Polymeric drug delivery has received tremendous attention in recent years. Polymeric drug delivery vehicles can be designed to deliver therapeutic agents either in a well-controlled manner or in response to a trigger. Drug delivery aims to ensure that the therapeutic agent reaches its target in the required quantity with minimal side effect. In this thesis, crosslinked polymers have been used to achieve controlled drug release. We have synthesized polymeric hydrogels from amino acid-derived monomers. Due to the hydrophilic nature of hydrogels, it is difficult to efficiently load hydrophobic drugs and hydrophilic drugs generally show a burst release. Various approaches have been developed in this work to tune and modulate the swelling, loading and release properties of hydrogels. The use of hydrogels as molecular separation systems to isolate, purify and concentrate compounds has been a well-known technique. However, the existing procedures mostly separate molecules by size exclusion and generally suffer selectivity with small molecules. We attempt to improve separation of molecules based on their charges. Nanogels have become very versatile vehicles for drug delivery. They are nanometer sized particles and can be administered parenterally to overcome the problems associated with the administration of drugs via the oral route i.e. degradation by digestive enzymes and first pass effect. Nanogel analogs of the hydrogels have been synthesized and evaluated for drug delivery.

By taking advantage of the unequal activity of the two NCO groups of toluene-2,4-diisocyanate at room temperature, a pure zirconium coordination compound with two reactive NCO functionalities is obtained, which can function as a precursor for polymerizations with organic primary amines and primary alcohols. A copolymer with poly(tetrahydrofuran) has been formed in this manner. A copolymer of Zr(sal)$\sb4$ (sal$\sp-$ = salicylaldehydato) and 3,3$\sp\prime$-diaminobenzidine, (Zr(tsdb)) $\sb{\rm n},$ which theoretically has one Zr(sal)$\sb2$ end-group and one diamine end-group in an average polymer chain, can strongly adhere to silica and alumina surfaces. To understand the hydrolytic behavior of the Zr(sal)$\sb2$ end-groups in the (Zr(tsdb)) $\sb{\rm n}$ polymer, the hydrolysis of Zr(sal)$\sb4$ has been studied by electronic, vibrational, and proton magnetic resonance spectroscopies. The results show that Zr(sal)$\sb4$ is almost insensitive to moisture in the solid state, but can be hydrolyzed quickly in solution. The adhesion of the (Zr(tsdb)) $\sb{\rm n}$ oligomer on silica or alumina has been further studied by x-ray photoelectron spectroscopy (XPS), including the use of Zr(sal)$\sb4$ as a model modifier. The XPS data show that both Zr(sal)$\sb4$ and (Zr(tsdb)) $\sb{\rm n}$ can strongly adhere to silica and/or alumina surfaces, and the adhesion of (Zr(tsdb)) $\sb{\rm n}$ is probably via both the Zr(sal)$\sb2$ and the diamine end-groups by forming the Zr-O-Si(Al) linkages and the (-NH$\sb2)($SiOH) H-bonds, and the latter may be broken under ultrasonication. Moreover, because (Zr(tsdb)) $\sb{\rm n}$ can initiate the polymerization of $\beta$-($\pm)$-butyrolactone ($\beta$-BL), a detailed study of the (Zr(tsdb)) $\sb{\rm n}$ initiated polymerization of $\beta$-BL has been conducted to clarify the polymerization mechanism. In addition, the polymerization of $\varepsilon$-caprolactone ($\varepsilon$-CL) has been also studied in the presence of (Zr(tsdb)) $\sb{\rm n}$. Model initiators, Zr(sal)$\sb4$ and o-diaminobenzene were used as well for comparison. The results from spectral and chromatographic investigations enable us to propose a dual-site ring-fission mechanism for the (Zr(tsdb)) $\sb{\rm n}$-initiated $\beta$-BL polymerization and a coordination-insertion mechanism for the Zr(sal)$\sb4$-initiated $\varepsilon$-CL polymerization.

Thermally induced phase separation in PS/PVME blends was studied by solid state NMR. The proton spin-lattice relaxation in both laboratory and the rotating frame were measured for the entire range of blend composition. Under conditions in which the blends are said to be compatible by other techniques, T$\sb{1\rho}\sp{\rm H}$ results obtained at -5$\sp\circ$C showed the fluctuation of local composition at a ten-angstrom scale. T$\sb{1\rho}\sp{\rm H}$ values at room temperature are closer to the longer relaxation time of PS than expected from simple weighted average of the relaxation times of the constituent homopolymers. This indicates incomplete averaging by spin diffusion and a restraining effect of PS on segmental motions of PVME. The blends were heated to cause phase separation and quenched. From the biphasic decay of $\sp{13}$C magnetization, the compositions of the separated phases were estimated to give a lower critical solution temperature phase diagram. NMR relaxation in PVME blends with PS molecular weight of 9K, 100K and 900K were compared. The mobility of the mesogenic group and the spacer in a series of twin liquid crystal polymers has been investigated by studying the cross polarization constant and the line width of $\sp{13}$C spectrum. Both moieties are found immobile in the crystalline state. The mesogenic group retains its rigidity while the spacer becomes mobile in the mesophase. The mobility of both moieties increases dramatically in the isotropic state. The mobility of the Si nuclei in a series of silarylene-siloxane copolymers has been investigated by studying $\sp{29}$Si NMR relaxation time. There is a correlation between the backbone mobility and the glass transition temperature. The lower the Tg, the more mobile is the molecule. The relaxation profiles for two of the samples can be superimposed by normalizing the free volume effect. The relaxation is dominated by the dipole-dipole interaction between Si and H.

The reaction of TiCl$\sb3$(THF)$\sb3$ with one equivalent of isopropyltetramethylcyclopentadienyllithium (7) in THF followed by oxidation with HCl afforded ($\eta\sp5$-(CH$\sb3$)$\sb2$CHC$\sb5$(CH$\sb3$)$\sb4$) TiCl$\sb3$ (8) in 66% yield. Treatment of 8 with C$\sb5$H$\sb5$Tl in refluxing benzene gave ($\eta\sp5$-(CH$\sb{\rm 3}$)$\sb2$CHC$\sb5$(CH$\sb3$)$\sb4$) ($\eta\sp5$-C$\sb5$H$\sb5$)TiCl$\sb2$ (9) in 95% yield. Reaction of TiCl$\sb3$(THF)$\sb3$ with two equivalents of 7 in THF followed by oxidation with HCl afforded ($\eta\sp5$-(CH$\sb3$)$\sb2$CHC$\sb5$(CH$\sb3$)$\sb4$) $\sb2$TiCl$\sb2$ (10) in 73% yield. Compound 10 was characterized by a single-crystal X-ray diffraction study. Ethylene polymerizations by 9/MAO (MAO = methylalumoxane), 10/MAO and Cp$\sb2$TiCl$\sb2$/MAO are compared at 1.3 atm. over the temperature range of 0-50$\sp\circ$C. Ethylene polymerizations by Cp$\sb2$ZrCl$\sb2$/MAO and Cp$\sb2$HfCl$\sb2$/MAO catalysts were compared. The Hf catalysts have about two-thirds the activity of the Zr catalysts. This difference may be attributed to the greater number of active centers present in the Zr catalyst. The Hf catalyst shows a smaller dependence of: (1) polymer molecular 45 reacts with CpTl to produce ($\eta\sp5$-1-vinyl-2,3,4,5-tetramethylcyclopentadienyl)($\eta \sp5$-cyclopentadienyl)titanium dichloride (46) in high yield. Reduction of CpTiCl$\sb3$ in THF by magnesium in the presence of ether excess trimethylphosphine or 2,6-dimethylphenylisonitrile at ca. $-$30$\sp\circ$C produces the titanium (III) complexes CpTiCl$\sb2$(PMe$\sb3$)$\sb2$ (51) and CpTiCl$\sb2$(CNC$\sb6$H$\sb3$(CH$\sb3$)$\sb2$) $\sb2$ (52), respectively, in good yields. The X-ray structure of 51 is reported. Reduction of Cp*TiCl$\sb3$ in THF by magnesium produces Cp*$\sb2$TiCl$\sb2$MgCl$\sb2$TiClCp* (53). A reaction of pentabenzylcyclopentadienyllithium with TiCl$\sb3$(THF)$\sb3$, followed by treatment with HCl gas produces ($\eta\sp5$-C$\sb5$Bz$\sb5$)TiCl$\sb3$ (54). An isomer of pentabenzylcyclopentadiene was characterized by 2d $\sp1$H $\times$ $\sp1$H NMR and $\sp{13}$C NMR methods and spectra were fully assigned.

New soluble linear cobalt(III) and chromium(III) $\beta$-diketone polymers have been prepared and characterized. Attempts to prepare linear coordination polymers analogous to the synthetic organic counterparts have historically posed serious problems for chemists particularly as a result of their intractability. In this study, bis($\beta$-diketonates) of the metal were first prepared and then allowed to react with sulfur halides of the form SCl$\sb2$ or S$\sb2$Cl$\sb2$ to yield thio- or dithio-bridged polymers, with the bridging occurring through the 3-carbons of the 2,4-diones. The polymers were found to be extremely soluble, with moderate molecular weights of at least 15,000 (as determined by NMR end-group analysis and viscosity measurements). GPC results were less satisfactory; they indicated polystyrene was not good as a standard for these polymers. Characterization of the materials was accomplished by Fourier-transform infrared (FT-IR), $\sp1$H- and $\sp{13}$C-nuclear magnetic resonance (NMR), pyrolysis-gas chromatograph/mass spectroscopy (py-GC/MS) and ultraviolet-visible (UV-vis) spectroscopy. Micro-analyses, gel permeation chromatography (GPC), thermal gravimetric analysis (TGA) and viscosity measurements were also performed. The synthesized materials also showed different degrees of thermostability (to at least 250$\sp\circ$C) and volatility as shown by their thermograms. In general, the trifluoroacetyl acetonate polymers were found to yield the more volatile polymers, while the Co(III)-containing materials were generally less volatile than their Cr(III) counterparts. A secondary goal of the investigation was to establish the ability of these materials to undergo chain scission upon exposure to radiation, with the reduction in molecular weight based on GPC measurements. Upon irradiation, GPC results clearly showed degradation to lower molecular weight materials. This reduction in molecular weight is an essential characteristic and requirement for positive acting resists, a possible application for these compounds.

The structure, morphology, phase transition behavior, and factors which govern the formation of helical crystalline syndiotactic polystyrene (sPS) have been investigated. The primary technique employed is vibrational spectroscopy, proven useful to obtain chain conformation distribution and chain and segmental orientation of polymers. Other techniques, such as wide angle X-ray diffraction and thermal analysis are used to characterize the crystalline state. Highly crystalline helical (TTGG) sPS has been prepared by isothermal growth from dilute solution, minimizing the amorphous structure. The crystals are observed to consist of a complexed structure of sPS and solvent molecules. Low frequency Raman spectra for sPS and their solvent complexes are reported. Although intramolecular, the phenyl ring torsion about the backbone is observed to be highly sensitive to the solvent complexed crystalline state and therefore the intermolecular ring environment. This suggests that such a band may be useful for examining the polymer-solvent specific interaction spectroscopically and therefore the mechanism of formation of the helical crystalline phase in sPS. The morphology of as-grown highly crystalline sPS/ethylbenzene mats consists of ribbon-like structures, which are irreversibly disrupted upon the expulsion of solvent from the crystal lattice. Complete molecular reordering during the helix to trans phase transition cannot be accounted for by cooperative bond rotation, consistent with the irreversible nature of the transition, and further emphasizing the critical role of solvent in the formation of helical crystallites. Crystalline syndiotactic polystyrene/solvent complexes prepared from different solvents exhibit a variety of different structures, as indicated by wide angle X-ray diffraction and thermal analysis. Differences in chain packing associated with these structures are reflected in the band shape and intensity of the low frequency phenyl ring torsional vibration. In addition, polarized infrared spectra show that phenyl rings of solvent molecules pack parallel to the syndiotactic polystyrene phenyl rings in these crystalline syndiotactic polystyrene/solvent complexes. A normal vibrational analysis is performed for the helical (TGGT) form of sPS. The calculated frequencies agree well with the observed infrared and Raman spectra, including conformationally sensitive bands.

To further elucidate the effects of atomic and bonding variations within metal coordination polymers on the properties of the bulk polymer, two new metal coordination polymers containing zirconium(IV) have been synthesized and characterized. Through the condensation polymerization of tetrakis(salicylaldhydato)zirconium(IV), Zr(sal)$\sb4$, and 3,3$\sp\prime,4,4\sp\prime$-tetra-aminodiphenylmethane or the chelation polymerization of Zr(sal)$\sb4$ and N,N$\sp\prime,\rm N\sp{\prime\prime},N\sp{\prime\prime\prime}$-tetrasalicylidene-$3,3\sp \prime,4,4\sp\prime$-tetraaminodiphenylmethane, H$\sb4$tstm, the polymer catena-poly (zirconium(IV)($\mu-\rm N,N\sp\prime,N\sp{\prime\prime},N\sp{\prime\prime\prime}$-tetrasalicylidene 3,3$\sp\prime,4,4\sp\prime$-tetraaminobiphenylmethanato-O,N,N$\sp\prime,\rm O\sp{\prime}$:$\rm O\sp{\prime\prime},N\sp{\prime\prime},N\sp{\prime\prime\prime},O\sp{\prime\prime\prime}$)), (Zr(tstm)) $\sb{\rm n}$, was prepared. Similarly, reaction of Zr(sal)$\sb4$ with 3,3$\sp\prime,4,4\sp\prime$-tetraaminodiphenylsulfone yielded catena-poly (zirconium(IV)($\mu$-$\rm N,N\sp\prime,N\sp{\prime\prime},N\sp{\prime\prime\prime}$-tetrasalicylidene-$3,3\sp\prime,4,4\sp\prime$-tetraamino-biphenylsulfonato-$\rm O,N,N\sp\prime,O \sp\prime$:$\rm O\sp{\prime\prime},N\sp{\prime\prime},N\sp{\prime\prime\prime}, O\sp{\prime\prime\prime})\rbrack$, (Zr(tsts)) $\sb{\rm n}$. Due to the instability of N,N$\sp\prime,\rm N\sp{\prime\prime},N\sp{\prime\prime\prime}$-tetrasalicylidene-$3 ,3\sp\prime,4,4\sp\prime$-tetraaminodiphenylsulfone,$\ H\sb4$tsts, in the polymerization solvent dimethylsulfoxide, the reaction of Zr(sal)$\sb4$ and H$\sb4$tsts yielded only oligomeric material. Molecular weight determinations by GPC on fractionated polymer samples in N-methylpyrrolidinone gave polystyrene equivalent molecular weights in excess of 13,000 for (Zr(tstm)) $\sb{\rm n}$ by both synthetic procedures described above and 8,700 for (Zr(tsts)) $\sb{\rm n}$ prepared via condensation polymerization. After capping the metal ends of the polymers with a N,N$\sp\prime$-bis(5-tert-butylsalicylidene)-1,2-diaminobenzenato(2-) group, end group analysis by $\sp1$H-NMR corroborated these data. The polymers were also characterized by IR and UV-vis spectroscopies. Thermal analyses of the polymers showed that they are air stable to greater than 400$\sp\circ$C. These new polymers were compared to another zirconium polymer, catena-poly (zirconium(IV)($\mu$-$\rm N,N\sp\prime ,N\sp{\prime\prime},N\sp{\prime\prime\prime}$-tetrasalicylidene-$3,3\sp\prime$-diaminobenzinato-$\rm O,N,N\sp\prime,O\sp\prime{:}O\sp{\prime\prime},N\sp{\prime \prime},N\sp{\prime\prime\prime},O\sp{\prime\prime\prime})\rbrack$, (Zr(tsdb)) $\sb{\rm n}$, and their cerium(IV) analogs, (Ce(tsdb)) $\sb{\rm n}$, (Ce(tstm)) $\sb{\rm n}$, and (Ce(tsts)) $\sb{\rm n}$. Films of the polymers cast on chrome-plated steel were found to be continuous by scanning electron microscopy. Electrical experiments on films of the six polymers cast on glass gave conductivities of 10$\sp{-7}$ S/cm. These conductivities were increased by a factor of 10$\sp{4}$ by doping with iodine.

Anhydrous proton conducting polymers are highly sought after for applications in high temperature polymer electrolyte membrane fuel cells (PEMFCs). N-heterocycles (eg. imidazole, triazole, and benzimidazole), owing to their amphoteric nature, have been widely studied to develop efficient anhydrous proton transporting polymers. The proton conductivity of N-heterocyclic polymers is influenced by several factors and the design and development of polymers with a delicate balance among various synergistic and competing factors to provide appreciable proton conductivities has been a challenging task. In this thesis, the proton transport (PT) characteristics of polymers functionalized with two diverse classes of functional groups— N-heterocycles and phenols have been investigated and efforts have been made to develop the molecular design criteria for the design and development of efficient proton transporting functional groups and polymers. The proton conduction pathway in 1H-1,2,3-triazole polymers is probed by employing structurally analogous N-heterocyclic (triazole, imidazole, and pyrazole) and benz-N-heterocyclic (benzotriazole, benzimidazole, and benzopyrazole) polymers. Imidazole-like pathway was found to dominate the proton conductivity of triazole and pyrazole-like pathway makes only a negligible contribution, if any. Polymers containing benz-N-heterocycles exhibited higher proton conductivity than those with the corresponding N-heterocycles. Pyrazole-like functional groups, i.e. the molecules with two nitrogen atoms adjacent to each other, were found not to be good candidates for PT applications. A new class of proton transporting functional groups, phenols, has been introduced for anhydrous PT. One of the highlighting features of phenols over N-heterocycles is that the hydrogen bond donor/acceptor reorientation can happen on a single -OH site, allowing for facile reorientational dynamics in Grotthuss PT and enhanced proton conductivities in phenolic polymers. Unlike the case of N-heterocycles, comparable conductivities were achieved between poly (3,4,5-trihydroxy) styrene and the corresponding small molecule, pyrogallol. This observation suggests that reorientation should be considered as a crucial design parameter for PT functional groups. The PT characteristics of phenol-based biaryl polymers are studied and compared with the analogous phenol-based linear styrenic polymers. The two-dimensional disposition of -OH moieties in biaryl polymers, although resulted in lower apparent activation energies (Ea), did not improve the net proton conductivity due to the accompanying increase in glass transition temperature (Tg). Thus, the ease of synthesis and lower Tg values of phenol-based styrene polymers make the styrenic polymer architecture preferable over the biaryl architecture. Finally, the synthesis of a series of poly(3,4-dihydroxy styrene)-b-polystyrene block copolymers has been demonstrated via anionic polymerization. These block copolymers will provide an opportunity to systematically investigate the effect of nanoscale morphology on proton transport.

Supramolecular chemistry is the study of discreet molecules assembled into more complex structures though non-covalent interactions such as host-guest effects, pi-pi stacking, electrostatic effects, hydrogen bonding, and metal-ligand interactions. Using these interactions, complex hierarchical assembles can be created from relatively simple precursors. Of the supramolecular interactions listed above, metal-ligand interactions are of particular interest due to the wide possible properties which they present. Factors such as the denticity, polarizability, steric hindrance, ligand structure, and the metal used (among others) contribute to a dramatic range in the physical properties of the metal-ligand complexes. Particularly affected by these factors are the kinetic and thermodynamic properties of the complexes. As a result metal-ligand interactions can vary from inert to extremely transient. Of the vast number of ligands available for study, this dissertation will center on substituted terpyridine ligands, with a particular focus on terpyridine-functionalized polymers. While polymer-functionalized terpyridine ligands and their complexes with transition metals have been heavily studied, the physical properties, particularly the effects of polymer functionalization on the stability of bis complexes of terpyridines, remain unexplored. In the course of investigating the kinetic stability of these complexes, polymer functionalization techniques were developed which were found to increase the stability of the metal-ligand interactions compared to conventional techniques. In addition to studying the effect of terpyridine substituents, the effects of solvent on the stability of the complexes was studied as well. As polymer-bound terpyridine complexes are often studied in solvents other than water, knowledge of the stability of the complexes in organic solvents is important to create supramolecular structures with more precisely controlled properties. It was found that, for unsubstituted terpyridyl complexes, the stability of the complexes varied by as many as five orders of magnitude in common solvents. It is believed that this decrease in stability is the result of the ability of the solvent to facilitate the movement of the ligands from the first and second coordination spheres. Although a large part of this dissertation is dedicated to the study of the kinetic stability of terpyridine complexes, synthetic techniques involving terpyridine and its complexes were investigated as well. It was found that terpyridine functionalized polystyrene could be produced by direction functionalization of terpyridine with polystyryllithium. Additionally heterloleptic terpyridine-based iron complexes were produced with high purity by reduction of the mono terpyridine complex of iron(III) in the presence of a second, functionalized terpyridine ligand. The culmination of these studies was the synthesis of supramolecular organogels, which were crosslinked using metal-terpyridine complexes, yielding dynamic mechanical properties could be broadly tuned by varying the metal used to form the crosslinks.

All-polymer solar cells (APSC) are a class of organic solar cells in which hole and electron transporting phases are made of conjugated polymers. Unlike polymer/fullerene solar cell, photoactive material of APSC can be designed to have hole and electron transporting polymers with complementary absorption range and proper frontier energy level offset. However, the highest reported PCE of APSC is 5 times less than that of polymer/fullerene solar cell. The low PCE of APSC is mainly due to: i) low charge separation efficiency; and ii) lack of optimal morphology to facilitate charge transfer and transport; and iii) lack of control over the exciton and charge transport in each phase. My research work is focused towards addressing these issues. The charge separation efficiency of APSC can be enhanced by designing novel electron transporting polymers with: i) broad absorption range; ii) high electron mobility; and iii) high dielectric constant. In addition to with the above parameters chemical and electronic structure of the repeating unit of conjugated polymer also plays a role in charge separation efficiency. So far only three classes of electron transporting polymers, CN substituted PPV, 2,1,3-benzothiadiazole derived polymers and rylene diimide derived polymers, are used in APSC. Thus to enhance the charge separation efficiency new classes of electron transporting polymers with the above characteristics need to be synthesized. I have developed a new straightforward synthetic strategy to rapidly generate new classes of electron transporting polymers with different chemical and electronic structure, broad absorption range, and high electron mobility from readily available electron deficient monomers. In APSCs due to low entropy of mixing, polymers tend to micro-phase segregate rather than forming the more useful nano-phase segregation. Optimizing the polymer blend morphology to obtain nano-phase segregation is specific to the system under study, time consuming, and not trivial. Thus to avoid micro-phase segregation, nanoparticles of hole and electron transporters are synthesized and blended. But the PCE of nanoparticle blends are far less than those of polymer blends. This is mainly due to the: i) lack of optimal assembly of nanoparticles to facilitate charge transfer and transport processes; and ii) lack of control over the exciton and charge transport properties within the nanoparticles. Polymer packing within the nanoparticle controls the optoelectronic and charge transport properties of the nanoparticle. In this work I have shown that the solvent used to synthesize nanoparticles plays a crucial role in determining the assembly of polymer chains inside the nanoparticle there by affecting its exciton and charge transport processes. To obtain the optimal morphology for better charge transfer and transport, we have also synthesized nanoparticles of different radius with surfactants of opposite charge. We propose that depending on the radius and/or Coulombic interactions these nanoparticles can be assembled into mineral structure-types that are useful for photovoltaic devices.