Phosphorylcholine based amphiphilic polymers for the solubilization of integral membrane proteins

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

The effects of additives and chemical modification on the solution properties of thermo-sensitive polymers

Cette thèse concerne l’étude de phase de séparation de deux polymères thermosensibles connus-poly(N-isopropylacylamide) (PNIPAM) et poly(2-isopropyl-2-oxazoline) (PIPOZ). Parmi des études variées sur ces deux polymères, il y a encore deux parties de leurs propriétés thermiques inexplicites à être étudiées. Une partie concerne l’effet de consolvant de PNIPAM dans l’eau et un autre solvant hydromiscible. L’autre est l’effet de propriétés de groupes terminaux de chaînes sur la séparation de phase de PIPOZ. Pour ce faire, nous avons d’abord étudié l’effet de l’architecture de chaînes sur l’effet de cosolvant de PNIPAMs dans le mélange de méthanol/eau en utilisant un PNIPAM en étoile avec 4 branches et un PNIPAM cyclique comme modèles. Avec PNIPAM en étoile, l’adhérence de branches PNIPAM de à un cœur hydrophobique provoque une réduction de Tc (la température du point de turbidité) et une enthalpie plus faible de la transition de phase. En revanche, la Tc de PNIPAM en étoile dépend de la masse molaire de polymère. La coopérativité de déhydratation diminue pour PNIPAM en étoile et PNIPAM cyclique à cause de la limite topologique. Une étude sur l’influence de concentration en polymère sur l’effet de cosolvant de PNIPAM dans le mélange méthanol/eau a montré qu’une séparation de phase liquide-liquide macroscopique (MLLPS) a lieu pour une solution de PNIPAM dans le mélange méthanol/eau avec la fraction molaire de méthanol entre 0.127 et 0.421 et la concentration en PNIPAM est constante à 10 g.L-1. Après deux jours d’équilibration à température ambiante, la suspension turbide de PNIPAM dans le mélange méthanol/eau se sépare en deux phases dont une phase possède beaucoup plus de PNIPAM que l’autre. Un diagramme de phase qui montre la MLLPS pour le mélange PNIPAM/eau/méthanol a été établi à base de données expérimentales. La taille et la morphologie de gouttelettes dans la phase riche en polymère condensée dépendent de la fraction molaire de méthanol. Parce que la présence de méthanol influence la tension de surface des gouttelettes liquides, un équilibre lent de la séparation de phase pour PNIPAM/eau/méthanol système a été accéléré et une séparation de phase liquide-liquide macroscopique apparait. Afin d’étudier l’effet de groupes terminaux sur les propriétés de solution de PIPOZ, deux PIPOZs téléchéliques avec groupe perfluorodécanyle (FPIPOZ) ou groupe octadécyle (C18PIPOZ) comme extrémités de chaîne ont été synthétisés. Les valeurs de Tc des polymères téléchéliques ont beaucoup diminué par rapport à celle de PIPOZ. Des micelles stables se forment dans des solutions aqueuses de polymères téléchéliques. La micellization et la séparation de phase de ces polymères dans l’eau ont été étudiées. La séparation de phase de PIPOZs téléchéliques suit le mécanisme de MLLPS. Des différences en tailles de gouttelettes formées à l’intérieur de solutions de deux polymères ont été observées. Pour étudier profondément les différences dans le comportement d’association entre deux polymères téléchéliques, les intensités des signaux de polymères correspondants et les temps de relaxation T1, T2 ont été mesurés. Des valeurs de T2 de protons correspondants aux IPOZs sont plus hautes.

Comparison of Microwave and Electrical Properties Selected Conducting Polymers

Microwave properties of conductive polymers is crucial because of their wide areas of applications such as coating in reflector antennas, coating in electronic equipments, firequenry selective .surfaces, EMI materials, satellite communication links, microchip antennas, and medical applications. This work involves a comparative study of dielectric properties of selected conducting polymers such as polyaniline. poly(3,4-eth),lenedio.syt2iophene), polvthiophene, polvpvrrole. and pohparaphenylene diazomethine (PPDA) in microwave and DC,fields. The inicrowave properties such as dielectric constant, dielectric loss. absorption coefficient, heating coefficient, skin depth, and conductivity in the microwave frequency (S hand), and DC fields were compared. PEDOT and polccuiiline were found to exhibit excellent properties in DC field and microwave frequencies, which make thein potential materials in many of the alorenientioned applications

Effect of curing temperature , fibre loading and bonding agent on the equilibrium swelling of isora-natural rubbercomposites

Isora fibre-reinforced natural rubber (NR) composites were cured at 80, 100, 120 and 150°C using a low temperature curing accelerator system. Composites were also prepared using a conventional accelerator system and cured at 150°C. The swelling behavior of these composites at varying fibre loadings was studied in toluene and hexane. Results show that the uptake of solvent and volume fraction of rubber due to swelling was lower for the low temperature cured vulcanizates which is an indication of the better fibre/rubber adhesion. The uptake of aromatic solvent was higher than that of aliphatic solvent, for all the composites. As the fibre content increased, the solvent uptake decreased, due to the superior solvent resistance of the fibre and good fibre-rubber interactions. The bonding agent improved the swelling resistance of the composites due to the strong interfacial adhesion. Due to the improved adhesion between the fibre and rubber, the ratio of the change in volume fraction of rubber due to swelling to the volume fraction of rubber in the dry sample (V,) was found to decrease in the presence of bonding agent. At a fixed fibre loading, the alkali treated fibre composite showed a lower percentage swelling than untreated one for both systems showing superior rubber-fibre interactions.

Photoacoustic evaluation of the thermal effusivity in the isotropic phase of certain comb-shaped polymers

The thermal effusivity values in the isotropic phase of certain comb-shaped polymers have been evaluated for the first time using an open photoacoustic cell configuration. The compounds investigated have siloxane and acrylate backbone and they carry mesogenic groups in their side chain. The results indicate that the polymer chain length as well as the side chain length have pronounced influence on the thermal effusivity values in liquid crystalline polymers

Development of Photorefractive Polymers: Evaluation of Photoconducting and Electro-optic Properties

This Thesis discussed molecules suitable for photorefractive effect. Out of the molecules studied, only one system was used to make photorefractive polymers system. Other molecules, especially, the electro-optic polymer, Poly(3-methacrloyl-1-(4'-nitro-4-azo-1'-phenyl)phenylalanine-co- methyl methacrylate) can be subjected to more detailed studies to explore the possibilities of using them for electro-optic applications. Though not included in the thesis, the efficient photoconductor, Poly(6-tert-butyl-3- phenyl-3,4-dihydro-2H-1,3-benzoxazine) sensitized with C60, which was described in Chapter 3 showed a low magnitude photovoltaic effect. This hints at the possibility of using this system for organic solar cells also. The thesis presented the initial observation of photorefractive effect in a polybenzoxazine based polymer system. A detailed analysis of the effect of C60, ECZ and DR1 can be carried out to check for the possibility of a high efficiency photorefractive system.

Design and Synthesis of Conjugated Polymers for Photovoltaic and Chemosensor Applications

Department of Applied Chemistry, Cochin University of Science and Technology

Spin-Peierls vs Peierls distortions in a family of conjugated polymers

Distortions in a family of conjugated polymers are studied using two complementary approaches: within a many-body valence bond approach using a transfer-matrix technique to treat the Heisenberg model of the systems, and also in terms of the tight-binding band-theoretic model with interactions limited to nearest neighbors. The computations indicate that both methods predict the presence or absence of the same distortions in most of the polymers studied.

Blue, Green and Orange-Red Light Emitting Polymers: Synthesis, Characterization and Prospects of Applications in Optoelectronic Devices

Light emitting polymers (LEPs) are considered as the second generation of conducting polymers. A Prototype LEP device based on electroluminescence emission of poly(p-phenylenevinylene) (PPV) was first assembled in 1990. LEPs have progressed tremendously over the past 20 years. The development of new LEP derivatives are important because polymer light emitting diodes (PLEDs) can be used for the manufacture of next-generation displays and other optoelectronic applications such as lasers, photovoltaic cells and sensors. Under this circumstance, it is important to understand thermal, structural, morphological, electrochemical and photophysical characteristics of luminescent polymers. In this thesis the author synthesizes a series of light emitting polymers that can emit three primary colors (RGB) with high efficiency

Studies On The Electrical Properties Of Some Crystalline Organic Compounds And Conducting Polymers

Solid electrolytes for applications like chemical sensing, energy storage, and conversion have been actively investigated and developed since the early sixties. Although of immense potential, solid state protonic conductors have been ignored in comparison with the great interest that has been shown to other ionic conductors like lithium and silver ion conductors. The non-availability of good, stable protonic conductors could be partly the reason for this situation. Although organic solids are better known for their electrical insulating character, ionic conductors of organic origin constitute a recent addition to the class of ionic conductors. However, detailed studies (N1 such conductors are scarce. Also the last decade has witnessed an unprecedented boom in research on organic "conducting polymers". These newly devised materials show conductivity spanning from insulator to metallic regimes, which can be manipulated by appropriate chemical treatment. They find applications in devices ranging from rechargeable batteries to "smart windows". This thesis mainly deals with the synthesis and investigations on the electrical properties of (i) certain organbc protonic conductors derived from ethylenediamine and (ii) substituted polyanilines

Development and microwave characterization of selected biocompatible materials and conducting polymers

The 20th century witnessed the extensive use of microwaves in industrial, scientific and medical fields. The major hindrance to many developments in the ISM field is the lack of knowledge about the effect of microwaves on materials used in various applications. The study of the interaction of microwaves with materials demanded the knowledge of the dielectric properties of these materials. However, the dielectric properties of many of these materials are still unknown or less studied. This thesis is an effort to shed light into the dielectric properties of some materials which are used in medical, scientific and industrial fields. Microwave phantoms are those materials used in microwave simulation applications. Effort has been taken to develop and characterize low cost, eco-friendly phantoms from Biomaterials and Bioceramics. The interaction of microwaves with living tissues paved way to the development of materials for electromagnetic shielding. Materials with good conductivity/absorption properties could be used for EMI shielding applications. Conducting polymer materials are developed and characterized in this context. The materials which are developed and analyzed in this thesis are Biomaterials, Bioceramics and Conducting polymers. The use of materials of biological origin in scientific and medical applications provides an eco-friendly pathway. The microwave characterization of the materials were done using cavity material perturbation method. Low cost and ecofriendly biomaterial films were developed from Arrowroot and Chitosan. The developed films could be used in applications such as microwave phantom material, capsule material in pharmaceutical applications, trans-dermal patch material and eco-friendly Band-Aids. Bioceramics with better bioresorption and biocompatibility were synthesized. Bioceramics such as Hydroxyapatite, Beta tricalcium phosphate and Biphasic Calcium Phosphate were studied. The prepared bioceramics could be used as phantom material representing Collagen, Bone marrow, Human abdominal wall fat and Human chest fat. Conducting polymers- based on Polyaniline, are developed and characterized. The developed materials can be used in electromagnetic shielding applications such as in anechoic chambers, transmission cables etc

Immobilization of Diastase α-amylase on to synthetic and natural polymers

Several natural and synthetic supports have been assessed for their efficiency for enzyme immobilization. Synthetic polymer materials are prepared by chemical polymerization using various monomers. As a kind of important carrier, synthetic polymer materials exhibit the advantages of good mechanical rigidity, high specific surface area, inertness to microbial attack, easy to change their surface characteristics, and their potential for bringing specific functional group according to actual needs. Hence, they have been widely investigated and used for enzyme immobilization. When it comes to the natural polymer materials, much attention has been paid to cellulose and other natural polymer materials owing to their wide range of sources, easy modification, nontoxic, and pollution-free, with a possibility of introducing wide variety of functional groups and good biocompatible properties. In this work report the use of synthetic polymer, polypyrrole and its derivatives and natural polymers coconut fiber and sugarcane bagasse as supports for Diastase α- amylase immobilization. An attempt was also made to functionalize both synthetic and natural polymers using Amino-propyl triethoxysilane. Supports and their immobilized forms were characterized via FT-IR, TG, SEM, XRD, BET and EDS techniques. Immobilization parameters were also optimized so as to prepare stable immobilized biocatalyst for starch hydrolysis.