Cyanine photosensitizers are visible-light absorbing dyes commercially useful in photography and available in a variety of structures with tunable redox, absorptivity and excited state properties. The areas of research described in this dissertation all utilize cyanine dyes to photosensitize various processes to visible-light within the confines of lamellar phospholipid assemblies. In Chapter III, an efficient three component, liposome-bound photochemical molecular device for transfer of energy and electrons is described. A porphyrin (free base or metallated) serves as the energy donor, a cyanine functions as the energy acceptor/electron acceptor and Ph₃BnB- acts as an electron donor. In Chapter IV, the first example of visible-light sensitized bilayer polymerization is presented. Sensitizing the polymerization of two-dimensional lipid assemblies to visible-light is part of a current research effort to exploit the properties of polymerized supramolecular structures. Extending the polymerization sensitivity of such amphiphile aggregates to lower energy visible-light creates possibilities for applications where UV photolysis would not be useful. Applications of liposomes as drug delivery vehicles thus far have relied upon such release mechanisms as pH sensitivity or target specific interactions to empty the liposome contents to the cell. Chapter V describes a new system for the successful destabilization of liposomes at pH 4.5 via visible-light sensitive polymerization of lipids. Visible-light sensitized polymerization induces the release of liposome aqueous contents providing temporal and spatial control over the release event and lower energy irradiation with more tissue penetration than UV photolysis.

Solid freeform fabrication processes (SFF) have been the subject of much research and discussion within recent years. Unlike other near net shape manufacturing processes (i.e. conventional injection molding, casting, or bulk machining), SFF techniques fabricate parts "from the ground up" by the sequential deposition and curing of raw material slurry layers upon each other until the final part results. Precise spatial control of deposited layers is achieved through CAD software and hardware interfaced with the SFF apparatus. The development of suitable SFF compatible raw material formulations and appropriate processing parameters are discussed in this dissertation. In particular, a wide range of materials have been fabricated and characterized at AML and ACR using this technique including alumina., crosslinked acrylate, and high molecular weight Nylon 6 thermoplastics. Comparisons are made between the mechanical properties of the SFF and corresponding commercial conventionally processed materials. Finally, the heat transfer and polymerization kinetics associated with three model SFF resin formulations are discussed and compared to corresponding empirical SFF process observations.

The main objective of this research work was the development, synthesis, and study of polymeric chelating derivatives. These derivatives were characterized in terms of their specific metal affinity interaction with biomolecules and metal ions. These engineered materials were used to test their feasibility as tools for separation of proteins and heavy metal ions from aqueous solutions using different affinity separation techniques. Linear and branched polymers were synthesized to create a variety of materials. Among the linear polymers synthesized was the chelated monomethoxy poly(ethylene) glycol (PEG-IDA). This derivative was used in metal affinity partitioning and metal affinity electrophoresis for fast protein-metal interaction analysis. Also a linear heterobifunctional poly(ethylene) glycol (Biotin - PEG - IDA) was synthesized and used as a tool to develop a modified enzyme-linked immuno sorbent assay (ELISA). A multi-armed high molecular weight chelating poly(ethylene) glycol (Star PEG-IDA) was prepared to enhance the separation of protein mixture in gel permeation chromatography. Iminodiacetic poly(ethyleneimine) (PEI-IDA) was prepared and used as a soluble chelating polymer in complexation-ultrafiltration studies for heavy metal ion removal from aqueous solutions. Similar PEIs were also used as casting polymers for the synthesis of affinity adsorbents useful in chromatographic applications. Either as a soluble macromolecule or as a casting polymer for the preparation of adsorbents, PEI chelated derivatives were used for ultratrace metal ion preconcentration and metal ion separations. All polymeric materials prepared were characterized using analytical techniques which include elementary analysis, atomic absorption, UV and IR spectroscopy, high performance liquid chromatography and several colorimetric assays for the determination of end groups and product purity. Metal affinity separation techniques studied with the aforementioned derivatives included: affinity partitioning, affinity electrophoresis and affinity size exclusion for protein purification; affinity complexation-ultrafiltration and metal ion affinity chromatography for removal of heavy metal. Efficient separation of protein mixtures were achieved based on selective affinity by some of the chelated polymers here described and extremely high metal adsorption capacities were found for some of the PEI-based adsorbents prepared. Even though, some of these techniques are still in developmental stages, the results are very promising and encouraging for biotechnical and environmental applications.

The design of sterically stabilized liposomes with surface grafted poly(ethylene glycol) (PEG-liposomes) for drug delivery requires a very low rate of leakage so that drugs will remain encapsulated during the 24 to 48 hr that these liposomes remain in circulation. This design can interfere with the rapid release of the encapsulated drugs at the site of action. An effective technique for the photodestabilization of PEG-liposomes is described. Photosensitive PEG-liposomes containing the polymerizable lipid 1,2-bis[10-(2',4 '-hexadienoyloxy)decanoyl]-sn-glycero-3-phosphatidylcholine (bis-SorbPC₁₇,₁₇) were prepared in the presence of a water soluble fluorescent probe and were polymerized with UV light (254 nm). Liposomes composed of PEG-DOPE/bis-SorbPC₁₇,₁₇/cholesterol/DOPC (15/30/40/15) showed a 200-fold increase in the rate of leakage at very high conversion of monomer (>98%). Liposomes composed of PEG-DSPE/bis-SorbPC₁₇,₁₇/cholesterol/DSPC (5/30/35/30) showed increases in the rate of leakage that were: 90-fold at only 20% conversion of monomer, 9-fold at 80 to 90% conversion, and 150-fold at greater than 95% conversion. These liposomes also exhibited a 17-fold increase in the rate of leakage near the main phase transition temperature (T(M)) of bis-SorbPC₁₇,₁₇ (28.8°C). These observations suggest that the polymerization of phase-separated domains of bis-SorbPC₁₇,₁₇ causes defects in the membrane that result in increased permeability. While the leakage kinetics at high conversion followed a first order rate law, leakage at low conversion did not. This, as well as the biphasic dependence of the rate of release on irradiation time in liposomes exhibiting enhanced release at low conversion, indicate that the mechanisms of leakage at low and high conversion are different. Syntheses of neutral and polymerizable PEG-lipids as well as polymerizable phosphatidylcholines are described here. Neutral PEG-lipids were used to study the effect of lipid charge on mechanical properties of PEG-lipids and on the interactions of PEG-liposomes with cells. The compressibility of a neutral PEG grafted supported bilayer could be fitted most closely with the MWC mean field model for a polymer brush (Efremova et al. Biochemistry 2000 39: 3441--3451). Neutral liposomes were endocytosed at a significantly higher rate than anionic liposomes by HeLa ovarian carcinoma cells, while murine macrophage cells showed no preference (Miller et al. Biochemistry 1998 37: 12875--12883).

The objective of this work was to investigate the cross-linking polymerization of lipids in supramolecular assemblies in order to stabilize the assembly structures. One approach to obtain a cross-linked polymer is by addition of a cross-linking agent. Homobifunctional lipids with two polymerizable groups, one in each of the two hydrophobic chains, can serve as a cross-linking agent. The lipids chosen were dienoyl-substituted lipids, mono- and bis-DenPC, where the reactive diene group is located near the glycerol backbone of the lipids. MonoDenPC 16,18 and bisDenPC18,18 were synthesized. Redox initiation was used to polymerize mixed mono/bisDenPC vesicles. To test the stability of the polymeric vesicles, Triton X-100 (TX-100) was added to the sample and the size determined by quasi-elastic light scattering (QELS). The stability of polymerized LUV to TX-100 depended on the initial composition of the LUV. It was found that 15 mol % bis-substituted lipids, bisDenPC, were needed for cross-linking polymerization. The capability of varying the cross-linking density in these poly(lipid) structures provides researchers with a means to further modify the physical properties of these polymers and membranes. Another approach to achieve cross-linking utilizes heterobifunctional lipids, which have two different reactive groups in one of the lipid tails. These heterobifunctional lipids formed bilayer vesicles or lamellar structures. The properties of the vesicles could be varied by the polymerization of the reactive groups. The design of heterobifunctional monomers allowed either simultaneous or selective polymerization of these groups. The difference in reactivity as well as the difference in polarity of each group also made possible selective polymerization of these reactive groups. Simultaneous polymerization of both reactive groups was achieved by either redox polymerization or direct photoirradiation. UV polymerization showed the formation of oligomers, which dissolved in organic solvents and TX-100. On the other hand, redox polymerization gave cross-linked polymers, which were insoluble in most organic solvents and stable towards addition of TX-100. The cross-linking density could be varied by choosing different polymerization techniques. Electron micrographs of the cross-linked polymeric vesicles showed they could retain their size and shape after freeze-drying and re-dispersal in water. The surface of the cross-linked vesicles could be modified for many applications.

The aim of this study was to explore applied and mechanistic aspects of the silane dehydropolymerization reaction catalyzed by cationic early transition metallocene compounds. This problem was dealt with by a combination of spectroscopic techniques, kinetic studies, and trapping of reaction intermediates. The results of this integrated approach allow the proposal of a new redox mechanism for the dehydropolymerization reaction which explains and predicts the reactivity and selectivity of cationic early transition metal catalysts. / The novel zirconocene complexes $ rm lbrack Cp sp prime sb2 Zr( mu$-H)(SiHR) rbrack$ sb2 sp{2+}$ lbrack BR$ sp prime sb{n}$(C$ sb6$F$ sb5) sb{4-n} rbrack sb2 sp{2-}$(Cp$ sp prime$ = Cp, MeCp, Me$ sb5$Cp; R = Ph or PhCH$ sb2;$ R$ sp prime$=Bu or H) were isolated from silane dehydropolymerization reaction mixtures catalyzed by Cp$ sp prime sb2$ZrCl$ sb2$/2BuLi/B(C$ sb6$F$ sb5) sb3$ or by $ rm lbrack Cp sp prime sb2Zr( mu$-H)H rbrack$ sb2$/2B(C$ rm sb6 F sb5) sb3$ combination catalysts. A total structure analysis of these compounds, performed by multinuclear, multidimensional NMR spectroscopy, shows that each zirconocene fragment bears a positive charge, which is delocalized between the metal center and the hydrosilane ligand. Reactions and intermediates leading to zirconocene complexes $ rm lbrack Cp sp prime sb2Zr( mu$-H)(SiHr) rbrack$ sb2 sp{2+}$ lbrack BR$ sp prime sb{n}$(C$ sb6$F$ sb5) sb{4-n} rbrack sb2 sp{2-}$ (Cp$ sp prime$ = Cp, MeCp, Me$ sb5$Cp; R = Ph or PhCH$ sb2;$ R$ sp prime$ = Bu or H.) were investigated { it in situ}, by NMR and EPR studies, and by trapping unstable intermediates with PMe$ sb3.$ Two novel Zr(III) complexes, $ rm lbrack Cp sb2Zr sp{III} rbrack sp+ lbrack$BBu$ sb{n}$(C$ sb6{ rm F} sb5) sb{4-n} rbrack sp-$ and $ rm lbrack Cp sb2Zr sp{III}(PMe sb3) sb2 rbrack sp+ lbrack$BBu$ sb{n}$(C$ sb6{ rm F} sb5) sb{4-n} rbrack sp-$ were identified by EPR spectroscopy. The unstable, diamagnetic compound $ rm lbrack Cp sb2Zr sp{IV}Bu rbrack sp+ lbrack$BBu$ sb{n}$(C$ sb6{ rm F} sb5) sb{4-n} rbrack sp-$ was identified by $ sp1$H-$ sp1$H COSY and $ sp1$H-$ sp{13}$C HMQC experiments at ${-}20 sp circ$C. Redistribution of the borate butyl and pentafluorophenyl ligands was found to occur by a direct boron to boron migration and not by a metal assisted mechanism. The latter was ruled out by an independent synthesis of expected reaction intermediates for both reaction pathways $ rm( lbrack Ph sb3C rbrack lbrack BBu(C sb6F sb5) sb3 rbrack, lbrack Cp sb2Zr(C sb / A key step in the synthesis of the active dehydrocoupling catalyst is the thermal decomposition of $ rm Cp sb2ZrBu sb2,$ which at room temperature affords paramagnetic Cp$ sb2$ZrR (R = Bu, crotyl and H) and other minor paramagnetic compounds. The pathway and the trends of this reductive decomposition were investigated in detail by EPR and multinuclear, multidimensional NMR spectroscopy. A number of intermediates were characterized. Reactions leading to the above compounds are rationalized from mechanistic and thermochemical points of view. Although it has not been possible to identify all of the decomposition products, the very fact that the $ rm Cp sb2ZrCl sb2$/2BuLi reagent contains substantial amounts of Zr(III) explains the origin of the unusual reactivity of the $ rm Cp sb2ZrCl sb2$/2BuLi reagent in dehydropolymerization of silanes and sheds new light on the reaction mechanism. / A kinetic study of the photochemical reaction of $ rm lbrack Cp sb2Zr(SiHPh)( mu$-H) rbrack$ sb2 sp{2+} lbrack$BBu$ sb{n}$(C$ sb6$F$ sb5) sb{4-n} rbrack sb2 sp{2-}$ with benzylsilane was carried out with a combination of NMR and EPR spectroscopy. The role of the paramagnetic intermediate, $ rm lbrack Cp sb2Zr sp{III} rbrack sp+ lbrack$BBu$ sb{n}$(C$ sb6$F$ sb5) sb{4-n} rbrack sp-,$ was investigated. The rate law and qualitative observations support a new Zr(IV)/Zr(III) redox mechanism. / The use of ``cation-like'' metallocene combination catalysts $ rm(Cp sp prime sb2MCl sb2$ - 2BuLi - $ rm B(C sb6F sb5) sb3; Cp sp prime{=} eta sp5$-cyclopentadienyl, or substituted $ eta sp5$-cyclopentadienyl; M=Ti, Zr, Hf, U) for dehydropolymerization of silane significantly improves the polymer molecular weight. (Abstract shortened by UMI.)

<p>HDAC inhibitors are known to have anti-inflammatory properties. HDAC inhibitors are used in combination with Oct4 to generate induced pluripotent stem cells. I hypothesized that polyesters based on simple aliphatic HDAC inhibitors like valproic acid (VPA) and phenylbutyric acid (PBA) can serve as alternatives to existing polyester biomaterials with improved anti-inflammatory properties and as scaffolds for generation of iPSCs when used in combination with layer-by-layer thin films delivering reprogramming transcription factors. Vinyl ester of phenylbutyric acid (VEPA) and vinyl ester of valproic acid (VEVA) were synthesized from their carboxylic acid precursors using an iridium complex catalyst at yields as high as 97% and 73%, respectively. Amorphous poly(VEPA) and poly(VEVA) polymers were prepared by free radical solution polymerization and characterized for molecular weight and glass transition temperature. Poly(VEPA) and poly(VEVA) microparticles of 20-40 um diameter were prepared by an emulsion-solvent evaporation method and examined under scanning electron microscopy (SEM). Their hydrolytic degradation was studied by dry weight loss and HDAC inhibitor release via high performance liquid chromatography (HPLC) in the presence of varied pH and lipase-containing buffers. No significant degradation occurred within 5 days, and an MTT assay conducted on HeLa cells in the presence of these microparticles confirmed an absence of cytotoxicity. Poly(VEPA) and poly(VEVA) microparticles were not found to be a suitable biomaterial for hypothesized applications in light of their poor degradation characteristics in vitro.

<p> Although the glass transition temperature (<i>T_g</i>) and dynamics of polymers confined to the nanoscale have been studied for twenty years, a physical understanding is still lacking. The reason for a polymer species dependent <i>T_g</i>-confinement effect and the role of neighboring polymer domains in perturbing the <i>T_g</i> of a confined species are areas with a need for greater study as they will inform many of the decisions regarding the use of polymers in nanomaterials. </p><p> In this work, fluorescence spectroscopy is used as the primary tool to characterize <i>T_g</i> in a number of systems. First, micelle core <i>T_g</i> and critical micelle temperatures can be determined via pyrenyl label fluorescence for block copolymers in organic solvent at polymer contents which cannot be reliably characterized by other standard methods. Next, measurements were extended to miscible polymer-polymer blend systems where two component <i>T_gs</i> can be determined via a single pyrene-labeled component. Fluorescence can characterize systems with small component <i>T_g</i> differences and near-infinitely dilute blend components unlike scanning calorimetry. </p><p> Studies of the near-infinitely dilute blend components reveal that a 0.1 wt% polystyrene component can have its <i>T_g</i> tuned over a 150 &deg;C range depending on the blend partner. Analogous tunability of <i>T_g</i> is also reported in multilayer film systems with an ultrathin PS layer surrounding by bulk neighboring domains. The same limiting <i>T_g</i> is reported by PS for a given neighbor indicating a common physical origin of perturbations in both systems. The perturbations are correlated with fragility which also tracks with the magnitude of <i>T_g</i>-confinement effects in single layer polymer films. Thus, fragility provides a unifying explanation of confinement effects in multilayer films, blends, and single layer films (in the absence of attractive interactions). </p><p> Surface wave dynamics are also examined in ultrathin polystyrene layers on various substrates. It is demonstrated that surface dynamics become much slower than anticipated by capillary wave theory as the film thickness decreases. Additionally, surface wave dynamics become orders of magnitude faster as the modulus of the supporting substrate decrease.</p>

The removal of acetylene by selective hydrogenation is a critical step in the purification of ethylene streams for industrial polyethylene production. Hydrogenation of 0.35-1.0% acetylene in ethylene over Pd/Al$\sb2$O$\sb3$ catalysts is accompanied by the formation of significant amounts of surface oligomers/polymers. During the initial stages of CSTR operations at 40-120$\sp\circ$C and P = 1 atm these accounted for 8 to 50% of the acetylene consumed. Ethylene selectivities calculated ignoring these polymers are incorrect. Approximately 30% of these products are volatile and soluble in hydrocarbon solvents. They consist of even carbon numbered chains from C$\sb8$ to at least C$\sb{30}$. Normal paraffins are the major species at each carbon number, although branched paraffins, linear and branched mono-and di-olefins, and alkylbenzenes are also produced. The remainder is nonvolatile and insoluble in any known solvent; its degradation products are consistent with those of polyacetylenes of carbon number greater than 24. A mechanism involving polymerization in regions of low surface hydrogen concentrations and terminated by hydrogenation is proposed. The accumulation of the liquids in catalyst pores imposes diffusion limitations on the acetylene reaction; both the rate of acetylene consumption and its selectivity to ethylene decrease. These effects are reversible upon removing the liquid polymers. The decrease in surface polymer selectivity observed during operation is compensated by an increase in gas phase oligomer selectivity; the total oligomer/polymer selectivity does not change appreciably. In conjunction with previous investigations showing nearly constant ethane production only from acetylene, this suggests that the product distribution from acetylene hydrogenation does not change significantly. All catalysts exhibited an induction period where the activity increased and the ethylene selectivity decreased, the latter due only to an increase in the rate of ethylene hydrogenation. The duration of this period increased sharply with decreasing catalyst metal loading, which is proposed to be inversely related to metal dispersion. The increasing duration of activation is therefore a form of structure sensitivity. Activation was only reversible upon moderate temperature hydrogen or oxygen/hydrogen treatments and represents the formation of some active surface species.

In 1970, solid phase direct fluorination, using modern flow control techniques, was pioneered in the laboratories of John Margrave. Modern direct fluorination is rooted in these developments. The direct fluorination of polycyclic aromatic hydrocarbons (pyrene, coronene, perylene, etc ...) and several commercially available polymeric materials (polyethylene, poly (vinyl fluoride), poly (vinyl chloride), and polystyrene) are here reexamined. The previously unreported direct fluorination of the new polymer, polycyclopentadiene, has been carried out. The direct fluorination of the natural materials; coal and gilsonite; along with man-made petroleum coke affords a rapid, direct synthesis of potentially useful perfluorocarbon compound mixtures. The tentatively successful exhaustive fluorination of these starting compounds have been carried out using longer reaction times, and heated reaction vessels. By using extensive mass spectral, FT-IR, and differential scanning calorimetry data, a more complete description of the course of polymer fluorination is made possible. The vacuum pyrolysis mass spectra of polymers of varying fluorine contents are now reported. Several characteristic stages of fluorination can be identified. The superior thermal stability of fluorinated polymers is demonstrated using differential scanning calorimetry. DSC curves were secured for polymers in all stages of fluorination and are compared with those of the respective starting materials. Chemical reactions of an active carbon derived "CFX" are here reported. Slurries of the compound were contacted with a variety of nucleophilic reagents, most notably, alcoholic KOH and an assortment of amines. The products were examined using diffuse reflectance fourier transform infrared spectroscopy (DRIFTS), electron spectroscopy for chemical analysis (ESCA), and elemental analysis. The susceptibility of the substance to nucleophilic attack was confirmed. Defluorination and rearomatization were the most readily apparent results. Hydroxy groups were detected in the products of the KOH/ethanol reactions using ESCA.