(267i) Anomalous Phase Formation in Self-Assembled Polymers Under Low Intensity Magnetic Fields
AIChE Annual Meeting
Tuesday, November 17, 2020 - 9:30am to 9:45am
The anomalous rheological response results from field-induced microstructure changes, which occur at field strengths far below that expected based on the polymer magnetic susceptibility anisotropy, ÎÏ. Using a combination of magneto-rheology (MR), SANS, and SAXS, three distinct field-induced behaviors have been identified, which may occur independently or in tandem: phase formation typically associated with a lyotropic or thermotropic phase transition, and grain growth and orientation. MR is performed at temperatures far below (>10 ÂºC) quiescent thermotropic phase transitions, and the induced elastic modulus, GâB, is up to an order of magnitude larger than results from temperature ramps at 0 T. Distinct time- and field intensity-dependent rheological features during magnetization suggest that phase selection and access to metastable states can be controlled by altering field strength and magnetization time. Understanding these directed-assembly mechanisms is of significant scientific interest for its potential to enhance assembly with minimal input from external fields, and the potential to discover new structures not accessible through traditional self-assembly routes.