Discipline: Chemistry and Chemical Sciences
Shaquwana Simpson - North Carolina Central University
Co-Author(s): Ockiya Hurbert (1), John Bang (2), and Darlene Taylor (1) ; 1 Department of Chemistry and Biochemistry, North Carolina Central University, Durham, NC; 2 Department of Environmental, Earth and Geospatial Sciences, North Carolina Central University, Durham, NC
Water is a necessity and it is becoming more challenging to access it in a clean drinkable form. Membranes can be designed to purify water of contaminants, such as dye molecules, making it drinkable and accessible. Development of reusable membranes that can be heated to rid of dye particles would be a huge benefit to the membrane technology field. Hyperbranched polyglycerol (HPG) based membranes are actively being pursued, as they provide many bonding sites for attaching of active molecules. The next generation of selective permeable membranes can be designed and tested by manipulating the best attributes of thermal responsive polymers and HPG material platforms. To this end, HPG was methacrylated in dimethyl sulfoxide (DMSO) with glycidyl methacrylate (GMA) in the presence of dimethylamino pyridine (DMAP), creating methacrylated hyperbranched polyglycerol (HPG-MA). The degree of methacrylate substitution ( 43%) was confirmed by NMR results where methacryloyl proton peaks at 5.6 ppm and 6 ppm are compared to the hydroxyl proton peaks of HPG at 3.14 ppm. HPG-MA was covalently linked with N-Isopropylacrylamide (NIPAAm) creating a hydrogel. The hydrogel was confirmed by FTIR where peaks at 3448 cm-1 indicated O-H and C-OH stretching as well as 2973 cm-1 arising from the methylene group in HPG and NIPAAm. thermogravimetric analysis (TGA) of hydrogel, NIPAAm, and HPG-MA was taken to measure the mass of each sample over time as the temperature change. Ultraviolet visible spectrophotometer (UV-Vis) refers to the absorption of rose bengal dye that was added to the membrane. A calibration curve for rose bengal was calculated. The stability of the hydrogel was confirmed by TGA were 20% loss was observed up to a temperature of 200 oC. The hydrogel underwent decomposition of its polyether skeleton with a weight loss of nearly 100% in temperature ranging from 400 – 450 oC. As a first approach, the hydrogel was evaluated as a permeation membrane for rose bengal dye which has a molecular end to end distance of 11.24 angstroms. Below 34 oC, most of the dye was removed. However, as the temperature increased less dye was removed as measured against a rose bengal UV-Vis calibration curve. A second dye, congo red, of a similar end to end molecular distance is being tested as a model dye with the hydrogel membrane. A nine point calibration curve was developed (R2= 0.9833) at a wavelength of 310 nm. Future studies will investigate the release of congo red and two additional dyes that increase in structural size.Not Submitted
Funder Acknowledgement(s): The research was funded by NSF's Research Triangle MRSEC (DMR-1121107).
Faculty Advisor: Dr. Darline Taylor, firstname.lastname@example.org
Role: I synthesized the hydrogel and conducted the calibration curve for the congo red dye.