid-solid mixtures has been developed. The intrinsic electrical and ionic conductivities observed in unmodified laponite coatings are combined with perfluoroalkyl-modified laponite clays. As a result, films with improved self-cleaning functionality based on dust-repellency and omniphobic liquid-repellence (sheet resistance in the range of 10⁷ Ω/□ and contact angles of 106° (H₂O) and 93° (oil)) were obtained. These unique films, being capable to repel dust and liquids, were applied to a variety of substrates (i.e., glass and plastics) and tested against solids and liquids of different nature with excellent performance. Bending tests of these holistic self-cleaning films deposited over flexible substrates showed better mechanical performance than unmodified laponite films.

Synthesis of clay-armored poly(vinylidene chloride-co-methyl acrylate) latexes by Pickering emulsion polymerization and their film-forming properties

Use of LAPONITE® clay platelets as Pickering stabilizers of vinylidene chloride-based latexes.

ATRP mediated encapsulation of Gibbsite: fixation of the morphology by using a cross-linker

Gibbsite platelets were successfully encapsulated using a cross-linker in ATRP-mediated starved feed emulsion polymerisation.

Minimizing Corrosion of Outdoor Metalworks Using Dispersed Chemically Stabilized Nanoclays in Polyvinylidene Fluoride Latex Coatings

Nanoclays are small enough to appear optically transparent, yet they have large surface-to-volume and high aspect ratios that can significantly inhibit water diffusion when incorporated into protective coatings. Clear coatings, which minimally affect the aesthetics of metalworks, are commonly applied to outdoor metalworks, such as sculptures, to prevent and slow corrosion. In recent years, waterborne clear coatings, rather than solvent-based clear coatings, are increasingly used in many applications to reduce the quantity of volatile organic components in the formulation, yet the performance of dry films produced from waterborne colloidal suspensions is generally poorer. In this work, we aim to improve the barrier properties of a highly weatherable waterborne acrylic/polyvinylidene fluoride emulsion by adding a synthetic nanoclay, Laponite, into the formulation. To improve clay-polymer compatibility, the clay was covalently modified using an acetoxy or perfluoroalkyl silane monomer that is reactive with the hydroxyl groups at the edges of the Laponite platelets. Cation exchange on the clay faces using phosphorylcholine was conducted to increase the stability in water and characterized by zeta potential. Resulting changes in barrier properties of the polymer nanocomposite films were characterized by gravimetry, colorimetry, and electrochemical impedance spectroscopy. Surface ablation after accelerated artificial weathering was monitored by attenuated total internal reflectance Fourier transform infrared microspectroscopy and Raman microspectroscopy, thin film X-ray diffraction (TF-XRD) and gloss and thickness measurements. The composite films showed many improved properties: reduced water sensitivity and ultraviolet-induced polymer degradation, which increased the barrier properties and reduced the diffusion constants over both short- and long-term weathering studies compared with films without nanoclays. The diffusion constant measured for the highest performing composite film showed that the performance gap between relevant water- and solvent-borne coatings used to protect outdoor metals was narrowed by half.

Encapsulation of unmodified Gibbsite via conventional emulsion polymerisation using charged co-oligomers

A simple procedure for the encapsulation of unmodified Gibbsite was developed using conventional emulsion polymerization and charged oligomers as stabilisers.

Fabrication of ultraviolet-responsive microcapsules via Pickering emulsion polymerization using modified nano-silica/nano-titania as Pickering agents

UV-responsive microcapsules were prepared via O/W Pickering emulsion templates using SiO₂ and TiO₂ nanoparticles as Pickering agents.

Polymer-inorganic coatings containing nanosized sorbents selective to radionuclides. 1. Latex/cobalt hexacyanoferrate(II) composites for cesium fixation

Here we present a new approach to improve fixation of radionuclides on contaminated surfaces and eliminate their migration after nuclear accidents. The approach consists in fabrication of latex composite coatings, which combine properties of polymeric dust-suppressors preventing radionuclides migration with aerosols and selective inorganic sorbents blocking radionuclides leaching under contact with ground waters and atmospheric precipitates. Latex/cobalt hexacyanoferrate(II) (CoHCF) composites selective to cesium radionuclides were synthesized via "in situ" growth of CoHCF crystal on the surface of carboxylic or amino latexes using surface functional groups as ion-exchange centers for binding precursor ions Co(2+) and [Fe(CN)6](4-). Casting such composite dispersions with variable content of CoHCF on (137)Cs-contaminated sand has yielded protective coatings, which reduced cesium leaching to 0.4% compared to 70% leaching through original latex coatings. (137)Cs migration from the sand surface was efficiently minimized when the volume fraction of CoHCF in the composite film was as low as 0.46-1.7%.

Recent advances in the preparation of hybrid nanoparticles in miniemulsions

In this review, we summarize recent advances in the synthesis of hybrid nanoparticles in miniemulsions since 2009. These hybrid nanoparticles include organic-inorganic, polymeric, and natural macromolecule/synthetic polymer hybrid nanoparticles. They may be prepared through encapsulation of inorganic components or natural macromolecules by miniemulsion (co)polymerization, simultaneous polymerization of vinyl monomers and vinyl-containing inorganic precursors, precipitation of preformed polymers in the presence of inorganic constituents through solvent displacement techniques, and grafting polymerization onto, from or through natural macromolecules. Characterization, properties, and applications of hybrid nanoparticles are also discussed.

Encapsulation of clay within polymer particles in a high-solids content aqueous dispersion

By using a two-step polymerization process, it was possible to encapsulate clay platelets within polymer particles dispersed in water. First, seed polymer particles with chemically bonded clay were obtained by batch miniemulsion polymerization. Then, the clay was buried within the particles by the addition of neat monomer in a second step. The final stable dispersions can have a solids content of up to 50 wt %. Transmission electron microscopy images clearly show the presence of clay platelets inside the polymer colloids, although they are not totally exfoliated. The obtained nanocomposites showed an increase in both the storage modulus in the rubbery state and the water resistance as the clay content increases. The approach presented here might be useful for encapsulating other high-aspect ratio nanofillers.