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Full-Text Articles in Physical Sciences and Mathematics
Synthesis And Characterization Of Peek Analogues Utilizing 3,5- And 2,4-Difluorobenzophenone., Zachary Ewing
Synthesis And Characterization Of Peek Analogues Utilizing 3,5- And 2,4-Difluorobenzophenone., Zachary Ewing
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Two routes to semi-crystalline, potentially functionalizable poly(ether ether ketone), PEEK, analogues were explored using varying percentages of 4,4’-difluorobenzophenone and either 3,5-difluorobenzophenone or 2,4-difluorobenzophenone as the electrophilic component in nucleophilic aromatic substitution polycondensation reactions with hydroquinone. PEEK analogues utilizing 3,5-difluorobenzophenone were carried out in a “one-pot” fashion and their properties were compared to the same materials prepared previously by a multi-step synthetic procedure. The use of 2,4-difluorobenzophenone led to completely new PEEK analogues. The polymers were characterized via NMR spectroscopy, Size Exclusion Chromatography, Thermogravimetic Analysis, and Differential Scanning Calorimetry. Molecular weight determinations showed the synthesized polymers to be of a variety …
The Synthesis Of Polyimides Containing Oxyalkylene Units, Kristy Wickman
The Synthesis Of Polyimides Containing Oxyalkylene Units, Kristy Wickman
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A series of oxyalkylene containing diamines, 1,4-bis(2-(4-aminophenoxy)-ethoxy)benzene, 2,2-bis[4-(2-(4-nitrophenoxy)ethoxy)phenyl]hexafluoropropane, 9,9-bis(4-(2-(4-nitrophenoxy)ethoxy)phenyl)fluorene, and bis(4-(2-(4-nitrophenoxy)ethoxy)-phenyl)diphenylmethane, has been synthesized from the reduction of 1,4-bis(2-(4-nitrophenoxy)ethoxy)benzene, 2,2-bis[4-(2-(4-nitrophenoxy)ethoxy)phenyl]-hexafluoropropane, 9,9-bis(4-(2-(4-nitrophenoxy)ethoxy)phenyl)fluorene, bis(4-(2-(4-nitrophenoxy)ethoxy)phenyl)diphenylmethane, respectively. The diamine compounds were reacted reacted with 6FDA to obtain the corresponding polyimide. The polymerization was done in a one-pot reaction with m-cresol and isoquinoline. The polyimides displayed glass transition temperatures ranging from 186-231°C and thermal stability <400°C.
Exploration Of Gradient-Type Poly(Arylene Ether)S Via An Abb' Monomer System, Alex V. Dolgov
Exploration Of Gradient-Type Poly(Arylene Ether)S Via An Abb' Monomer System, Alex V. Dolgov
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Evidence shows that a gradient like copolymer can be synthesized using nucleophilic aromatic substitution, NAS, chemistry. Using the 4-chloro-3-fluoro-4'hydroxydiphenylsulfone monomer, 5, it is possible to control the ratios of the leaving groups, in this case the fluorine and the chlorine, with the right solvent and temperature. Alternating the temperatures will alter the substitution of the leaving groups, thus forming a polymer backbone of gradient characteristics. Initial reactions to determine the relative rates of displacement of the chlorine and fluorine atoms were carried out using a model compound, 1, which possessed the chlorine and fluorine leaving groups, but not the phenol …
Tailoring Branching For Poly (Arylene Ether)S Via Reactivity Ratio Controlled Polymerizations, Amanda Ike
Tailoring Branching For Poly (Arylene Ether)S Via Reactivity Ratio Controlled Polymerizations, Amanda Ike
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The ability to control physical and mechanical properties of polymer systems has become an important aspect of polymer science. In order to tailor the branching in polymer systems, an understanding into the reactivity of the electrophilic sites in the monomer is important. Kinetic methods have been explored in order to determine the reactivity of monomers in preparing poly(arylene ether)s and to predict the degree of branching that will occur in a polymer of this kind. The reactivity of AB2 sulfones and phosphine oxides was explored, along with the reactivity of ABB'B'' sulfones. NMR spectroscopy was used as a probe into …