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Stress in a Stimuli-Responsive Polymer Brush

Manav, M. and Ponga, M. and Phani, A. Srikantha (2021) Stress in a Stimuli-Responsive Polymer Brush. Macromolecules, 54 (1). pp. 170-182. ISSN 0024-9297.

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This work studies the stress in stimuli-responsive planar polymer brushes of neutral water-soluble polymers with low to very high graft densities using strong stretching theory (SST). SST with the Langevin force–extension relation for a polymer chain is extended to the study of stimuli-responsive brushes. The stress profile and other structural properties of a poly(N-isopropylacrylamide) (PNIPAm) brush are then obtained using the extended SST and an empirical Flory–Huggins parameter. The swelling ratio predicted by our model is in good qualitative agreement with experimental measurements from the literature. Our model predicts that the stress in a PNIPAm brush is inhomogeneous and compressive at all temperatures and graft densities. The resultant stress is predicted to increase in magnitude with increasing graft density. A temperature increase results in a decrease in the resultant stress magnitude in low graft density brushes but a mild increase in high density brushes. This contrasting behavior arises from the minimum in the interaction free energy density versus polymer volume fraction curve for a PNIPAm solution at a large volume fraction and the stiffening of chains due to finite extensibility. Our results indicate that the ability to tune the resultant stress by changing the temperature diminishes with increasing graft density.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Manav, M.0000-0002-8498-4144
Ponga, M.0000-0001-5058-1454
Phani, A. Srikantha0000-0003-2835-2721
Additional Information:© 2020 American Chemical Society. Received: July 30, 2020; Revised: November 9, 2020; Published: December 28, 2020. The authors thank Natural Sciences and Engineering Research Council of Canada (NSERC) for its funding through CREATE (NanoMat program at UBC), Discovery grant, and the Collaborative Health Research project jointly with the Canadian Institute of Health Research (CIHR). The authors declare no competing financial interest.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Canadian Institutes of Health Research (CIHR)UNSPECIFIED
Issue or Number:1
Record Number:CaltechAUTHORS:20200908-151457421
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Official Citation:Stress in a Stimuli-Responsive Polymer Brush. M. Manav, M. Ponga, and A. Srikantha Phani. Macromolecules 2021 54 (1), 170-182; DOI: 10.1021/acs.macromol.0c01783
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105275
Deposited By: Tony Diaz
Deposited On:08 Sep 2020 23:42
Last Modified:13 Jan 2021 18:16

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