Polymer Solutions in Microflows: Tracking and Control over Size Distribution.

Microfluidics provides cutting-edge technological advancements for the in-channel manipulation and analysis of dissolved macromolecular species. The intrinsic potential of microfluidic devices to control key characteristics of polymer macromolecules such as their size distribution requires unleashing its full capacity. This work proposes a combined approach to analyzing the microscale behavior of polymer solutions and modifying their properties. We utilized the idea of modeling cross-channel diffusion in polydisperse polymer microflows using dynamic light scattering size distribution curves as the source data. The model was implemented into a Matlab script which predicts changes in polymer size distribution at microfluidic chip outputs. We verified the modeling predictions in experiments with a series of microchips by detecting the optical responses of injected nematic liquid crystals in the presence of microfluidic polymer species and analyzing the polymer size distribution after microfluidic processing. The results offer new approaches to tuning the size and dispersity of macromolecules in solution, developing auxiliary tools for such techniques as dynamic light scattering, and labs-on-chips for the combined diagnostics and processing of polymers.