A study of novel ultrathin films is presented in two sections. The first section presents an investigation of several unconventional film-forming molecules at the air/water interface using the surface film balance apparatus. Strongly hydrophobic fullerenes (C$ sb{60}$ and C$ sb{70}$) were found to spread at the air/water interface to form Langmuir films of multilayer rather than monolayer thicknesses. The formation of these well-defined multilayers is independent of the initial surface density of the fullerene. The films adopt discrete thicknesses of 4-5 monolayer equivalents. The multilayer of the non-spherical C$ sb{70}$ exhibited a transition attributed to a reorientational process that was not observed with the C$ sb{60}$ multilayer. A calculation of the work of compression for the two fullerene films confirmed important differences between the C$ sb{60}$ and C$ sb{70}$ films. 1,3,5- Phenylene-based hydrocarbon starburst dendrimers were also found to form multilayer Langmuir films at the air/water interface. The formation of these multilayers, however, is dependent on the initial surface density of dendrimer, and believed to rely upon interpenetration amongst dendrimer molecules. Langmuir-Blodgett films of dendrimer co-spread with fatty acid were examined by Atomic Force Microscopy. A series of amorphous polyimides also appear to form multilayer Langmuir films, possibly because they adopt a conformation on the water surface that renders them more rigid than in the bulk material. / The second section describes the electrochemical and interfacial properties of two series of thiophene/ferrocene conjugates. The detailed electrochemistry of these compounds is described, including their electro-oxidative polymerization and the subsequent characterization of the polymer film. Their unique bifunctional nature leads to the formation of a polymer material that is intrinsically limited to the formation of monolayers. At the air/water interface, these molecules have a well-defined phase transition from a disordered state to an ordered state. Their oxidative polymerization was effected chemically at the air/water interface in both their expanded form, in which they are extended on the water surface, and a more condensed form, although it was observed to proceed more rapidly in the expanded form. / In both studies, the properties of the ultrathin films that are formed are discussed in the context of the transition from aggregates to bulk material. The implication of the present results is also discussed with respect to the nature of the surface tension measurement in the surface film balance experiment. Finally, the importance of an architecture imposed by the properties of the molecules such as that observed in the electropolymerization of the thiophene/ferrocene compounds is discussed.

Natural polymers such as polysaccharides have been used as self-assembled matrices for drug delivery. Modified high amylose starch tablets swell to a limit when submerged in water, yielding a hydrogel with quasi-reversible viscoelastic properties. Such tablets display slow-release properties with a near zero-order drug delivery kinetics. Mechanical properties, electron microscopy imaging and swelling behavior have been investigated. Results from the foregoing investigations and from 13C CP/MAS NMR studies, which showed a clear transition from amorphous to crystalline organization upon wetting, were used to propose a model. The latter proposes that the viscoelastic hydrogel is formed due to the propensity of amylopectin and amylose, the two components of starch, to organize into double helices. The so formed pseudo-crosslinks, as water penetrates the dry tablet, explain the shape retention (limited swelling). This model was tested using Curdlan, a beta-1,3-glucan that is known to crystallize as triple helices. Studies on Curdlan tablets demonstrated limited swelling and shape retention, but unsuitable mechanical properties. This supported the model and added a feature that takes into account the heterogeneous nature of starch as an important factor in the obtention of a good viscoelastic hydrogel. / Because hydrophobic drugs are difficult to release by diffusion through matrices of hydrophilic polysaccharides, synthesis of compatibilizers was undertaken. Using a natural hydrophobic polyester: poly([R]-3-hydroxybutyric acid), PHB, possessing a high enthalpy of crystallization, a self-assembly amphiphilic system was created. Diblock copolymers of monomethoxy poly(ethylene glycol), mPEG and PHB were synthesized in a one-step, solvent-free, transesterification reaction. The resulting diblock copolymers were used to form colloidal suspensions of nanoparticles that are potential drug carriers and compatibilizers.

In plastics manufacturing, the morphology and crystallinity are important in the determination of the properties of the final product. They are influenced by several parameters, in particular the pressure and the temperature history during solidification. Therefore, the study of the influence of pressure and temperature on crystallization kinetics is important. In this study, the crystallization kinetics and the PVT behavior of various grades of polyethylene resins were evaluated and compared using a high-pressure dilatometer under both isothermal and isobaric conditions. Also, the PVT behavior was compared to the predictions of the Tait equation of state. It was found that polyethylene chain structure, as determined by branching and branching uniformity; influences nucleation, crystallization kinetics, and the effect of pressure an these processes. In addition, the results confirm the decrease of the surface free energy of the crystal nucleus with increasing pressure.

It is becoming generally accepted that wall slip, the loss of adhesion of a polymer to a solid substrate, occurs when the shear stress exceeds a critical value. Wall slip probably plays a much more important role in plastics processing than has been previously thought. For example, the extrudate distortion called sharkskin is thought to involve slip. Recent experiments have shown that this phenomenon is highly material dependant. The surface chemistry of both the molten polymer and the bounding surface interface play important roles in both the occurrence and magnitude of wall slip. The initial objectives of the research were to study slip in further detail, concentrating on the effects of the molecular weight and molecular weight distribution of the polymer. The effects of surface properties were also to be investigated. The research was performed using a sliding plate rheometer. Erratic stress signals were observed when the shear stress exceeded a critical level, and there was strong evidence that these were related to a highly complex type of slip. Thus, a steady slip velocity, which could be simply related to the shear stress, could not be determined. It was concluded that wall slip is, in general, a chaotic process with a strong dependence on initial conditions, sample history, and boundary conditions. Further research is suggested to elucidate this phenomenon.

This study focuses on understanding the physicochemical properties of cellulose as it undergoes the oxygen delignification process. Cellulose contributes to fibre strength but is degraded by oxygen attack. Four different types of cellulose, namely a fully bleached softwood pulp (Q-90), hemicellulose reduced pulp derived from Q-90, cotton cellulose and microcrystalline cellulose (Avicel), were subjected to pressurised oxygen and nitrogen treatments in a kettle reactor. The changes in relative degree of crystallinity, viscosity and carboxylic acid content as a function of time were used to evaluate cellulose degradation. X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and 13C solid state nuclear magnetic resonance (NMR) spectroscopy determined the relative degree of crystallinity. Viscosity and conductometric titration measurements followed the changes in the degree of polymerisation and carboxylic acid content respectively. / A plot of relative degree of crystallinity as a function of oxidation time showed reproducible and consistent results for all celluloses with all applied techniques. The relationship showed a common trend wherein three phases were apparent: an initial increase in relative degree of crystallinity was followed by a decrease and then another gradual increase. The change from a decrease in relative degree of crystallinity to an increase occurred at fifteen minutes for Q-90 and hemicellulose reduced pulp, and at minutes for cotton cellulose. No change in the relative degree of crystallinity with time was evident for Avicel. These trends were rationalised using the concept of the fringed micelle model.

Hydrazine reacts with phthalic anhydride to give a mixture of cyclic hydrazide and N-aminophthalimide. However, the N-aminoimide is exclusively formed in high yield by the reaction of 1,8-naphthalic anhydride with hydrazine. N-aminoimides act as amines and react further with cyclic anhydrides to yield stable bisimides containing an N-N linkage. The syntheses of several bis(N-aminoimide)s from the corresponding bisanhydrides which contain the naphthalic anhydride moiety have been described. Novel high molecular weight polyimides have been synthesized by the reaction of these bis(N-aminoimide)s with cyclic dianhydrides. Most of the polymers are amorphous and are soluble in solvents such as chloroform, o-dichlorobenzene, N-methylpyrrolidinone and m-cresol. Only those polyimides having less flexible groups in their structure or containing a significant amount of perylene units show some degree of crystallinity. / All of the polymers show remarkably high glass transition temperatures, as high as 455$ sp circ$C. Their 5% weight loss by thermogravimetric analysis in an atmosphere of air or nitrogen are all above 440$ sp circ$C. Most of these polymers are highly fluorescent. Their emission spectra are in the visible region and show some evidence for an excited energy transfer and molecular aggregation.

Several new families of chemically amplified photoresists were designed, synthesized and evaluated for microlithography. These materials were based on copolymers of the following but-2-enedioic acid derivatives: (i) maleic anhydride, maleic acid, fumaric acid; (ii) maleic or fumaric acid monoester; and (iii) fumaric acid di-t-butyl ester. Heating with photogenerated strong acid induced significant alteration of copolymer properties by acid-catalyzed reactions of, respectively: (i) dehydration, (ii) dehydroallcoxylation, and (iii) de-alkenation. Depending on the developing solvent, both negative-tone and positive-tone relief images were obtained with 1 micron resolution. The material alteration also allowed further patterned chemical modification ("functional development"), such as through sorption of various organic and inorganic species from contacting solutions or vapours into either exposed or unexposed resist areas.

General methodologies are elaborated for the modification of residual vinyl groups resulting from the polymerization of technical grade divinylbenzene to obtain polymer supported reagents, catalysts, protecting groups, separation media and chemosensors. These residual vinyl groups undergo anti-Markovnikov addition reactions via free-radical mechanisms to give polymer supported halides, sulfides, phosphines, phophonates, amines, silanes, carboxylic acid derivatives such as amides, amidines, esters and also b -diketones, crown ethers or acetals. Reaction of these pendant styryl units via electrophilic or nucleophilc mechanisms also give useful polymeric products. / Diels-Alder reactions of the pendant styryl units are also investigated, showing that these may react as dienophiles or, with the participation of the aromatic group, as a diene. Thus, one mole of diene such as hexachlorocyclopentadiene or 3,6-dipyridyl-1,2,4,5 tetrazine add per mole of alkene, or two moles of dienophile such as maleic acid derivatives add in a fashion analogous to the Wagner-Jauregg reaction. / Transition metal catalysed hydrosilylation of the substrate (vinyl)polystyrene using Co2(CO)8 gives exclusively dimethylene linked polymer supported dialkylchlorosilanes. These may be used to selectively protect primary hydroxyls in the presence of secondary or tertiary hydroxyls. Cleavage of the silyl ethers can be effected with aqueous acid, base or more conveniently with fluoride ions which then could be regenerated back to the polymeric silylchlorides using BCl3/CH2Cl2. / Resins bearing amino acid functionalities, obtained by free-radical addition of cysteine, may be converted to polymer supported azlactones which smoothly immobilize enzymes such as lipase, and retain their hydrolytic activity. / Functional polymer particles of nanometer dimensions bearing fluorescent molecular imprinted sites are obtained using a core-shell polymerization approach in conjunction with technique described above. The resulting clear particle dispersions show some ability to distinguish between molecules and even between enantiomers through weak interactions, as shown by fluorescence spectroscopy. / Small molecule fluorescent probes based on dimethylaminostyrylpyridinium salts are demonstrated to be useful fluorescent probes due to their great sensitivity to solution microviscosity. Caged derivatives are applied in microbial and cell cultures.

In order to obtain some insight into the deformation behavior of the dispersed phase in the various flows and to evaluate the effects of various variables such as concentration of the dispersed phase and viscosity ratio, affine deformation equations were derived for some stratified shear and elongational flows. It was shown by the derived deformation equations that the volume fraction of the dispersed phase is a factor affecting the deformation of the dispersed phase, and the effect depends on viscosity ratio. The results from the stratified simple shear flow model predict that, for viscosity ratio >1, the deformation rate increases with the volume fraction, and the shear stress also increases, leading to the increase of the breakup time. Therefore, the total deformation of the dispersed phase, before breakup, increases with the increase of the volume fraction, resulting in the decrease of the size of the dispersed phase particles. The prediction was verified experimentally, in both the Haake batch mixer and the Couette flow mixer, using polyethylene/polyamide-6 blends compatibilized by adding maleic anhydride grafted polyethylene, when coalescence was suppressed. In the analysis of particle size data for the verification of the volume fraction effect, an effort was made to identify the contribution of coalescence. The experimental results of particle sizes in 1 wt% blends of the Haake mixer are in reasonable agreement with the transient deformation and breakup theory for simple shear flow. This suggests that the dominant flow in the mixer was shear flow. In some reactively compatibilized blends, at high shear rate, the particle sizes showed a maximum when either the weight fraction or the shear rate was increased. This behavior may be explained by coalescence effects related to the redistribution of the produced copolymers at the interface. It was shown experimentally that, for very high viscosity ratio (>3.5∼4), the deformation of large drops between gaps i

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