This work has explored the capability of a mixed film composed of oligonucleotides and oligomers to improve the selectivity for the detection of fully complementary oligonucleotide targets in comparison to partially complementary targets which have one and three base-pair mismatched sites. The intention was to introduce a “matrix isolation” effect on oligonucleotide probe molecules by surrounding the probes with oligomers, thereby reducing oligonucleotide-to-oligonucleotide and/or oligonucleotide-to-surface interactions. This resulted in a more homogeneous environment for probes, thereby minimizing the dispersity of energetics associated with formation of double-stranded hybrids. The mixed film was constructed by immobilizing pre-synthesized oligonucleotides onto a mixed aminosilane layer and then growing the oligomer portion by surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxy methacrylate (PHEMA). The performance of the mixed film was compared to films composed of only oligonucleotides in a series of hybridization and melt curve experiments. Surface characterization techniques were used to confirm the growth of the oligomer portion as well as the presence of both oligonucleotides and oligomer components. Polyatomic bismuth cluster ions as sources for time-of-flight secondary ion mass spectrometry experiments could detect both components of the mixed film at a high sensitivity even though the oligomer portion was at least 200-fold in excess. At the various ionic strengths investigated, the mixed films were found to increase the selectivity for fully complementary targets over mismatched targets by increasing the sharpness of melt curves and melting temperature differences (delta Tm) by 2- to 3-fold, and by reducing non-specific adsorption. This resulted in improved resolution between the melt curves of fully and partially complementary targets. A fluorescence lifetime investigation of the Cy3 emission demonstrated that Cy3-labeled oligonucleotide probes experienced a more rigid microenvironment in the mixed films. These experiments demonstrated that a mixed film composed of oligonucleotides and PHEMA can be prepared on silica-based substrates, and that they can improve the selectivity for SNP discrimination compared to conventional oligonucleotide films.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

The self-assembling properties of a core-shell system are considered to be the most desirable characteristics that allow using this class of polymers in different applications. New hairy nanoparticles (HNPs) with hydrophobic polystyrene cores (PS Cores) and hydrophilic poly(2-hydroxyethylmethacrylate) (PHEMA) shells were synthesized by coupling polymerization methods. Living anionic polymerization in one-pot step was used to synthesize cross-linked polystyrene cores functionalized with hydroxyl groups and atom transfer radical polymerization (ATRP) was then carried out to prepare PHEMA hairs following the grafting form technique. The structural characterizations were carried out by FT-IR and NMR spectroscopy (1H NMR, 13C NMR, APT 13C NMR and 1H 13C HMQC). Dynamic light scattering measurements of obtained HNPs show small increase in the order of nanometers of their hydrodynamic radii after the grafting. Thermal properties were studied by TGA and DSC. The thermal stability of PS cores was affected by functionalization with the hydroxyl group. However, the stability of the PS core was not affected by grafting of PHEMA on their surfaces. DSC thermograms of the HNPs shows two distinct transition temperatures corresponding to glass transition temperatures (Tg) of a PS phase and of a PHEMA phase indicating the formation of a hydrophobic-hydrophilic phase separated system. SEM and AFM were utilized to study the morphologies and self-assembly of nanoparticles. The self-assembled HNPs morphologies were dependent on the solvents used. Complexes of the synthesized HNPs and R- or S-mandelic acid were prepared and characterized by circular dichroism (CD) and AFM. CD was used to study the induced chiral properties of the complexes. The CD spectra indicated the formation of enantiomeric chiral structures and the AFM images show toroidal self-assembled structures. Polymer blends of polystyrene functionalized with hydroxyl groups and PHEMA show different morphology and different thermal properties than the core-shell HNP system.

Facile, one-step synthesis of self-assembling, cationic block copolymers of poly(2-N-(dimethylaminoethyl) methacrylate) (pDMAEMA) and PEO-PPO-PEO (Pluronic®) is developed. The copolymers are obtained via free-radical polymerization of DMAEMA initiated by Pluronic-radicals generated by cerium (IV). The copolymers possess surface activity, are polycationic at pH<7.1, and self-assemble into micelle-like aggregates when neutralized. Potential applications of the novel copolymers for DNA transfection in gene therapy are discussed. / Singapore-MIT Alliance (SMA)

Three series copolyesters [poly(butylene succinate-co-propylene succinate) (PBPSu), poly(butylene succinate-co-2-methyl-1,3-propylene succinate) (PBMPSu) and poly(ethylene succinate-co-butylene succinate) (PEBSu)] and their homopolyesters [poly(butylene succinate) (PBSu), poly(ethylene succinate) (PESu), poly(propylene succinate) (PPSu) and poly(2-methyl-1,3-propylene succinate) (PMPSu)] were synthesized by a two-step reaction (esterification and polycondensation) with titanium tetraisopropoxide as the catalyst. Molecular weights of all synthesized polyesters were determined by intrinsic viscosity and gel permeation chromatography (GPC) measurements. The values of intrinsic viscosity (0.97 ~ 1.62 dL/g) and relative molecular weight (2.4x10000 ~ 11.9x10000 g/mol) indicate that these polyesters can be made into films without complications. Compositions and sequence distributions of copolyesters were determined by analyzing the spectra of 1H NMR and 13C NMR. The randomness values of these copolyesters are closed to 1.0 that represents random sequence distribution of the comonomers. Thermal properties and stabilities were characterized using differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA), respectively. All copolyesters exhibited a single glass transition temperature (Tg). For PBPSu copolyesters, incorporating propylene succinate units to PBSu not only narrows the window between Tg and melting temperature (Tm), but also retards the cold crystallization ability, thereby lowering the crystallinity to a considerable extent. This phenomenon also occurred in PBMPSu and PEBSu copolyesters when the 2-methyl-1,3-propylene succinate (MPS) and butylene succinate (BS) units were incorporated into PBSu and PESu, respectively. Tstart is the temperature of first detectable deviation from the derivative curve of weight loss. Tstarts of all synthesized polyesters around 240 £jC, higher than the temperature of polycondensation reaction (220 £jC), demonstrates that there is no necessity of using a thermal stabilizer during the synthesis of these polyesters. Additionally, the thermal stability does not vary significantly with compositions in the same series polyester. Wide-angle X-ray diffractograms (WAXDs) at room temperature were obtained from polyesters crystallized isothermally at a temperature around 5-20 £jC below their melting temperatures. WAXD patterns of two series polyesters elucidated that the incorporation of PS or MPS units into PBSu markedly inhibits the crystallization behavior of PBSu. The phenomenon also occurred in PEBSu copolyesters when BS units were incorporated into PESu. Results of WAXD and DSC measurements showed that PMPSu is a amorphous polyester. The retarding effect on crystallization by methyl substituents on the polymer chain is efficient.

ABSRACT: This research focuses on two hydrophilic polymers that form hydrogels when they sorb water: Poly(2-hydroxyethyl methacrylate) (PHEMA) and Poly(2,3-dihydroxypropyl methacrylate) (PDHPMA). Present work in the field obviated the need to properly characterize the thermal and dielectric properties of these materials.The dielectric permittivity, e', and the loss factor, e", of dry poly(2-hydroxyethyl methacrylate) and poly(2,3-dihydroxypropyl methacrylate) were measured using a dielectric analyzer in the frequency range of 0.1Hz to 100 kHz and between the temperature range of -150 °C to 275°C. The dielectric response of the sub-Tg gamma transition of PHEMA has been widely studied before but little to no DEA data above 50°C is present in the literature. This study is the first to present the full range dielectric spectrum of PHEMA, PDHPMA and their random copolymers up to and above the glass transition region. The electric modulus formalism and several mathematical proofs were used to reveal the gamma, beta, alpha and conductivity relaxations. Dielectric analysis gives insight into the network structure of the polymer; it has been shown through thermal analyses that as the DHPMA content increased in HEMA-DHPMA copolymers the polymer matrix increased in available free volume and facilitated the movement of ions in its matrix. This is of significance as we then investigated the feasibility of using PHEMA, PDHPMA and their random copolymers as materials for a biocompatible coating for an implantable glucose sensor. The biocompatibility of hydrogels can be attributed to the low interfacial tension with biological fluids, high gas permeability, high diffusion of low molecular weight compounds, and reduced mechanical and frictional irritation to surrounding tissue. Once the biocompatibility of the hydrogels was established, the task to coat the polyurethane (PU)/epoxy coated metal glucose sensor was addressed. Plasma polymerization was found to be the most feasible technique for the application of the biocompatible hydrogel as a coating on the implantable glucose sensor. It has also been shown that thermal analysis techniques provide a mode of investigation that can be used to investigate the interfacial interactions of a novel hydroxylated, self-assembled nanoparticle with two functionally different polymers, poly(2-dihydroxyethyl methacrylate) and poly(methyl methacrylate).

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

This work has explored the capability of a mixed film composed of oligonucleotides and oligomers to improve the selectivity for the detection of fully complementary oligonucleotide targets in comparison to partially complementary targets which have one and three base-pair mismatched sites. The intention was to introduce a “matrix isolation” effect on oligonucleotide probe molecules by surrounding the probes with oligomers, thereby reducing oligonucleotide-to-oligonucleotide and/or oligonucleotide-to-surface interactions. This resulted in a more homogeneous environment for probes, thereby minimizing the dispersity of energetics associated with formation of double-stranded hybrids. The mixed film was constructed by immobilizing pre-synthesized oligonucleotides onto a mixed aminosilane layer and then growing the oligomer portion by surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxy methacrylate (PHEMA). The performance of the mixed film was compared to films composed of only oligonucleotides in a series of hybridization and melt curve experiments. Surface characterization techniques were used to confirm the growth of the oligomer portion as well as the presence of both oligonucleotides and oligomer components. Polyatomic bismuth cluster ions as sources for time-of-flight secondary ion mass spectrometry experiments could detect both components of the mixed film at a high sensitivity even though the oligomer portion was at least 200-fold in excess. At the various ionic strengths investigated, the mixed films were found to increase the selectivity for fully complementary targets over mismatched targets by increasing the sharpness of melt curves and melting temperature differences (delta Tm) by 2- to 3-fold, and by reducing non-specific adsorption. This resulted in improved resolution between the melt curves of fully and partially complementary targets. A fluorescence lifetime investigation of the Cy3 emission demonstrated that Cy3-labeled oligonucleotide probes experienced a more rigid microenvironment in the mixed films. These experiments demonstrated that a mixed film composed of oligonucleotides and PHEMA can be prepared on silica-based substrates, and that they can improve the selectivity for SNP discrimination compared to conventional oligonucleotide films.

Poly(2-ethyl-2-oxazoline) (PEOX) is a nonionic, synthetic polymer which is soluble in both a variety organic solvents and water. The negative entropy of mixing of this polymer in aqueous solution suggested that it adopts a rigid conformation such as a helix in aqueous solution. Hydrogen bonding between PEOX and water molecules is thought to facilitate a special conformation that is specific to aqueous solution. The intent of this work is to investigate the conformation of PEOX in aqueous solution and consequently propose the mechanism by which it would adsorb onto cellulose and make it a valuable additive in paper processing. This work ultimately contributes to the greater matter of understanding the mechanisms by which water solvates nonionic polymers. Viscometry measurements of PEOX in water show that its shape scales similar to a random coil and that its molecules collapse in the presence of sodium chloride. Investigation into the molecular structure of PEOX through molecular scale simulations have revealed that although a rigid helical conformation does not exist, the potential exists for PEOX to have secondary helical structure in both water and other solvents. Without the rigid predicted structure, however, it is not surprising that PEOX does not adsorb well on cellulose. Comparing this folded helical conformation to a random coil conformation reveals that the random coil produces a lower energy system in water.

Poly (2-ethyl-2-oxazoline)-based amphiphilic diblock copolymer has the potential to form promising membrane materials for water purification due to the thermal stability and good solubility in aqueous solution and also for gas separation because of the presence of polar amide group along the polymer backbone. Moreover, their self-assembly into micelles renders them candidate materials as nanocarriers for drug delivery applications. In this study, a novel well-defined linear PEtOx-based amphiphilic diblock copolymer with a hydrophobic fluoropolymer, i.e., PVDF, have been successfully synthesized by implementing a synthesis methodology that involves the following four steps. In the first step, poly (2-ethyl-2-oxazoline) (PEtOx) was synthesized via living cationic ring-opening polymerization (LCROP) of 2-ethyl-2-oxazoline (EtOx) monomer. The “living” nature of LCROP allows the desirable termination to occur by using the proper termination agent, namely, water, to achieve the polymer with a terminal hydroxyl group, i.e., PEtOx-OH. The hydroxyl end group in PEtOx-OH was converted to PEtOx-Br using 2-bromopropionyl bromide via an esterification reaction. In the third step, the PEtOx-Br macro-CTA was subsequently reacted with potassium ethyl xanthate to insert the necessary RAFT agent via nucleophilic substitution reaction to obtain PEtOx-Xanthate. It s worth mentioning that this step is vital for the sequential addition of the second block via the RAFT polymerization reaction of fluorinated monomer, i.e., VDF, to finally obtain the well-defined amphiphilic diblock copolymer with variable controlled chain lengths. Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR) and Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the structure of the macroinitiator and final copolymer, respectively. Size Exclusion Chromatography (SEC) determined the number-average molecular weight (Mn) and the polydispersity index (PDI) of the obtained copolymer. Furthermore, the polymorphism of the diblock copolymer characterized by X-Ray Diffraction (XRD) indicated that the copolymer displays the electroactive α-phase. The resultant amphiphilic diblock copolymer exhibits spherical micelles morphology, as confirmed by Dynamic Light Scattering (DLS) and Atomic Force Microscopy (AFM). Moreover, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) investigated the thermal decomposition behavior of the copolymer and determined the glass transition temperature (Tg ≈ 70 °C), melting temperature (Tm ≈ 160-170 °C), and crystallization temperature (Tc ≈ 135-143 °C) of the diblock copolymer, respectively.