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Articles 1 - 5 of 5
Full-Text Articles in Polymer Science
Molecular Origins Of Non-Frozen Water In Polyelectrolyte Brushes, Ali Dhinojwala, Saveen Jayaweera, Md Golam Kibria, George Mallinos
Molecular Origins Of Non-Frozen Water In Polyelectrolyte Brushes, Ali Dhinojwala, Saveen Jayaweera, Md Golam Kibria, George Mallinos
University Research
Polyelectrolyte brushes (PEBs) are promising coatings for reducing ice adhesion and regulating water freezing at interfaces, yet direct measurements of nonfrozen water retention at subzero temperatures remain scarce. Here, we investigate the freezing behavior of water confined in poly([2-(methacryloyloxy)ethyl]trimethylammonium) (PMETA) brushes with chloride, iodide, and sulfate counterions using a custom-built low-temperature attenuated total reflectance infrared spectroscopy system. Furthermore, we quantify the fraction of water that was present within the brush that does not freeze as well as the changes in polymer volume fraction within the brush as a function of temperature. Spectroscopic analysis of water vibrational modes reveals that PMETA …
Filtration Apparatus Design For Oil-Water Separation Using Membranes And Sponges, Alec Jerger
Filtration Apparatus Design For Oil-Water Separation Using Membranes And Sponges, Alec Jerger
Williams Honors College, Honors Research Projects
It can be difficult to separate water and oil emulsions through traditional filtration. Therefore, investigations of filtering using thermo-responsive (TR) polymers, in this case poly(vinyl methyl ether) (PVME), was conducted. It’s hypothesized that below its lower critical solution temperature (LCST), PVME has an affinity for water while oil substances do not. Above the LCST the opposite will be true. To verify this hypothesis, iterations of filtration designs were created to provide optimum control over the parameters to measure flow. The final optimized experimental apparatus was a Chromaflex glass column which was air tight and controlled all parameters besides fluid flow. …
Elucidating The Properties And Mechanism For Cellulose Dissolution In Tetrabutylphosphonium-Based Ionic Liquids Using High Concentrations Of Water, Brad Crawford
Graduate Theses, Dissertations, and Problem Reports (ETD)
The structural, transport, and thermodynamic properties related to cellulose dissolution by tetrabutylphosphonium chloride (TBPCl) and tetrabutylphosphonium hydroxide (TBPH)-water mixtures have been calculated via molecular dynamics simulations. For both ionic liquid (IL)-water solutions, water veins begin to form between the TBPs interlocking arms at 80 mol % water, opening a pathway for the diffusion of the anions, cations, and water. The water veins allow for a diffusion regime shift in the concentration region from 80 to 92.5 mol % water, providing a higher probability of solvent interaction with the dissolving cellulose strand. The hydrogen bonding was compared between small and large …
Separation Of Water From Ulsd Using Superhydrophobic Ps Nanofiber Mats, Alisa G. Webel
Separation Of Water From Ulsd Using Superhydrophobic Ps Nanofiber Mats, Alisa G. Webel
Williams Honors College, Honors Research Projects
Superhydrophobic polystyrene nanofiber membranes have potential to separate micron scale water droplets from organic due to their hydrophobicity and small pore openings. Polystyrene nanofibers were electrospun into flat sheets and cylindrical filter membranes. The fibers were crosslinked to increase strength and reduce solubility in diesel fuel. The filters were tested and the filtration efficiency was compared to their non-crosslinked counterparts. The optimal electrospinning conditions to create superhydrophobic nanofibers were found to be 20 wt. % PS fibers at 1 mL/hr. under a current of 20kV and at a distance of 20 cm away from the ground. It was found that …
Understanding Rubber Friction In The Presence Of Water Using Sum-Frequency Generation Spectroscopy, Kumar Nanjundiah, Ping Yuan Hsu, Ali Dhinojwala
Understanding Rubber Friction In The Presence Of Water Using Sum-Frequency Generation Spectroscopy, Kumar Nanjundiah, Ping Yuan Hsu, Ali Dhinojwala
College of Polymer Science and Polymer Engineering
Infrared-visible sum-frequency-generation spectroscopy (SFG) was used to study the molecular structure of water between a poly(dimethylsiloxane) (PDMS) and a sapphire substrate. The observation of SFG peaks associated with the dangling surface hydroxyl groups (3690 cm(-1)) and water bands (3000-3400 cm(-1)) indicates that the contact spot between the PDMS lens and the sapphire substrate is heterogeneous. Within the contact spot there are regions where the methyl groups of the PDMS chains are in direct contact with the surface hydroxyl groups on the sapphire substrate. In the other regions, a thin water layer is trapped between the two surfaces with spectral features …