Student Presentations at Recent American Chemical Society Meetings
"Hydrogels based
upon random copolymers of 2-hydroxyethyl acrylate and 2-hydroxyethyl
methacrylate"
Amy Luce
Poly(2-hydroxyethyl acrylate) and poly(2-hydroxyethyl methacrylate) are hydrogel materials. The former is capable of absorbing over 400 percent its weight in water, whereas the later absorbs only 40 percent. Random copolymers of 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate have been synthesized by radical polymerization with a goal of controlling the degree of water absorption by regulating the fraction of each monomer in the copolymer. Details of the synthetic route and the characterization of the product copolymers are presented.
"Refractive Index Measurements using a Michelson Interferometer with a
Low-Coherence Light Source"
Sarah Caudill
We have constructed an interferometric apparatus that is capable of measuring refractive index in bulk optical samples over the wavelength range 300 – 2000 nm. The device utilizes a tunable xenon arc-lamp light source and a Michelson interferometer where one of the mirrors is translated with a precision motorized translation stage that has 8 nm resolution. Refractive index and its dispersion has been evaluated in several inorganic and polymer materials, including fused silica glass, BK7 glass, Borofloat glass, MgF2, polycarbonate, poly(methyl methacrylate), and polystyrene. The results of these measurements are presented and the advantages and disadvantages associated with these measurements, in comparison to tradition refractometric measurements, are discussed.
An Investigation of Polymerization Contraction In Light Cured Resin-Based Dental
Restorative
Elizabeth A.
Fogleman.
Dentists presently use light cured polymer resins to restore and replace missing teeth and tooth structure, and to seal fissures against the ingress of bacteria. Despite the wide use, these polymer restoratives are known to exhibit significant polymerization contraction upon cure which can lead to poor adhesion and low material performance. We have constructed a low cost laser interferometer that allows one to measure the degree of linear polymer contraction during cure. The apparatus is based on a low power Helium-Neon laser and a Michelson interferometer optical arrangement. Interferometric measurements have been carried out on a number of commercially available light curable dental restoratives. The interferometric method will be described and the degree of polymerization contraction in the restoratives will be reported and compared.
A Spectroscopic Investigation Of
Methlene Blue Dimerization In Aqueous Solution
Siu Wah
Wong
Methylene Blue, a common redox indicator, is known to self-associate in aqueous solution to form dimers, trimers, and higher order complexes. Several previous investigations have used the concentration dependence of the visible absorption spectrum to infer the monomer-dimer equilibrium constant. Unfortunately, there is much disagreement between these 'spectrally determined' equilibrium constants. We have developed a simplified spectral analysis procedure that allow one to readily obtain the monomer-dimer equilibrium constant in aqueous methylene blue solutions. This procedure will be illustrated along with the results of a preliminary investigation.
Laser Interferometric
Measurements of Photo-Polymerization Contraction And Inhibition
Jason M. Zebert
A low cost optical apparatus, based on a Helium-Neon laser and a Michelson interferometer, is used to monitor polymerization kinetics in several photocurable coatings. This recently developed method allows one to measure the variations in refractive index and film thickness throughout a polymerization reaction. The device is used in the present study to measure the percent linear contraction in three commercially available UV photocurable resins. The obtained 'interferograms' allow comparisons to be made concerning the cure rate, film shrinkage, and polymerization inhibition.
Several Undergraduate
Research Posters
Are on Display in Sage Hall
You Are Invited to Stop By And Take a Look!