This thesis describes the synthesis and characterization of segmented, triblock and star block copolymers with mesogenic hard segments and long flexible spacers. This thesis explores two important aspects of structure-property relationships of phase separated block copolymers: (1) the effect of soft segment structure on the polymer thermal phase behavior; (2) the effects of hard segment structure and soft segment topology on polymer properties. The first part tests the hypothesis that the soft segment substituents that are adjacent to the hard segment lower the polymer thermal transitions temperatures. Copolymers with pentad hard segments and soft segments with varying degrees of substitution were synthesized to test this hypothesis. Pentad copolymers with completely substituted soft segments showed the lowest melting transition and exhibited no liquid crystallinity. When the substituents are separated from the hard segment, the polymer exhibits higher melting transitions and liquid crystalline behavior. In the second part, efforts were concentrated to synthesize block co-oligomers that behave as high polymers at ambient temperatures but have low melt viscosities. As part of this study, block co-oligomers with dyad esteramide and bisamide hard segments and amine terminated poly(propylene glycol)s of linear and star topologies were synthesized. The block co-oligomers showed that variations in the hard segment structure have a dramatic effect on both the melting temperature and the stability of the liquid crystalline phase. Topology of the soft segment does not effect the thermal transitions, but does affect hard segment organization. In general, star block co-oligomers showed better organization than their linear counterparts.

Part I of this dissertation deals with the surface modification of poly(tetrafluoroethylene-co-hexafluoro-propylene) (FEP). The reduction of FEP using sodium naphthalide was studied with regard to the kinetics of reaction and the product structure. The thickness of the resulting modified surface layer could be controlled, using reaction time and temperature, in the ranges of 45-90 and 250-800 A. The air-sensitive reduction product contained carbon-carbon double and triple bonds, aliphatic C-H bonds, alcohols, carbonyls and very little fluorine. Hydroboration/oxidation introduced hydroxyl groups in high yield to the surface. The alcohols exhibited low reactivity in esterification reactions in the absence acylation catalysts. Treatment of this surface with ethylene oxide in the presence of LDA rendered a more reactive, primary alcohol-containing, surface. Reaction of the hydroxyl surface produced by hydroboration and oxidation with 1,4-toluene diisocyanate or isophorone diisocyanate resulted in surface-bound isocyanate groups. The reactivity of these surfaces towards nucleophiles was investigated. Part II deals with graft polymerization from surface-confined initiator species. Halogenated surfaces were prepared by treating reduced FEP with chlorine or bromine. Treatment of these surfaces with silver trifluoromethane-sulfonate in the presence of tetrahydrofuran (THF) resulted in the polymerization of THF from the surface. Initiation at temperatures less than $-$10$\sp\circ$C, followed by polymerization at $-$10$\sp\circ$C, resulted in a relatively thick, homogeneous overlayer of the graft polymer. Neopentyl and n-propyl alcohol groups were introduced to the surface of poly(chlorotrifluoroethylene) (PCTFE) by reaction with the appropriate protected alcohol-containing lithium reagent. The corresponding tosylate surfaces were prepared and the reaction of these surfaces with 2-methyloxazoline was studied. Acrylamide monomers were polymerized from hydroxyl surfaces derived from FEP using ceric ion redox initiation. The introduction of trimethylsilyl ketene acetal groups to polymer surfaces was also investigated. Part III deals with the surface chemistry of fibrillar carbon. Oxidation and reactions with carbenes were studied as a means of introducing functional groups to the surface. X-ray photoelectron spectroscopy was used to characterize the products; chemical derivatization was used to determine the functional group composition of the oxidized surface.

Thermotropic polyesters are a new class of high strength materials of significant commercial importance because of their ease of melt processing and superior properties. Several series of homopolyesters and copolyesters containing 3,3,3$\sp\prime$,5$\sp\prime$-tetrakis(sec-butyl)-4,4$\sp\prime$-biphenol, 3,3$\sp\prime$-bis(tert-butyl)-4,4$\sp\prime$-biphenol, 3-phenyl-4,4$\sp\prime$-biphenol, 3,3$\sp\prime$-bis(phenyl)-4,4$\sp\prime$-biphenol and 1,1$\sp\prime$-binaphthyl-4,4$\sp\prime$-diol were synthesized by the melt polycondensation method and characterized for their thermotropic behavior by conventional techniques. Many of these aromatic polyesters exhibited an anisotropic melt with either relatively low melting transitions or flow temperatures well below 300$\sp\circ$C, which is much lower than the thermal transitions of currently available thermotropic polyesters. Another aspect of this research program was concerned with the application of WAXD techniques to study the effect of molecular packing in the solid state of these wholly aromatic polyesters for three different series of polymers, which contained either symmetrically or unsymmetrically substituted biphenol residues in their mesogenic groups. The unsymmetrically substituted polymers showed considerably reduced crystalline order or perfection as expected, compared to the symmetrically substituted polymers which had very high degree of crystalline order or perfection. Copolymerization of both types of monomers reduced the degree of crystallization order or perfection and the melting or flow temperatures of the resulting thermotropic polyesters, as expected.

Copolymers of 2-ethylacrylic acid (EAA) and methacrylic acid (MAA) were prepared in bulk and in N,N-dimethylformamide (DMF). Best-fit terminal model reactivity ratios were determined by a non-linear least squares technique to be r$\sb{\rm MAA}$ = 1.14 and r$\sb{\rm EAA}$ = 0.23 in bulk, and r$\sb{\rm MAA}$ = 1.91 and r$\sb{\rm EAA}$ = 0.09 in 50% DMF solution, respectively. Examination of $\sp{13}$C NMR spectra provided convincing evidence for the formation of statistical copolymers. The pH-dependent structural reorganization of dipalmitoylphosphatidylcholine vesicle membranes could be effected in aqueous phosphate buffer solutions of EAA-MAA copolymers. The reorganization process is sensitive to the composition of the copolymer. Decreasing the 2-ethylacrylic acid content in copolymer shifted the 'critical' pH to lower values. Copolymers of 2-ethylacrylic acid content equal to or less than 40 mole % showed complicated aggregation in the interaction with dipalmitoyl phophatidylcholine vesicle membranes. Results from potentiometric titrations suggested that the shifts in the critical pH in the structural reorganization of DPPC vesicle membranes should be attributed to the different hydrophobic interactions of polymers. Photosensitive 3,3$\sp\prime$-dicarboxydiphenyliodonium bisulfate and hexafluorophosphate, which produced the strong acids (H$\sb2$SO$\sb4$, HPF$\sb6$) upon irradiation at 254 nm were prepared. Using these iodonium salts as proton sources, the structural reorganizations of phosphatidylcholine vesicle membranes by poly(2-ethylacrylic aicd) were demonstrated by optical density measurement and by monitoring the efflux of the calcein in entrapped vesicles. Copolymers of EAA and MAA were employed in specific enhancement of cytotoxicity of immunotoxins. It was found that the copolymer of 49 mole % 2-ethylacrylic acid content is not toxic to HeLa cells and potentiates the action of 5E7-gelonin immunotoxin. To improve the potentiating effect the copolymer was modified to have 0.9 and 1.6 mole % disulfide linkage in the side chain for attachment to the 5E7-gelonin molecule.

The advent of MgCl$\sb2$ supported Ti catalysts and more recently the chiral ansa-bridged metallocene homogeneous systems has sparked interest concerning the stereochemical nature of these two classes of Ziegler-Natta catalysts. A classical method of separating chiral sites in heterogeneous systems is by the introduction of an optically active third component and studying the physical properties of the fractionated polymer obtained from the polymerization of racemic monomer. In the homogeneous case an optically pure catalyst may be obtained and as described above, information may be gleaned from racemic monomer polymerization. The system MgCl$\sb2\cdot$3ROH/phthalic anhydride/TiCl$\sb 4$/dialkylphthalate//triethylaluminum/phenyltriethoxysilane was studied. The effect of changing the alkyl group of the ester was that the bulkier alkyl resulted in poorer stereospecific yields of the system. Magic angle spinning cross-polarization $\sp{13}$C NMR revealed that the ester was rigidly bound to the support and that the above system had clearly more than one type of complexation of the ester unlike an earlier supported system indicating more diverse defect structures on the surface. The system was modified with (R,S)- and (S)-2-methyl-1-butanol accompanied by the respective phthalate esters. Activities of 3- and 4-branched $\alpha$-olefins were more depressed than that of earlier supported systems. Active site counting in the polymerization of 4-methyl-1-pentene with a supported system revealed that fewer active sites are available for this monomer than for propylene. Polymerizations of racemic monomer were stereoelective but for the 3-branched monomer the polymer produced was more stereoirregular than those from earlier supported systems. Polymerization of racemic 4-methyl-1-hexene with the homogeneous (S)-ethylenebis($\eta\sp 5$-tetrahydroindenyl)zirconiumbis(O-acetyl-(R)-mandalate)/methylaluminumoxane system produced more optically pure and stereoregular polymer than the heterogeneous systems. The existence of fractions in the polymer of opposite optical rotation suggests that at least two stereochemical environments exist during the course of the polymerization, disputing earlier beliefs that this system is stereochemically rigid. Also, it was found that the type of solvent used in the polymerization could affect the stereochemical distribution of the system.

This thesis has two main objectives (1) synthesizing block copolymers containing specifically functionalized segments in well-defined locations and densities and (2) studying the interfacial activity of these copolymers as a function of composition. Interfacial activity is assessed through adsorption at the solution/solid interface and the polymer/air interfaces. The approach for preparing these functionalized diblock copolymers involved anionically copolymerizing an unfunctionalized monomer with a functionalized monomer. The functionalized copolymer, poly (styrene-co-(p-hydroxystyrene)), because of the acidity of the phenolic group protective group chemistry was required. Therefore the protected monomer, 4-(tert-butyldimethylsilyl)oxystyrene, was synthesized. Poly (styrene-co-(p-hydroxystyrene)) of known composition and structure was synthesized through the copolymerization of styrene and 4-TBDMSoxystyrene. Subsequent desilylation of the tert-butyldimethylsilyl ether generated the phenol functionality. This deprotection was quantitative, generating poly (styrene-co-(p-hydroxystyrene)). The protected and the deprotected copolymers were used to characterize the copolymer's composition. The adsorption behavior of poly (styrene-co-(p-hydroxystyrene)) was studied at the solution/solid interface. The amount of polymer adsorbed was studied as a function of copolymer composition. Using UV depletion, adsorption was studied from THF to alumina generating for each polymer studied adsorption isotherms. At each molecular weight, polystyrene served as a control and the amount of copolymer adsorbed was found to be a function of composition. The adsorption results agreed qualitatively with theoretically predicted behavior. The reactivity of the phenol functionality was used as a reactive handle to incorporate surface-active groups (perfluoroalkyl groups) at defined locations and densities along the copolymer chain, generating a surface-active polymer (SAP) of known composition. The adsorption behavior of these SAPs was studied from a 10K polystyrene matrix. Adsorption was studied as a function of SAP concentration and composition. Heat treated 10K polystyrene films served as a control. At all SAP compositions studied there was an enrichment of the surface region with SAP. The perfluoroalkyl groups preferentially adsorbed at the polymer/air interface as indicated by XPS and contact angle data. The amount of SAP adsorbed was found to be a function of composition. This adsorption data provides experimental evidence that copolymer composition influences adsorption behavior and ultimately surface composition.

The orientation of nematic liquid crystals in electrical fields is commonplace in flat-panel watch and calculator displays. In 99% of these devices, the optical path and the electrical field are parallel to each other. When an alternating electrical field is applied perpendicular to the optical path unusual optical patterns result. The physics and properties of the wave-like optical pattern were previously unreported. The geometry and wave-like optical pattern are described in chapter two for a room-temperature nematic liquid crystal: 4-4$\sp\prime$-n-pentylcyanobiphenyl. Physical conditions of wave stability, i.e. temperature, field and frequency were investigated and discussed in terms of nematic liquid crystalline theory. It was determined that the wave pattern was stabilized at low temperatures and high frequencies. It was also concluded that the mechanism of deformation was dielectric rather than ionic. The macroscopic observations were quantified into two molecular orientation profiles in the succeeding chapter. The orientation profiles given are based on two possible cases of surface orientation for the nematic layer. The analysis of molecular orientation relies heavily on the theory of electrical deformation developed by Deuling. To understand the importance of the material parameters of the nematic in relationship to the optical effect, binary blends of 4-4$\sp\prime$-n-pentylcyanobiphenyl and 4-(4-alkylcyclo-hexyl) -cyanophenyl homologs were prepared. The complete phase behavior of these mixtures is the subject of chapter 4. A thorough physical characterization, regarding the dielectric and elastic properties, response times and threshold voltages, of four selected nematic fluids is given in chapter five. Finally, in chapter six, the effect of the blending on the electrical deformation of the nematic mesophase in a transverse-electrode cell is studied.

A study of the adsorption of block copolymers with respect to such variables as adsorption rate, concentration, molecular weight, relative block sizes, architecture, adsorption solvent, and temperature was conducted for the adsorption block copolymers to silanol surfaces. Poly(styrene-b-isoprene) and poly(styrene-b-1,2-butadiene) with precise molecular weight and narrow polydispersity were synthesized by anionic polymerization techniques. These block copolymers were then specifically modified to incorporate an organic moiety (sticky foot) which would promote adsorption. Hydrosilylation to incorporate trimethoxysilanes into the diene block was unsuccessful due to low reaction yields and crosslinking. Hydroboration/oxidation to incorporate alcohols into the diene block was used to prepare polymers for adsorption studies due to the high reaction yields with no crosslinking. Adsorption studies examining the effects of molecular weight, number of adsorbing segments, time, concentration, polymer architecture, and adsorption solvent were conducted for the adsorption to aerosil 130. Adsorptions were analyzed by UV spectroscopy and thermal gravimetric analysis. Adsorption studies examining the effects of molecular weight, relative block sizes, and temperature were conducted for the adsorption to glass slides. Adsorptions were analyzed by water contact angle and X-ray photoelectron spectroscopy. The competitive polymer adsorptions between two different polymers adsorbing to aerosil 130 were studied. Simultaneous adsorptions for two polymers with respect to concentration were examined for three separate sets of polymers. The polymers were adsorbed to aerosil 130 and analyzed by gel permeation chromatography. Sequential competitive adsorptions for these same polymer sets were also conducted using the same substrate and analysis technique. The effect of surface affinity on polymer adsorption was examined by adsorbing one polymer sample to a series of different surfaces. Poly(chlorotrifluoroethylene) polymers with carboxylic acid, alcohol, amine, and ethyl ester surfaces as well as glass slide and aminated glass slide surfaces were prepared and used for adsorptions. These adsorptions were analyzed by X-ray photoelectron spectroscopy.