Biodegradable polymers, derived from multifunctional hydroxyacids for slow release biomedical applications, were the objectives of this investigation. Poly((beta)-malic acid) was prepared by the ring opening polymerization of benzyl malolactonate, followed by hydrogenolysis of the resulting benzyl ester. Malolactonate ester monomers, including the methyl, ethyl, i-propyl, t-butyl, and benzyl esters, were prepared in 80 percent yields from aqueous solutions of the sodium salts of the various bromosuccinate esters utilizing a two phase system. Proper selection of the reaction temperature and the organic phase afforded high yields in short reaction times without the need for catalysts. Anionic, cationic, and organometallic initiators were used for the polymerizations. Anionic reactions gave the best results, but reactions with impurities and transfer to monomer during polymerization prevented the formation of living polymers, although molecular weights up to 50,000 were obtained. Conversion of poly(benzyl malolactonate) to poly((beta)-malic acid) was accomplished by catalytic hydrogenolysis at room temperature and atmospheric pressure. No backbone degradation occurred under these conditions. The effect of molecular weight, solvent, and catalyst on the rate of hydrogenolysis was studied. The polymers were characterized by spectroscopic techniques and thermal analysis. Biological-related evaluations to date, including toxicity and immunogenicity studies, are summarized.

A new synthetic route to symmetrical 2,6-diarylphenols (1) has been developed. This route has, as its key step, a phase transfer catalyzed double nucleophilic displacement reaction of 1,3-dibromopropane by a 1,3-diarylpropanone leading to a 2,6-diarylcyclohexanone. The latter compound is then converted to 1 by catalytic dehydrogenation. Phenols prepared in this way were 2,6-bis(p-tolyl)phenol (1a), 2,6-bis(p-methoxyphenyl)phenol (1b) and 2,6-bis(p-biphenylyl)phenol (1c). All intermediates and products were characterized by elemental analysis, IR, ('1)H NMR and ('13)C NMR spectroscopy. These phenols were then polymerized oxidatively to give the corresponding polyoxyphenylenes which were characterized by IR, ('1)H NMR and ('13)C NMR spectroscopy. Molecular weights and molecular weight distributions were derived from gel permeation chromatography. Glass transition temperatures, crystallization temperatures and crystalline melting points were determined by differential scanning calorimetry. Thermal stability was monitored by thermal gravimetric analysis. The desired goal of a high molecular weight soluble polymer which crystallizes thermally but which has a lower crystalline melting point than poly(oxy-2,6-diphenyl-1,4-phenylene) (PDPP) (480(DEGREES)C) was achieved with poly{oxy-2,6-bis(p-tolyl)-1,4-phenylene} (PDTP), which melted at 321(DEGREES)C. The homopolymer from 1b (PDAP) could not be prepared with high molecular weight due to extensive crystallization and insolubilization during polymerization. Attempted polymerization of 1c produced only dimer. The three monomers were each copolymerized randomly with 2,6-diphenylphenol. All copolymers were completely amorphous as determined by differential scanning calorimetry. The blending behavior of PDTP and PDAP with PDPP was investigated by differential scanning calorimetry. Both blends produced clear films. In each case, however, the homopolymers crystallized and melted independently.

This work has studied the effect of shear on the melt crystallization behavior of three poly(1-butene) materials at several shear rates and degrees of undercooling. The poly(1-butene) samples investigated varied in number average molecular weight from 35,000 to 105,000. Crystallization was carried out using a parallel plate rotary shearing apparatus mounted on the stage of an optical microscope. Photographic techniques were used to record nuclei formation and size during crystallization over a shear rate range of 0 sec('-1) to 12 sec('-1). The data was analyzed in light of classical nucleation theory and Avrami kinetics. The imposition of shear during crystallization generally accelerated the transformation process through increased nucleation rates. The process was also characterized by a reduction in induction times which generally showed a saturation effect with shear. The negative temperature coefficient of the nucleation rate becomes less negative for shear crystallization over the range studied. Shear stresses of the crystallizing melt were measured on a separate instrument and were found to increase rapidly with the onset of crystallization. The rise in shear stress paralleled the rise in nuclei formation. The corresponding increase in viscosity could be accounted for by using an effective nuclei volume concept during the early stages of crystallization. Morphological studies of sheared samples show deformed spherulites and row-nucleated structures. The observations here lead to the conclusion that the shear stress in the system induce a certain amount of molecular orientation which greatly accelerates the overall crystalline transformation process. The large increase in the nucleation process which is believed to be directly related to the orientation in the system, is the main contributing factor to the rapid crystallization as well as the decrease in induction period.

Mechanistic studies were carried out on the cationic polymerization reactions of a series of para-substituted alpha-methylstyrenes, including p-fluoro-, p-chloro-, p-bromo- and p-isopropyl-alpha-methylstyrene, using Friedel-Crafts initiators. Solvent polarity was found to have a large effect on polymer yield, molecular weight and tacticity for the more electron withdrawing p-chloro monomer but not for the p-fluoro monomer. These results were interpreted in terms of free ion and ion pair reaction mechanisms and carbenium ion stabilization by the p-fluoro group. Polymers with bimodal molecular weight distributions (MWD's) were fractionated by preparative gel permeation chromatography and analyzed for tacticity by nuclear magnetic resonance spectroscopy. The two modes were postulated to have been formed by free ions and by ion pairs. Polymerization reactions producing polymers with very narrow MWD's were found not to be living polymerization systems on the basis of copolymerization and polymer conversion studies. Theoretical calculations by Morawetz predicting narrow MWD's in the presence of chain termination were investigated and found not to apply to these systems. The presence of sterically hindered bases such as 2,6-di-tert-butyl-4-methylpyridine (DBMP) had a profound effect on the polymerization reaction. A reaction mechanism was proposed to account for the observations. As a sidelight, studies of some crystalline properties of these polymers showed that crystallinity could be enhanced by annealing or dilute solution crystallization of polymers already showing signs of crystallinity by differential scanning calorimetry. The addition of 15% meta-substituted monomer units was found to completely disrupt crystallinity in p-methyl-alpha-methylstyrene.

Several series of thermotropic polyesters were prepared by solution polymerization methods using various specially prepared diols and diacid chlorides. The effect that different flexible spacers and mesogenic units based on oxybenzoate terephthalate dyads and triads had on liquid crystallinity was studied by microscopic and thermal analysis techniques. Polymers combining triad aromatic mesogenic groups and polymethylene flexible spacers in the main chain were shown to possess a single mesophase. The transition temperatures of the homologous series were determined by polarized-light microscopy, differential scanning calorimetry (DSC), and thermal-optical analysis (TOA), and were shown to follow an even-odd relationship. Those polymers with less than seven methylene groups in the spacer possessed nematic mesophases while those polymers with seven or more methylene groups showed the optical textures of smectic mesophases. Other polymers were prepared based upon the mesogenic triad and either a poly(ethylene oxide) (PEO), or a poly(propylene oxide) (PPO) flexible spacer. Some polymers with spacers of PEO exhibited two mesophase transitions. Polymers with PPO spacers showed a single mesophase and no melt transition. More than 50 weight-% spacer led to mesophase loss. Polymers with flexible spacers and mesogenic dyads were prepared which showed either a random or alternating placement of the dyads. All of the liquid crystalline polymers containing the mesogenic dyad were nematic, and the arrangement of the dyads in the polymer chain was important, because two polymers with decamethylene spacers and differing dyad sense had different melt behaviors. A final series of polyesters was prepared by melt-transesterification that contained the mesogenic elements described above. In order to incorporate oxybenzoate groups into the polymer chain, it was necessary to use terephthalate copolymers that contained ethylene glycol in addition to a second diol. These materials were found to be more "weakly" liquid crystalline than the other polymers with mesogenic aromatic dyads and triads.

Tetraneopentyltitanium initiates slow homopolymerizations and copolymerizations of styrene and of methyl methacrylate in the dark. Reactivity ratios derived from copolymer compositions indicate a free radical process. The rates of polymerizations are greatly enhanced upon irradiation. Photolysis of tetraneopentyltitanium produces trivalent titanium species as shown by EPR studies. The photolyzed products behave in the dark similarly to unphotolyzed tetraneopentyltitanium. Mechanisms for these polymerizations are discussed. Terpolymers with various degree of crosslinking were prepared. After converting the olefinic units in the crosslinked polymer into (alpha)-glycol units, the polymer support was reacted with TiCl(,4) to provide the catalyst. The activity of the catalyst toward ethylene polymerization was examined vs. crosslink density. Also studied was the swelling effect on the catalyst activity. Results indicate that catalyst activity increases with increasing rigidity of the support. However, diffusion restriction becomes important with highly crosslinked support. The chemical compositions of a MgCl(,2) supported catalyst have been determined at every stage of its preparation. Ball-milling of MgCl(,2) with ethyl benzoate resulted in the incorporation of the ester. Addition of p-cresol resulted in the retention of p-cresol. Treatment with AlEt(,3) gave a rapid reaction between AlEt(,3) and p-cresol. Further reaction with TiCl(,4) resulted in the incorporation of titanium. Activation with AlEt(,3)/methyl p-toluate complex reduces most of the Ti('+4) to lower oxidation states. IR, MS, and GC-MS analyses showed quantitative reaction between p-cresol and AlEt(,3), and reduction and alkylation of the esters. Proton and carbon NMR techniques were also used to study the reaction mechanisms. EPR showed that the catalyst contains a single Ti('+3) species. Activation with preformed AlEt(,c)/methyl p-toluate complex produced another single Ti('+3) species having rhombic symmetry and displaying ('27)Al superhyperfine splitting which are attributes for a stereospecific active site. Finally, FTIR study of the solid supports, the catalyst, and the activated catalyst gave results which complement and agree with the above results.

The effect of solvent polarity on the anionic polymerization rates of (alpha), (alpha)-disubstituted-(beta)-propiolactones was studied. Polymerization of (alpha)-methyl-(alpha)-propyl-(beta)-propiolactone in tetrahydrofuran was a living polymerization. In dimethyl sulfoxide, however, nucleophilic attack on the monomer by the sulfoxide oxygen initiated polymerization, obscuring the study of solvation effects. Similar behavior was observed in N, N-dimethylformamide. When other dipolar aprotic solvents were used, living polymerization systems were obtained. Polymerization rates were greatest in solvents of high dielectric constant, where cation solvation is greatest. Unlike (alpha)-methyl-(alpha)-propyl-(beta)-propiolactone, (alpha)-ethyl-(alpha)-n-butyl-(beta)-propiolactone is unreactive towards dimethyl sulfoxide. When (alpha)-ethyl-(alpha)-n-butyl-(beta)-propiolactone was polymerized in dimethyl sulfoxide, the polymerization rate decreased abruptly at low conversions because of gelation of the growing polymer. The decrease in overall polymerization rate upon gelation was caused by a sudden decrease in the number of polymer chains capable of growth. The polymerization rate of the active chains ends was unaffected by gelation. Bimodal molecular weight distributions arose because two types of chain ends were present after gelation. Anionic polymerization of (alpha)-ethyl-(alpha)-n-butyl-(beta)-propiolactone in N-methylpyrrolidone continued despite precipitation of the growing polymer at low conversions. N-Methylpyrrolidone is a better solvent than dimethyl sulfoxide despite its lower dielectric constant. Solvent-solvent interactions in dimethyl sulfoxide compete with cation-solvent interactions, resulting in decreased cation solvation. The polymerization rate of (alpha)-ethyl-(alpha)-n-butyl-(beta)-propiolactone in N-methylpyrrolidone was substantially less than that of (alpha)-methyl-(alpha)-propyl-(beta)-propiolactone. Either the increase in substituent size or the decrase in polymer solubility may have been responsible.

This dissertation discusses studies relating to the physical properties of thermoplastics. Separate investigations involving the melting temperature of a slow-to-crystallize polymer, thermal behavior of a miscible polymer blend, and thermal conductivity of oriented polyethylenes are presented. Polycarbonate is known to thermally crystallize slowly and to a limited extent, with a range of reported melting points. In this study, the melting temperature of polycarbonate was modified from 195(DEGREES)C to 300(DEGREES)C by employing a sequence of vapor-induced crystallization and annealing treatments. The crystals formed by the treatment with organic vapor act as a precursor state for further crystallization into larger, more perfect lamellae. An equilibrium melting point of 335(DEGREES)C has been obtained for PC from an extrapolation of reciprocal lamellar thickness. FTIR and SEC measurements confirm the Kolbe rearrangement reaction occurs only to a limited extent for the annealing procedure employed. The miscibility of bisphenol A polycarbonate (PC) / poly-(epsilon)-caprolactone (PCL) was investigated using DSC. A single glass transition was found across the compositional diagram, in accordance with an earlier study, yet no depression was observed in the melting points of either PC or PCL. For the PCL-rich blends, Hoffman-Weeks extrapolations are linear, and identical to the PCL homopolymer, thus the Flory ((chi)) interaction parameter must be zero or slightly positive for this blend. The PC Hoffman-Weeks extrapolation could not be made, since the blends are reactive at high crystallization temperatures. This reaction was demonstrated by FTIR, NMR, and turbimetric titration to be thermo-oxidative chain branching rather than transesterification between these two polyesters. Thermal conductivity measurements are not a routine experimental technique in the field of polymer science. In this dissertation, experimental methods for cylindrical and film sample geometries are explored. The flash technique for thermal diffusivity has been critically examined with regard to rear-face rise and front-to-rear temperature difference modes of analysis on a systematic series of drawn low-density polyethylenes. Correction procedures have been put forth for losses due to radiation and surrounding air. The increase in thermal conductivity was shown to be proportional to draw ratio. Work on a steady-state fin and a pulsed method for thin film measurements is also discussed.

The substitution of deuterated polystyrene (PSD) for hydrogenated PS (PSH) in PS/PVME blends raised the LCST of the blend by about 40(DEGREES)C. This deuteration effect has been qualitatively interpreted by the larger percentage of negative excess volume of mixing for PSD/PVME relative to that of PSH/PVME. Both blends have the same glass transition temperature (T(,g)) for the same composition. Dynamic parameters--maximum scattering vector (q(,m)) and time (t) of spinodal decomposition for critical composition 30/70 wt% of PSD/PVME and PSH/PVME blends studied by light scattering are scaled to the reduced variables Q(,m) and (tau), respectively, in terms of the characteristic parameters--diffusion constant (D) and q(,m) (t = 0). Phase separation process is found to be the same for PSD/PVME, PSH/PVME and other systems such as metallic alloys, inorganic glasses and small molecule systems. Their exponent has the same value (1.0) according to the power-law approach. The phase separation kinetics for PSD/PVME is much faster than that for PSH/PVME with the same degree of superheating simply due to its lower viscosity and higher diffusion constant. The "neutron cloud point" was observed by the temperature scanning Small Angle Neutron Scattering (SANS) for PSD/PVME blends, which was in good agreement with "light cloud point". Phase reversibility of the blends are also investigated. By employing the de Gennes' scattering function for blends, the correlation length ((xi)), average statistical segment length ((')b) and interaction parameter((chi)) were obtained as functions of temperature and composition from SANS measurements. The observed (')b value was 7.7(ANGSTROM) consistent with the calculated value of 8.5(ANGSTROM) considering the polydispersity effect. The spinodal temperature was obtained by the correlation length approach. The critical exponents (nu) and (gamma) were close to 0.5 and 1.0, respectively, which implies that the blend can be described by the mean field theory. The composition dependence of (chi) was observed and explained in terms of Sanchez's fluid lattice theory. Also, modified Noryl blends--PpMS/PPO and P(pMS-Co-St)/PPO have been found to be miscible from DSC measurements.

Alkyl esters of styrenesulfonic acid were synthesized, homopolymerized, and copolymerized with a variety of comonomers. The polymers were investigated for hydrolysis behavior under a variety of reaction conditions. Several methods for the synthesis of alkyl styrenesulfonates were investigated. Methyl, ethyl, n-propyl, and isopropyl styrenesulfonates were successfully synthesized in yields of 65, 55, 50, and 40 percent, respectively, starting with sodium styrenesulfonate. Monomer synthesis procedures involving the sulfochlorination of (2-bromoethyl)benzene were found to be inferior because of sulfone formation which led to insoluble, crosslinked resins. Alkyl styrenesulfonates were homopolymerized and copolymerized by free-radical initiation. Bulk, solution, and emulsion polymerization systems were successfully employed. Comonomers investigated included styrene, acrylamide, acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, maleic anhydride, sodium styrenesulfonate, and sodium 2-sulfoethyl methacrylate. Copolymerization reactivity ratios (r(,1), r(,2)) for the copolymerization of methyl styrenesulfonate with styrene, acrylic acid, and maleic anhydride were determined. Hydrolysis studies in aqueous dimethyl sulfoxide solutions were performed. The effect of a variety of variables, including copolymerization, solvent, temperature, alkalinity, acidity, and molecular weight, on the kinetics of hydrolysis was investigated. The various homopolymers and copolymers were found to behave similarly to low molecular weight analogs and exhibited the following reactivity towards hydrolysis: methyl > isopropyl > ethyl > n-propyl. However, in solvent systems containing high concentrations of dimethyl sulfoxide ((GREATERTHEQ) 90 vol %) the reaction is characterized by two different steps, a first rapid step analogous to the reaction of low molecular weight alkyl toluenesulfonates, and a second, slower step. This retardation has been attributed to neighboring group effects in which the sulfonic acid groups formed during the hydrolysis reaction "tie" up surrounding water molecules via hydrogen bonding thus inhibiting reaction with and/or solvation of neighboring unreacted ester groups.