Various environmentally friendly approaches have been studied in recent years for effectively controlling biofouling on marine structures. Among these, two distinct and successful approaches are (1) the use of hydrophilic surfaces that control biofouling by resisting the adhesion of fouling organisms and (2) the use of hydrophobic elastomeric surfaces that function by facilitating their easy removal. In this study, we attempted to investigate amphiphilic surfaces for their effectiveness in controlling marine biofouling. Polyurethane surfaces containing tethered hydrophilic, hydrophobic, and amphiphilic moieties were designed and synthesized. The wetting behaviors of these surfaces, as a function of the external environment, were studied by dynamic contact angle (DCA) measurements and their morphologies by atomic force microscopy (AFM). The results from DCA measurements and AFM postulate interesting characteristics of the amphiphilic surfaces. Bioassays with the green fouling alga Ulva showed that the amphiphilic surfaces had fouling-resistance and fouling-release potential and provide an insight into the scope of the development of smart marine coatings.

Recently, stimuli-responsive surfaces have gained considerable interest among coatings researchers in industry as well as in academe. To date, many switchable surfaces based on such external stimuli as temperature, electricity, pH, and many others have been designed and developed. Environmentally switchable surfaces have been among the most widely studied surfaces since they are known to exhibit smart behavior under external influence. In the present work, we report the synthesis of hydrophobic, hydrophilic, and amphiphilic polyurethane coatings with tethered hydrophilic and/or hydrophobic moieties. These coatings have been characterized and tested for mechanical properties and surface characteristics using such advanced instruments as the scanning probe microscope (SPM), dynamic contact angle analyzer (DCA), adhesion tester, and nanoindenter. The surfaces with tethered hydrophobic or hydrophilic moieties, when immersed in water, showed remarkable changes in the surface topography, hence, their dynamic surface characteristics. The amphiphilic surfaces, containing both hydrophobic and hydrophilic moieties, showed intelligent behavior in response to the external environment. The ability to tailor surfaces with predictable behavior upon exposure to the external environment opens up enormous opportunities for their potential end-use applications.

Latexes have many product applications including functioning as a binder in coatings. For many years, coatings researchers in industry as well as in academe have been exploring various modes of crosslinking latexes. Quite often, the goal of preparing crosslinked latexes is to upgrade film properties relative to the film properties of uncrosslinked latexes. In the present report, the synthesis and properties of crosslinkable acrylic latexes prepared with either an internal crosslinker (1,3-butylene glycol dimethacrylate)-''precoalescence crosslinking''-or an external crosslinker (adipic dihydrazide)-''postcoalescence crosslinking''-at various levels of crosslinking were studied. For postcoalescence crosslinking, diacetone acrylamide was copolymerized into the latex to provide sites for subsequent reaction with adipic dihydrazide. Fundamental properties of films cast from the two types of latexes were systematically compared. These properties included gel content, dynamic mechanical properties, nano-indenter hardness and modulus, stress-strain properties as well as the characterization of latex morphology by atomic force microscopy (AFM). In addition, some specific end-use properties were determined. This study assesses the effect of type (precoalescence or postcoalescence) and level of crosslinking on the film formation process and the resulting fundamental and end-use properties as well as resulting latex film morphology.

Interest in the development of biodegradable/bioresorbable material for use in tissue engineering has grown significantly over the past decade. These new biodegradable/bioresorbable materials would be especially useful for the redevelopment of bone tissue in areas where bone has been extracted or destroyed. The purpose of this project is to develop biodegradable/bioresorbable polymer scaffolding for the reproduction and regrowth of bone tissue. The scaffolding can then be characterized by SEM and TEM. Following the bone cell growth in vitro, the SEM can again be utilized to determine the extent of penetration and cell viability within the scaffolding.The scaffolding specimens were formed by two different techniques. The first technique involved mixing a biodegradable/bioresorbable polymer with a ceramic powder. The polymer/ceramic blend was then mixed with a water extractable material of various particle sizes. The formulations were then compression molded. Following the compression molding, the particles were extracted with de-ionized water yielding scaffolds of various pore sizes. The second technique involved electrospinning. Three different scaffolding specimens were formed with electrospinning; the first used only the polymer, the second was of the polymer/ceramic blend, and the third was formed with hyaluronic acid. All of the scaffolds were then seeded with osteoblast cells in vitro. The major variables in the process were; pore size (compression molded samples only), percentage of ceramic blended with the polymer, effect on cell growth between the polymeric scaffolding and the hyaluronic acid scaffolding, and the effect on cell growth between the compression molded scaffolding and the electrospun scaffolding.The goal of this research is to characterize the biodegradable/bioresorbable scaffolds with SEM, and TEM prior to the seeding of the osteoblast cells and to examine the extent of penetration and viability of the incubated cells using the SEM (FIG 1-3). TEM has been utilized in characterizing the electrospun scaffolding samples, to examine fiber size, shape and networking between fibers (FIG 4). The SEM is used to characterize all of the scaffolding samples; information on pore size, distribution, and shape are gathered from the compression-molded samples; information on fiber size and shape and the presence of ceramic deposits are gathered from the electrospun samples. The SEM is also utilized in determining the extent of cell penetration into the scaffolding. After fixation of the cells, the samples are dried with ethanol and cross-sectioned. Prior to viewing, a thin layer of gold was sputter coated onto the samples. Once all of the samples have been characterized, a comparison will be made to determine which sample(s) are the most viable for cell growth.

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