Jump to main content
Jump to site search

Issue 12, 2020

Aqueous solution behavior of stimulus-responsive poly(methacrylic acid)-poly(2-hydroxypropyl methacrylate) diblock copolymer nanoparticles

Author affiliations

Abstract

Poly(methacrylic acid)-poly(2-hydroxypropyl methacrylate) (PMAA50-PHPMA237) diblock copolymer nanoparticles are synthesized via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization, which is an example of polymerization-induced self-assembly (PISA). These nanoparticles exhibit complex stimulus-responsive behavior in dilute aqueous solution. They undergo macroscopic precipitation at low pH owing to protonation of the PMAA steric stabilizer. However, adjusting the solution pH above the pKa of 6.3 for the PMAA block ensures colloidal stability and confers thermoresponsive behavior. The degree of ionization of these anionic stabilizer chains increases at high pH, which leads to increasingly negative zeta potentials as judged by aqueous electrophoresis. Variable temperature dynamic light scattering (DLS) studies indicate the formation of progressively larger nanoparticles at higher temperatures, with TEM images providing evidence for weakly anisotropic nanoparticles at 50 °C. These observations are consistent with variable temperature 1H NMR spectroscopy studies, which indicate gradual dehydration of the structure-directing PHPMA block. Rheology measurements on a 20% w/w copolymer dispersion indicate a critical gelation temperature of around 10 °C and a gel modulus (G′) of approximately 1000 Pa at 25 °C. Shear-induced polarized light imaging (SIPLI) studies confirm the presence of weakly anisotropic worm-like particles under such conditions.

Graphical abstract: Aqueous solution behavior of stimulus-responsive poly(methacrylic acid)-poly(2-hydroxypropyl methacrylate) diblock copolymer nanoparticles

Supplementary files

Article information


Submitted
13 Jan 2020
Accepted
11 Feb 2020
First published
19 Feb 2020

Polym. Chem., 2020,11, 2147-2156
Article type
Paper

Aqueous solution behavior of stimulus-responsive poly(methacrylic acid)-poly(2-hydroxypropyl methacrylate) diblock copolymer nanoparticles

S. M. North and S. P. Armes, Polym. Chem., 2020, 11, 2147 DOI: 10.1039/D0PY00061B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.


Social activity

Search articles by author

Spotlight

Advertisements