Savannah Snyder

Engine oil is mainly comprised of base oils and various additives, which are low molecular weight polymers mixed into the oil resulting in a polymer blend. Dispersants and detergents, the two most abundant additives, are intended to keep the engine free of particulate but are not always successful. At high temperatures, species not combusted may undergo oxidation and degradation or create other byproducts, generating particulate deposition. Knowledge of the molecular makeup of these byproducts… Show more

Engine oil is mainly comprised of base oils and various additives, which are low molecular weight polymers mixed into the oil resulting in a polymer blend. Dispersants and detergents, the two most abundant additives, are intended to keep the engine free of particulate but are not always successful. At high temperatures, species not combusted may undergo oxidation and degradation or create other byproducts, generating particulate deposition. Knowledge of the molecular makeup of these byproducts is essential, as particulate accumulation can cause serious issues to the engine and ultimately to the operator. In this study, unknown deposits from the air-intake valve of a vehicular engine have been analyzed via a palette of mass spectrometry (MS) methods, including matrix-assisted laser desorption/ionization MS with postacquisition data processing, atmospheric solids analysis probe MS, and electrospray ionization MS interfaced with 2D separation via reversed-phase liquid chromatography and ion mobility spectrometry. Low molecular weight, aminated poly(propylene glycol) and polyisobutylene detergents and a poly(methyl methacrylate) viscosity modifier were conclusively identified in the deposit, along with oxidized polyethylene chains leaked into the oil/additives blend from vehicular tubing and tanks. The use of different methods was essential for the confident elucidation of the low molecular weight macromolecules giving rise to the vehicular engine particulates. Show less

Understanding prebiotic RNA synthesis is essential to both the RNA world and RNA‐protein co‐evolution theories of the origin of life. Nonenzymatic templated RNA synthesis occurs in solution or by montmorillonite clay heterogenous catalysis but the high magnesium concentrations required are deleterious to protocell membranes. Here, we explore a multicomponent environmental system consisting of amino acids, RNA mononucleotides and montmorillonite at various Mg2+ concentrations. We show that… Show more

Understanding prebiotic RNA synthesis is essential to both the RNA world and RNA‐protein co‐evolution theories of the origin of life. Nonenzymatic templated RNA synthesis occurs in solution or by montmorillonite clay heterogenous catalysis but the high magnesium concentrations required are deleterious to protocell membranes. Here, we explore a multicomponent environmental system consisting of amino acids, RNA mononucleotides and montmorillonite at various Mg2+ concentrations. We show that specific alpha amino acids, especially those that were prebiotically most relevant, act as prebiotic coenzymes and further enhance montmorillonite‐catalyzed polymerization in a cooperative mechanism to produce even longer RNA oligomers. Significantly, and different from template‐directed nonenzymatic RNA polymerization by primer extension, added Mg2+ is not required for montmorillonite‐catalyzed polymerization, especially as enhanced by specific amino acids. Thus amino acid specific montmorillonite‐catalyzed RNA polymerization is compatible with protocell membranes and could occur in a wider variety of geochemical environments of various Mg2+ concentrations. Show less

Polyether based side-chain liquid crystalline (SCLC) copolymers with distinct microstructures were prepared using living anionic polymerization techniques. The composition, end groups, purity, and sequence of the resulting copolymers were elucidated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and tandem mass spectrometry (MS/MS). MALDI-MS analysis confirmed the presence of (CH3)3CO– and –H end groups at the initiating (α) and terminating (ω) chain end… Show more

Polyether based side-chain liquid crystalline (SCLC) copolymers with distinct microstructures were prepared using living anionic polymerization techniques. The composition, end groups, purity, and sequence of the resulting copolymers were elucidated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and tandem mass spectrometry (MS/MS). MALDI-MS analysis confirmed the presence of (CH3)3CO– and –H end groups at the initiating (α) and terminating (ω) chain end, respectively, and allowed determination of the molecular weight distribution and comonomer content of the copolymers. The comonomer positions along the polymer chain were identified by MS/MS, from the fragments formed via C–O and C–C bond cleavages in the polyether backbone. Random and block architectures could readily be distinguished by the contiguous fragment series formed in these reactions. Notably, backbone C–C bond scission was promoted by a radical formed via initial C–O bond cleavage in the mesogenic side chain. This result documents the ability of a properly substituted side chain to induce sequence indicative bond cleavages in the polyether backbone. Show less

PEG-based hydrogels are used widely in
exploratory tissue engineering applications but in general
lack chemical and structural diversity. Additive manufacturing
offers pathways to otherwise unattainable scaffold morphol-
ogies but has been applied sparingly to cross-linked hydrogels.
Herein, monomethyl ether poly(ethylene glycol) (PEG) and
PEG−diol were used to initiate the ring-opening copoly-
merization (ROCOP) of maleic anhydride and propylene oxide to yield well-defined… Show more

PEG-based hydrogels are used widely in
exploratory tissue engineering applications but in general
lack chemical and structural diversity. Additive manufacturing
offers pathways to otherwise unattainable scaffold morphol-
ogies but has been applied sparingly to cross-linked hydrogels.
Herein, monomethyl ether poly(ethylene glycol) (PEG) and
PEG−diol were used to initiate the ring-opening copoly-
merization (ROCOP) of maleic anhydride and propylene oxide to yield well-defined diblock and triblock copolymers of PEG− poly(propylene maleate) (PPM) and ultimately PEG-poly(propylene fumarate) (PPF) with different molecular mass PEG macroinitiators and block length ratios. Using continuous digital light processing (cDLP), hydrogels were photochemically printed from an aqueous solution which resulted in a 10-fold increase in elongation at break compared to traditional diethyl fumarate (DEF) based printing. Furthermore, PPF−PEG−PPF triblock hydrogels were also found to be biocompatible in vitro across a number of engineered MC3T3, NIH3T3, and primary Schwann cells. Show less

Abstract: "The reactions of [PCl2N]3 with oxygen containing Lewis bases (O=E) such as hexamethylphosphoramide (HMPA) and triethylphosphine oxide result in Cl/O exchange. The reactions occur via a two-step process which involves (1) formation of an intermediate salt [P3N3Cl5O]- P3N3Cl4O-O=E and [E-Cl]+[Cl]−. In addition to spectral characterizations, both phosphazene products of the HMPA reactions have been characterized by X-ray crystallography. As shown by reaction chemistry and the… Show more

Abstract: "The reactions of [PCl2N]3 with oxygen containing Lewis bases (O=E) such as hexamethylphosphoramide (HMPA) and triethylphosphine oxide result in Cl/O exchange. The reactions occur via a two-step process which involves (1) formation of an intermediate salt [P3N3Cl5O]- P3N3Cl4O-O=E and [E-Cl]+[Cl]−. In addition to spectral characterizations, both phosphazene products of the HMPA reactions have been characterized by X-ray crystallography. As shown by reaction chemistry and the Gutmann–Beckett Lewis acidity scale, the P=O of the phosphazene ring in P3N3Cl4O-O=E has a strong Lewis acid character. We also discuss attempts to use other O=E and more vigorous reaction conditions with the goal of preparing [PON]3 or its base-stabilized adducts. Such molecules could be precursors to novel PNO materials." Show less

Substitution of oxygen atoms onto a trichlorophosphazene molecule was attempted, succeeding in partial substitution.