<p>Chemotherapy combinations for cancer treatments harbor immense therapeutic potentials which have largely been untapped. Of all diseases, clinical studies of drug combinations are the most prevalent in oncology, yet their effectiveness is disputable, as complete tumor regressions are rare. Our research has been devoted towards developing delivery vehicles for combinations of chemotherapy drugs which elicit significant tumor reduction yet limit toxicity in healthy tissue. Current administration methods assume that chemotherapy combinations at maximum tolerable doses will provide the greatest therapeutic effect ? a presumption which often leads to unprecedented side effects. Contrary to traditional administration, we have found that drug ratios rather than total cumulative doses govern combination therapeutic efficacy. In this thesis, we have developed nanoparticles to incorporate synergistic ratios of chemotherapy combinations which significantly inhibit cancer cell growth at lower doses than would be required for their single drug counterparts. The advantages of multi-drug incorporation in nano-vehicles are many: improved accumulation in tumor tissue via the enhanced permeation and retention effect, limited uptake in healthy tissue, and controlled exposure of tumor tissue to optimal synergistic drug ratios. To exploit these advantages for polychemotherapy delivery, two prominent nanoparticles were investigated: liposomes and polymer-drug conjugates. Liposomes represent the oldest class of nanoparticles, with high drug loading capacities and excellent biocompatibility. Polymer-drug conjugates offer controlled drug incorporations through reaction stoichiometry, and potentially allow for delivery of precise ratios. Here, we show that both vehicles, when armed with synergistic ratios of chemotherapy drugs, significantly inhibit tumor growth in an aggressive mouse breast carcinoma model. Furthermore, versatile drug incorporation methods investigated here can be broadly applied to various agents. Findings from our research can potentially widen the therapeutic window of chemotherapy combinations by emphasizing investigations of optimal drug ratios rather than maximum drug doses and by identifying appropriate nanoparticles for their delivery. Application of these concepts can ultimately help capture the full therapeutic potential of combination regimens.

Interactions between surfactants and polymeric nanostructures have gained increasing attention due to their potential application in many disciplines. In this study, a well-defined random copolymer containing 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA2080) (poly(MEO2MA-co-PEGMA2080)) was synthesized using the atom transfer radical polymerization (ATRP) process, and its thermo-responsive behaviors in aqueous solution were investigated. In comparison to other thermo-sensitive random copolymers based on oligo(ethylene glycol) methacrylates (OEGMA), this copolymer exhibited an unusual thermal induced two-stage aggregation process. The copolymer chains associated at the first thermal transition followed by a rearrangement process at the second thermal transition to produce a stable core-shell micellar structure. Furthermore, the binding interactions between cationic surfactants and this copolymer were examined below and above its cloud point. In general, the binding interactions between cationic surfactants and neutral polymers are weak and cationic surfactants are very selective and only bind to those polymers with specific hydrophobic groups. Significant hydrophobic interactions were observed between surfactant monomers and the polymer backbone. The binding occurred uncooperatively at low surfactant concentration, which was confirmed by electromotive force (EMF) measurements. Moreover, the binding affinity of three cationic surfactants follows the sequence: CTAB > TTAB > DoTAB. Cellulose Nanocrystals (CNC) with diameter of 10-20 nm and length of 200-400 nm, derived from native cellulose, is a promising new class of nanomaterials due to its high specific strength, high surface area, and unique optical properties. Currently, most of researches focused on the improvement of its steric stability, dispersability and compatibility in different solvents or matrices. A thermo-responsive polymer, namely Jeffamine M600 (a 600 Da polypropylene glycol) was grafted on the surface of cellulose nanocrystals (CNC) via a peptide coupling reaction. The better dispersion of the modified CNC in water was demonstrated, and the interactions between surfactants and M600-grafted CNC were investigated via isothermal titration calorimetry (ITC). Three types of surfactants with dodecyl alkyl chain and different head groups, namely cationic dodecyltrimethylammonium bromine (DoTAB), anionic sodium dodecyl sulfate (SDS), and nonionic poly(ethylene glycol) dodecyl ether (Brij 30) were studied. Physical mechanisms describing the interactions of cationic, anionic and nonionic surfactants and M600-grafted CNC were proposed. Chitosan molecules are water-soluble in acidic media due to the protonation of amino groups. However, some applications of chitosan are restricted by its poor solubility in basic media. A biocompatible derivative of chitosan, N-carboxyethylchitosan (CECh) was synthesized by Michael addition reactions, which possessed high solubility in both acidic and basic media due to the modification by carboxyl groups. The aggregation behavior of CECh in aqueous solution under the effects of pH, polymer concentration, as well as a gemini surfactant, was investigated by turbidity, zeta potential, fluorescence spectroscopy, viscosity, and surface tension measurements. This research demonstrates that nanostructures comprising of thermo-responsive copolymers can be controlled and manipulated by temperature and surfactants, and they play an important role in the physical properties of surfactants-polymeric complexes. The results from this research provide the fundamental knowledge on the self-assembly behavior and the binding mechanism of various novel polymeric systems and surfactants, which can be utilized to design and develop systems for personal care formulations and drug delivery systems.

Interactions between surfactants and polymeric nanostructures have gained increasing attention due to their potential application in many disciplines. In this study, a well-defined random copolymer containing 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA2080) (poly(MEO2MA-co-PEGMA2080)) was synthesized using the atom transfer radical polymerization (ATRP) process, and its thermo-responsive behaviors in aqueous solution were investigated. In comparison to other thermo-sensitive random copolymers based on oligo(ethylene glycol) methacrylates (OEGMA), this copolymer exhibited an unusual thermal induced two-stage aggregation process. The copolymer chains associated at the first thermal transition followed by a rearrangement process at the second thermal transition to produce a stable core-shell micellar structure. Furthermore, the binding interactions between cationic surfactants and this copolymer were examined below and above its cloud point. In general, the binding interactions between cationic surfactants and neutral polymers are weak and cationic surfactants are very selective and only bind to those polymers with specific hydrophobic groups. Significant hydrophobic interactions were observed between surfactant monomers and the polymer backbone. The binding occurred uncooperatively at low surfactant concentration, which was confirmed by electromotive force (EMF) measurements. Moreover, the binding affinity of three cationic surfactants follows the sequence: CTAB > TTAB > DoTAB. Cellulose Nanocrystals (CNC) with diameter of 10-20 nm and length of 200-400 nm, derived from native cellulose, is a promising new class of nanomaterials due to its high specific strength, high surface area, and unique optical properties. Currently, most of researches focused on the improvement of its steric stability, dispersability and compatibility in different solvents or matrices. A thermo-responsive polymer, namely Jeffamine M600 (a 600 Da polypropylene glycol) was grafted on the surface of cellulose nanocrystals (CNC) via a peptide coupling reaction. The better dispersion of the modified CNC in water was demonstrated, and the interactions between surfactants and M600-grafted CNC were investigated via isothermal titration calorimetry (ITC). Three types of surfactants with dodecyl alkyl chain and different head groups, namely cationic dodecyltrimethylammonium bromine (DoTAB), anionic sodium dodecyl sulfate (SDS), and nonionic poly(ethylene glycol) dodecyl ether (Brij 30) were studied. Physical mechanisms describing the interactions of cationic, anionic and nonionic surfactants and M600-grafted CNC were proposed. Chitosan molecules are water-soluble in acidic media due to the protonation of amino groups. However, some applications of chitosan are restricted by its poor solubility in basic media. A biocompatible derivative of chitosan, N-carboxyethylchitosan (CECh) was synthesized by Michael addition reactions, which possessed high solubility in both acidic and basic media due to the modification by carboxyl groups. The aggregation behavior of CECh in aqueous solution under the effects of pH, polymer concentration, as well as a gemini surfactant, was investigated by turbidity, zeta potential, fluorescence spectroscopy, viscosity, and surface tension measurements. This research demonstrates that nanostructures comprising of thermo-responsive copolymers can be controlled and manipulated by temperature and surfactants, and they play an important role in the physical properties of surfactants-polymeric complexes. The results from this research provide the fundamental knowledge on the self-assembly behavior and the binding mechanism of various novel polymeric systems and surfactants, which can be utilized to design and develop systems for personal care formulations and drug delivery systems.

Doping in bulk semiconductors (e.g., n- or p-type doping in silicon) allows for precise control of their properties and forms the basis for the development of electronic and photovoltaic devices. Recently, there have been reports on the successful synthesis of doped semiconductor nanocrystals (or quantum dots) for potential applications in solar cells and spintronics. For example, nanocrystals of ZnSe (with zinc-blende lattice structure) and CdSe and ZnO (with wurtzite lattice structure) have been doped successfully with transition-metal (TM) elements (Mn, Co, or Ni). Despite the recent progress, however, the underlying mechanisms of doping in colloidal nanocrystals are not well understood. This thesis reports a comprehensive theoretical analysis toward a fundamental kinetic and thermodynamic understanding of doping in ZnO, CdSe, and ZnSe quantum dots based on first-principles density-functional theory (DFT) calculations. The theoretical predictions of this thesis are consistent with experimental measurements and provide fundamental interpretations for the experimental observations. The mechanisms of doping of colloidal ZnO nanocrystals with the TM elements Mn, Co, and Ni is investigated. The dopant atoms are found to have high binding energies for adsorption onto the Zn-vacancy site of the (0001) basal surface and the O-vacancy site of the (0001) basal surface of ZnO nanocrystals; therefore, these surface vacancies provide viable sites for substitutional doping, which is consistent with experimental measurements. However, the doping efficiencies are affected by the strong tendencies of the TM dopants to segregate at the nanocrystal surface facets, as indicated by the corresponding computed dopant surface segregation energy profiles. Furthermore, using the Mn doping of CdSe as a case study, the effect of nanocrystal size on doping efficiency is explored. It is shown that Mn adsorption onto small clusters of CdSe is characterized by high binding energies, which, in conjunction with the Mn surface segregation characteristics on CdSe nanocrystals, explains experimental reports of high doping efficiency for small-size CdSe clusters. In addition, this thesis presents a systematic analysis of TM doping in ZnSe nanocrystals. The analysis focuses on the adsorption and surface segregation of Mn dopants on ZnSe nanocrystal surface facets, as well as dopant-induced nanocrystal morphological transitions, and leads to a fundamental understanding of the underlying mechanisms of dopant incorporation into growing nanocrystals. Both surface kinetics (dopant adsorption onto the nanocrystal surface facets) and thermodynamics (dopant surface segregation) are found to have a significant effect on the doping efficiencies in ZnSe nanocrystals. The analysis also elucidates the important role in determining the doping efficiency of ZnSe nanocrystals played by the chemical potentials of the growth precursor species, which determine the surface structure and morphology of the nanocrystals.

<p> An increasing demand exists for the treatment of hypersaline industrial wastewaters such as those from the shale gas industry, seawater desalination plants, and thermoelectric power-generating facilities. Membrane distillation (MD) is an emerging thermal-based desalination process, which can potentially treat hypersaline industrial wastewaters by exploiting low-grade or waste heat. High performance MD membranes are the key to the advancement and further commercialization of this emerging desalination technology. This research aims at (i) developing novel MD membranes with special surface wettability using advanced materials and surface engineering techniques and (ii) gaining fundamental understanding of the scaling and fouling mechanisms of the newly developed MD membranes.</p><p> Engineering the wettability of materials and interfaces can effectively be leveraged to membrane fabrication. Omniphobic membranes that resist wetting from both water and oil can extend MD applications for desalination of emerging high-salinity wastewaters containing diverse low surface tension contaminants. Fundamental understanding of interfacial phenomena and relating such knowledge to membrane surface wettability are crucial to improving omniphobic MD membrane design and performance. This work elucidates the factors that determine surface omniphobicity of microporous membranes and evaluates the potential application of these membranes in desalination of low surface tension wastewaters by membrane distillation. Specifically, the effects of surface morphology and surface energy on membrane surface omniphobicity were systematically investigated by modifying a prototype glass fiber substrate with silica nanoparticles and fluoroalkylsilane. A re-entrant structure, defined as a nanoscale architecture with increased air to solid ratio, developed by the spherical silica nanoparticles was found to play a critical role in rendering the membrane surface omniphobic, </p><p> Electrospinning is a promising and versatile technique to fabricate omniphobic membranes, because electrospun nanofibers with cylindrical shape feature a re-entrant structure and could be further engineered for additional levels of re-entrant structures. This work presents a facile approach to fabricate a robust omniphobic membrane by exploiting the versatility of electrospinning, which allows the preparation of a nanofiber scaffold with targeted physical and chemical properties. The fabricated electrospun omniphobic MD membranes were evaluated in terms of wetting resistance to various low surface tension liquids and desalination performance with feed solutions of varying surface tensions. </p><p> Microporous polyvinylidene fluoride (PVDF) membranes have been widely used for MD applications because of their hydrophobic nature, excellent chemical compatibility, and facile processability. However, application of conventional hydrophobic PVDF membranes in MD is limited due to their susceptibility to wetting and fouling by low surface tension contaminants. This study presents scalable surface engineering of a conventional hydrophobic PVDF microporous substrate to produce an omniphobic membrane. Desalination performance of the fabricated omniphobic membrane was evaluated in direct contact membrane distillation with synthetic wastewaters containing low surface tension contaminants, including surfactants and mineral oil. The performance of the fabricated omniphobic membrane with produced water from the shale gas industry was further examined to highlight its potential application in desalinating complex, high salinity industrial wastewaters.</p><p> The performance of MD systems is hampered by fouling and inorganic scaling, particularly when a system treats hypersaline industrial wastewaters with high levels of total dissolved solids and organic matter. This dissertation research investigated fouling and scaling mechanisms of omniphobic membranes, focusing on the impact of surface chemistry. The omniphobic membranes were fouled by hydrophobic, low surface tension contaminants via attractive interactions, but further adsorption into the pores was prevented by a thermodynamic barrier created by a re-entrant structure, which sustains a metastable non-wetting condition. Also, the non-adhesive and slippery surface nature of the omniphobic membrane was shown to delay both homogeneous and heterogeneous nucleation, demonstrating its potential for a high recovery MD system to treat hypersaline industrial wastewaters.</p><p> This work presents pioneering advances in the development of novel MD membranes with special wettability for extended MD applications. The fundamental understanding of the interfacial phenomena, advanced materials, and surface engineering techniques as well as fouling and scaling mechanisms will shed light on the design parameters for high membrane performance and efficient process operation. These important insights can inform the realization of emerging membrane-based technologies for sustainable treatment of challenging industrial wastewaters. The implications of the results in this dissertation are potentially far-reaching; we anticipate that they will shape the discussion of next generation desalination technologies.</p><p>

<p> Self-assembly of soft materials represents a compelling approach to realize a wide variety of useful nanostructured materials. In particular, self-assembly of block copolymers by microphase separation results thermodynamically in the formation of a range of nanostructures including lamellae, cylinders, gyroids and spheres. There is significant potential to use these structures in applications ranging from energy generation to water purification. Despite their significant potential however, the use of block copolymers in the aforementioned areas has been critically limited by general inability to precisely direct their self-assembly, i.e. to control the orientational and positional order of their self-assembled structures over device or application relevant length scales and geometries.</p><p> In this context, we explore two distinct approaches to attain advanced ability to control the block copolymer microphase. First, this dissertation explores the self-assembly and directed self-assembly of novel liquid crystalline block copolymers. Result are presented from a systematic series of experimental investigations of the phase behavior and directed self-assembly of rationally designed liquid crystalline block copolymers (LC BCPs) under magnetic fields and in the presence of engineered surfaces. We specifically designed a block copolymer platform comprising etchable poly(D,L-lactide) (PLA) with brush architecture and side chain cyanobiphenyl LC block that imparts magnetic anisotropy on the system. Interestingly, this class of brush-like block copolymers behave in accordance with the canonical phase behavior of the conventional linear coil-coil block copolymers. With inclusion of labile mesogen, the magnetic field response of the system was significantly enhanced due to the increased grain size and faster mobility. By adopting cross-linkable mesogen, the LC phase can be readily polymerized and subsequent etching of the PLA produces well-defined nanopores with controlled orientation. At higher blending stoichiometric ratio, the system transforms its morphology from hexagonal cylinders to face-centered cubic (FCC) spheres and, strikingly, we observe the alignment of FCC spheres regardless of the 3 dimensional symmetry of the cubic structure.</p><p> In the second part, we adopt the use of electrospray deposition and soft-shear laser zone annealing process as tools to direct the self-assembly of structurally complex thin films of block copolymers. Conventionally, block copolymers confined in thin film were examined based on the equilibrium structure as a result of a single annealing process. Here we propose non-equilibrium processing methods that enable us to achieve non-conventional morphologies. Sequential electrospray deposition (ESD) was adopted to form multi-layered BCP thin films which exhibit heterolattice structure that can be precisely tuned by kinetic parameters. We also examine pathway-engineered two-step processing, shear aligning followed by thermal annealing on a neutral substrate, to achieve biaxial alignment of the BCP cylinders array with minimum defect density. </p><p> Overall, this dissertation provides new insight regarding the self-assembly of LC brush block copolymers and their orientation in the presence of magnetic fields. Further, it establishes a new mechanism for controlling the orientation of these materials in thin films. The results of the research presented here are relevant for the use of block copolymers in lithography and membrane fabrication, among other areas.</p><p>

Increasing energy demand makes the development of higher energy storage batteries, imperative. However, one of the major advantages of fossil fuels as an energy source is they can provide variably large quantities of power when desired. This is where electrochemical capacitors can continue to carve out a niche market supplying moderate energy storage, but with high specific power output. However, current issues with carbon precursors necessitate further development. Further, production requires high temperature, energy intensive carbonization to create the active pore sites and develop the pores. Double-layer capacitive materials researched to replace active carbons generally require properties that include: very high surface area, high pore accessibility and wettability, strong electrical conductivity, structural stability, and optionally reversible functional groups that lend to energy storage through pseudocapacitive mechanisms. In recent years, nanostructured carbon materials which could in future be tailored through bottom up processing have the potential to exhibit favourable properties have also contributed to the growth in this field. This thesis presents research on graphene, an emerging 2-dimensional carbon material. So far, production of graphene in bulk exhibits issues including restacking, structural damage and poor exfoliation. However, the high chemical stability, moderate conductivity and high electroactive behaviour even with moderate exposed surface area makes them an excellent standalone material or a potential support material. Two projects presented focus on enhancing the capacitance through functionality and controlling graphene formation to enhance performance. The first study addresses graphene enhancement possible with heteroatom functionality, produced by a single step low temperature hydrothermal reduction process. The dopant methodology was successful in adding nitrogen functionality to the reduced graphene oxide basal and the effect of nitrogen type was considered. The second study addresses the need for greater control of the rGO structure on the macro-scale. By harnessing the change in interactions between the GO intermediate and final rGO sheets we were able to successfully control the assembly of graphene, creating micro and macro-pore order and high capacitive performance. Further, self assembly directly onto the current collector eliminates process steps involved in the production of EDLC electrodes.

<p>Hybrid organic/inorganic photovoltaics can overcome many traditional shortcomings of organic photovoltaics, including recombination due to short exciton diffusion length scales, incomplete or tortuous charge transport pathways, and low charge mobility. In this work, aligned pore arrays are electrochemically etched into GaN films, and the semiconducting polymer polyhexylthiophene (P3HT) is intruded into these porous films. This hybrid device uses the polymer as the photoactive phase, electron donor, and hole transport medium, and the GaN as the electron acceptor and electron transport medium. Not only does the nanoporous geometry result in ultrafast charge transfer between the P3HT and the GaN, but a nanoconfined geometry can also drastically enhance charge mobility in the polymer by orienting the polymer alignment such that the fast charge transport direction is oriented vertically.</p><p> Optimal etching parameters are found in various etchants to produce an aligned morphology, and a method to remove the low-porosity overlayer via UV-assisted etching is described. Additionally, the first reported pore formation in GaN using a neutral etching solution is demonstrated, opening up the possibility of safe and environmentally-friendly etching of GaN, in contrast to traditional methods that use extremely toxic hydrofluoric acid.</p><p> Multiple methods to introduce polymer into the pores are described, and it is shown that hot pressing can achieve favorable polymer alignment. Ultrafast charge transport is demonstrated between the confined polymer and the GaN template by time-resolved terahertz spectroscopy. This geometry of an aligned nanoporous template surrounding an organic semiconductor is proposed as a general and beneficial strategy to improve performance of organic solar cells. </p>

Increasing energy demand makes the development of higher energy storage batteries, imperative. However, one of the major advantages of fossil fuels as an energy source is they can provide variably large quantities of power when desired. This is where electrochemical capacitors can continue to carve out a niche market supplying moderate energy storage, but with high specific power output. However, current issues with carbon precursors necessitate further development. Further, production requires high temperature, energy intensive carbonization to create the active pore sites and develop the pores. Double-layer capacitive materials researched to replace active carbons generally require properties that include: very high surface area, high pore accessibility and wettability, strong electrical conductivity, structural stability, and optionally reversible functional groups that lend to energy storage through pseudocapacitive mechanisms. In recent years, nanostructured carbon materials which could in future be tailored through bottom up processing have the potential to exhibit favourable properties have also contributed to the growth in this field. This thesis presents research on graphene, an emerging 2-dimensional carbon material. So far, production of graphene in bulk exhibits issues including restacking, structural damage and poor exfoliation. However, the high chemical stability, moderate conductivity and high electroactive behaviour even with moderate exposed surface area makes them an excellent standalone material or a potential support material. Two projects presented focus on enhancing the capacitance through functionality and controlling graphene formation to enhance performance. The first study addresses graphene enhancement possible with heteroatom functionality, produced by a single step low temperature hydrothermal reduction process. The dopant methodology was successful in adding nitrogen functionality to the reduced graphene oxide basal and the effect of nitrogen type was considered. The second study addresses the need for greater control of the rGO structure on the macro-scale. By harnessing the change in interactions between the GO intermediate and final rGO sheets we were able to successfully control the assembly of graphene, creating micro and macro-pore order and high capacitive performance. Further, self assembly directly onto the current collector eliminates process steps involved in the production of EDLC electrodes.

The enhanced functionality and tunability of electronic nanomaterials enables the development of next-generation photovoltaic, optoelectronic, and electronic devices, as well as biomolecular tags. Design and efficient synthesis of such semiconductor nanomaterials require a fundamental understanding of the underlying process-structure/composition-property-function relationships. To this end, this thesis focuses on a systematic, comprehensive analysis of the physical and chemical phenomena that determine the composition and properties of semiconductor nanomaterials. Through synergistic combination of computational modeling and experimental studies, the thesis addresses the thermodynamics and kinetics that are relevant during synthesis and processing and their resulting impact on the properties of silicon thin films and ternary quantum dots (TQDs) of compound semiconductors. The thesis presents a computational study of the growth mechanisms of plasma deposited a-Si:H thin films based on kinetic Monte Carlo (KMC) simulations according to a transition probability database constructed by first-principles density functional theory (DFT) calculations. Based on the results, a comprehensive model is proposed for a-Si:H thin-film growth by plasma deposition under conditions that make the silyl (SiH3) radical the dominant deposition precursor. It is found that the relative roles of surface coordination defects are crucial in determining the surface composition of plasma deposited a-Si:H films and should be properly accounted for. The KMC predictions for the temperature dependence (over the range from 300 K to 700 K) of the surface concentration of SiHx(s) (x = 1,2,3) surface hydride species, the surface hydrogen content, and the surface dangling-bond coverage are in agreement with experimental measurements. In addition, the thesis details a systematic analysis of equilibrium compositional distribution in TQDs and their effects on the electronic and optoelectronic properties. Formation of hetero-nanostructures, such as core/shell-like structures, through atomic-scale assembly driven by equilibrium surface segregation is studied as a function of nanocrystal size, composition, and temperatures for TQD morphologies that include faceted equilibrium nanocrystal shapes for ZnSe1-xTex and InxGa1-xAs TQDs; the results are based on coupled compositional, structural, and volume relaxation of the nanocrystals according to Monte Carlo and conjugate-gradient methods employing a DFT-parameterized description of interatomic interactions. A phenomenological species transport theory also is developed that explains the concentration profiles due to surface-segregation-induced ordering of constituent and dopant atoms in the dilute limit. The nm-scale diffusion lengths in nanocrystals introduce an interesting interplay between the kinetic and thermodynamic stability of interfaces. The thermodynamic stability of such interfaces in ZnSe 1-xSx TQDs are investigated based on DFT calculations combined with X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectra of TQDs that are synthesized and annealed using colloidal methods. The results demonstrate the possibility of compositional redistribution that causes degradation over time of core/shell TQD electronic properties, with far reaching implications for the use of such nanostructures in devices. Electronic structure calculations of ZnSe1-xSx (type-I) and ZnSe1-xTe x (type-II) TQDs elucidate the impact of composition and compositional distribution on the electron density distribution, density of states, and band gap of the TQDs. The resulting relationships with respect to the distributions in the TQDs of constituent/dopant/impurity atoms (core/shell vs. alloyed TQDs) provide an interpretation for the key features observed in the PL spectra, as well as useful guidelines for improving the design and device performance of TQDs.