Paper Number
PO60 

Session
Poster Session

Title
Magneto-rheological studies on the role of hydration in anomalous magnetically-induced block copolymer ordering

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom 1-2-3-4

Authors (Click on name to view author profile)

1. Kresge, Grace V. (University of Minnesota Twin Cities, Chemical Engineering and Materials Science)
2. Calabrese, Michelle A. (University of Minnesota, Chemical Engineering and Materials Science)

Author and Affiliation Lines (in printed abstract book)
Grace V. Kresge and Michelle A. Calabrese
Chemical Engineering and Materials Science, University of Minnesota Twin Cities, Minneapolis, MN 55455

Speaker / Presenter 
Kresge, Grace V.

Keywords
gels; micelles; polymer solutions; surfactants

Text of Abstract
The directed assembly of block copolymers via external stimuli is central to improving structural control and expanding viable applications of the materials. In particular, magnetic fields have emerged as a promising new external stimuli for processing block copolymers. Yet directed assembly of block copolymers via magnetic fields suffers from limitations including the need for large applied fields (> 6 T) or anisotropic constituents such as crystalline blocks. Recent work has demonstrated the anomalous disorder/order transition of poloxamer micellar solutions under weak magnetic fields and without the need for anisotropic constituents. This project seeks to understand the mechanism behind this anomalous transition with the goal of furthering BCP processing and advanced materials design. This presentation focuses on the role of micelle hydration in the magnetically-induced disordered/ordered transition. Hydration of the micelles was varied via solvent quality, relative block solubility, hydrogen bond strength, and ionic strength to elucidate the proposed ordering mechanism. The current hypothesized mechanism focuses on a magnetically-induced change in polymer solvent interactions which results in an alteration in the hydration of the PEO corona and/or the PPO core. The hydration and size of the micelles under various solvent and environmental conditions were observed via X-ray scattering following magneto-rheological studies. Parameters extracted from magneto-rheology studies such as plateau modulus and critical transition time provide insight into the role of hydration on the kinetics of the magnetically-induced transition.