Quantitative Scaling of Polymer Solutions as a Tool for Polymer Molecular Weight Determination

Project Description

Abstract

Continuous flow chemistry is a favorable method for polymer production due to its ability to produce large volumes of material in short time scales, efficient mixing and heat transfer, and precise control of reagents. While much effort has been focused on the synthesis of polymers in this manner, there has been less progress to also characterize polymers in a rapid manner. The extensive time required to characterize polymers creates a bottleneck in polymer production which could be alleviated by incorporating near real time analysis. We envision being able to determine polymer molecular in a rapid and near real time manner. In order to determine molecular weight in a continuous flow set up, we will leverage the theoretical scaling relationship outlined by the Dobrynin group, in which weight average molecular weight can be calculated from the solution specific viscosity. In order to quantify this relationship and form a calibration curve relating specific viscosity and molecular weight, a set of polymer standards of different chemical identities and molecular weights needs to be synthesized and characterized. We have chosen polyurethanes as a starting model system and have produced an optimized set of reaction conditions which allow us to target varying molecular weights reproducibly. With a library of polyurethane standards, we have developed a reliable method for collecting viscosity data, and begun to quantify the specific viscosity of varying molecular weights across the dilute, semi-dilute and concentrated regimes. We hope to implement this into a continuous flow reactor with a pressure transducer that can be attached to the terminal end of a flow reactor which calculates pressure drop which can be used to calculate viscosity using the Hagen–Poiseuille equation. With the viscosity of our unknown molecular weight sample in hand we can use the calibration curve produced earlier to determine molecular weight of our sample.

Instruments