The work encompassed by this thesis is partially a reproduction of the results obtained by John A. Marcia in his work on the photo-chemical reactions of branched hydrocarbons. The previous work done on this particular problem was rendered partially valueless because of the loss of the liquid hydrocarbon product when a fractionation column at the Texas Company Laboratory, Beacon, New York, broke during the fractionation run.

It was decided to determine whether or not 2,2,3-trimethylbutane could be formed by the photochemical reaction of isobutane and propane in the presence of mercury vapor energized by ultraviolet radiation from a mercury vapor lamp.

abstract: The focus of this thesis is to study dissolved organic carbon composition and reactivity along the Colorado and Green Rivers. Dissolved organic carbon (DOC) in large-scale, managed rivers is relatively poorly studied as most literature has focused on pristine unmanaged rivers. The Colorado River System is the 7th largest in the North America; there are seventeen large dams along the Colorado and Green River. DOC in rivers and in the lakes formed by dams (reservoirs) undergo photo-chemical and bio-degradation. DOC concentration and composition in these systems were investigated using bulk concentration, optical properties, and fluorescence spectroscopy. The riverine DOC concentration decreased from upstream to downstream but there was no change in the specific ultraviolet absorbance at 254 nm (SUVA254). Total fluorescence also decreased along the river. In general, the fluorescence index (FI) increased slightly, the humification index (HIX) decreased, and the freshness index (β/α) increased from upstream to downstream. Photo-oxidation and biodegradation experiments were used to determine if the observed changes in DOC composition along the river could be driven by these biogeochemical alteration processes. In two-week natural sunlight photo-oxidation experiments the DOC concentration did not change, while the SUVA254 and TF decreased. In addition, the FI and ‘freshness’ increased and HIX decreased during photo-oxidation. Photo-oxidation can explain the upstream to downstream trends for TF, FI, HIX, and freshness observed in river water. Serial photo-oxidation and biodegradation experiments were performed on water collected from three sites along the Colorado River. Bulk DOC concentration in all samples decreased during the biodegradation portion of the study, but DOC bioavailability was lower in samples that were photo-oxidized prior to the bioavailability study. The upstream to downstream trends in DOC concentration and composition along the river can be explained by a combination of photo-chemical and microbial degradation. The bulk DOC concentration change is primarily driven by microbial degradation, while the changes in the composition of the fluorescent DOC are driven by photo-oxidation. / Dissertation/Thesis / Masters Thesis Chemistry 2015

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The central objective of this work is developing convenient general procedures for controlling the formation and stabilization of nanoscale transition metal particles. Contemporary interest in developing alternative synthetic approaches for producing nanoparticles arises in large part from expanding applications of the nanomaterials in areas such as catalysis, electronics and medicine. This research focuses on advancing the existing nanoparticle synthetic routes by using a new class of polymer colloid materials as a chemical approach, and the laser irradiation of metal salt solution as a photo-chemical method to attain size and shape selectivity. Controlled synthesis of small metal nanoparticles with sizes ranging from 1 to 5nm is still a continuing challenge in nanomaterial synthesis. This research utilizes a new class of polymer colloid materials as nano-reactors and protective agents for controlling the formation of small transition metal nanoparticles. The polymer colloid particles were formed from cross-linking of dinegatively charged metal precursors with partially protonated poly dimethylaminoethylmethacrylate (PDMAEMA). Incorporation of [PtCl6]2- species into the colloidal particles prior to the chemical reduction was effectively employed as a new strategy for synthesis of unusually small platinum nanoparticles with narrow size distributions (1.12 ± 0.25nm). To explore the generality of this approach, in a series of proof-of-concept studies, this method was successfully employed for the synthesis of small palladium (1.4 ±0.2nm) and copper nanoparticles (1.5 ±0.6nm). The polymer colloid materials developed in this research are pH responsive, and are designed to self-assemble and/or disassemble by varying the levels of protonation of the polymer chains. This unique feature was used to tune the size of palladium nanoparticles in a small range from 1nm to 5nm. The procedure presented in this work is a new convenient room temperature route for synthesis of small nanoparticles, and its application can be extended to the formation of other transition metals and alloy nanoparticles. This research also focuses on developing new photo-chemical routes for controlling the size and shape of the nanoparticles through high-intensity ultra-fast laser irradiation of metal salt solution. One of the core objectives of this work is to explore the special capabilities of shaped laser pulses in formation of metal nanoparticles through irradiation of the solutions by using simultaneous spatial and temporal focusing (SSTF). Femtosecond laser irradiation has not yet been widely applied for nanoparticle synthesis, and offers new regimes of energy deposition for synthesis of nanomaterials. Photo-reduction of aqueous [AuCl4]- solution to the gold nanoparticles (AuNPs) has been applied as a model process for optimizing the experimental procedures, and evaluating the potential of shaped laser pulses in the synthesis of AuNPs. Systematic manipulation of the laser parameters and experimental conditions provided effective strategies to control the size of Au nanoparticles in strong laser fields. Varying the concentration of polyethylene glycol (PEG45) as a surfactant effectively tuned the size of AuNPs from 3.9 ±0.7nm to 11.0 ±2.4nm, and significantly increased the rate of Au(III) reduction during irradiation. Comparative studies revealed the capability of shaped laser pulses in the generation of smaller and more uniform AuNPs (5.8 ±1.1nm) relative to the other conventional laser irradiation methods (7.2 ±2.9nm). Furthermore, a new laser-assisted approach has been developed for selective formation of triangular Au nanoplates in the absence of any surfactant molecule. This method relies on rapid energy deposition by using shaped, ultra-intense laser pulses to generate Au seeds in aqueous [AuCl4]- solution, and the slow post-irradiation reduction of un-reacted [AuCl4]- species by using H2O2 as a mild reducing agent. Variation of the laser irradiation-time was found as an effective strategy to tune the morphology of Au nanomaterials from nanospheres to triangular nanoplates. The surfactant-free Au nanoplates produced in this research can be readily functionalized with a variety of target molecules or surfactants for desirable applications such as biomedicine. The concept of rapid laser processing followed by in situ chemical reduction can be expanded as a general methodology for high-yield production of nanomaterials, and provides a series of new laser dependent parameters for controlling the nanoparticle formation. / Chemistry

L’objectif de cette thèse est de développer des matériaux polymérisés par rayonnement ultra-violet possédant une bonne balance des propriétés thermomécaniques entre résistance à la température, rigidité (strength) et résistance à l’impact. Une direction vers cet objectif est l’utilisation de résines (meth)acrylate modifiées avec des thiols polyfonctionnels. Cependant, les thiol-ene en général sont sujets à un problème de polymérisation prématurée incontrôlée même à l’abri de la lumière. Ce problème doit être traité puisque celui-ci conditionne le succès des thiol-ene dans le domaine des photopolymères. La première partie de cette thèse concerne l’élaboration de résine (meth)acrylate modifiée par l’incorporation d’un polythiol, le pentaerythritol tetrakismercaptopropionate (PETMP), à différents ratio. Les propriétés thermomécaniques et photochimiques de ces résines sont à l’étude. La seconde partie traite du problème de polymérisation prématurée incontrôlée des thiol-ene. Une étude de stabilité thermique aboutissant à des résultats très encourageant est proposée. Finalement, la dernière partie porte sur la caractérisation des réseaux photo-réticulés par pyrolyse-GC/MS. La compréhension de la constitution des réseaux tridimensionnels devraient apportés des avancées dans l’élaboration de nouveaux matériaux. Une nouvelle méthode de caractérisation utilisant la pyrolyse-GC/MS directe à multi-étapes est développée. Enfin, des résultats sur l’application de la méthode sur des matériaux à base de (meth)acrylate difonctionnel photopolymérisés ainsi qu’une tentative de caractérisation de matériaux à base de polythiol/(meth)acrylates photopolymérisés sont reportés puis discutés. / This thesis fall within an approach aiming to develop UV-processed materials having a good thermo-mechanical properties balance between strength, temperature resistance and impact resistance. A direction toward this objective is the use of photocurable (meth)acrylate resins modified with polyfunctional thiols. Indeed, thiol-ene chemistry is known to have poor sensitivity toward oxygen inhibition, to improve the dimensional stability and toughness properties of photocured materials. However, thiol-ene resins are subjected to premature uncontrolled dark polymerization, an issue that has to be solved for their success in the photopolymers area. The first part of this work is focused on the thermo-mechanical and the photopolymerization properties investigation of a pentaerythritol tetrakismercaptopropionate (PETMP) modified (meth)acrylate based resin by looking at different ratio of polythiol/(meth)acrylate. The second part is dedicated to the understanding of the thermal instability of such systems and to the solving of this issue. Finally, a special interest is brought to the characterization of photopolymeric networks by pyrolysis-GC/MS. The lake of deep understanding and view about how the cured networks are really constituted due to the difficulty to analyze insoluble cured polymers, prevents improvements in the formulation of high performance materials. Further information on cured networks constitution could bring useful information for the elaboration of new materials. A new characterization method based on direct multi-step pyrolysis-GC/MS is developed and an attempt on the characterization of polythiol (meth)acrylate material by Py-GC/MS is reported and discussed.