The free radical addition of saturated polymers and small molecules to unsaturated monomers is used to prepare functional derivatives under solvent-free, reactive extrusion conditions. Of particular interest are the dynamics and yields of conventional peroxide-initiated grafting of vinyltrialkoxysilanes to polyethylene, as well as the mechanisms through which bicumene initiates the process at high temperatures. Knowledge of these commercial processes is applied toward the development of new graft modification technology, including radical initiated polymer addition to alkynes, and a new variation of precipitation polymerization chemistry. The thermolysis of bicumene at temperatures ranging from 220°C to 270°C was used to initiate C-H bond addition from alkanes to vinylsilanes in a high-temperature analogue of conventional grafting practice. The initiation mechanism is shown to involve direct hydrogen atom abstraction by intermediate cumyl radicals, as well as autooxidation processes involving cumyl radicals and available oxygen. Conventional peroxide initiated graft modifications of polyethylene with vinylsilanes are examined from the standpoint of reaction dynamics and yields. The influence of peroxide loading and monomer concentration on these reaction variables can be described using a simple quasi-steady state kinetic analysis, while the unusual insensitivity of reaction yields to temperature requires further investigation. A new chemical modification of saturated polymers involving free radical addition to mono-substituted alkynes is presented and examined in terms of reaction yield, graft structure, and changes to molecular weight. Model compounds are used to characterize alkyne grafting products, and to probe the relationship between reagent properties, reaction yields, and product structures. The discovery of cross-linked particles in the products of polypropylene graft modifications with triallyltrimesate has led to a variation of precipitation polymerization wherein C-H bond addition to an allyl monomer contributes to molecular weight growth, thereby incorporating a significant amount of saturated hydrocarbon into the solid phase. The relationships between reaction conditions and solid-phase composition and morphology are discussed. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2008-12-18 14:35:52.483

There has been considerable interest over the past decade in the preparation and applications of copolymers of ethylene with functionalized polar olefins. Such copolymers are expected to exhibit a variety of potentially very useful properties such as paintability, adhesion to polar surfaces, and miscibility with polar polymers such as polyesters and polyamides, but there are limitations associated with producing copolymers of ethylene with polar monomers via Ziegler-Natta processes. Many classes of Ziegler-Natta catalysts, especially those of the early transition metals (Ti and Zr), are highly oxophilic and hence are poisoned by functionalities such as -OH groups. This problem can in principle be alleviated by implementing the use of protecting groups such as –OSiMe3, which has previously been shown to be an effective masking agent both for steric reasons and because O-Si π bonding decreases the Lewis basicity of the ether oxygen atom. One can also utilize late transition metal catalyst systems, which are generally less Lewis acidic and therefore less susceptible to poisoning by functional groups. In this thesis the results of an investigation of the copolymerization of ethylene with CH2=CH(CH2)nOSiMe3 (n = 1, 2, 8) will be presented. We have been using MAO activated dibromo[1,4-bis(2,6-diisopropylphenyl)acenaphthenediimine]nickel(II) (D) as catalyst, as this system is known to produce reasonably linear polyethylene and hence may be expected to produce essentially LLDPE containing –(CH2)nOSiMe3 branches. The latter can be hydrolyzed to give polar –(CH2)nOH branches. / Thesis (Master, Chemistry) -- Queen's University, 2009-01-31 14:43:09.93

Light-emitting electrochemical cells (LECs) are solid state polymer devices operating through the formation of a light-emitting p-n junction by in situ electrochemical doping. The LEC film contains a luminescent polymer and a polymer electrolyte. A sufficiently high voltage bias initiates the electrochemical p-doping reaction at the anode interface and n-doping reaction at the cathode interface. With time the doped regions expand in volume until they make contact to form a light-emitting p-n junction. In this thesis, I present my original research on both the light-emitting and photovoltaic properties of LECs. I discovered that continued doping after p- and n-doped regions have made first contact accounts for most of LEC turn-on time. I showed that because the electronic charges must be injected from an external circuit for the electrochemical doping to occur, the LEC turn-on response is limited to no faster than milliseconds. I also demonstrated that the lifetime of LECs can be affected by various factors such as stress temperature, stress current, substrate thermal conductivity, and luminescent polymer end group. With the right combination of substrates and materials, LECs exhibit a remarkable half lifetime on the order of hundreds of hours when stressed at a current density of 1A/cm2. I also observed that an as-formed p-n junction can even relax into a p-i-n junction upon the removal of applied voltage bias. A p-i-n junction LEC exhibits more efficient electroluminescence due to less photoluminescence quenching in the quasi-intrinsic emission zone. Frozen p-i-n junction LECs also exhibit a much improved photovoltaic response. By carefully controlling the relaxation (dedoping) temperature and duration, I have demonstrated p-i-n junction photovoltaic cells with record-high open-circuit voltage of 2.25V and short-circuit current density in excess of 10mA/cm2 under simulated sunlight of ~300mW/cm2. By optimizing film thickness and electrolyte content, I have achieved a thirty-fold increase in power conversion efficiency of p-i-n junction photovoltaic cells. My results demonstrate that a polymer homojunction such a p-n or a p-i-n junction is a promising device concept that has potential application in high performance polymer-based photonic devices. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-05-25 13:06:45.646

The principal aims of the thesis were to carry out a systematic analytical study to determine the solution properties of narrow-distribution and broad-distribution linear poly(ethylene oxide) (PEO) polymer samples in aqueous and organic solution and to study the adsorption properties of these polymer samples onto glass interfaces and spherical latex particles. The deposition characteristics of various types of bare and PEO coated latex particles onto collector surfaces were also studied. / These studies allowed to ascertain the presence of PEO clusters in aqueous solution. The cluster size was found to be time dependent and to vary between 0.45 $ mu$m and 0.90 $ mu$m. The clusters were found to be in a thermodynamic equilibrium with the free polymer in solution and were found to reform spontaneously after a 30 minute period following filtration. / Adsorption studies indicated that the adsorption of PEO onto latex particles is kinetically controlled and that increased surface roughness and polarity of the latex particles decreases PEO adsorption. PEO clusters in solution were found to increase the value of the effective diffusion constant, D$ rm sb{eff}$ and thus decrease the calculated hydrodynamic layer thickness. / Evanescent wave light scattering was used in conjunction with a hydrodynamic impinging jet method for the study of depositing and non-depositing colloidal systems near interfaces. For non-depositing systems a comparison of the measured particle concentration profiles to the theoretically expected particle concentration profiles, calculated from DLVO theory, was made. The agreement was found to be very good. / The deposition of bare and PEO-coated latex particles onto glass interfaces was also investigated. From the data it was found that bare and smooth latex particles adsorb much more strongly onto collector surfaces than "hairy" latex particles which have long copolymer chains, such as itachonic acid, grafted onto their surfaces. The results indicated that the thicker the adsorbed polymer layer, the stronger the steric force preventing deposition of the polymer coated colloidal particles onto the collector surface. When the combined ellipsometric layer thickness of the particles and the collector surface exceeded a critical value, found to be about 15 nm, no particle deposition onto the collector surface was possible.

The kinetic and mechanistic details involved in the morphological transitions occurring in aggregates prepared from the copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) in dioxane-water mixtures and the ability of sodium dodecyl sulfate to induce architectural changes in these aggregates are described in this dissertation. The kinetics of the sphere-to-rod, rod-to-sphere, and vesicle-to-rod transitions were determined by following the change in the solution turbidity as a function of time after the transitions were induced by a sudden jump in one of the solvent components of the system. The kinetics of each transition was explored as a function of the initial solvent composition, the magnitude of the solvent content jump, and the initial polymer concentration. In another study, the amphiphile, sodium dodecyl sulfate (SDS), was found to induce morphological transitions in the copolymer aggregates at lower water contents than those required in the absence of surfactant. The effect was studied as a function of SDS concentration, solvent composition, and copolymer concentration.

The micellization of polystyrene based block copolymers was investigated in aqueous and in organic media. Micelles formed from polystyrene-b-poly(sodium acrylate) (PS-b-PANa) in sodium chloride solutions were investigated by static light scattering (SLS). The aggregation numbers (N$ rm sb{agg})$ were influenced by low salt concentrations ($<$0.10 M) and they were essentially independent of the soluble block lengths. The core radii ($ rm sb{e}$ agreed well with previous solid state results on similar samples studied by small-angle X-ray scattering (SAXS). It was thus concluded that no supermicellar aggregates were present and that the cores were solvent free. / A method to evaluate the critical micelle concentrations (cmc's) of block copolymer micelles by SLS was developed to account for the effects of polydispersity on the cmc. It was found that for block copolymers which have a significant dependence of the cmc on the insoluble block length and which are polydisperse only the present approach was able to evaluate the cmc. / The micellization of PS-b-PANa and PS-b-poly(acrylic acid) (PS-b-PAA) block copolymers were investigated in organic solvents. The cmc's were found to range from $1 times10 sp{-7} { rm to} 5 times10 sp{-9}$ M for insoluble block lengths ranging from 2.6 to 18 units. The N$ rm sb{agg}$ and R$ rm sb{e}$ values for four PS-b-PANa series in tetrahydrofuran, were found to be a function of the length of both blocks. The effect of the degree of neutralization of the PAA block on micellization was probed by SLS and SAXS; micelle formation was found to commence at 5% neutralization. The distribution of water between toluene and the polar cores of block ionomer and sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles was investigated by proton chemical shift measurements as a function of temperature. The amount of water solubilized and the thermodynamic parameters of transfer were found to be a function of the core nature.

Modified biphenols which contain 2,2$ sp prime$-disubstituents on the biphenyl groups and also hydroquinones containing multiple substituents were synthesized in order to prepare novel thermally stable polymers. The structure/properties relationship which were investigated using viscometry, DSC, TG/DTA, TMA, and GPC are discussed. / The prepared polymers (polysulfones and poly(ether ketone)s) exhibit considerably enhanced glass transition temperatures and are soluble in common organic solvents due to the noncoplanar biphenyl rings which increase the disorder along the polymer backbone thereby reducing interchain interactions. The polyesters prepared show poor solubility and their Tg's and Tm's increase considerably over the unhindered polyester analogs due to the chain stiffness. / Polyimides were prepared from the reaction of novel dianhydrides and m- and p-phenylene diamines. A series of bisanhydrides were prepared via the nitro-displacement reaction of hindered biphenols and N-methyl-4-nitrophthalimide. The polymers exhibit good solubility in common organic solvents and show high Tg's. Blends of polycarbonate and polyimides, prepared from m-phenylene diamine, show better miscibility compared to those of polyimides from p-phenylene diamine. / The 2,2$ sp prime$-substituted biphenols which can be oxidized to bisphenoxydiradicals are applicable as oxidizing agents for diphenylmethanes and primary alcohols, and also undergo C-O coupling reactions with activated methylene groups. An additional modified biphenol was synthesized for REDOX polymers applications and the properties of these polymers are discussed.

Thermolysis was investigated as a process to convert waste olefin-based polymers into value-added products at a moderate temperature. Virgin, linear low density polyethylene was used for the majority of the experiments. The thermolysis of virgin polystyrene, recycled polyethylene and 3:2 mixtures of polyethylene and polystyrene were also investigated. The final process that was developed employed the reactive distillation of polyolefins under an inert atmosphere and at moderate reaction temperatures, ranging from 375 to 450$ sp circ$C. The major products from thermolysis of polyethylene were a distribution of low-molecular-weight straight chain alkanes and $ alpha$-olefins ranging from C$ sb6$ to C$ sb{25}.$ Overall volatile product yields up to 90% were obtained from the starting polymer. The initial molecular structure of the polyethylene was found to have a large effect on the rate of molecular weight reduction. A significantly enhanced rate of thermolysis was also observed when polyethylene was processed as a mixture with polystyrene. The mechanisms of thermolysis of polyethylene, polystyrene and mixtures of the two polymers were elucidated. Furthermore, the mechanism of dimer production from polystyrene was found to be different than what has been reported previously.

Studies of the use of enzymes to both produce and degrade polyhydroxyalkanotes (PHAs) under in vitro conditions are presented in this thesis. PHAs were produced using a lipase-catalyzed ring-opening polymerization of the corresponding lactones. Poly(3-hydroxybutyrate), PHB, was obtained in up to 89% yield with a degree of polymerization of 3--12. Polymerization of other lactones, including beta-propiolactone, gamma-butyrolactone, and e -caprolactone, also yielded the corresponding polyesters in good yields with degrees of polymerization up to 25. MALDI-TOF mass spectroscopy was used to characterize the polymer products. The growth and kinetics of PHB granules produced in an in vitro polymerization were studied using TEM and CRYO-TEM in conjunction with image analysis. The in vitro reaction was confirmed to be a pseudoemulsion polymerization. The average granule diameter and volume increased with reaction time while the number of granules fell throughout the reaction due to coalescence. Basic kinetic parameters including KM, Vmax, and the rate constants of polymerization were determined and compared to those obtained for the in vivo biosynthesis of poly(3-hydroxybutyrate). / With the aim of improved understanding of the mechanism of depolymerase action on water insoluble crystalline PHAs, folded chain lamellar single crystals of PHAs were partially degraded with PHA depolymerases and examined using TEM. Enzymatically degraded single crystals of bacterial PHB were found to be splintered by PHB-depolymerase A from Pseudomonas lemoignei parallel to their long axes into a needle-like morphology. These results support an "edge attack" model for the degradation of PHB single crystals and suggest that PHB-depolymerase A has both endo and exo activity. A further study was performed using single crystals of a number of PHAs which were partially degraded with depolymerases from Pseudomonas lemoignei and examined by TEM. In contrast to previous results with single crystals of bacterial PHB, the predominant effect observed with all crystals was a significant narrowing of the lamellae. This suggests an edge attack mechanism which because of lateral disorder of the crystals (caused by the introduction of valerate or repeat units of opposite stereochemistry) leads to a narrowing of the crystalline lamellae as opposed to the splintering effect previously observed.

(Acetyl)(ethyl)cellulose (AEC) polymers with an ethyl degree of substitution (DS) of 2.5 and acetyl DS ranging from 0 to 0.5 form chiral nematic liquid crystals in many organic solvents. The chiroptical properties of these lyotropic AEC mesophases are extremely sensitive to the acetyl DS of AEC and the nature of the solvents although the acetyl group and solvents are achiral and all the polymers share the same chiral cellulose backbone. As the acetyl DS increases from 0 to 0.5, the pitch of AEC mesophases in a given solvent varies from a few nanometer to infinity and a reversal of handedness occurs as a compensated degree of acetylation (DA$ sp*$), where the corresponding mesophase is characterized by an infinite pitch and the absence of macroscopic chirality. The value of DA$ sp*$ and the sign of the temperature dependence of pitch depend on the solvent. Achiral dyes dissolved in these AEC mesophases display liquid crystal induced circular dichroism (LCICD), which results from the helicoidal orientation of the dyes by their chiral matrices. The sign and magnitude of the LCICD are correlated with the handedness and pitch of the AEC mesophases. The mechanism for the handedness inversion for lyotropic AEC mesophases with variation in acetyl DS is discussed.