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Organic/inorganic (O/I) composite latexes combine the best attributes of inorganic solids with the processability, lightweight and handling advantages of organic polymers. There are common methods to produce polymer nanocomposites: melt compounding, in-situ polymerization and solution mixing. Emulsion polymerization is an unique chemical process widely used to produce waterborne resins with various colloidal and physicochemical properties. This free radical polymerization process involves emulsification of the relatively hydrophobic monomer in water by an oil-in-water emulsifier, followed by the initiation reaction with a water insoluble initiator. This research focuses on the synthesis and reactions kinetics of polyacrylic latex with the incorporation of various nanospheres (SiO2, TiO2, Al2O3 and Fe2O3), and layered silicate (Bentonite nanoclay) nanoparticles via emulsion polymerization. The influence of nanoparticle concentration on reaction kinetics was also investigated. The results showed that the concentration of nanoparticles has significant influence on the monomer conversion, particle size, coagulum content and viscosity of the emulsion. Furthermore, the nanostructured emulsions were shear thinning, exhibiting a power-law behavior, and the viscosity was influenced by the nanoparticle morphology.

The addition of nanoparticles into polymeric materials has changed dramatically the properties of the host polymers, promising a novel class of composite materials with different properties and added functionalities. This research focuses on the influence of inorganic nanospheres particles such as SiO2, Al2O3, Fe2O3, TiO2 and nanoplatelets, such as Bentonite nanoclay, on the thermo-mechanical properties of a polyacrylic latex (utilized in commercial coatings). The analysis of the thermal and mechanical properties showed a decrease of Young's modulus and glass transition temperature Tg in the presence of spherical nanoparticles. However, there was an increase of these properties in the presence of nanoplatelets (Bentonite), as demonstrated by the dynamic mechanical analysis and uniaxial tensile analysis. Moreover, water contact angle measurements demonstrated significant increase in hydrophobic behavior when incorporating nanosphere particles as compared to nanoplatelets. These results showed that the metallic oxides nanoparticles greatly influenced the physical and mechanical properties of the neat polyacrylic matrix.

Thermosetting polyurethane coating formulations which stratify into two distinct layers after application have been prepared. In a thermosetting system the polymer phase separation among other factors is seen to be kinetically controlled and have less dependence on parameters such as surface tension gradient and polymer solubility. Certain coating applications including those used in architectural, automotive, industrial maintenance and aerospace require a combination of primer/topcoat or basecoat/clearcoat layers. These multilayered systems necessitate complex application and curing procedures. Multiple product formulation, application and processing steps not only require significant amounts of processing time, and contributing to environmental waste generation and pollution they also consume excessive amount of energy and manpower until a solid film has been produced. It would be desirable to reduce the number of layers to a minimum while providing the equal or better overall performance. In this paper we report the design and development of thermosetting polyurethane coatings that self-stratify to two distinct phases upon application and cure. It was demonstrated that kinetically controlled reactions aided by incompatible polymers possessing gradient surface free energies can afford self-stratifying coatings. This investigation also revealed that solvent type, evaporation rate, and gravity did not contribute to stratification of thermosetting coatings. Prototype pigmented systems were applied and cured and characterized by FTIR, SEM/EDX and were evaluated using standard coating test methods. The results of this investigation provide a new understanding of stratification phenomenon and establish that preferentially reactive polymers can be a basis for formulating cross-linkable self-stratifying coatings.

The research on a self-decontaminating surface has received significant attention because of the growth of pathogenic microorganisms on surfaces. In this study, a novel and simple technique for producing an active surface with antimicrobial functionality is demonstrated. A tethering platform was developed by grafting the biocide ampicillin (Amp) to a nanoclay and dispersing the nanoclay in a UV-curable acrylate coating applied on polypropylene films as the substrate. A coupling agent, [3-(glycidyloxy)propyl]trimethoxysilane, was used as a linker between the nanoclay and Amp. The Amp-functionalized clay was further modified with an organic surfactant to improve the compatibility with the coating. Several characterization assays, such as Fourier infrared transform analysis, thermogravimetric analysis, and X-ray diffraction, were conducted to confirm the presence of Amp in the nanoclay. Transmission electron microscopy images revealed that the clay particles were well dispersed in the coating and had a partial exfoliated morphology. The active coating surface was effective in inhibiting the growth of Gram-positive Listeria monocytogenes and Gram-negative Salmonella Typhimurium via contact. These findings suggest the potential for the development of active surfaces with the implementation of nanotechnology to achieve diverse functionalities.