Effect of nanoparticle loading and magnetic field application on the thermodynamic, optical, and rheological behavior of thermoresponsive polymer solutions
Although processing via external stimuli is a promising technique to tune the structure and properties of polymeric materials, the impact of magnetic fields on phase transitions in thermoresponsive polymer solutions is not well-understood. As nanoparticle (NP) addition is also known to impact these thermodynamic and optical properties, synergistic effects from combining magnetic fields with NP incorporation provide a novel route for tuning material properties. Here, the thermodynamic, optical, and rheological properties of aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions are examined in the presence of hydrophilic silica NPs and magnetic fields, individually and jointly, via Fourier-transform infrared spectroscopy (FTIR), magneto-turbidimetry, differential scanning calorimetry (DSC), and magneto-rheology. While NPs and magnetic fields both reduce the phase separation energy barrier and lower optical transition temperatures by altering hydrogen bonding (H-bonding), infrared spectra demonstrate that the mechanism by which these changes occur is distinct. Magnetic fields primarily alter solvent polarization while NPs provide PNIPAM–NP H-bonding sites. Combining NP addition with field application uniquely alters the solution environment and results in field-dependent rheological behavior that is unseen in polymer-only solutions. These investigations provide fundamental understanding on the interplay of magnetic fields and NP addition on PNIPAM thermoresponsivity which can be harnessed for increasingly complex stimuli-responsive materials.
Neal, C. A. P., Kresge, G. V., Quan, M. C., León, V., Chibambo, N. O., Calabrese, M. A., J. Vinyl Addit. Technol. 2022, 1. https://doi.org/10.1002/vnl.21968
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Journal of Vinyl & Additive Technology
© 2022 The Authors. Journal of Vinyl & Additive Technology published by Wiley Periodicals LLC on behalf of Society of Plastics Engineers.