This thesis is focused on the design, synthesis and characterization of magnetite-ionic copolymer complexes as nanocarriers for drug delivery and magnetic resonance imaging. The polymers included phosphonate and carboxylate-containing graft and block copolymers. Oleic-acid coated magnetite nanoparticles (8-nm and 16-nm diameters) were investigated. Cisplatin and carboplatin were used as sample drugs. The potentials of the magnetite-ionomer complexes as dual drug delivery carriers and magnetic resonance imaging agents were evaluated. An acrylate-functional poly(ethylene oxide) macromonomer and hexyl (and propyl) ammonium bisphosphonate methacrylate monomers were synthesized. Conventional free radical copolymerizations were conducted to synthesize the graft copolymers. The acrylate-functional poly(ethylene oxide) macromonomer was also used to form graft copolymers with tert-butyl acrylate. Block ionomers containing poly(tert-butyl acrylate) were synthesized via atom transfer radical polymerization, then the tert-butyl groups were removed to afford anions. All the monomers and polymers were characterized by 1H NMR to confirm their structures and assess their compositions. Phosphonate-containing polymers were also characterized by 31P NMR. Magnetite nanoparticles (8-nm diameter) were synthesized by reducing Fe(acac)3 with benzyl alcohol. The 16-nm diameter magnetite was synthesized by thermal decomposition of an iron oleate precursor in trioctylamine as a high-boiling solvent. The iron-oleate precursor was synthesized with iron (III) chloride hexahydrate and sodium oleate with mixed solvents. TEM images of the magnetite were obtained. Magnetite-ionomer complexes were synthesized by binding a portion of the anions (carboxylate or phosphonate) on the copolymers onto the surfaces the magnetite. The remainder of the anions was used to bind with cisplatin and carboplatin via chelation. Physicochemical properties of the complexes were measured by dynamic light scattering. All the complexes with different polymers and magnetite nanoparticles displayed relatively uniform sizes and good size distributions. The magnetite-ionomer complexes displayed good colloidal stabilities in simulated physiological conditions for at least 24 hours. Those graft and block copolymer-magnetite complexes may be good candidates as drug carriers for delivery applications. After cisplatin and carboplatin loading, the sizes of the complexes increased slightly and the zeta potential decreased slightly, which indicated that the loadings were successful. Minimal loss of iron was found, signaling that the binding strengths between the magnetite and the anions of the graft copolymers were strong. 8.7 wt% of platinum was found in the cisplatin loaded complexes and 6.9% in the carboplatin loaded complexes. The results indicated that the magnetite-graft ionomer complexes were capable of loading drugs. Drug release studies were performed at pH 4.6 and 7.4 to mimick endosomal conditions and the physiological environment. Sustained release of drugs was observed. This further indicated the potential for using the magnetite-ionomer complexes as drug carriers. Transverse relaxivities of the magnetite-ionomer complexes with and without drugs were measured and compared to a commercial T2-weighted iron MRI contrast agent-Feridex®. All the complexes had higher relaxivities compared to Feridex®. Thus, the magnetite-ionomer complexes are promising candidates for dual magnetic resonance imaging and drug delivery.Moreover, the aqueous dispersion of the complexes was found to heat upon exposure to an AC magnetic field, thus potentially allowing heat-induced drug release. / Master of Science

published_or_final_version / abstract / Dentistry / Doctoral / Doctor of Philosophy

Ionomers are valued for their exceptional physical properties, antimicrobial activity and superior adhesion to high surface energy solids and polymer blend components. Carboxylate, or sulfonate derivatives, of ethylene-rich thermoplastics are the most commercially available ionomers. Elastomeric ionomers bearing quaternary ammonium and phosphonium halide functionality have a literary standing in both scientific and patent-based publications. Currently cationic ionomers have shown great prominence in their inactivity to a wide range of bacteria and fungi. The specific focus of this research is in the derivatives of isobutylene-rich elastomers due to their exceptional impermeability, oxidative stability and vibration dampening characteristics. Imidazole-derived ionomers support a wider range of ionomer chemistry compared to ammonium and phosphonium analogues. N alkylation of nucleophiles including butyl imidazole, vinyl imidazole and 1,1’(1,4-butanediyl)bis(imidazole) by brominated poly(isobutylene-co-isoprene) yield thermally stable imidazolium bromide salts capable of supporting free radical cures and/or siliceous filler dispersions through further chemical modifications. The versatility of imidazole chemistry extends to the synthesis of isobutylene rich thermoset ionomers. This derives material properties from both a network of covalent crosslinks and a network of ion pair aggregates. Un-crosslinked elastomers are prone to creep and stress relaxation, hence a need for thermoset ionomer chemistry. Ion pairs are poorly solvated by the low dielectric constant of the polymer backbone and favoured thermodynamically by way of self assembly of the ionic functionality. The aggregation of ion pairs establishes a non covalent network of polymer chains whose dynamic mechanical properties approach those of conventional covalent thermosets comprised of carbon-carbon and/or sulfide crosslinks. However, the lability of this ionic network leads to a poor response to static loads leaving the thermoformable ionomers unqualified for engineering applications. A direct route is a more desirable method in preparing thermoset ionomers comprised of covalent crosslink networks and ionic functionality. In all, these reactive imidazolium ionomers look promising in supporting new value added applications for isobutylene rich derivatives, which include yet are not limited to elastomer thermosets, emulsions, filler composites and clay nanocomposites. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2013-12-11 15:34:32.691

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Macromonomers bearing oligomerizable C=C functionality have been prepared by the nucleophilic displacement of allylic bromide functionality on brominated poly(isobutylene-co-isoprene) (BIIR). Whereas commercial grades of isobutylene-rich elastomers do not cure under the action of peroxides, these materials undergo simultaneous cross-linking and degradation when activated by radical initiators, with the competitive balance dictated by the reactivity of the oligomerizable group. Vinyl benzoate, vinyl imidazolium, and acrylate functionalities cure rapidly to high cross-link density whereas the maleimide graft is too reactive and unstable for any utility. Methacrylate and itaconate macromonomers cure to moderate extent while maleate esters and unactivated terminally unsaturated groups are unable to significantly counteract the degradation mechanism and do not afford any appreciable cross-link density to BIIR. The most reactive macromonomers display the potential for scorch, an effect that is efficiently mitigated with the introduction of (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) to quench free radical cure activity. Furthermore, an acrylated adduct, AOTEMPO, is able to recover more of the cross-link density that would otherwise be lost to irreversible free radical coupling. These nitroxyls display longer than expected induction times, likely due to the catalytic nature of TEMPO when alkoxyamine decomposition is significant. A suite of elastomeric ionomers bearing N-functional imidazolium bromide functionality have been prepared in order to investigate the N-alkylation dynamics with brominated poly(isobutylene-co-para-methylstyrene) (BIMS) as well as the subsequent peroxide cure activity of the reactive ionomer. A functional imidazole bearing a methacrylate group displayed moderate alkylation rate and good cure activity whereas a 4-vinylbenzyl analogue provides fast alkylation at the expense of storage stability. N-Allylimidazole is rapidly alkylated by BIMS in both solution and solvent free processes and the resulting ionomer displays unique cure dynamics. This phenomenon is investigated by model compound polymerization and is likely due to the unique free radical reactivity of allyl imidazolium moieties. The cross-linked ionomer displays many of the beneficial physical properties associated with a hybrid ionic/covalent network including good resistance to stress relaxation and thermal stability. / Thesis (Master, Chemical Engineering) -- Queen's University, 2014-01-29 17:09:42.428

Thesis (Ph.D.)--University of Melbourne, Faculty of Medicine, Dentistry and Health Science, 2005. / Author's name on cover: Leon Hugh Prentice. Typescript. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xii, 63 p. : ill. (some col.) Includes abstract. Includes bibliographical references.

Phenylene-based conjugated polymers are of interest for their fascinating electronic and optical properties. The introduction of bound ions into these materials adds great versatility because it can affect solubility, aggregation properties, doping chemistry, luminescence, and response to electrical stimuli. Despite ionic density being a central materials parameter in ionically functionalized conjugated polymers (IFCPs), it has been explored only in limited ranges. The primary advance reported in this dissertation is the development of three complementary synthetic routes to anionic and cationic poly(fluorene)s where the density of ionic functional groups was systematically varied between 0.05 and 0.5 per phenylene unit. There have been very few reports of IFCPs in this range. The three routes all use the Suzuki polycondensation reaction (SPR) to form poly[(R-fluorene)-co-alt-(R'-fluorene)] (PFF) IFCPs, and they differ from one another in when ionic functionality is introduced to the polymer. The development of these approaches grew out of studies on the SPR as it applies to ionically functionalized monomers, specifically, complications created by the two-phase nature of typical Suzuki couplings. In the first route, ions are added to the monomer and directly polymerized into the polymer using a single-phase SPR made possible by using oligoether functionality and a judiciously chosen solvent system. This route was used in the synthesis of a family of sulfonate and oligoether containing PFFs. In the second and third routes, ionic functionality is added after the polymer is formed either in solution or in solid films, respectively. The use of all nonionic monomers during the SPR avoided the complications encountered with two-phase reactions involving ionic monomers. The precursor polymers synthesized for these routes included a family of hexyl and bromohexyl containing PFFs and a family of oligoether and bromohexyl containing PFFs. The former were used to demonstrate post-polymerization quaternization to form cationic PFFs in solid films, and the later were quaternized in solution to yield soluble cationic PFFs. All of the polymers had very similar optical properties with the wavelengths of maximum absorption and emission in the range of 370-385 and 416-425 nm, respectively, and molecular weights greater than 10kDa and exhibited both positive and negative solvatofluorchromism due to aggregation phenomena.

Made available in DSpace on 2014-06-11T19:27:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-01-25Bitstream added on 2014-06-13T20:56:54Z : No. of bitstreams: 1 mata_m_me_arafo.pdf: 873853 bytes, checksum: 871f78b9e17a3ffeb34d531adfa84d2f (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste estudo foi avaliar in vitro o efeito da aplicação do ultrassom (US) na produção de calor na superfície e no interior do cimento de ionômero de vidro (CIV) Ketac Molar Easymix, assim como a temperatura transmitida à câmara pulpar através de restaurações de Ketac Molar Easymix (K) e Vitremer (V) após aplicação de US. Para avaliação da temperatura interna e superficial foi confeccionada uma matriz a partir de um incisivo bovino. A temperatura superficial foi aferida no grupo controle (TSC) e no grupo experimental (TSU) por meio de uma câmera termográfica infravermelha, calibrada e fixada há 15 cm do espécime, a qual captou as variações de temperatura por 80s. Para aferir a temperatura no interior do material, uma cânula de nylon foi inserida via abertura do conduto radicular do dente bovino até atingir o interior do CIV inserido na matriz, na qual foi adaptado um termômetro de vareta digital portátil. Após US por 45s, nos grupos controle (TIC) e experimental (TIU), a temperatura interna foi aferida em 0, 45, e 120s, totalizando 2 min após a inserção do material na cavidade. A temperatura transmitida à câmara pulpar durante a aplicação de US por 45s foi avaliada em 48 pré-molares humanos, os quais tiveram seus ápices seccionados para remoção da polpa, substituída por uma pasta condutora de calor. Foram divididos nos grupos: controle (KC), experimental (KU), controle (VC) e experimental (VU). Após a realização das restaurações na face vestibular dos dentes, estas receberam a aplicação de US por 45s e fotopolimerização por 40s para o grupo VU. Através da abertura dos condutos radiculares dos dentes, um termístor foi inserido até entrar em contato com a parede interna da superfície vestibular, possibilitando a captação... / The aim of this study was to evaluate in vitro the effect of ultrasound (US) application in the production of heat at the surface and inside the glass ionomer cement (GIC) Ketac Molar Easymix, as well the temperature transmitted to the pulp chamber through restorations of Ketac Molar Easymix (K) and Vitremer (V) after ultrasound application. For evaluation of the internal and surface temperature was made a matrix of one bovine incisor. The surface temperature was measured in the control group (STC) and the experimental group (STU) through an infrared thermographic camera, calibrated and fixed for 15 cm of the specimen, which raised the temperature variations for 80s. In order to measure the temperature inside the material, a nylon cannula was inserted through opening of the root canal bovine tooth until the interior of the GIC inserted into the array, which was adapted an portable digital thermometer. After US for 45s, in the control group (ITC) and experimental group (ITU), the internal temperature was measured at 0, 45, and 120s, totaling 2 minutes after material insertion in the cavity. The temperature transmitted to the pulp chamber during the application of ultrasound for 45s was evaluated in 48 human premolars, which had their apices disconnected to remove the pulp, replaced by a heat-conductive paste. They were divided into groups: control (KC), experimental (KU), control (VC) and experimental (VU). After performing of the restorations on the vestibular surface of the teeth, they received the ultrasound application for 45s and photopolymerization for 40s for the group VU. Through the opening of the root canal tooth, a thermistor was inserted until contact with the inner wall of the vestibular surface, allowing the collection of temperature variations. After verification of normality in the STC, STU, ITC, ITU groups... (Complete abstract click electronic access below)

Orientador: Angela Cristina Cilense Zuanon / Banca: Renata Cristiane da Silva / Banca: Ticiane Sidorenko de Oliveira Capote / Resumo: O objetivo deste estudo foi avaliar in vitro o efeito da aplicação do ultrassom (US) na produção de calor na superfície e no interior do cimento de ionômero de vidro (CIV) Ketac Molar Easymix, assim como a temperatura transmitida à câmara pulpar através de restaurações de Ketac Molar Easymix (K) e Vitremer (V) após aplicação de US. Para avaliação da temperatura interna e superficial foi confeccionada uma matriz a partir de um incisivo bovino. A temperatura superficial foi aferida no grupo controle (TSC) e no grupo experimental (TSU) por meio de uma câmera termográfica infravermelha, calibrada e fixada há 15 cm do espécime, a qual captou as variações de temperatura por 80s. Para aferir a temperatura no interior do material, uma cânula de nylon foi inserida via abertura do conduto radicular do dente bovino até atingir o interior do CIV inserido na matriz, na qual foi adaptado um termômetro de vareta digital portátil. Após US por 45s, nos grupos controle (TIC) e experimental (TIU), a temperatura interna foi aferida em 0, 45, e 120s, totalizando 2 min após a inserção do material na cavidade. A temperatura transmitida à câmara pulpar durante a aplicação de US por 45s foi avaliada em 48 pré-molares humanos, os quais tiveram seus ápices seccionados para remoção da polpa, substituída por uma pasta condutora de calor. Foram divididos nos grupos: controle (KC), experimental (KU), controle (VC) e experimental (VU). Após a realização das restaurações na face vestibular dos dentes, estas receberam a aplicação de US por 45s e fotopolimerização por 40s para o grupo VU. Através da abertura dos condutos radiculares dos dentes, um termístor foi inserido até entrar em contato com a parede interna da superfície vestibular, possibilitando a captação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate in vitro the effect of ultrasound (US) application in the production of heat at the surface and inside the glass ionomer cement (GIC) Ketac Molar Easymix, as well the temperature transmitted to the pulp chamber through restorations of Ketac Molar Easymix (K) and Vitremer (V) after ultrasound application. For evaluation of the internal and surface temperature was made a matrix of one bovine incisor. The surface temperature was measured in the control group (STC) and the experimental group (STU) through an infrared thermographic camera, calibrated and fixed for 15 cm of the specimen, which raised the temperature variations for 80s. In order to measure the temperature inside the material, a nylon cannula was inserted through opening of the root canal bovine tooth until the interior of the GIC inserted into the array, which was adapted an portable digital thermometer. After US for 45s, in the control group (ITC) and experimental group (ITU), the internal temperature was measured at 0, 45, and 120s, totaling 2 minutes after material insertion in the cavity. The temperature transmitted to the pulp chamber during the application of ultrasound for 45s was evaluated in 48 human premolars, which had their apices disconnected to remove the pulp, replaced by a heat-conductive paste. They were divided into groups: control (KC), experimental (KU), control (VC) and experimental (VU). After performing of the restorations on the vestibular surface of the teeth, they received the ultrasound application for 45s and photopolymerization for 40s for the group VU. Through the opening of the root canal tooth, a thermistor was inserted until contact with the inner wall of the vestibular surface, allowing the collection of temperature variations. After verification of normality in the STC, STU, ITC, ITU groups... (Complete abstract click electronic access below) / Mestre