As part of ongoing efforts aimed at the development of extensive structure−property relationships for moisture-curable polysiloxane coatings containing tethered quaternary ammonium salt (QAS) moieties for potential application as environmental friendly coatings to combat marine biofouling, a combinatorial/high-throughput (C/HT) study was conducted that was focused on four different compositional variables. The coatings that were investigated were derived from solution blends of a silanol-terminated polydimethylsiloxane (HO-PDMS-OH), QAS-functional alkoxysilane, and methyltriacetoxysilane. The compositional variables investigated were alkoxysilane functionality of the QAS-functional silane, chain length of the monovalent alkyl group attached to the QAS nitrogen atom, concentration of the QAS-functional alkoxysilane, and molecular weight of the HO-PDMS-OH. Of these variables, the composition of the alkoxysilane functionality of the QAS-functional silane was a unique variable that had not been previously investigated. The antifouling (AF) and fouling-release (FR) characteristics of the 24 unique coating compositions were characterized using HT assays based on three different marine microorganisms, namely, the two bacteria, Cellulophaga lytica and Halomonas pacifica, and the diatom, Navicula incerta. Coatings surfaces were characterized by surface energy, water contact angle hysteresis, and atomic force microscopy (AFM). A wide variety of responses were obtained over the compositional space investigated. ANOVA analysis showed that the compositional variables and their interactions significantly influenced AF/FR behaviors toward individual marine microorganisms. It was also found that utilization of the ethoxysilane-functional QASs provided enhanced AF character compared to coatings based on methoxysilane-functional analogues. This was attributed to enhanced surface segregation of QAS groups at the coating-air interface and confirmed by phase images using AFM.

Electrically conductive, cationically UV‐cured composites were prepared using exfoliated graphite plates (EGP) with cycloaliphatic epoxy resin and polyalcohol binder system. Exfoliated graphite (EG) was obtained from natural flake graphite through chemical and thermal treatment. Sonication of EG in solvent produced EGP. Characterization of graphite samples by XRD showed structural similarity between original graphite and EGP. UV curing behavior was characterized using photoDSC. Electrical resistivity measurements of the composites as a function of EGP concentration showed that at low filler concentration the binder system can influence the electrical percolation behavior. Some formulations showed electrical percolation at less than 1 vol.‐% of EGP filler. magnified image

Corporation iv PART I ABSTRACT STABILIZATION OF NEPHELINE SYENITE FILLER IN A UV-CURE POLYURETHANE DISPERSION WOOD COATING MAUNG YE HTETNepheline syenite is a naturally occurring, silica deficient, sodium potassium aluminum silicate functional filler used in polymeric coatings, adhesives, and inks. Due to its unique optical characteristics, it can be utilized in formulating a low-viscosity polyurethane dispersion UV-cure clear wood coating system to enhance its functional properties. However, when the coating is formulated with the ultrafine filler, especially at a high loading level (e.g. >10% solids), the filler rapidly settles after formulated, forming a densely packed sediment layer shortening its shelf-life.Suspension of the filler was attempted using rheology additives while minimizing their negative effects on the coating's optical properties. Compatibility of the additives in the polyurethane dispersion system was qualitatively screened using a starting-point UV-cure polyurethane dispersion formulation. A design of experiments was set up to investigate optimum loading levels of the additives given by the screening step. The starting-point formulation was modified using the potential additives at the optimum loading levels and nepheline syenite with a median particle size of 1.7 µm (Minex 12 m (Minex 12 ® ) at 15% solids. The starting-point formulation was also modified with both rheology additives. The modified samples were heat-aged for up to 28 days at 50ºC to evaluate their anti-settling performance. Optical properties, pH, package stability and viscosity of the samples were also assessed.A polymeric dispersant was used to prepared a nepheline syenite slurry, which was then incorporated into the polyurethane dispersion formulation. As previously discovered, the polymeric hyper-dispersant, Solsperse 46000 at 8%, was the best dispersant. Therefore, this dispersant was used in all the modified samples.Soft-pack settling was observed in most samples modified with the rheology additives.The sediments could be re-dispersed into the coating system. A near-perfect suspension of the filler was observed in a 1.0% Rheotech 4800 modified sample. A pH drop in the sample lowered v the viscosity and increased the haze significantly to 6%. The best optical properties were obtained with a combination of 0.8% Byk425 and 3.0% Aquatix8421. However, the low-shear viscosity of this sample (3500 cP/ 3.5 Pa.s) is about 3 times higher than that of the Rheotech 4800 modified sample. Although most optimized samples had soft-pack settling with some degree of suspension of the filler, their high viscosities may not be desirable in most coating formulations requiring a low-viscosity system.