Thermoset–thermoplastic hybrid nanoparticles and composite coatings

Silicone-containing aqueous polymer dispersions with hybrid particle structure

In this paper the synthesis, characterization and application of silicone-containing aqueous polymer dispersions (APD) with hybrid particle structure are reviewed based on available literature data. Advantages of synthesis of dispersions with hybrid particle structure over blending of individual dispersions are pointed out. Three main processes leading to silicone-containing hybrid APD are identified and described in detail: (1) emulsion polymerization of organic unsaturated monomers in aqueous dispersions of silicone polymers or copolymers, (2) emulsion copolymerization of unsaturated organic monomers with alkoxysilanes or polysiloxanes with unsaturated functionality and (3) emulsion polymerization of alkoxysilanes (in particular with unsaturated functionality) and/or cyclic siloxanes in organic polymer dispersions. The effect of various factors on the properties of such hybrid APD and films as well as on hybrid particles composition and morphology is presented. It is shown that core-shell morphology where silicones constitute either the core or the shell is predominant in hybrid particles. Main applications of silicone-containing hybrid APD and related hybrid particles are reviewed including (1) coatings which show specific surface properties such as enhanced water repellency or antisoiling or antigraffiti properties due to migration of silicone to the surface, and (2) impact modifiers for thermoplastics and thermosets. Other processes in which silicone-containing particles with hybrid structure can be obtained (miniemulsion polymerization, polymerization in non-aqueous media, hybridization of organic polymer and polysiloxane, emulsion polymerization of silicone monomers in silicone polymer dispersions and physical methods) are also discussed. Prospects for further developments in the area of silicone-containing hybrid APD and related hybrid particles are presented.

Synthesis of functionalized graphene oxide nanoflakes using silane coupling agents

Carbon-based nanomaterials have captured significant interest in academics for decades. Recently, graphene has been found to be a promising nanomaterial. In this study, novel functionalized graphene oxide nanoflakes (FGONs) were successfully synthesized using silane coupling agents via a chemical approach and used as a reinforcement in cyanate ester (CE)/bismaleimide (BMI) copolymers. The curing mechanism and thermal properties of the FGONs/CE/BMI nanocomposites were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry. The results show that the addition of FGONs not only catalyzed the entire curing process but also increased the thermal stability of the nanocomposites. The flexural and impact strengths reached optimum values of 110 MPa and 10.98 kJ m−2 with a load of 1.0 wt% FGONs, respectively. Moreover, the glass transition temperature and dielectric properties of the nanocomposites were lower than those of the CE/BMI copolymer.

Alternative Pathway for the Stabilization of Reactive Emulsions via Cross-Linkable Surfactants

Highly reactive emulsions were stabilized by employing a surfmer analogous concept. An interfacial reaction between an emulsion droplet and a cross-linkable reactive surfactant was used to provide colloidal stability and simultaneously maintain the majority of the reactive groups. Polyaddition-type reaction between epoxy and amine was chosen as a model system to spontaneously and covalently bond the surfactant to the emulsion droplets. The interfacial reaction was monitored via isothermal titration calorimetry analysis. With this method, the increased colloidal stability could be attributed to a reaction rather than a pure physical adsorption. The maintained reactivity of the emulsion droplets enables consecutive conversions with coreactive components, e.g., for cross-linking reactions, corrosion protection, or functional coatings.