My current thesis is regarding the application of Gel Permeation Chromatography (GPC) equipment and principles to the study of polyelectrolyte configuration in solution. The main focus of this study is the effect of salt on the hydrodynamic volume/solution properties of polyelectrolytes and the ability of GPC to effectively determine the degree of variation. This involves the comparison of different salt types and concentrations in aqueous solution. The specific polyelectrolyte examined is poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), a zwitterionic polymer (i.e. one having both positive and negative charges on the monomer). PMPC is a fairly new and promising polyelectrolyte for use in protein drug delivery and biomaterial surface applications. Understanding the effects of salt on this polyelectrolyte will aid in the development of technologies involving this polymer as well as other zwitterionic polymers. Different salts were utilized to formulate an effect of salt ions so that a systematic analysis could be performed. Using a control as reference it was determined that the salt does have an effect on the solution properties of the polyelectrolytes, as expected. The specific properties examined were characterized into two categories; solution properties and ion properties. Solution properties involved the investigation of salt concentration, solution ionic strength and solution pH effects. For ion properties, salts were selected on the basis of ion charge, charge type and ion size, so that the effects of both the cation and anion components could be analyzed. Two parameters, namely, ion size/type and ion valency were examined for both the cation and the anion. In addition the configuration of the anion was also investigated. vSpecific conclusions found in this study were as follows: 1) The salt concentration has an effect up to a certain "saturation" point. 2) The ionic strength has no visible effect (any effect is related to the concentration component). 3) There is no observable solution pH effect. 4) There is no observable cation effect. This includes no cation type/size or cation valency effect. 5) There is a significant anion effect. 6) A smaller anion has a greater effect than a larger anion. 7) A divalent anion has a greater effect than a monovalent anion. 8) A monatomic anion has a greater effect than a polyatomic anion. It was found that the effect of ion properties is related to mechanisms associated with the geometry of the polyelectrolyte. The negative charge group of the polyelectrolyte which is situated closer to the backbone (inside) is less important to the change in hydrodynamic volume resulting from ionic interactions with the salts since it is shielded by the positive charge group situated at the end of the side chain (outside). The observed phenomena were also explained by other chemical and physical properties such as charge density and ionic potential. In addition to the original plan of study, other phenomena were observed and later explained, such as the presence of four distinct regions associated with salt concentration and the variation m the degree of hydrodynamic volume change with different molecular weight samples. The application of aqueous GPC equipment (including a differential refractive index detector (DRI)) and principles to the study of polyelectrolyte solution effects minimizes the detection equipment required and, provides sufficient resolution and accuracy for examination of solution properties while remaining time and cost effective. The project discoveries have shown that size exclusion chromatography provides an excellent means of obtaining a complete and accurate set of correlations between polyelectrolyte charge and salt effects. / Thesis / Master of Applied Science (MASc)

No description available.

Branching in poly(methyl methacrylate) (PMMA) is produced by incorporating a pre-prepared polymeric chain transfer agent (PCTA) into a single stage radical polymerisation. Samples of PCTA having a range of transfer functionalities and molar masses were synthesised by modifying a methacrylate-based copolymer. Control of branching in PMMA has been studied as a function of transfer functionality and molar mass in the PCT A and a function of MMA and initiator concentrations in the MMA polymerisation. The branched samples of PMMA have been characterised by size exclusion chromatography (SEC) with multi-detectors to determine Mark–Houwink and other parameters to assess levels of branching. Some PCTA samples have been prepared with a UV chromophore to facilitate characterisation by SEC-UV.

Yes / Size Exclusion Chromatography is traditionally carried out in either aqueous or non-polar solvents. A system to present molar mass distributions of polymers using methanol as a mobile phase is presented. This is shown to be a suitable system for determining the molar mass distributions poly(N-isopropylacrylamide)s (PNIPAM); a polymer class that is often difficult to analyze by size exclusion chromatography. DOSY NMR was used to provide intrinsic viscosity data that was used in conjunction with a viscometric detector to provide absolute calibration. Then the utility of the system was shown by providing the absolute molar mass distributions of dispersed highly branched PNIPAM with biologically functional end groups. / Wellcome Trust

Ammonium ionenes are macromolecules with quaternized nitrogen groups in the main chain. Ionenes are commonly referred to as x,y-ionene, where x and y represent the number of methylene groups between quaternized nitrogens. Synthesis of aliphatic ammonium ionenes has been studied since the early twentieth century; however, absolute molecular weight characterization has only been performed using extensive light scattering and viscosity experiments. Performing aqueous size exclusion chromatography (SEC) on ammonium ionenes provides absolute molecular weight determinations while eliminating the need for separate viscosity and light scattering experiments. We developed a mobile phase composition that provides reliable separation of aliphatic ammonium ionenes using aqueous SEC. For the first time, we report absolute molecular weights of aliphatic ammonium ionenes using this technique. We investigated the influence of charge density and structural symmetry on thermal and mechanical properties of ammonium 6,6-, 12,6- and 12,12-ionenes. Thermal properties were measured using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), and mechanical properties were measured using dynamic mechanical analysis (DMA) and an Instron. Incorporating low molecular weight polymer segments into the main chain of the ionene allows tailoring of polymer characteristics. Poly (tetramethylene oxide) segments decrease hydrophilicity and increase elastomeric character. Linear PTMO based ionenes have been synthesized previously, and we were interested in how branching affected thermal and mechanical properties. We synthesized bis(dimethylamino) poly(tetramethylene oxide) segments, and subsequently, synthesized linear and branched ionenes to study the effects of topology on thermal and mechanical properties. Polymers were analyzed using DMA, DSC, TGA, SAXS, and an Instron. / Master of Science

Size exclusion chromatography (SEC) separates molecules based on their actual size rather than their molecular weight. This indicates that the smaller a molecule is, the longer it will be held in the column since it can penetrate the pores more effectively than a bigger molecule, resulting in a longer retention time, whereas the larger molecule has a shorter retention time. In order to achieve reliable and accurate results the asymmetry factor of the packed columns should be between 0.6-1.4. The aim for this project was to examine whether or not the batch variations of the base matrix used to derive WorkBeads™ 40S and 40Q displayed either hydrophobic or hydrophilic interactions by running different types of proteins through columns packed with the base matrices. The project was performed using an ÄKTA explorer equipped with an ultraviolet (UV) detector and a refractive index detector (RID). The data was gathered and analyzed with the Unicorn™ by Cytiva. The results from the first experiments showed that lysozyme did not elute as expected or not at all, thus leading to a concern that the there might be some hydrophobic interactions in the base matrix, which is a porous media in the form of spherical particles that have been selected for their physical stability and inertness (lack of reactivity and adsorptive properties), and lysozyme. With this suspicion in mind, the different batches of the base matrix underwent hydrophobic interaction chromatography (HIC), where the results may be interpreted in a way that there might electrostatic interactions instead of hydrophobic interactions. However, due to the gel not being suitable for HIC the results were unreliable. By subsequently running lysozyme and other proteins through the columns at different NaCl concentrations the results showed consistent elution at NaCl concentrations > 150 mM, yet inconsistent at a concentration of 150 mM for lysozyme. The elution order by size showed that although lysozyme has a larger hydrodynamic radius (Rh) than cytochrome c it eluted later, which is theoretically incorrect, but it might be owing to some of the base matrix's characteristics or the lysozyme's dual nature of expressing both hydrophobic and hydrophilic interactions on the base matrix. Because of the inconsistent results from lysozyme, another experiment just at 150 mM was conducted where lysozyme did elute consistently with a KD value < 1.  Lastly, a titration was performed on the base matrix where some of it was brominated and some of it was not, which was the reference. The results showed that there could be hydrophobic interactions on the brominated sample and hydrophilic interactions on the reference sample. However, what is more likely is that lysozyme is an unreliable protein to use to determine hydrophobicity on this type of gel. / Size exclusion chromatography (SEC) separerar molekyler baserat på deras faktiska storlek snarare än deras molekylvikt. Detta indikerar att ju mindre en molekyl är, desto längre kommer den att hållas i kolonnen eftersom den kan tränga sig in i porerna mer effektivt än en större molekyl, vilket resulterar i en längre retentionstid, medan den större molekylen har en kortare retentionstid. För att uppnå tillförlitliga och nogranna resultat bör asymmetrifaktorn hos de packade kolonnerna vara mellan 0.6-1.4. Syftet med detta projekt var att undersöka huruvida batchvariationerna av basmatrisen som användes för att ta fram WorkBeads™ 40S och 40Q uppvisade antingen hydrofoba eller hydrofila interaktioner genom att köra olika typer av proteiner genom kolumner packade med basmatriserna. Projektet utfördes med en ÄKTA explorer utrustad med en ultraviolett (UV) detektor och en refractive index detector (RID). Data samlades in och analyserades med Unicorn™ av Cytiva. Resultaten från de första experimenten visade att lysozym inte eluerade som förväntat eller inte alls, vilket ledde till en oro för att det kan finnas vissa hydrofoba interaktioner i basmatrisen, som är ett poröst medium i form av sfäriska partiklar som har har valts ut för deras fysikaliska stabilitet och inerthet (brist på reaktivitet och adsorptiva egenskaper), och lysozym. Med denna misstanke i åtanke genomgick de olika bactherna av basmatrisen hydrofob interaktionskromatografi (HIC), där resultaten kan tolkas på ett sätt att det kan förekomma elektrostatiska interaktioner istället för hydrofoba interaktioner. Men på grund av att gelen inte var lämplig för HIC var resultaten opålitliga. Genom att efteråt köra lysozym och andra proteiner genom kolonnerna vid olika NaCl-koncentrationer visade resultaten konsekvent eluering vid NaCl-koncentrationer > 150 mM, men ändå inkonsekventa vid en koncentration av 150 mM för lysozym. Elueringsordningen efter storlek visade att även om lysozym har en större hydrodynamisk radie (Rh) än cytokrom c, eluerade det senare, vilket är teoretiskt inkorrekt, men det kan bero på några av basmatrisens egenskaper eller lysozymets dubbla natur att uttrycka både hydrofoba och hydrofila interaktioner på basmatrisen. På grund av de inkonsekventa resultaten från lysozym, utfördes ett annat experiment enbart vid 150 mM där lysozym eluerade konsekvent med ett KD-värde < 1. Slutligen utfördes en titrering på basmatrisen där en del av den var bromerad och en del av den inte, vilket var referensen. Resultaten visade att det kunde finnas hydrofoba interaktioner på det bromerade provet och hydrofila interaktioner på referensprovet. Men vad som är mer troligt är att lysozym är ett opålitligt protein att använda för att bestämma hydrofobicitet på denna typ av gel.

<p><em>Size exclusion chromatography</em> (SEC) was applied for purification of psychoactive biomolecules from plants. These molecules are in the same molecular weight range, but do not necessarily share other chemical properties, that makes the SEC technique efficient. By applying SEC as a first purification step much of the co-extractives from the plants can easily be removed. Large amounts of target substance can be obtained with little effort if the system is automated. Combining SEC with a second purification step, consisting of normal phase chromatography, provides high purity of the target substance.</p><p>Both known and unknown psychoactive biomolecules can easily be purified using the purification method developed in this Master's Thesis. Purifications that previously required long time and much "hands-on" can be completed much faster and with less manual work.</p><p>The method developed was tested on cannabis, coffee and 'Spice' with good results.</p>

Size exclusion chromatography (SEC) was applied for purification of psychoactive biomolecules from plants. These molecules are in the same molecular weight range, but do not necessarily share other chemical properties, that makes the SEC technique efficient. By applying SEC as a first purification step much of the co-extractives from the plants can easily be removed. Large amounts of target substance can be obtained with little effort if the system is automated. Combining SEC with a second purification step, consisting of normal phase chromatography, provides high purity of the target substance. Both known and unknown psychoactive biomolecules can easily be purified using the purification method developed in this Master's Thesis. Purifications that previously required long time and much "hands-on" can be completed much faster and with less manual work. The method developed was tested on cannabis, coffee and 'Spice' with good results.

Polyethylene (PE) is produced in a huge scale globally and has plenty of desirable properties. It is used in coating, packaging, and artificial joint replacements. The growing need for high performance polyethylene led to the development of new catalysts, monomers and polymerizations. The synthesis of polymethylene (equivalent to polyethylene) by living polyhomologation opened the way to well-defined polymethylenes-based polymeric materials with controlled structure, molecular weight and narrow polydispersity. Such model polymers are substantial to study the structure-properties relationships. This research presents a new strategy based on the in situ formation of B-thexyl-silaboracyclic serving as initiating sites for the polyhomologation of dimethylsulfoxonium methylide. Combination with metal-free ring-opening polymerization (ROP) of ɛ-caprolactone (CL) and atom transfer radical polymerization (ATRP) of styrene led to three polymethylene-based 3-miktoarm stars copolymers PCL(PM-OH)2, Br-PCL(PM-OH)2 and PS(PM-OH)2.

abstract: Atmospheric particulate matter has a substantial impact on global climate due to its ability to absorb/scatter solar radiation and act as cloud condensation nuclei (CCN). Yet, little is known about marine aerosol, in particular, the carbonaceous fraction. In the present work, particulate matter was collected, using High Volume (HiVol) samplers, onto quartz fiber substrates during a series of research cruises on the Atlantic Ocean. Samples were collected on board the R/V Endeavor on West&ndash;East (March&ndash;April, 2006) and East&ndash;West (June&ndash;July, 2006) transects in the North Atlantic, as well as on the R/V Polarstern during a North&ndash;South (October&ndash;November, 2005) transect along the western coast of Europe and Africa. The aerosol total carbon (TC) concentrations for the West&ndash;East (Narragansett, RI, USA to Nice, France) and East&ndash;West (Heraklion, Crete, Greece to Narragansett, RI, USA) transects were generally low over the open ocean (0.36&plusmn;0.14 &mu;g C/m3) and increased as the ship approached coastal areas (2.18&plusmn;1.37 &mu;g C/m3), due to increased terrestrial/anthropogenic aerosol inputs. The TC for the North&ndash;South transect samples decreased in the southern hemisphere with the exception of samples collected near the 15th parallel where calculations indicate the air mass back trajectories originated from the continent. Seasonal variation in organic carbon (OC) was seen in the northern hemisphere open ocean samples with average values of 0.45 &mu;g/m3 and 0.26 &mu;g/m3 for spring and summer, respectively. These low summer time values are consistent with SeaWiFS satellite images that show decreasing chlorophyll a concentration (a proxy for phytoplankton biomass) in the summer. There is also a statistically significant (p<0.05) decline in surface water fluorescence in the summer. Moreover, examination of water&ndash;soluble organic carbon (WSOC) shows that the summer aerosol samples appear to have a higher fraction of the lower molecular weight material, indicating that the samples may be more oxidized (aged). The seasonal variation in aerosol content seen during the two 2006 cruises is evidence that a primary biological marine source is a significant contributor to the carbonaceous particulate in the marine atmosphere and is consistent with previous studies of clean marine air masses. / Dissertation/Thesis / M.S. Chemistry 2011