This dissertation is a study of the phase transition and melt crystallization of ferroelectric copolymers of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) containing 83 mol% poly(vinylidene fluoride). The microstructure of crystallized P(VDF-TrFE) are characterized by vibrational spectroscopy to determine their chain conformation distribution, wide-angle X-ray diffraction (WAXD) to measure the crystal structure and determine the content of $\alpha$ and $\beta$ crystal phases. Differential scanning calorimetry (DSC) is used to measure the transition temperatures and their enthalpies. P(VDF-TrFE) is a polymorphic system exhibiting a Curie transition below its melting temperature, at which the copolymer undergoes a long range conformational change from a predominantly trans structure ($\beta$ phase) which can be ferroelectric, to a structure which has a mixture of trans and gauche conformations and is called the paraelectric $\alpha$ phase. Variable temperature FTIR studies have been made to follow the phase transition and to understand the multiple phase behavior that has been suggested for these copolymers. Factor analysis has been applied to the FTIR data to determine the number of crystal phases present for this copolymer composition. Melt crystallization under nonisothermal and isothermal conditions has been used to modify the structure of the copolymers and change both the Curie and melting temperatures. It is found that with slow cooling rates from the melt through the crystallization temperature, there is a stabilization of the paraelectric $\alpha$ phase which is then retained to different degrees on passing through the Curie transition on cooling. Under all crystallization conditions the copolymers exhibit two Curie transitions on cooling whose temperatures and intensities vary with cooling rate and crystallization time. The Curie temperature on cooling and subsequent heating is decreased upon slower cooling, reflecting an increase in the gauche chain conformers as evidenced by FT-Raman spectroscopy. WAXD data show that there are $\alpha$ and $\beta$ phase crystals present in samples that have been cooled slowly, accompanied by an increase in interplanar spacing which indicates that the $\beta$ phase also contains gauche defects. Longer isothermal crystallization at 135$\sp\circ$C shows also that there is an increase in $\alpha$ phase content with longer crystallization time, though when crystallization is carried out at 135$\sp\circ$C there is always a coexistence of $\alpha$ and $\beta$ phases in the final room temperature structure. Highly oriented P(VDF-TrFE) copolymers were prepared by solid-state coextrusion to aid in understanding the vibrational assignments in the copolymer. Infrared dichroism and WAXD were used to assess the sample orientation and measure the transition moment angles for some of the vibrations in the spectrum.

The partitioning of solvated polymer molecules with a bimodal molecular weight distribution between a confined geometry such as a porous medium and an external free volume is investigated. It is found that, as the concentration of the high molar mass macromolecule exceeds the overlap concentration in the exterior, the low molar mass fraction is driven into the restricted pore channels, while the high molar mass fraction remains outside. It is noted that this segregation effect could in principle be used to fractionate polydisperse polymers in solution. A novel scheme for the fractionation of polydisperse polymers in solution by utilizing nano-scale porous materials is presented. The efficiency of this fractionation scheme is estimated and the protocols to be followed for an optimal separation are proposed. The tracer diffusion of probe polystyrene (PS) molecules in a matrix polymer solution confined in a porous medium is studied by using dynamic light scattering (DLS). In these experiments, a sample of controlled pore glass was equilibrated with a ternary solution consisting of PS, the matrix polymer (polytetrahydrofuran (PTHF) or poly(vinyl methyl ether) (PVME) at higher matrix concentration), and the common solvent 2-fluorotoluene (2FT); the matrix polymer and 2FT are isorefractive with the porous glass. The PS concentration was held low, whereas the concentration of matrix polymer exterior to the pore was systematically increased within the homogeneous regime. The tracer diffusion coefficient D$\sb{\rm p}$ of PS in the interior of the pore decreased more rapidly than did the tracer diffusion coefficient D$\sb{\rm f}$ in the exterior as matrix concentration exterior to the pore increased in the range below the overlap concentration; this is ascribed to the enhanced polymer-polymer interactions in the narrow pore channels. However, D$\sb{\rm p}$ showed a weaker dependence on matrix concentration than D$\sb{\rm f}$ as matrix concentration exceeded overlap concentration. This result is ascribed to the smaller topological constraint exerted by matrix molecules in the interior of the pore than in the exterior free solution because of the lower interior matrix concentration.

Two series of aminoiminate compounds, the aminotroponimines (ATI) and the β-iminoamines (β-IAM), were synthesized and used for the design of new catalysts for α-olefin polymerizations. The obtained aminoirninate complexes of titanium and zirconium were found to be highly active catalysts for ethylene polymerization. In contrast, the amimoiminate palladium complexes were inactive in ethylene polymerization. A novel and simple route has been developed to prepare a series of N,N ′-dialkyl aminotroponimine compounds and one β-iminoamine compound, N,N′-diphenyl-β-IAM. During the titanium metallation of a bulky N,N′-di(2,6-diisopropylphenyl)-β-IAM compound, the β-IAM was found to be dimerized to produce a potential ligand for the dimetallic complex. A series of β-IAM-Zr complexes were successfully synthesized through simple reactions between deprotonated b-IAM and ZrCl4·2THR. The ATI-Zr, ATI-Ti and β-IAM-Ti complexes were obtained from the amine elimination reaction of dimethylamino metal complexes with the aminoimine compounds. The β-IAM palladium complexes were prepared through the reactions between deprotonated β-IAM and (COD)Pd(Me)CI. A Full structure analysis of a β-IAM-Zr complex was achieved through X-ray analysis. Activated by methyl aluminoxane, all of the aminoirninate titanium and zirconium complexes are active catalysts. The activity of the ATI-Zr complex is close to that of the β-IAM-Zr complexes and the β-IAM titanium catalysts are more active than their zirconium analogues. The molecular weight distribution of polyethylene from aminoirninate Zr complexes is trimodal. In contrast, the polymer from titanium catalyst is close to a single mode distribution. Steric factors appear to be the over-ridding criteria in determining both of the activities of the β-IAM-Zr catalysts and molecular weight distribution of the obtained polyethylene. The steric crowding of the ligands decreases the polymerization activities and increases the molecular weight dispersities. The β-IAM zirconium catalysts are very stable and maintain constant activities during polymerization for long time periods. Polymerization temperature, solvents and catalyst/cocatalyst ratio strongly affect the polymerization activities of zirconium and titanium catalysts. The NMR and DSC studies indicate that chain-transfer to aluminum is the predominant chain termination reaction. The β-IAM Zr and Ti complexes are also active for propylene and 1-hexene polymerization; however, the activities are much lower than ethylene polymerization.

Polyelectrolyte-surfactant complexes (PSCs) are used to create nanostructured solid materials through two methods. First, they are combined with co-surfactant and oil to form electrostatically self-assembled amphiphilic complexes (ESAs). These materials exhibit long-range order at the nanoscale for cubic, hexagonal, and lamellar morphologies and demonstrate the ability to swell upon addition of a hydrophobic species. The effects of polyelectrolyte charge density and co-surfactant identity were investigated in regards to their influence on phase transitions and extent of swelling. The impact that molecular weight and charge density of the polyelectrolyte have on ESA structure was given a detailed look. A methodology was developed whereby ESAs that showed morphological coexistence when first formed could be forced into a well-ordered hexagonal phase, and the effects of ionic strength and co-surfactant content on this process were examined. Small angle x-ray scattering (SAXS) was the primary instrumentation used for this work. Secondly, PSCs were formed from a crosslinkable biopolymer to eventually form crosslinked polyelectrolyte hydrogels. A chemical route was extablished and the gels characterized by SAXS, rheology, and light scattering.

The conformational statistics of isotopically labeled amorphous atactic polystyrene (aPS) and amorphous poly(ethylene terephthalate) (PET) were examined by solid-state NMR. Double-quantum pulse sequences were used to select 13C–13C spin pairs and correlate their chemical shift anisotropies, providing torsion angle information. A trans:gauche ratio of 68:32 (±10%) was determined for 13CH2–CH(Ph)– 13CH2 labeled segments in aPS while a cis:trans ratio of 60:40 was determined for O=13C–(Ph)–13C=O labeled segments in amorphous PET. The position and width (ψt = 185° ± 15°) of the trans peak in C2H(Ph)– 13CH2–13CH(Ph) labeled segments of aPS was determined by correlating well defined 2H quadrupolar and 13C–13C dipolar interactions. Auxiliary NMR experiments were performed on suitably labeled aPS to determine the 13CH2 chemical shift tensor orientations, the backbone bond angles (&thetas;α = 117° ± 3° and &thetas; β = 114° ± 3°), and separate the 13C MAS signals of 13CH2 and 13CH(Ph) units. An average angular amplitude of 5°–8° was determined for the backbone motion of aPS by examining the C–2H motion in C2H(Ph)–CH2 labeled aPS by 2H NMR with 1H decoupling. A distribution of motional amplitudes was determined for 13C=O groups in amorphous PET by CSA lineshape changes at different temperatures.

The work described in this dissertation reveals the potential of electrophoretic techniques for the characterization and better understanding of polyelectrolyte solutions. The dependence of electrophoretic mobility μ on parameters such as solution ionic strength, polymer charge density, molecular weight, and chain architecture are explored. For oligomers, the free solution electrophoretic mobility μ0 exhibits an unambiguous maximum with respect to molecular weight M; lowering solution ionic strength I accentuates this poorly understood phenomenon. Though the dependence of μ0 on M disappears at higher M, electrophoretic migration through dilute neutral polymer solutions will give M-dependent μ-distributions for high M polyelectrolytes. Until now, this capillary electrophoresis technique was limited to polyanion analysis; a method of overcoming the technological challenges of analyzing polycations with this technique is presented here. The new ability to analyze polycations via capillary electrophoresis opens the door to many new investigations into polyelectrolyte solution behavior. This capability is demonstrated by a comprehensive study of protonated dendrimers: μ 0 is investigated as a function of I, dendrimer charge, and dendrimer radius. The results match predictions of the standard electrokinetic model for a dielectric sphere, revealing that the relaxation effect dominates the electrophoretic behavior of highly charged dendrimers.

The work presented in this thesis applies primarily the techniques of Raman and infrared spectroscopy to characterize the structural transformations in polymers. An overview of the problems studied is given in Chapter 1. Particular emphasis is given to mainly syndiotactic polypropylene structural transformations influenced by configurational defects (Chapter 2), and thermal history and mechanical deformation (Chapter 3). In Chapter 4, the influence of a confining surface in the structural transformation of poly(dimethyl siloxane) Langmuir films at the air-water interface is characterized. Using a combination of Raman spectroscopy, and normal coordinate analysis of both ordered and disordered chains, it was possible to relate the Raman spectrum to the amorphous phase and ordered phase structures. With this relationship, it was possible to directly relate the Raman spectrum to the population of meso(isotactic) defects in mainly syndiotactic polypropylene. In addition, time, temperature, and mechanical stretching-dependent transformations were characterized. With external reflectance infrared spectroscopy, it was possible to characterize chain conformation and the local environment of the polymer backbone. Dependence of band intensity and frequency was related to the average segmental orientation and the proximity of the water surface.

During the synthesis of zirconium Schiff-base polymers it became apparent that the polymers adhere quite strongly to the silica (glass) vessels in which they were recrystallized from dimethyl sulfoxide solution. This observation inspired the following research: A new soluble linear Schiff-base zirconium-containing coordination polymer poly((N,N$\sp\prime$,N$\sp{\prime\prime}$,N$\sp{\prime\prime\prime}$-tetrasalicylidene-3,3$\sp\prime$-diaminobenzidine)-zirconium(IV)) ((Zr(tsdb)) $\sb{\rm n}$) has been synthesized via the condensation of 3,3$\sp\prime$-diaminobenzidine with tetrakis(salicylaldehydato-O,O$\sp\prime$)zirconium(IV) in dry dimethyl sulfoxide. Molecular weights have been characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, and viscosity measurements. A copolymer average degree of polymerization of up to 92 has been obtained by careful stoichiometric control and fractionation. The polymer shows high thermal stability to about 500$\sp\circ$C and has a glass transition temperature of about 74$\sp\circ$C. An electronic charge-transfer transition occurs at about 400 nm with a molar extinction coefficient of 30,000 L(mol Zr)$\sp{-1}$cm$\sp{-1}$. The interface interaction between the polymer and oxides (glass and alumina) has been studied. A series of (Zr(tsdb)) $\sb{\rm n}$ polymers with different end group ratios were used for the surface coverage studies. Polymers with more zirconium end groups obtain higher surface coverage. The interface bonding, Zr-O-Si, is identified from Fourier-transform infrared at 990 cm$\sp{-1}$. Scribe-stripping tests show adhesion vanishes after the polymers are end-capped. (Zr(tsdb)) $\sb{\rm n}$ oligomers couple with ($\pm$)-$\beta$-butyrolactone and stearoyl chloride to produce organic hybrid copolymers. These copolymers have been synthesized for the study of adhesion promotion for polymeric coatings on glass and aluminum substrates. Based on scribe-stripping, indentation debonding, and peel tests, results with films of poly(methyl methacrylate), polybutyrolactone, polythylene, and polypropylene show that adhesion increases when the substrates are pretreated with these hybrid copolymers.

The research field of homogeneous Ziegler-Natta catalysts based on metallocene and methylaluminoxane has now attracted a tremendous attention because of their high activity, well illustrated mechanism and kinetics aspect. We focused our research on catalysts synthesis, kinetics and mechanistic study of polymerization with ethylene as the monomer. The soluble catalysts are group IV transition metallocene compounds such as CP$\sb2$ZrCl$\sb2$, CpZrCl$\sb3$, (NMCp)$\sb2$ZrCl$\sb2$, and (NMCp)$\sb2$HfCl$\sb2$ with methylaluminoxane, MAO, as cocatalyst. The catalysts showed the highest productivity for ethylene polymerization in the temperature range of 70$\sp\circ$C to 90$\sp\circ$C. Take Cp$\sb2$ZrCl$\sb2$/MAO system for example, when (Cp$\sb2$ZrCl$\sb2$) = 1.1 x 10$\sp{-6}$ M, (Al) = 1.7 x 10$\sp{-2}$ M, the productivity is 3.9 x 10$\sp7$ g $\cdot$ PE/mole Zr $\cdot$ hr $\cdot$ atm at 70$\sp\circ$C. The kinetics of ethylene polymerization was studied using different metallocene catalysts. The active sites concentrations were determined by radiotagging with tritiated methanol and $\sp{14}$CO. For Cp$\sb2$ZrCl$\sb2$, virtually all the Zr are transformed into active sites, (C$\sp*$) = (Zr), at 70$\sp\circ$C and Al/Zr = 10$\sp4$. About 80% of the Zr formed active sites at a lesser Al/Zr ratio of 10$\sp3$. Lowering the temperature of 50$\sp\circ$C and at Al/Zr = 5.5 x 10$\sp3$, only 20% of CpZrCl$\sb3$ became catalytically active center. By varing polymerization conditions such as (Cat.), (C$\sb2$H$\sb4$), temperature and Al/Zr, Al/Hf ratio, the propagation rate constants, K$\sb{\rm p}$, were determined. The average molecular weight and molecular weight distribution have been determined by GPC and viscosity. The hydrogen effect on ethylene polymerization also been studied.

Electrostatic interactions may direct the behavior of polyelectrolytes at solution/solid interfaces, with these comparatively long-ranged interactions influencing both the adsorbed chain conformation and the amount of polymer adsorbed. The microscopic structure of adsorbed polyelectrolyte layers is difficult to measure, however, and present knowledge on the subject derives from a relatively small number of experiments. To provide further insight into the role of electrostatic interactions, this thesis examines, using in situ ellipsometry, the effect of a variable applied surface potential on the structure of an adsorbed polyelectrolyte layer at the solution/metal interface. Previous investigators reported that significant changes in layer thickness accompanied variations in surface potential, a phenomenon presumably traced to the attraction or repulsion of segments from the surface. However, oxidation/reduction of the surface also accompanies variations in this potential, and these chemical rearrangements were ignored when the ellipsometric data were analyzed, resulting in an inaccurate determination of thicknesses and adsorbances. Our study is thus the first to establish a method by which ellipsometry can be combined with voltammetry to correctly determine the effects of an applied surface potential on the structure of an adsorbed polyelectrolyte layer. As part of this method, we have established a protocol by which ellipsometric results can be corrected for surface oxidation/reduction. Two amphoteric polyelectrolyte systems are examined: $\gamma$-globulin, which possesses a rigid globular structure, and gelatin, which exhibits a flexible coil conformation in solution. Both are adsorbed onto platinum from phosphate buffers at pH values above their isoelectric points, creating a net negative polymer charge. Locally, however, both positive and negative charges exist simultaneously on the polymer chains. Due to the extremely rigid conformation of $\gamma$-globulin, provided by 16 disulfide bond linkages, no potential-induced changes in adsorbed layer thickness or plateau adsorbance are observed after ellipsometric data is corrected for surface oxidation/reduction. In contrast, gelatin's flexible nature would appear more conducive to adsorbed layer alterations with surface potential. Again, however, upon investigation, no changes in adsorbed layer thickness or amount adsorbed are detected, irrespective of ionic strength. The results suggest that lateral segment-segment interactions within a flexible polyelectrolyle layer are more important to layer structure than long-range segment-surface interactions.