Functionalized poly(para-xylylene) (PPX) coatings can be useful for biomaterials applications due to their biocompatibility and useful chemistry for the immobilization of biomolecules. However, their application is not widespread due to the difficulty in synthesizing the corresponding precursors. Here, a two-step method for amine functionalization of [2.2]paracyclophane (PCP) via direct nitration and reduction is developed. Nitration at super acidic conditions and temperatures as low as -78 °C, improved the stability of PCP toward strong acids and successfully minimized side reactions such as oxidation and polymerization. This procedure resulted in quantitative yields of 4-nitro-PCP, which was successively reduced by Raney nickel catalysis with sodium borohydride. Compared to the many other reduction systems, this method is simple, inexpensive and applicable in large scales. Additionally, carboxylation of PCP using the Freidel-Crafts acylation was attempted and so far, we have been able to show the synthesis of intermediate acylated products. Then, through the chemical vapour deposition polymerization of amino-PCP amine-functionalized poly(para-xylylene) (PPX-A) thin films were coated on Si wafer substrates. The substrates coated with PPX-A showed a higher surface energy compared with those of coated with un-substituted or chlorine substituted PPX films. Furthermore, results of the surface characterization demonstrated that the CVD process was able to transfer the functionalities of the precursors to deposited polymer films without alteration. However, the stability of primary amine groups in air and aqueous solutions is a matter of concern. Aging of amino-PCP and corresponding PPX-A films showed a decrease in the amount of primary amines which was accompanied by the appearance and increase of oxygen, indicating that the decrease of available amine groups is associated with oxidation. Nevertheless, both aminated precursor and polymer films remained intact under argon. The method presented here has great potential for widespread application of PPX-A as a convenient biomaterial for microarrays and cell culture. / Thesis / Master of Science (MSc)

Functionalized reactive polymer coatings can be used in various biomaterials applications such as immunoassays and biomolecule immobilization. Poly(para-xylelene) is a relatively new biomaterial that has attracted attention over the past few decades in these areas due to its unique properties and biocompatibility. The introduction of functionalized, particularly aminated, poly(para-xylylene) will extend the application of these polymer coatings to a wide variety of biological studies. However, their application is not widespread due to the difficulty in synthesizing the corresponding precursors. Here, a two-step method for amine functionalization of [2.2]paracyclophane via direct nitration and reduction is developed. Nitration at super acidic conditions and temperatures as low as -78 °C, improved the stability of [2.2]paracyclophane toward strong acids and successfully minimized side reactions such as oxidation and polymerization. This procedure resulted in quantitative yields of 4-nitro[2.2]para-cyclophane, which was successively reduced by Raney nickel catalysis with sodium borohydride. Compared to the many other reduction systems, this method is simple, inexpensive and applicable in large scales. It does not require harsh reaction conditions and within short reaction times, delivers quantitative amounts of the reduced product. At the end, 4-amino[2.2]paracyclophane was collected in 77% overall yield. Additionally, carboxylation of [2.2]paracyclophane using the Freidel-Crafts acylation was attempted and so far, we have been able to show the synthesis of intermediate acylated products. The successful syntheses of products were verified by FT-IR, NMR and MS, and comparison of their solubility and physical properties showed significant changes upon substitution of the pristine [2.2]paracyclophane. Then, through the chemical vapour deposition polymerization of 4-amino[2.2]paracyclophane amine-functionalized thin films were coated on Si wafer substrates and their properties were compared with Parylene N and C, two well-known poly(para-xylylene) films. The substrates coated with amino-poly(para-xylylene) showed a higher surface energy compared with those of coated with un-substituted or chlorine substituted poly(para-xylylene) films. Furthermore, results of the surface characterization conducted by grazing angle reflectance IR spectroscopy and XPS, demonstrated that the CVD process was able to transfer the functionalities of the precursors to deposited polymer films without alteration. However, with the applied process parameters we obtained a higher functional density of amine groups on the surface. These polymer films can be deposited on a variety of substrates and be used as functional surfaces for a variety of applications. However, the stability of primary amine groups in air and aqueous solutions is a matter of concern. Aging of 4-amino-[2.2]paracyclophane and corresponding poly(para-xylylene) films in air and mili-Q water was studied via XPS and NMR spectroscopies. The results showed a decrease in the amount of primary amines with storage time in air or water for both aminated precursor and polymer. The kinetics for these changes, however, were not equal for the precursors and polymer films. The decay of amine groups was accompanied by the appearance and increase of oxygen, indicating that the decrease of available amine groups is associated with oxidation which can transform them to more stable amide and nitro compounds. In total, practical challenges involved in manufacture, durability and applications of amine-functionalized Parylene coatings are discussed and a reliable scheme for fabricating such films with high tunabiliy of the surface functional density is demonstrated. The highly practical method presented here provides great potential for widespread application of amine-functionalized poly(para-xylylene) as an outstanding biomaterial for microarrays, tissue engineering and cell culture studies. / Thesis / Master of Science (MSc)

No description available.

<p>Low molecular weight functionalized polyolefins are mainly used as additives in adhesive formulations, compatibilizing agents and aqueous dispersions. However, the low viscosity and functionality they offer has never been explored to generate high molecular weight products that offer improved processing routes for polyolefins as well as wider applications.</p> <p>The aim of this thesis work was to investigate the preparation and characterization of thermoset material by reactions between a highly functionalized, low viscosity maleic anhydride grafted polyethylene and diamines. Reactions were performed both in solution and in the melt state to generate the target thermoset materials. Products from these reactions were extensively explored using different techniques to understand the reaction kinetics and mechanism. Thermosets generated were also characterized for the degree of crosslinking, thermal, mechanical and thermomechnical properties.</p> <p>Reactions in solution showed that the degree of reaction could be easily controlled by manipulating the concentration of reactants in the reaction mixture. Mixing torque data from the melt blender generated during reactions in the melt phase suggested that reaction between anhydride and amine moieties in these systems happen at much slower rate than widely reported for conventional high molecular weight polymeric systems. Unlike a single or two closely merged peaks in mixing torque associated with melting of polymer and chain extension and crosslinking due to reaction between anhydride and amine functionality widely reported, two separate peaks were observed in this study. A combination of FTIR and insoluble fraction data generated suggested that the first peak observed in mixing torque represents a combination of melting and partial reaction between anhydride and amine functionality. Whereas, the second peak in the mixing torque represents the initiation of crosslinking. The slower kinetics observed in the current investigation was found not to be a consequence of immiscibility of polyether diamine and polyethylene or the relatively higher molecular weight of diamines utilized in some reactions since using a low molecular weight aliphatic diamine, hexamethylenediamine, produced similar trends. FTIR and gel content (insoluble fraction) data generated on the prepolymers by processing them at high temperatures, suggested residual anhydride presence in products which could not be assessed using FTIR. This observation renders the popular monitoring of anhydride peak in such systems to assess the degree of reaction highly questionable. Cured thermosets from the prepolymers produced showed gel fractions of the same scale as in traditional crosslinked products. DSC heat scans on the thermosets showed separate crystal populations for polyethylene in cured and uncured fraction. Dynamic mechanical analysis result showed the thermosets withstood temperature up to 200 °C without failure and a crosslink plateau could be observed following the melting transition. Tensile properties of the thermosets were observed to be promising and composition dependent.</p> <p>These thermosets are expected to extend the polyolefins applications in areas like sealant, adhesive and coatings. The low viscosities of starting materials could also lead to new processing routes for polyolefins.</p> / Doctor of Philosophy (PhD)

<p>N-chloramide containing and primary amine-containing microgels were prepared by post-modification of thermosensitive microgels in alkaline bleach. The objective of this project was to develop simple strategies for preparation of functionalized microgels.</p> <p>N-chlorination of linear poly(N-isopropylacrylamide) (PNIPAM) in bleach at high pH resulted in a novel N-chloramide containing copolymer: poly(NIPAM-co-NIPAMCl). The chlorinated PNIPAM showed controlled phase transition temperature and oxidative ability. The N-chlorination of linear PNIPAM inspired the preparation of N-chloramide containing PNIPAM microgels in a similar way. The phase transition temperature of the resulted chlorinated microgels, which corresponds to the extent of N-chlorination, was affected by the reaction temperature and salt concentration. The reaction between the chlorinated microgels and glutathione is proposed as diffusion controlled.</p> <p>The N-chlorination of poly(N-isopropylmethacrylamide) (PNIPMAM) microgels in bleach was restricted, in comparison with PNIPAM microgels. The active chlorine content of chlorinated PNIPMAM microgels was about one-tenth of that of chlorinated PNIPAM microgels under the same N-chlorination condition. It is proposed that the high stability of PNIPMAM in bleach is a result of the electron-donating effect of methyl groups on PNIPMAM backbone. Hence, core-shell microgels with PNIPAM cores and poly(NIPAM-co-NIPMAM) shells showed improved colloidal stability after N-chlorination because the shell was less chlorinated and served as a steric stabilizer.</p> <p>Finally, primary amine-containing microgels were prepared via Hofmann rearrangement of copolymers of methacrylamide, which decomposed to give amines, and NIPMAM, which did not react. The method was further extended to give amphoteric microgels by including acrylic acid in the starting microgels. Although other approaches to aminated and amphoteric microgels have been developed, this approach is particularly attractive because of the ease of the reaction and the ability to control the microgel isoelectric points.</p> / Doctor of Philosophy (PhD)

While the Canadian food supply is among the healthiest in the world, almost 4 million (1 in 8) Canadians are affected by food-borne illnesses, resulting in 11,600 hospitalizations and 238 deaths per year. Microbial pathogens are one of the major causes of foodborne sicknesses that can grow in food before or following packaging. Food distribution is an important part of the food processing chain, in which food supplies are at a higher risk of contamination due to lack of proper monitoring. Among myriad of research around biosensors, current devices focusing on packaged food monitoring, such as leakage indicators or time temperature sensors are not efficient for real-time food monitoring without separating the sample from the stock. Packaged food such as meat and juice are directly in touch with the surface of their containers or covers. Therefore, real-time sensing mechanisms, installed inside the food packaging and capable of tracing the presence of pathogens, are of great interest to ensure food safety. This work involves developing thin, transparent, flexible and durable sensing surfaces using DNA biosensors, which report the presence of a target bacterium in food or water samples by generating a fluorescence signal that can be detected by simple fluorescence detecting devices. The covalently-attached DNA probes generate the signal upon contact with the target bacteria with as low as 103 CFU/mL of Escherichia coli in meat and apple juice. The fabricated sensing surfaces remained stable up to several days under varying pH conditions (pH 5 to 9). In addition to detecting pathogens on packaged food or drinking bottles, these surfaces have the potential to be used for a variety of other applications in health care settings, environmental monitoring, food production chain, and biomaterials like wound dressing. / Thesis / Master of Science (MSc) / Microbial pathogens can grow in food following packaging and preceding consumption. Current biosensors are not efficient for post-packaging real-time food monitoring without separating the sample from the stock. Packaged food such as meat and juice are directly in touch with the surface of their containers or covers. Therefore, real-time sensing mechanisms, installed inside the food packaging, tracing the presence of pathogens, are much useful to ensure the food safety. Here we report on developing thin, transparent, flexible and durable sensing surfaces using DNA biosensors, which generate a fluorescence signal in the presence of a target bacterium in food or water samples. The covalentlyattached DNA probes can detect as low as 103 CFU/mL of Escherichia coli in meat, sliced apple and apple juice. The fabricated sensing surfaces remained stable up to several days under varying pH conditions (pH 5 to 9). In addition to pathogen monitoring in packaged food or drinking bottles, these surfaces are promising for a variety of other applications in health care settings, environmental monitoring, and biomaterials like wound dressing.

No / The aim of this study was to develop a synthetic hydrogel to act as a corneal substitute capable of selectively supporting the adhesion and proliferation of limbal epithelial cells (LECs) while inhibiting growth of limbal fibroblasts. Deficiency of LECs causes conjunctival epithelial cells to move over the cornea, producing a thick scar pannus. Unilateral defects can be treated using LEC cultured from the unaffected eye, transplanting them to the affected cornea after scar tissue is removed. The underlying wound bed is often damaged, however, hence the need to develop a corneal inlay to aid in corneal re-epithelialization. Transparent epoxy-functional polymethacrylate networks were synthesized using a combination of glycerol monomethacrylate, ethylene glycol dimethacrylate, lauryl methacrylate and glycidyl methacrylate that produced two different bulk hydrogel compositions with different equilibrium water contents (EWCs): Base 1 and Base 2, EWC=55% and 35%, respectively. Two sets of amine-functional hydrogels were produced following reaction of the epoxide groups with excesses of either ammonia, 1,2-diamino ethane, 1,3-diamino propane, 1,4-diamino butane or 1,6-diamino hexane. Neither series of hydrogels supported the proliferation of limbal fibroblasts irrespective of amine functionalization but they both supported the adhesion and proliferation of limbal epithelial cells, particularly when functionalized with 1,4-diamino butane. With Base 1 hydrogels (less so with Base 2) a vigorous epithelial outgrowth was seen from small limbal explants and a confluent epithelial layer was achieved in vitro within 6days. The data support the development of hydrogels specific for epithelial formation.

Yes / A mass transfer model was developed for CO2 capture from a binary gas mixture of N2/CO2 in hollow fibre membrane contactors under laminar flow conditions. The axial and radial diffusions through membrane and convection in tube and shell sides with chemical reaction were investigated. COMSOL software was used to numerically solve a system of non-linear equations with boundary conditions by use of the finite element method. Three different amine solutions of monoethanolamine (MEA), diethanolamine (DEA) and n-methyldiethanolamine (MDEA) were chosen as absorbent in lumen to consider the mass transfer rate of CO2 and compare their removal efficiency. The modelling results were compared with experimental data available in the literature and a good agreement was observed. The CFD results revealed that MEA had the best performance for CO2 removal as compared to DEA and MDEA under various operating conditions due to the different CO2 loading factor of absorbents. Furthermore, efficiency of CO2 removal was highly dependent on the absorbent concentration and its flow rate, increasing of the gas flow rate caused a reduction in gas residence time in the shell and consequently declined CO2 mass transfer. The modelling results showed the influence of the absorbent concentration on the CO2 mass transfer has improved due to availability of absorbent reactants at the gas-liquid interface.

The synthesis of dipyridyl functionalized polysulfones with improved hydrophilicity, enhanced membrane morphology and excellent ATRP polymeric ligand properties was conducted by the following method: (a) the formation of lithiated polysulfone from unmodified polysulfone and the subsequent reaction with 2,2'-vinylidenedipyridine in tetrahydrofuran at -78 oC under argon atmosphere to afford the corresponding dipyridyl functionalized polysulfone. The stoichiometry of the reaction affects the degree of functionalization of the product. When equimolar amounts of 2,2'-vinylidenedipyridine are added to the lithiated polysulfone, the degree of functionalization obtained was 45%. However, the addition of 10% and 20% molar excess of 2,2'-vinylidenedipyridine to the corresponding lithiated polysulfone produced dipyridyl functionalized polysulfones with degrees of functionalization of 80% and 95%, respectively; and (b) the membranes obtained from unmodified polysulfone as well as dipyridyl functionalized polysulfones were characterized by atomic force microscopy, scanning electron microscopy, pure water permeation measurements and contact angle measurements. Amine chain end functionalized polystyrene and poly(methyl methacrylate) were prepared by Atom Transfer Radical Polymerization (ATRP) methods as follows: (a) •-Aminophenyl functionalized polystyrene was prepared in quantitative yields by ATRP methods using a new primary amine functionalized initiator adduct, formed in situ by the reaction of 1-(4-aminophenyl)-1-phenylethylene and (1-bromoethyl)benzene in the presence of copper (I) bromide/2,2'-bipyridyl as catalyst in diethyl ether at 110 oC, for the polymerization of styrene.(b) New •-bis(aminophenyl) and •,ω-tetrakis(aminophenyl) functionalized polymers were prepared in quantitative yields by the ATRP method using the following synthetic strategy: (i) the initiation of styrene polymerization with a new primary diamine functionalized initiator adduct, generated in situ by the reaction of stoichiometric amounts of 1,1-bis(4-aminophenyl)ethylene with (1-bromoethyl)benzene in the presence of copper (I) bromide/2,2'-bipyridyl as catalyst, afforded •-bis(aminophenyl) functionalized polystyrene; and (ii) •-bis(aminophenyl) functionalized poly(methyl methacrylate) was prepared by the ATRP method using the primary diamine functionalized initiator adduct as initiator for methyl methacrylate polymerization; and (iii) well defined •,ω-tetrakis(aminophenyl) functionalized polystyrene was prepared by the post ATRP chain end modification reaction of •-bis(aminophenyl) functionalized polystyrene with 1,1-bis(4-aminophenyl)-ethylene at the completion of the polymerization reaction. (c) Similarly, •-bis(4-dimethylaminophenyl) functionalized polystyrene was prepared by using a new tertiary diamine functionalized initiator adduct, formed in situ by treatment of equimolar amounts of 1,1-bis[(4-dimethylamino)phenyl]-ethylene with (1-bromoethyl)benzene in the presence of copper (I) bromide/2,2'-bipyridyl as the catalyst in diphenyl ether at 110 oC for the initiation of styrene polymerization by the ATRP method. Furthermore, the ATRP of methyl methacrylate, initiated by the new tertiary diamine functionalized initiator adduct, produced •-bis(4-dimethylaminophenyl) functionalized poly(methyl methacrylate). In addition, •,ω-tetrakis(4-dimethylaminophenyl) functionalized polystyrene was synthesized via a post ATRP chain end modification reaction of •-bis(4-dimethylaminophenyl) functionalized polystyrene with equimolar amounts of 1,1-bis[(4-dimethylamino)phenyl]ethylene at the completion of the polymerization process. vi Quantitative yields of the different amine functionalized polymers with predictable number average molecular weights (Mn = 1.3 x 103 – 16.4 x103 g/mol), narrow molecular weight distributions (Mw/Mn = 1.03 – 1.29) and controlled chain end functionality were obtained. Polymerization kinetics data was employed to determine the controlled/living character of each ATRP reaction leading to the formation of the different amine chain end functionalized polymers. The polymerization processes were monitored by gas chromatographic analyses. Polymerization kinetics measurements for all reactions show that the polymerizations follow first order rate kinetics with respect to monomer consumption. The number average molecular weight of the amine functionalized polymers increases linearly with percentage monomer conversion and polymers with narrow molecular weight distribution were obtained. The ATRP of styrene, catalyzed by a novel dipyridyl functionalized polysulfone/CuBr supported catalyst system, afforded well defined polystyrene with predictable number average molecular weight and narrow molecular weight distribution in a controlled/living free radical polymerization process. The substituted 1,1-diphenylethylene initiator precursor derivatives and the functionalized polymers were characterized by nuclear magnetic resonance spectrometry, fourier transform infrared spectroscopy, thin layer chromatography, column chromatography, size exclusion chromatography, non-aqueous titrations, differential scanning calorimetry and thermogravimetrical analysis. / Chemistry / M. Sc. (Chemistry)

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