Synthesis of new electroactive monomers are highly desired since these compounds can be utilized as active layers in many device applications such as ECDs, LEDs and solar cells. EDOT (3,4 ethylenedioxythiophene) and thiophene bearing polymers were also proven to be excellent candidates as electrochromic materials. Benzotriazole can be coupled to EDOT and thiophene to yield materials that can be polymerized to give donor acceptor type polymers. These materials are promising candidates as components in fast switching polymeric electrochromic devices. Donor acceptor type materials / 2-dodecyl-4-(2,3-dihydrothieno [3,4- b][1,4]dioxin-5-yl)-7- (2,3-dihydrothieno[3,4-b] [1,4] dioxin-7-yl)-2H-benzo [d][1,2,3]triazole and 2-dodecyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole were synthesized via N-alkylation, bromination, stannylation and Stille coupling reactions. Electrochemical and electrochromic properties of the polymers were examined in detail.

Organic semi-conductors are of great interest since these compounds can be utilized as active layers in many device applications such as ECDs, LEDs and solar cells. Incorporating the benzotriazole units into the polymer backbone enhances the optical properties of donor units. Hexyl thiophene and pyrrole are commonly used as electron donor materials. Benzotriazole can be coupled to hexyl thiophene or pyrrole to yield materials which can be polymerized to give donor acceptor type polymers. These materials are promising components in fast switching polymeric electrochromic devices and highly efficient photovoltaic devices. During thesis studies,poly(2-dodecyl-4,7-bis(4-hexylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole) (PHTBT) and poly(2-dodecyl-4,7-di(1H-pyrrol-2-yl)- 2H- benzo [d] [1,2,3] triazole) (PPyBT) will be synthesized via N-alkylation, bromination, stannylation and Stille coupling reactions. Electrochromic and photovoltaic properties of the polymers will be investigated in detail.

No description available.

A new neutral state green polymer, poly (2,3-bis(4-tert-butylphenyl)-5,8-di(1H-pyrrol-2-yl) quinoxaline) (PTBPPQ) was synthesized and its copolymer with bis(3,4-ethylenedioxythiophene) (BiEDOT) and 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-dodecyl-2H-benzo [1,2,3] triazole (BEBT) were produced. Finally polymers&rsquo / potential use as an electrochromic material was investigated. Electrochromic properties of the polymers were investigated by several methods including spectroelectrochemistry, kinetic and colorimetry studies. Key properties of conjugated polymers such as band gap, maximum absorption wavelength, the intergap states that appear upon doping and evolution of polaron and bipolaron bands were investigated via spectroelectrochemistry experiments. Switching times and optical contrasts of the homopolymer and the copolymer were evaluated via kinetic studies. Copolymer of TBPPQ with BiEDOT and BEBT were electrochemically synthesized and characterized. Resulting copolymer films have distinct electrochromic properties and revealed multichromism through the entire visible region. Although BiEDOT and BEBT have different oxidation potentials, the resulting copolymers have very similar redox behaviors. In a monomer free solution, both copolymers show four colors from purple, gray, light green to transmissive blue with the variation of the applied potential. Copolymerization with BiEDOT and BEBT not only decreases the band gap, Eg, but also enhances the electrochromic and optical properties. Hence, electrochemical copolymerization is considered to be a powerful tool to improve the electrochromic properties of quinoxaline derivatives. It should be noted that PTBPPQ is one of the few examples of neutral state green polymeric materials with superior switching properties. Hence, PTBPPQ can be used as a green polymeric material for display technologies.

Power Quality (PQ) has gained a lot of importance in the last decade. Several solutions to power quality problems have been proposed and developed. With the advent of solid state technology and power electronics in the power system protection devices, faster switching is achievable. In order to control and minimize the power quality problems which occur in extremely short times of less than 100ms, the need arises for a selection of devices that can switch faster than today. Also, the economic losses that occur in the network due to the power quality problems increase the incentive to transform the existing devices into faster and e fficient devices. This transformation can be seen as valuable from both a technical and economical point of view to the distribution networks today where a large number of customers are connected. However, in order to interpret the value these fast switching devices render to the distribution network a prior study is required. This thesis presents a picture of the devices that can be suitable for fast switching in today’s distribution network, and how to determine their value to the distribution network. Further it summarizes the research work related to this field. The description of the devices and technical aspects is presented first. A literature review of proposed devices is given. The technical aspects of power quality and its problems is described. An approach to estimate the value of the fast switching devices is detailed from different literature. The study shows that fast switching devices can be worthy to invest in when seen from a distribution network’s perspective provided that different technical aspects are taken into account.

No description available.

3D printing technology, which has its origins in rapid prototyping, is increasingly used to build functional devices. Although 3D printing technology has been well developed for thermoplastic polymers and metals, it is still in the research phase for soft polymeric materials such as silicones. Silicones are an industrially vital polymer characterized by a broad spectrum of chemical and physical properties for several smart applications, including on skin printing, smart sensors, multigradient material, and soft actuators. Extrusion-based multimaterial printing is one of the 3D printing techniques that have been adapted due to its compatibility to process silicone-based materials for constructing various functional devices. However, there are several challenges such as achieving on the fly mixing at low Reynolds numbers regime, achieving fast switching while using Newtonian/non-Newtonian inks, and achieving multimaterial printing on nonplanar surfaces. The development of suitable and robust printheads that are able to tackle those challenges can expand the application of this technology to a wide range of fields. In this thesis, several deposition-controlled printhead designs have been created for 3D printing multifunctional devices using an understanding of microfluidics. The established printhead can be controlled to formulate different multigradient structures through on the fly mixing during the material printing. Moreover, the developed printhead can be adapted to print multi viscous inks with high switching rates up to 50 Hz. Through the developed system, the printhead was able to track topologies in real-time, allowing objects to be printed over complex substrates. These new capabilities were applied to fabricate functional structures in order to demonstrate the potential of the developed printhead approaches that can be used in various applications, including smart sensors, soft robotics and multigradient objects. / Thesis / Doctor of Philosophy (PhD) / 3D printing techniques, such as extrusion-based multimaterial printing, have recently been utilized to process silicones due to their versatility in different smart applications, including multigradient material and soft actuators. Although it represents significant progress, there are still several challenges, including the proper mixing during printing with a laminar flow regime, the fast switching between different inks, and the printing over complex topographies. Therefore, various printhead designs have been developed in this thesis to tackle these challenges. In particular, a mixer printhead has been designed to allow mixing during printing for building multigradient objects. Also, a scalable printhead has been developed to allow fast switching for creating pixelated structures. Finally, a simple mechanical system has achieved multimaterial printing over various nonplanar surfaces. To the best of the author's knowledge, the developed printheads can be used in many fields, such as soft robotics and smart devices.

This thesis work regards free viewpoint TV. The main idea is that users can switch between multiple streams in order to find views of their own choice. The purpose is to provide fast switching between the streams, so that users experience less delay while view switching. In this thesis work we will discuss different video stream switching methods in detail. Then we will discuss issues related to those stream switching methods, including transmission and switching. We shall also discuss different scenarios for fast stream switching in order to make services more interactive by minimizing delays. Stream switching time varies from live to recorded events. Quality of service (QoS) is another factor to consider which can be improved by assigning priorities to the packets. We will discuss simultaneous stream transmission methods which are based on predictions and reduced quality streams for providing fast switching. We will present prediction algorithm for viewpoint prediction, propose system model for fast viewpoint switching and make evaluation of simultaneous stream transmission methods for free viewpoint TV. Finally, we draw our conclusions and propose future work. / Degree project