Viscosity Testing of PEG-PDMAEMA and Preliminary ARGET ATRP Synthesis

Abstract

Polymers are present in our everyday life such as clothing, plastics, and electronics. “Smart polymers” are a subset of polymers unique in that they change their properties due to varying external stimuli and can be used in a wide range of applications in the pharmaceutical, environmental, and biomedical fields. This research focuses more on diblock copolymers, which are two separate homopolymers covalently bonded together, of poly(ethylene glycol)-block-poly(2-(dimethylamino)ethyl methacrylate) PEG-PDMAEMA. Solutions of different concentrations of diblock copolymers (1 mg/mL and 10 mg/mL) were paired with different buffer concentrations (.1M and .01M) and different pH (8 and 12) to analyze the specific behavior of each synthesized diblock copolymer to external stimuli. Viscosity, or a fluid’s resistance to flow, was tested on a rheometer for different solutions at different shear rates with stress being measured to determine viscosity. The smart polymer viscosity is expected to substantially increase as temperature increases near the cloud point, which is when the solution becomes cloudy, and is due to the polymer changing from water soluble to water insoluble. The cloud point depends on the molecular weight of the polymer, pH and buffer concentration. The examined smart diblock copolymer PEG-PDMAEMA is currently synthesized by Atom Transfer Radical Polymerization (ATRP). A new synthesis procedure, Activator ReGenerated by Electron Transfer (ARGET) ATRP, was tested because it is able to tolerate being exposed to air and requires less catalyst. Current work includes synthesizing PDMAEMA homopolymers and diblock copolymers. By updating the synthesis and understanding how the viscosity of PEG-PDMAEMA responds to changes in pH and temperature, it can be tailored to specific environments and applications such as enhanced oil recovery.