QSpace Collection:http://hdl.handle.net/1974/7892015-10-09T12:18:06Z2015-10-09T12:18:06ZControlled Radical Polymerization: Towards Industrially Relevant ConditionsPAYNE, KEVINhttp://hdl.handle.net/1974/137622015-10-05T05:46:25Z2015-10-03T04:00:00ZTitle: Controlled Radical Polymerization: Towards Industrially Relevant Conditions
Authors: PAYNE, KEVIN
Abstract: Reversible deactivation radical polymerization (RDRP), also known as controlled radical polymerization (CRP), has been a significant area of polymer research for more than 20 years, allowing the facile synthesis of complex macromolecules previously unattainable by conventional free radical polymerization (FRP). However, industrial adoption of RDRP has been minimal largely due to the significant economic barrier to commercialization, with complex synthesis of the mediating agents required and the necessary post polymerization processing to recover the mediating agent. In an effort to overcome this obstacle to industrial adoption, the mediating agent concentration can be significantly reduced, such as the copper level in activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), or the mediating agent can be incorporated into the polymer as in nitroxide-mediated polymerization (NMP), where no post polymerization processing is required other than removal of residual monomer. This thesis presents a study of these two chemistries towards industrially relevant conditions.
To build upon recent developments of continuous ARGET ATRP, a systematic batch study is conducted to pursue decreased copper levels in the generation of short chain acrylic and methacrylic polymers of interest to the coatings industry. The limitations to reducing copper levels are understood with the development of a kinetic model, with the improved understanding of the ARGET ATRP system suggesting that a reduction in copper loading must be accompanied by an increase in reducing agent loading in order to maintain an appreciable polymerization rate.
Alternatively, NMP does not require a reduction in mediating nitroxide level as it reversibly terminates the polymer chain end, and may present a smaller barrier to commercialization. Indeed, certain nitroxides are currently produced at pilot scale. However, limited research has been conducted into continuous operation which is commonly used in industry to improve productivity. A batch NMP study at elevated temperatures demonstrates the effectiveness of a novel alkoxyamine to mediate the polymerization of styrene and butyl acrylate under industrially relevant conditions. A kinetic study is developed to understand the novel system, and the polymerization is implemented in a continuous stirred-tank reactor (CSTR), the first demonstration of NMP in an existing industrial process.
Description: Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2015-10-01 08:45:38.9492015-10-03T04:00:00ZEstimation of Time-Varying Parameters and Its Application to Extremum-Seeking ControlMoshksar, Ehsanhttp://hdl.handle.net/1974/137422015-10-05T05:44:29Z2015-10-03T04:00:00ZTitle: Estimation of Time-Varying Parameters and Its Application to Extremum-Seeking Control
Authors: Moshksar, Ehsan
Abstract: This dissertation considers the adaptive estimation of time-varying parameters and its use in extremum-seeking control problems. The ability to estimate uncertain time-varying behaviour can have a significant impact on a control system's performance. Hence, the problem of time-varying parameter estimation has been of considerable interest over the last two decades.
The present work provides a formal scheme for time-varying parameter estimation in a class of nonlinear systems. The geometric concept of invariance is the key concept for the parameter estimation techniques developed in this thesis. The techniques use a number of high gain estimators and filters that generate an almost invariant manifold. The almost invariance property allows an implicit mapping and a parameter update law that guarantees exponentially convergence to a small region of the true values of the time-varying parameters. A generalization of the invariant manifold approach
is considered to deal with the estimation of periodic parameters with unknown periodicity.
In another step, this thesis seeks to apply the proposed time-varying estimation technique to the solution of extremum-seeking control problems. In extremum-seeking control, a gradient descent algorithm is used to find the optimal value of a measured but unknown cost functions. The contribution of this aspect of the thesis is the formulation of the extremum-seeking control problem where the unknown gradient of the cost is estimated as a time-varying parameter using the proposed invariance based estimation technique. The proposed approach is extended for the solution of constrained steady-state optimization problems.
We establish two methods for finding the optimal points for systems with unknown objective functions that are subject to unknown/uncertain dynamics. For systems with unknown dynamics, a nonlinear proportional-integral controller is designed to find the optimal solution. Then for a class of control affine systems with known high frequency gains, an inverse optimal control technique is used for the direct design of a gradient-based controller.
Description: Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2015-09-29 16:55:10.6352015-10-03T04:00:00ZNonlinear Observer Design Using Metric Based PotentialsBennett, RYANhttp://hdl.handle.net/1974/137382015-10-05T05:46:10Z2015-10-03T04:00:00ZTitle: Nonlinear Observer Design Using Metric Based Potentials
Authors: Bennett, RYAN
Abstract: This thesis addresses observer design for nonlinear dynamical systems which can be approximated with dissipative Hamiltonian realizations. The design methods builds upon earlier developments that allow the approximate dissipative potential to be extracted using a homotopy operator. This potential is obtained by decomposition of the observer error associated one-form using the homotopy operator which generates the potential. A time-varying differential metric equation dependent on the Hessian of the potential and the measured output function is proposed, which is used to design a state observer. The stability of both the observer and metric equation are assessed using Lyapunov theory. A time-invariant metric is then proposed making use of the Hessian of the potential on a metric-state based observer. Using several process simulations, the approach is shown to provide an effective design alternative for nonlinear observer design.
Description: Thesis (Master, Chemical Engineering) -- Queen's University, 2015-10-03 16:35:54.0292015-10-03T04:00:00ZLiving Radical Polymerization in Aqueous Dispersed Systems with Water-Soluble CatalystsBultz, ELIJAHhttp://hdl.handle.net/1974/137282015-10-03T18:40:51Z2015-10-03T04:00:00ZTitle: Living Radical Polymerization in Aqueous Dispersed Systems with Water-Soluble Catalysts
Authors: Bultz, ELIJAH
Abstract: Living radical polymerization is an important technique for synthesizing advanced macromolecules including block copolymers. Since its discovery in the early 1990s the capability of the field has expanded with new types of chemistry and techniques. One of the most widely used chemistries is atom transfer radical polymerization (ATRP) also known as “metal mediated living radical polymerization” (Mt-LRP). Mt-LRP has also expanded its use to aqueous dispersed systems including emulsion, miniemulsion and microemulsion, with the biggest advancements seen in miniemulsion where the droplets act as nanosized reactors. Extremely hydrophobic catalyst complexes are typically used in miniemulsion. While effective in controlling the polymerization, these hydrophobic catalyst complexes also get trapped in the final polymer particles and are difficult to remove. Herein I report the progress made using thermoresponsive polymer bound catalysts for Mt-LRP reactions in miniemulsion, which allow the successful LRP in miniemulsion with facile catalyst removal. Polymers could be prepared with less than 10 ppm of ruthenium in the final polymer compared to >500 ppm in the reaction mixture. The polymerizations were improved by the addition of ferrocene (FeCp2) in miniemulsion, to give almost complete conversion in significantly shorter times. The addition of ferrocene adds a second catalytic cycle that is ionic in nature and requires excess halogens present for a successful polymerization to occur. The ionic species in this catalytic cycle meant that the use of cationic surfactants with halogen counter-ions could directly affect the polymerization chemistry, which was shown by increasing rates with the addition of a bromine counter-ion versus a chlorine counter ion in the cationic surfactant used. Water-soluble FeCp2 derivative cocatalysts were also used to improve the rates and conversions of Mt-LRP of ruthenium catalyzed polymerizations while also allowing colourless polymers to be synthesized. Finally, the ligand EHA6TREN, was found to be active in bulk or solution (anisole) when complexed to iron (III) bromide with reverse ATRP, or to iron (II) bromide with AGET ATRP, yielding an iron-mediated living radical polymerization.
Description: Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2015-09-28 21:30:15.6992015-10-03T04:00:00Z