Three types of acoustic nonlinearity parameters for solids are discussed. The results of measurements of these parameters for three polymers--polymethyl methacrylate, Polystyrene, and polysulfone--are presented.;The author has developed a new technique, using piezoelectric transducers directly bonded to the specimens, which allows the measurements of fundamental and second harmonics generated in the solids, and thereby the determination of nonlinearity parameter {dollar}\beta\sb3{dollar}, which is the ratio of a linear combination of second- and third-order elastic coefficients to the second-order elastic coefficient.;The second nonlinearity parameter, B/A can be determined from the temperature and pressure derivatives of the sound velocity. We derive its exact relationship for the case of solids. The results from the two techniques are shown to be consistent.;The pressure derivative of the sound velocity is also related to the Gruneisen parameter, which can be used to describe the anharmonicity of interactions in polymer molecules, especially of interchain vibrations. The interchain specific heat for these polymers is then calculated from the Gruneisen parameters; and the characterization of polymers by using these thermoacoustic parameters is discussed.

Aluminosilicate inorganic polymers (AIPs) are network heteropolymers consisting of Si04 and AlO4 tetrahedra linked by a shared oxygen. The use of these materials as a cementing agent, toxic waste storage and fibre reinforced material, amongst a multitude of prospective applications, has grown in recent years. The utilisation of AIPs is hampered by a lack of knowledge about their formation and structure. In order to allow the materials to achieve their full potential, the way in which the material behaves and forms under different conditions must be elucidated. The basic questions that this study aimed to answer were: 1) How does the structure of these AIPs change with composition? and 2) Can this change in structure explain the material properties of the AIP? The AIPs investigated in the study covered the molar composition ranges Si:Al ratio = 1 - 3 and Na:Al ratio = 0.5 - 2. They were made by the sodium hydroxide activation of metakaolinite, derived from the dehydroxylation of kaolinite. The Si content of the AIP was altered by the addition of amorphous silica fume via the activation solution. The study considered the structural nature of the AIPs at the macro, micro and nanoscales, and found that the structure changed at all scales and with all compositions. The nature of the AIP structure was studied at the macroscale utilising compressive strength testing. The results from this work showed that the compressive strength of the AIPs varied systematically with the chemical composition. The strengths recorded ranged from 0.4 ± 0.2 MPa for a sample with Si:Al:Na molar ratios = 1.08:1:0.5, to 64 ± 3 MPa for a sample with Si:Al:Na molar ratios = 2.5:1:1.3. The higher strengths measured exceed those exhibited by Portland cement pastes. The microstructure of the AIPs was investigated by scanning electron microscopy and energy dispersive spectroscopy. / Microscopy showed that the microstructure variations correlated with the compressive strength. In general, AIPs with low compressive strengths exhibited an inhomogeneous two-phase microstructure; grain and matrix. The grain phase consisted of undissolved metakaolinite, whilst the matrix was the fully formed inorganic polymer. AIPs with high compressive strengths exhibited a microstructure that was more homogeneous than the samples with low compressive strength. The compressive strength of the AIPs depended on both the chemical composition and the level of residual MK present in the microstructure. EDS microanalysis showed that the composition of the two phases was significantly different, and that the differences depended on the overall composition of the AIP. EDS results also demonstrated that the impurity elements present in the metakaolinite were affected by the polymerisation process. Soluble elements such as Ca and Mg were found primarily in the matrix, indicating that they had leached out of the metakaolinite grains, whereas insoluble elements such as Fe and Ti were found primarily in the grains. The nanoscale structure of the AIPs was examined by solid-state nuclear magnetic resonance (NMR) and x-ray scattering (XRS). The NMR measurements revealed that the average coordination of Si varied according to the composition of the AIP, whereas the coordination of Al was constant. Na is present in the network in both hydrated and non-hydrated forms. It is postulated that the variation in the Si coordination can be explained by the formation of Si-O-Na bonds with Na forming an ionic bond with 0 in the polymer network. Radial distribution function (RDF) analysis of the XRS patterns revealed little difference in the structure of the different AIPs beyond ~2.5 Å. / Unfortunately, the data were of insufficient resolution to allow for a full evaluation of the differences in the Si-O and Al-O bonds between different AIPs. However, the trends present in the shape and position of the RDF peak corresponding to the Si-O and Al-O bonds do follow the composition of the AIP. It has been shown that a variety of experimental techniques can be used in concert to obtain information on the structural nature of AIPs. To this end, it has been found that the compressive strength of AIPs can be optimised, and that the microstructure of the AIPs changes systematically with variations in the compressive strength. An improved model for the structure of AIPs has also been proposed.

The polymer industry is an ever growing industry, and, as it grows, companies are continuously looking for ways to study and understand the behaviors of polymers in relation to the processing and production. This is to ensure the production of high quality products and to improve existing products.An important parameter during polymer processing is temperature. Temperature control affects several rheological parameters such as viscosity, and in turn the quality of the final products. Frictional or viscous heating is a very important part of polymer processing and occurs in almost every polymer processing operation.The objective of this research is to design the apparatus and setup the equipment to examine the validity of the Theory of Purely Entropic Elasticity (PPE) on non-isothermal flow of concentrated polymeric solutions under a wide range of shear rates. A basic rheological study of the polymer in use is performed. PEE once played an important role in polymer processing. PEE is the assumption that the internal energy of a polymeric material is solely dependent on temperature, and specifically is not dependent on the polymer deformation, as developed by Astarita and co-workers [1-3, 16].The design and results are presented. Potential improvements and future considerations are also presented.

Many coatings only need to either be durable or fast drying, usually sacrificing long term stability in favor of quick setting, or vice versa. One coating type that cannot afford to sacrifice either performance feature is traffic paint. These paints are made up of a weak polycation, an anionic latex, and a volatile base which evaporates upon application. The high pH in the initial formulation deprotonates the polycation, rendering it charge neutral. However, upon evaporation, the resulting drop in pH allows for the electrostatic complexation between the polycation and the latex. The electrostatic interactions used in these formulations parallels that of complex coacervation, an associative liquid-liquid phase separation. In this thesis, we will take advantage of model coacervate systems to elucidate the design parameters necessary for the formulations to serve as paints. We used a series of simplified systems, starting with a system consisting of a weakly cationic homopolymer and weakly anionic homopolymer before moving on to anionic copolymers with decreasing charge density, and ultimately an anionic latex. We investigated the effects of pH, charge stoichiometry, and salt concentration for each of these systems, using turbidimetry and optical microscopy as a means of measuring the extent of coacervation. We determined that, the removal of 99.9% of the charge on our polymers was necessary for coacervation to no longer occur. This can be achieved using either salt or pH, however, salt may be preferable, due to the inherent hazardous properties of highly acidic or basic solutions. Very excitingly, we were able to observe coacervation with latex particles. To our knowledge, there are no known observations of polymer-particle coacervation prior to this study. These results suggest that the underlying physics and design principles associated with fast setting paints can be explored using complex coacervation, and that a much broader range of parameters can be used to control the setting of these materials, beyond just pH used in existing technology. Future efforts are still needed to better understand the effect that polymer chemistry has on the complexation of these materials, and how it also affects the mechanical and adhesive properties of coating produced by such formulations.

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Conjugated polymer based electronics, a type of flexible electronic devices, can be produced from solution by traditional printing and coating processes in a roll-to-roll format such as papers and graphic films. This shows great promise for the emerging energy generation and conversion. The device performance of polymer electronics is largely dependent of crystalline structures and morphology of photoactive layers. However, the solution crystallization kinetics of conjugated polymers in the presence of electron acceptor nanoparticles has not been fully understood yet. In this study, solution crystallization kinetics of poly (3-hexylthiophene) in the presence of carbon nanotubes and graphene oxide has been investigated by using UV-visible absorption spectroscopy and transmission electron microscope. Various kinetics parameters such as crystallization temperature, polymer solution concentration and nanoparticle loading will be discussed. The crystallization rate law and fold surface free energy will be addressed by using polymer crystallization theory of heterogeneous nucleation. This fundamental study will provide a foundation of fabricating high efficiency polymer based electronics.

My PhD work focuses on developing new methods to create the macroscopic patterns in a simple, robust, and versatile way. For macroscopic pattern formation, we first use flow coating as an assembly technique, uniquely balancing two driving forces: (i) evaporative deposition of nonvolatile solutes at a three-phase contact line and (ii) precision movement of a confined meniscus layer. This balance leads to the formation of line-based patterns that range in height and width from nanometers to microns, with lengths greater than centimeters. Moreover, we couple this deposition methodology with functional ligand chemistry on the nanoparticle surface, which allows us to create complex nanoparticle structures. By lifting crosslinked nanoparticle ribbons and ropes, exceptionally intriguing structures emanate from this process. The nanoparticle ribbons and ropes demonstrate a leap forward in nanomaterials fabrication, since the nanoscale properties are embedded within a macroscale object that can be manipulated with conventional methods and engineered into advanced technologies Using mechanical instability, we fabricate a simple, robust stimuli-responsive surface with periodic structures over a large area based upon osmotically-driven surface wrinkling. Although surface wrinkling has received considerable attention in the scientific literature, only a handful of papers have shown the ability to harness perhaps the greatest potential attribute of surface wrinkles: their active reversible nature. The ability to precisely control surface topographic morphologies in accordance with established scaling relationships opens a wide array of advanced materials applications, which do not rely upon cost-limiting fabrication techniques. Specifically, the surfaces respond to solvent exposure by developing well-defined topographic structures over laterally extensive areas due to osmotically-driven differential strains between a surface layer and underlying soft substrate. The observed wrinkling occurs spontaneously, forming hierarchical morphologies with controlled dimensions, and vanishes upon removal of the solvent driving force. The combined responsiveness and reversibility of wrinkling allow for the realization of functional devices, such as smart windows, smart microlens arrays, reversible channels in microfluidic devices. Moreover, by using thermal and osmotic approaches, we study the influence of geometry and material properties on surface instability such as cracking and wrinkling in a trilayer system consisting of a thin film on a soft foundation supported by a rigid substrate.

This dissertation aims to both deepen and broaden our understanding of copolymers with pendent benzophenone (BP) in relation to both established applications and novel directions in materials science. Photo-reaction of these BP copolymers is explored in attempts to achieve three distinct goals: (1) robust and efficiently photo-crosslinkable solid polymer films, (2) photo-reacted polymer blends with disordered bicontinuous nanostructures, and (3) photo-patterned hydrogel materials with environmental UV stability. We begin by investigating the fundamental gelation behavior of solid polymer films, finding BP copolymers to be particularly effective crosslinkable materials. Gelation efficiency can be tuned according to comonomer chemistry, as BP hydrogen abstraction on the main polymer chain increases chain scission, reducing crosslinking efficiency. This knowledge is then applied in Chapter 3, wherein we discuss two potential methods for preparing nanostructured polymer blends from these copolymers, namely spinodal decomposition of a photo-crosslinked polymer blend and solution-state photografting to create interfacially active species. While each technique shows promise, the ultimate goal of a disordered bicontinuous morphology will require further tuning of materials systems and protocols. Finally, chemical deactivation of BP photo-crosslinker in copolymers for use as photo-patternable and environmentally stable hydrogel materials is investigated. Reduction of BP by sodium borohydride proves a feasible route toward deactivating residual photo-crosslinker in patterned hydrogel films. These results confirm the utility of copolymers with pendent benzophenone photo-crosslinkers as useful tools for complex material systems.

The primary objective of this research is to investigate the morphological and mechanical properties of composite materials and porous materials prepared by thermally induced phase separation. High melting crystallizable diluents were mixed with polymers so that the phase separation would be induced by the solidification of the diluents upon cooling. Theoretical phase diagrams were calculated using Flory-Huggins solution thermodynamics which show good agreement with the experimental results. Porous materials were prepared by the extraction of the crystallized diluents after cooling the mixtures (hexamethylbenzene/polyethylene and pyrene/polyethylene). Anisotropic structures show strong dependence on the identity of the diluents and the composition of the mixtures. Anisotropic crystal growth of the diluents was studied in terms of thermodynamics and kinetics using DSC, optical microscopy and SEM. Microstructures of the porous materials were explained in terms of supercooling and dendritic solidification. Dual functionality of the crystallizable diluents for composite materials was evaluated using isotactic polypropylene (iPP) and compatible diluents that crystallize upon cooling. The selected diluents form homogeneous mixtures with iPP at high temperature and lower the viscosity (improved processability), which undergo phase separation upon cooling to form solid particles that function as a toughening agent at room temperature. Tensile properties and morphology of the composites showed that organic crystalline particles have the similar effect as rigid particles to increase toughness; de-wetting between the particle and iPP matrix occurs at the early stage of deformation, followed by unhindered plastic flow that consumes significant amount of fracture energy. The effect of the diluents, however, strongly depends on the identity of the diluents that interact with the iPP during solidification step, which was demonstrated by comparing tetrabromobisphenol-A and phthalic anhydride. A simple method to prepare composite surfaces that can change the wettability in response to the temperature change was proposed and evaluated. Composite surfaces prepared by nanoporous alumina templates filled with polymers showed surface morphology and wettability that depend on temperature. This effect is attributed to the significant difference in thermal conductivity and the thermal expansion coefficient between the alumina and the polymers. The reversibility in thermal response depends on the properties of the polymers.