Sulfur containing polymers are very important as rubbers, conducting materials, and high performance polymers. Examples are poly(aliphatic disulfide)s, poly(phenylene sulfide) (PPS), poly(sulfone), and polybenzothiazole. Several new polymerization reactions have been described in this thesis for the preparation of sulfur containing materials. / The synthesis of a series of cyclic(arylene disulfide) oligomers was accomplished by catalytic oxidation of arylenedithiols with oxygen in the presence of a copper-amine catalyst. The cyclic(arylene disulfide) oligomers underwent a novel free radical ring-opening polymerization at elevated temperatures in the melt to form high molecular weight poly(arylene disulfide)s. Cyclic(arylene disulfide) oligomers were copolymerized with elemental sulfur at 250°C to form stable poly(arylene sulfane)s containing 3--7 sulfur linkages. They also copolymerized with diiodoaromatic compounds, or dibromoaromatic compounds, in the presence of potassium iodide at 270°C to give poly(thioaryiene)s with the formation of iodine as the coproduct in both cases. / The novel self-polymerization of 4-bromobenzenethiol was realized at 270°C in m-terphenyl solution in the presence of a catalytic amount of free radical initiator. Hydrogen bromide is the sole side product. This novel reaction has also been extended to the synthesis of poly(thioarylene)s from arylenedithiols and dibromoaromatic compounds. / Another novel polymerization reaction to prepare poly(arylene thioether)s has been realized by a one-pot reaction of bis(N,N'-dimethyl-S-carbamate)s with activated dihalocompounds in diphenylsulfone in the presence of a mixture of Cs2CO3/CaCO3. Bis(N,N'-dimethyl-S-carbamate)s can be conveniently prepared from dihydroxy compounds via the Newman-Kwart rearrangement reaction. This polymerization reaction opens a new route for the synthesis of new poly(arylene thioether)s and poly(arylene sulfone)s. / A series of novel cyclic(arylene ether)s has also been synthesized and characterized. The ring-opening polymerization of these cyclic oligomers in the melt represents a new way to prepare high performance polymers.

A Monsanto Automatic Capillary Rheometer and a sliding plate rheometer were used to study the spurt phenomenon and to discover whether it is the result of a system instability or a material property. The capillary rheometer has been the only instrument able to operate at spurt stresses up to present time, because capillary rheometers operate at shear stresses that are out of the range of rotational shear rheometers. However, a sliding plate rheometer can generate shear stresses in the spurt range. A comparative study using two linear polybutadiene samples at 50°C was carried out using these two rheometers. Special attention was paid to the evaluation of the actual pressure drop in the capillary in order to determine the true shear stress at the wall. It was found that spurt occurs only in the capillary rheometer. In other words, the flow curve generated by the sliding plate rheometer is continuous in the shear stress range where spurt is observed in the capillary rheometer. Slip velocities were determined using data from the two rheometers, and the slip velocities for the post-slip capillary flow all fall on the smooth curve based on sliding plate data, provided that the pressure drop in the capillary, and not the overall driving pressure, is used to calculate the wall shear stress.

Polyelectrolyte multilayer thin films adsorbed onto colloidal particles have been studied by solid-state nuclear magnetic resonance (NMR) spectroscopy in order to characterize the dynamic properties of the film components. In addition, the growth of the multilayer films was observed directly for the first time and quantification of the amount of polyelectrolyte adsorbed during each step was achieved. NMR relaxation measurements demonstrate that the polyions are more mobile when incorporated into a multilayer film than when in the bulk complex. The polycation, poly(diallyl dimethyl ammonium chloride) (PDADMAC) was found to exhibit greater mobility than the polyanion, poly(styrene-4-sulfonate) (PSS), becoming increasingly less mobile as layers were added to the multilayer assembly. Solid-state deuterium NMR further demonstrates the limited mobility of the PSS chain when incorporated into a multilayer film. No significant motion is observed on the kHz timescale under ambient conditions for PSS in a strong-strong polyelectrolyte film. However, a small mobile fraction, the result of loops and tails or chain ends is present when the multilayer films are exposed to humidity and salt solutions. / The behavior of the adsorbed water within this multilayer system was found to be dependent on the nature of the terminating layer. The changes in water mobility represent changes in the environment throughout the entire film, while the observed changes in the polymer dynamics are associated only with the surface layer. Additionally the water is found to be more closely associated with the polyanion, associating with the polycation only when it is the terminating layer. The behavior of the water for films comprised of a weak-strong polyelectrolyte combination are similar to that of the strong-strong multilayer system, when films are assembled with the polyions having high charge density. An increase in polyelectrolyte mobility is observed when the polyanion is the terminating layer in the poly(allylamine hydrochloride) (PAH)/poly(styrene-4-sulfonate) system, the reverse of what is observed in the strong-strong system. These differences are due to the differences in intrinsic mobility between the polyions within the multilayer film. / Finally multilayer films of PAH/PSS were prepared on alumina membranes and both the flux and selectivity could be controlled over a wide range, simply by varying the pH of the layer assembly and pH of the filtrate solution. Membranes assembled at pH 3 and pH 9 have water flux values which are dependent on the solution pH, while membranes assembled at pH 7 have constant flux regardless of filtrate solution pH. The selectivity for PAH/PSS modified membranes for dye molecules in pH 7 solutions was found to be the greatest and was the result of a combination of electrostatic and hydrophobic interactions of the polyelectrolyte chains at this pH value.

Polymer-supported reagents and catalysts have been extensively studied in the past few decades as they not only facilitate separation and isolation of products after reactions but also enable reuse of reagents/catalysts. In particular, chemistry using polymer-supported organocatalysts has the advantage of avoiding the use of sometimes toxic transition metals. Since organocatalysts are often used at high mol% loading in catalytic reactions, immobilizing organocatalysts on polymers for recycling and reusing makes chemistry using organocatalysts attractive in larger scale syntheses. Chapter II of this dissertation focuses on using variable temperature 31P NMR spectroscopy to study and compare the dynamic behavior of silver complexes prepared from soluble polymer-supported phosphines and electronically similar low molecular weight phosphine ligands. The phosphine-silver complexes supported on terminally functionalized polyisobutylene (PIB) and poly(ethylene glycol) show similar kinetic behavior compared to their low molecular weight counterparts. However, the dynamic behavior of phosphine-silver complexes supported as pendent groups on a linear polystyrene is difficult to study because of significant line-broadening on 31P NMR spectra. Chapter III of this dissertation aims at examining the recyclability and reusability of PIB-supported phosphines as organocatalysts and reagents. PIB-supported alkyldiphenyl- and aryldiphenylphosphines were prepared and used as recyclable organocatalysts in addition and allylic amination reactions. The PIB-bound phosphines were useful reagents in aza-Wittig and Mitsunobu reactions. The PIB-bound phosphine oxides formed either from adventitious oxidation or during the course of reactions can be reduce to PIB-phosphines for reuse. Chapter IV of this dissertation describes preliminary studies on soluble polymer-supported N-heterocyclic carbene (NHC) organocatalysts. PIB- and polyethylene oligomer (PE_Olig)-supported NHC adducts were synthesized and the corresponding polymer-supported NHC catalysts were generated in situ in lactide polymerization and phenyl isocyanate trimerization reactions. The PIB-bound NHC catalyst generated in situ was not recyclable in a lactide polymerization. However, PIB- and PEOlig-bound NHC precatalysts showed modest recyclability in lactide polymerization and phenyl isocyanate trimerizations.

Lignosulphonates are by‐products from the sulphite pulping process for the manufacture ofspecialty dissolving pulps and paper. During the liberation of the cellulose, the lignin isfractionated and solubilised through covalent addition of sulphonic acid groups at variouspositions in the structure. The formed sulphonated lignin, lignosulphonate is then furtherisolated and refined. The amphiphilic nature of lignosulphonates has enabled them to be used as additives to varioussuspensions to improve their dispersion and stability. The by far largest utilisation oflignosulphonates is as dispersants in concrete. Here, lignosulphonates act by dispersing cementparticles to prevent flocculation, un‐even particle distribution and reduced strengthdevelopment. The dispersion is achieved through steric and electrostatic repulsion of the cementparticles by the lignosulphonate polymer. This behaviour is intimately linked with the overallsize and amount of charged groups in the dispersing polymer. Traditional modifications oflignosulphonates have been limited to removal of sugars, filtration and fractionation. Thesemodifications are not sufficient for utilisation of lignosulphonates in high‐strength concrete. Heresynthetic dispersants and superplasticisers are used which are considerably more efficient evenat low dosages. To compete with these, additional modifications of lignosulphonates are likely tobe necessary. The molecular weight and functional group composition have been identified anddescribed as the most interesting parameters that can be modified. Currently, no suitable method exists to increase the molecular weight of lignosulphonates.Oxidation by the natural radical initiating enzyme laccase is an interesting tool to achieve suchmodifications. In this thesis several aspects of the mechanism through which this enzyme reactswith lignin and lignosulphonate structures have been elucidated through model compoundstudies. Further studies showed that laccase alone was a highly efficient tool for increasing themolecular weight of commercial lignosulphonates at low dosages and in short incubation times.Immobilisation of the laccase to a solid support to enable re‐utilisation was also investigated. Modification of functional group composition of lignosulphonates was achieved throughozonolysis and the Fenton’s reagent, a mixture of hydrogen peroxide and iron(II)acetate.Introduction of charged carboxylic groups was achieved through opening of the benzyl rings oflignosulphonates. It was found that a two‐stage process consisting of laccase oxidation followedby ozonolysis was an efficient technique to create a polymer enriched with carboxylic acidgroups with a sufficient molecular size. Oxidation by the Fenton’s reagent was shown to yield similar modifications as the combinedlaccase/ozonolysis treatment albeit with less pronounced results but with a large level of controlthrough variation of a number of reaction parameters. The Fenton’s reagent can therefore be aninteresting alternative to the aforementioned two‐stage treatment. These modifications are interesting for large‐scale applications not only because of theirsimplicity in terms of reaction parameters but also because of the ubiquity of the used enzymeand the chemicals in the pulp and paper industry. / QC 20110427

Rheological and processing behavior of a number of linear low-density polyethylene(LLDPE)/low-density polyethylene (LDPE) blends was studied with emphasis on the effects of long chain branching. First, a linear low-density polyethylene (LL3001.32) was blended with four LDPE's having distinctly different molecular weights. At high LDPE weight fractions, DSC melting thermograms have shown three different polymer phases; two for the pure components and a third melting peak of co-crystals. Different rheological techniques were used to check the thermo rheological behavior of all blends in the melt state and the effect of long chain branching. It was found that all blends are miscible in the melt state at small LDPE concentrations. The elongational behavior of the blends was studied using a uniaxial extensional rheometer, SER. The blends exhibit strain hardening behavior at high rates of deformation even at LDPE concentrations as low as 1%, which suggests the strong effect of branching added by the LDPE component. On the other hand, shear rheology was found to be insensitive to detect addition of small levels of LDPE up to lwt%. The second set of blends prepared and studied consisted of two Ziegler-Natta LLDPE's (LL3001.32 and Dowlex2045G) and two metallocene LLDPE's(AffinityPL1840 and Exact 3128) blended with a single LDPE. In DSC melting thermograms, it was observed that blends with metallocence LLDPE's exhibit a single melting peak at all compositions; whereas the Ziegler-Natta blends exhibit three melting peaks at certain compositions. It was found also that the metallocene LLDPE's are miscible with the LDPE at all concentrations. On the other hand, the Ziegler-Natta LLDPE's were found to be miscible with LDPE only at small LDPE concentrations. The processing behavior of all blends with emphasis on the effects of long chain branches was also studied in capillary extrusion. The critical shear stresses for the onset of sharkskin and gross melt fracture are slightly delayed with the addition of LDPE into LLDPE. Furthermore, the amplitude of the oscillations in the stick-slip flow regime, known as oscillating melt fracture, were found to scale with the weight fraction of LDPE. Amounts as low as 1 wt% LDPE have a significant effect on the amplitude of pressure oscillations. These effects are clearly due to the presence of LCB. It is suggested that the magnitude of oscillations in the oscillating melt fracture flow regime can be used as a method capable to detect low levels of LCB. Finally, the sharkskin and stick-slip polymer extrusion instabilities of a linear low-density polyethylene were studied as a function of the type of die geometry. The critical wall shear stress for the onset of flow instabilities, the pressure and flow rate oscillations, and the effects of geometry and operating conditions on the instabilities are presented for a LLDPE. It was found that sharkskin and stick-slip instabilities were present in the capillary and slit extrusion. However, stick-slip and sharkskin in annular extrusion are absent at high ratios of the inside to outside diameter of the annular die. This observation also explains the absence of these instabilities in polymer processing operations such as film blowing. These phenomena are explained in terms of the surface to volume ratio of the extrudates.

Interpenetrating polymer networks (IPNs) of polystyrene-polybutadiene-polystyrene (SBS) block copolymers and polystyrene (PS) were prepared using sequential network formation with the polybutadiene (PB) of the SBS crosslinked thermally and the styrene network formed thermally or by ??-radiation. The use of ??-radiation to cure the added PS network at room temperature successfully avoided thermal degradation of the butadiene segments within the SBS which had been observed in earlier studies. Both linear SBS and radial SB4 IPNs were studied to compare the influence of linear or branched block copolymers on the IPN morphology. The molecular morphology was examined using a suite of techniques including thermal analysis (DSC and DMA), transmission electron microscopy (TEM), atomic force microscopy (AFM) and smallangle X-ray and neutron scattering (SAXS and SANS). The primary SBS/SB4 network morphology was found to dominate the IPN morphology with the secondary styrene network limited to selectively swelling the PS domains. The linear SBS IPNs displayed a more ordered morphology than the radial SB4 IPNs, and this morphology was investigated in pseudo three-dimensions by sectioning samples in two perpendicular directions. The morphology was found to be consistent with thermally formed systems prepared in previous studies, and contained styrenic domains of 20-50 nm within a continuous butadiene matrix. The weight of evidence suggested that the lamella structure dominated the linear SBS IPNs and a cylindrical structure for the radial SB4 IPNs. Maximum values of tensile strength and elongation at break (20 MPa and 140% respectively) were observed in samples with a styrene cure ??-radiation dose of 200 kGy. The SANS analysis of these polymer systems was expanded to investigate the thermal formation of the added PS network in real time. Time-resolved SANS allowed the development of nanostructures in the bulk samples to be measured, and compared to previous time-independent TEM studies on thin sections. The formation of the styrene network was most noticeably observed in a linear SBS IPN system, in which an increase in long-range order was observed and attributed to movement of styrene monomer into the styrenic domains and sharpening of the phase boundaries between the PS and the PB regions.

Thesis (Ph.D.)--University of Texas at Dallas, 2007. / Includes vita. Includes bibliographical references (leaves 185-196)

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 264-269). Also available via the Internet

Thesis (Ph.D.)--Lehigh University, 2007.