Dual Temperature and pH Responsiveness of Poly(2-(N,N-dimethylamino)ethyl methacrylate-co-n-butyl acrylate) Colloidal Dispersions and their Films
Document Type
Article
Publication Date
9-9-2008
School
Polymer Science and Engineering
Abstract
2-(N,N-Dimethylamino)ethyl methacrylate (DMAEMA) and n-butyl acrylate (nBA) monomers were copolymerized to form p(DMAEMA/nBA) colloidal particles that exhibit pH- and temperature-responsive behavior. Aqueous p(DMAEMA/nBA) colloidal dispersions exhibit second-order lower critical solution temperature (II-LCST) transition, referred to as stimuli-responsive temperature (TSR) for solid films, in the 27−37 °C range manifested by the particle size changes from 148 to 80 nm. Upon pH changes from 2 to 10, the particle size also changed from 205 to 139 nm. When p(DMAEMA/nBA) colloidal particles were allowed to coalesce which was facilitated by the presence of nBA component, the films retained their dual responsiveness and shrink in all the directions at T> TSR while expanding upon pH changes from basic to acidic. Thermodynamic molecular simulations combined with spectroscopic analysis showed that the temperature-responsive behavior results from the collapse of the (dimethylamino)ethyl groups and twisting/buckling of the copolymer backbone, while the pH responsiveness is attributed to protonation/deprotonation of amine functional groups. Molecular simulations also showed that the total volume (V) above TSR decreases by 21.6%, whereas a 13.26% increase occurs at the protonation state, which is in good agreement with the experimental data.
Publication Title
Macromolecules
Volume
41
Issue
17
First Page
6531
Last Page
6539
Recommended Citation
Liu, F.,
Urban, M. W.
(2008). Dual Temperature and pH Responsiveness of Poly(2-(N,N-dimethylamino)ethyl methacrylate-co-n-butyl acrylate) Colloidal Dispersions and their Films. Macromolecules, 41(17), 6531-6539.
Available at: https://aquila.usm.edu/fac_pubs/12825