This thesis focuses on the development of new compounds or new processes that are more environmentally friendly and economical than those currently in use. The decomposition of hydrazine, a well established liquid rocket fuel for both the aerospace and defense industries, to the product ammonia is studied. Control of this reaction will allow hydrazine to be used as a propellant for both chemical and electric propulsion. From this a dual stage thruster will be developed that will be more efficient than current systems decreasing the amount of propellant needed and allowing for either a larger mission payload or a longer duration of individual missions. Hydrazine, while beneficial and well established, is also highly toxic, so other work in this thesis focuses on the synthesis of the novel molecule 1,1-dimethyl-2-[2-azidoethyl]hydrazine or DMAEH and its hydrazone intermediate 1,1-dimethyl-2-[2-azidoethyl]hydrazone or De-DMAEH as less toxic hydrazine replacements. Novel "switchable" ionic liquids have been investigated in this research. These are solvents that can change from molecular liquids to ionic liquids and back, simply with the addition or removal of CO₂ from the system. They can be used for a variety of applications, including as solvents for a reaction and separation system. Due to the recyclable nature of these solvents, waste is decreased making their development and implementation both environmentally and economically beneficial. Finally, the grafting reaction of vinyl silanes onto a hydrocarbon backbone is investigated. Fundamental work is being performed to study the graft distribution, selectivity and mechanism by which this reaction occurs. A more thorough understanding of how this reaction proceeds will allow for the development of a more efficient industrial process.

<p>Despite tremendous achievements, the field of conjugated polymers is still in its infancy, mimicking the more mature inorganic, i.e. silicon-based, technologies. We may though look forward to the realisation of electronic and electrochemical devices with exotic designs and device applications, as our knowledge about the fundamentals of these promising materials grow ever stronger. </p><p>My own contribution to this development, originating from an idea first put forward by my tutor, Professor Magnus Berggren, is a design for a switchable polymer-based diode. Its architecture is based on a modified version of a recently developed highly-rectifying diode,12 where an intermediate molecular layer has been incorporated in the bottom contact. Due to its unique ability to switch its internal resistance during operation, this thin layer can be used to shift the amount of (forward) current induced into the rectifying structure of the device, and by doing so shift its electrical characteristics between an insulating and a rectifying behaviour (as illustrated below). Such a component should be of great commercial interest in display technologies since it would, at least hypothetically, be able to replace the transistors presently used to address the individual matrix elements. </p><p>However, although fairly simple in theory, it proved to be quite the challenge to fabricate the device structure. Machinery errors and contact problems aside, several process routes needed to be evaluated and only a small fraction of the batches were successful. In fact, it was not until the very last day that I detected the first indications that the concept might actually work. Hence, several modifications might still be necessary to undertake in order to get the device to work properly.</p>

abstract: It is well known that the geckos can cling to almost any surface using highly dense micro/nano fibrils found on the feet that rely on Van Der Waals forces to adhere. A few experimental and theoretical approaches have been taken to understand the adhesion mechanism of gecko feet. This work explains the building procedure of custom experimental setup to test the adhesion force over a temperature range and extends its application in space environment, potentially unsafe working condition. This study demonstrates that these adhesive capable of switching adhesive properties not only at room environment but also over a temperature range of -160 degC to 120 degC in vacuum conditions. These conditions are similar to the condition experienced by a satellite in a space orbiting around the earth. Also, this study demonstrated various detachment and specimen patch preparation methods. The custom-made experimental setup for adhesion test can measure adhesion force in temperature and pressure controlled environment over specimen size of 1 sq. inch. A cryogenic cooling system with liquid nitrogen is used to achieve -160 degC and an electric resistive heating system are used to achieve 120 degC in controlled volume. Thermal electrodes, infrared thermopile detectors are used to record temperature at sample and pressure indicator to record vacuum condition in controlled volume. Reversibility of the switching behaviour of the specimen in controlled environment confirms its application in space and very high or very low-temperature conditions. The experimental setup was developed using SolidWorks as a design tool, Ansys as simulation tool and the data acquisition utilizes LabVIEW available in the market today. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2016

Une famille de pinces moléculaires commutables par coordination métallique basées sur une architecture modulaire de type bis(M-salphen) terpyridine (salphen = N,N’-disalicylidene-o-phenylenediamine) a été synthétisée dans le but de moduler, par un effet mécanique, des propriétés physiques ou chimiques à l’échelle moléculaire. Deux pinces fonctionnalisées par des complexes phosphorescents de platine(II) ont été synthétisées par une approche modulaire. Un mouvement réversible de fermeture et d’ouverture par coordination / décoordination a été obtenu ainsi qu’une extinction de la luminescence via un contrôle allostérique de la reconnaissance de Hg2+. Une pince comportant des complexes paramagnétiques de cuivre (II) a permis l’observation par RPE et SQUID d’une commutation réversible de l’interaction d’échange à travers l’espace entre les deux centres métalliques. Du manganèse(III) a également été utilisé afin de permettre la commutation de l’interaction d’échange via un ligand pontant cyanure grâce à un contrôle allostérique de l’intercalation. De manière similaire, la synthèse d’une pince moléculaire incorporant des unités molécule aimant a été mise au point. D’autre part les propriétés rédox d’une pince à base de nickel(II) ont aussi pu être contrôlées par le mouvement et l’intercalation de pyrazine dans la forme oxydée nickel(III). Finalement, la synthèse d’une pince catalytique a été mise au point, ouvrant la voie à des catalyseurs commutables biomimétiques fonctionnant par effet allostérique. / A family of switchable molecular tweezers based on a bis(M-salphen) terpyridine (salphen = N,N’-disalicylidene-o-phenylenediamine) structure has been developed to study the influence of a mechanical motion on physical properties at the molecular level. Two tweezers functionalized by phosphorescent platinum (II) complexes were synthesized using a modular approach. The reversible mechanical motion by coordination / decoordination of a first metal cation allowed reversible quenching of the luminescence thanks to mercury (II) intercalation with allosteric control. Similar tweezers bearing paramagnetic copper (II) permitted to reversibly switch through-space exchange interactions between the two metallic centers according to EPR and SQUID measurements. manganese (III) was also used in order to switch the exchange interaction through a cyanide bridging ligand whose intercalation can be controlled by allosteric effect. With a similar strategy, the synthetic route towards tweezers showing single-molecule-magnet behavior has beendeveloped. The redox property of nickel(II) based tweezers was also controlled by the mechanical motion and the intercalation of pyrazine in the oxidized nickel (III) closed form. Finally, the synthesis of catalytic tweezers was developed, opening the way to switchable biomimetic catalysts operating with allosteric control.

Les récepteurs purinergiques P2Xs sont impliqués dans de nombreux processus physiopathologiques et représentent des cibles thérapeutiques majeures. Leur étude souffre néanmoins d’un manque de molécules pharmacologiques sélectives des différents sous-types et les mécanismes impliqués dans les transitions allostériques restent putatifs.Nous avons développé des outils optochimiques innovants, dérivés d’azobenzènes permettant une maîtrise spatiale et temporelle inégalée de la fonctionnalité du récepteur : d’une part,un outil dérivé d’une stratégie de pharmacologie optogénétique contrôlant l’activité d’un récepteur ingéniéré et d’autre part, une sonde moléculaire capable d’induire des mouvements entre des résidus au sein de la protéine et d’étudier les mécanismes lors de l’activation. Ces travaux nous ont permis de proposer un nouveau mécanisme d’activation du récepteur. Ces deux outils pourraient être utilisés sur d’autres cibles pour des investigations moléculaires et physiologiques. / Purinergic P2X receptors are implicated in a diverse range of physiopathological processes and are therefore promising therapeuthic target. Their study suffers from the lack of pharmacological tools selective of one subtype only and mechanisms by which the receptor switches between different conformational states remain elusive.We have developed novel optochemical tools based on azobenzene derivatives to obtain a spatio temporal control of the functionality of the receptor. Inspired by optogenetic pharmacology, we have designed an engineered receptor to control electrical activity of cultured neurons. Molecular photo-switchable tweezers have been developed to explore allosteric transitions of the protein and giving new insights into the P2X pore gating mechanism. This approach provides data enabling us to purpose a new model of the active state. The versability of the two strategies makes these tools promising for molecular and physiological studies of other membrane proteins.

Reverse engineering of hardware IP block is a common practice for competitive purposes in the semiconductor industry. What is done with the information gathered is the deciding legal factor. Once this information gets into the hands of an attacker, it can be used to manufacture exact clones of the hardware device. In an attempt to prevent the illegal copies of the IP block from flooding the market, layout-level obfuscation based on switchable dopant is suggested for the hardware design. This approach can be integrated into the design and manufacturing flow using an obfuscation tool (ObfusTool) to obfuscate the functionality of the IP core. The ObfusTool is developed in a way to be flexible and adapt to different standard cell libraries and designs. It enables easy and accurate evaluation of the area, power and delay v/s obfuscation trades-offs across different design approaches for hardware obfuscation. The ObfusTool is linked to an obfuscation standard cell library which is based on a prototype design created with Obfuscells and 4-input NAND gate. The Obfuscell is a standard cell which is created with switchable functionality based on the assigned dopant configurations. The Obfuscell is combined with other logic gates to form a standard cell library, which can replace any number of existing gates in the IP block without altering it's functionality. A total of 160 different gates are realized using permutated combinations starting with 26 unique gate functions. This design library provide a high level of obfuscation in terms of the number of combinations an adversary has to go through increase to 2 2000 approximately based on the design under consideration. The connectivity of the design has been ignored by previous approaches, which we have addressed in this thesis. The connectivity of a design leaks important information related to inputs and outputs of a gate. We extend the basic idea of dopant-based hardware obfuscation by introducing "dummy wires". The addition of dummy wires not only obfuscates the functionality of the design but also it's connectivity. This greatly reduces the information leakage and complexity of the design increases. To an attacker the whole design appears as one big 'blob'.This also curbs the attempts of brute force attacks. The introduced obfuscation comes at a cost of area and power overhead on an average 5x, which varies across different design libraries.

The ultimate goal of the modern wireless communication industry is the full integration of digital, analog, and radio frequency (RF) functions. The most successful solution for such demands has been complementary metal oxide semiconductor (CMOS) technology, thanks to its cost-effective material and great versatility. Power amplifier (PA), the biggest bottleneck to integrate in a single-chip transceiver in wireless communications, significantly influences overall system performance. Recent advanced wireless communication systems demand a power amplifier that can simultaneously support different communication standards. A fully integrated single-chip tunable CMOS power amplifier is the best solution in terms of the cost and level of integration with other functional blocks of an RF transceiver. This work, for the first time, proposes a fully integrated band-switchable RF power amplifier by using a novel approach towards switching the matching networks. In this approach, which is called Bit Optimized Reconfigurable Network (BORN), two matching networks which can be controlled by digital bits will provide three operating frequency bands for the power amplifier. In order to implementing the proposed BORN PA, a robust high-power RF switch is presented by using resistive body floating technique and 6-terminal triple-well NMOS. The proposed BORN PA delivers measured saturated output power (Psat) of 21.25/22.25/ 23.0dBm at 960MHz/1317MHz/1750MHz, respectively. Moreover, the proposed BORN PA provides respective 3-dB bandwidth of 400MHz/425MHz/550MHz, output 1-dB compression point (P1dB) of 19.5dBm/20.0dBm/21.0dBm, and power-added efficiency (PAE) of 9/11/13% at three targeted frequency bands, respectively. The promising results show that the proposed BORN PA can be a practical solution for RF multiband applications in terms of the cost and level of integration with other functional blocks of an RF transceiver.

Les travaux de recherche de cette thèse concernent sur la préparation et l’étude des propriétés physiques de nanocristaux commutables basés sur des matériaux de type transition de spin et photomagnétiques potentiellement candidats en tant que nanocapteurs. Les nanocristaux à transition de spin appartiennent à la famille des réseaux de coordination basés sur les chlatrates de Hoffman [Fe(pyrazine)] [Pt(CN)4]. L’étude se concentre sur le contrôle de la taille des nano-bâtonnets et sur l’étude de leur bistabilité thermique en relation avec leur environnement et de leur interaction avec les molécules invitées. Nous montrons que la croissance des nanocristaux en forme de bâtonnets est obtenue en présence de nanoparticules préformées de 2 à 3 nm de l’analogue du bleu de Prusse CsNiCr(CN)6, censées diriger la croissance anisotrope des objets. Les nano-bâtonnets formés sont stables pendant une longue période en solution en raison de leurs charges négatives. Ils possèdent une hystérèse thermique assez large centrée sur la température ambiante. La largeur et la position en température de l’hystérèse thermique dépendent de la nature de l'environnement des nanocristaux. Avec des sels d'ammonium à longue chaîne (tels que le bromure de dodécyltrimentylammonium ou le bromure de dexhyl triméthyl ammonium), l’hystérèse thermique se rétrécit et se décale vers les basses températures. Avec des chaînes alkyles plus courtes, le décalage de l’hystérèse est plus petit sans que sa largeur ne change beaucoup. Lorsque les tiges sont noyées dans une matrice de silice rigide, la transition est déplacée à très basse température et l'hystérésis thermique disparaît. L'insertion de molécules de I2 conduit à une hystérèse thermique plus large centrée sur une température plus élevée que la température ambiante. Les nanoparticules photomagnétiques appartiennent à la famille des réseaux bimétalliques d’analogues du bleu de Prusse (PBA) basés sur le CoFe. Ce type de matériaux peut subir une transition thermique de l'état paramagnétique CoIIFeIII à l'état diamagnétique CoIIIFeII. L'état de haute température peut ensuite être rétabli par un éclairage lumineux à basse température. Nous nous sommes concentrés sur trois types de nanoparticules de CoFe contenant les ions alcalins CsI (11 nm) et RbI avec deux tailles différentes : 30 et 80 nm pour ces dernières. La taille des objets était contrôlée par différents paramètres tels que la nature de l'ion alcalin, la concentration des précurseurs et leur stœchiométrie. La combinaison de différentes techniques, telles que les spectroscopies électronique et infrarouge, associée à la spectroscopie par résonance paramagnétique électronique et à la diffraction des rayons X sur poudre permet de suivre l’évolution de la composition des nanoparticules avec le temps en solution à la température ambiante. L’étude de l’évolution conduit à la conclusion générale que le phénomène de transfert d’électrons de CoII à FeIII se produit en solution pendant plusieurs jours avant que les objets n’atteignent leur état thermodynamique stable qui dépendait de la nature de l’ion alcalin et de la taille des objets. Le comportement (photo)magnétique a ensuite été étudié à l’état solide pour différents temps d’évolution des trois types de particules, ce qui a permis de proposer un mécanisme qualitatif de leur formation en solution. / The research work in this thesis is focused on the preparation and the study of the physical properties of switchable nanocrystals based on spin crossover and photomagnetic materials that are potential candidates as nanosensors. The spin crossover nanocrystals belong to the coordination network family based on the Fe(II) Hoffman chlatrates [Fe(pyrazine)][Pt(CN)4]. The study is focused on controlling the size of self-standing nanorods and on the investigation of their thermal bistability in relation with their environment and their interaction with guest molecules. We show that the growth of the rod-shaped nanocrystals is obtained in the presence of preformed 2-3 nm nanoparticles of the Prussian Blue Analogue CsNiCr(CN)¬6 that is thought to direct to anisotropic growth of the objects. The formed rods can be stable for a long time due to their negative charge. They possess a rather wide thermal hysteresis centered around room temperature. The width and position in temperature of the thermal hysteresis depends on the nature of the environment of the nanocrystals. With very long ammonium salt (such as dodecyl trimetylammonium bromide or dexhyl trimethyl ammonium bromide), the thermal hysteresis becomes narrower and shifts to low temperature. While with shorter alkyl chains, the shift of the hysteresis is smaller without much change in its width. When the rods are embedded in a rigid silica matrix, the transition is shifted to very low temperature and the thermal hysteresis vanishes. The insertion of I2 molecules leads to a wider thermal hysteresis centered at a higher temperature.The photomagnetic nanoparticles belong to the bimetallic Prussian Blue Analogues (PBAs) family based on CoFe. This type of materials may undergo a thermal transition from the paramagnetic CoIIFeIII state to the diamagnetic CoIIIFeII one. The high temperature state can then be restored at low temperature by light illumination. We focused on three types of CoFe PBAs nanoparticles containing the CsI (11 nm) and the RbI alkali ions with two different sizes 30 and 80 nm for the latter. The size of the objects was controlled by different parameters such as the nature of the alkali ion, the concentration of the precursors and their stoichiometry. The combination of different techniques such as electronic and infra spectroscopies together with Electron Spin Resonance Spectroscopy and X-ray powder diffraction allows following the evolution of the nanoparticles’ composition with time in solution at room temperature. The evolution study leads to the general conclusion that the electron transfer phenomenon from CoII to FeIII occurs in solution during several days before the objects reach their thermodynamic stable state that was found to depend on the nature of the alkali ion and on the size of the objects. The (photo)magnetic behavior was then investigated in the solid state for different evolution time of the three types of particles, which allowed proposing a qualitative mechanism of their formation in solution.

Thesis advisor: Jeffery A. Byers / Thesis advisor: Petter Zhang / This thesis discusses the development of a surface-initiated N-carboxyanhydride (NCA) polymerization system from a redox-switchable catalyst for polyamide synthesis and further efforts towards the synthesis of polypeptide-based materials through the integration of NCA synthesis and its polymerization. In Chapter one, the most used methods to obtain polypeptide-based materials as well as their significant limitations are introduced. A new strategy is presented to access the polypeptide-based materials based on the integrated catalysis under spatial and temporal control. In Chapter two, a strategy to allow the attachment of a redox-switchable NCA polymerization catalyst on surface of titania for the synthesis of polyamide brushes will be demonstrated. Investigations about the kinetics of this surface-initiated ring-opening polymerization will be presented by carrying out the reaction in batch and under flow. Chapter three will discuss efforts towards achieving the integration of NCA synthesis and NCA polymerization, which includes an additional anchoring method to support polymerization catalyst and compatibility tests between the two separate reactions. / Thesis (MS) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

No description available.