Effects of copolymer concentration and chain length on the pH-responsive behavior of diblock copolymer micellar films

Kenichi Sakai, Emelyn G. Smith, Grant B. Webber, Erica J. Wanless, Vural Bütün, Steven P. Armes, Simon Biggs

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The pH-responsive behavior of adsorbed diblock copolymer films of PDMA-PDEA (poly(2-(dimethylamino)ethyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate)) on silica has been characterized using a quartz crystal microbalance with dissipation monitoring (QCM-D), an optical reflectometer (OR) and an atomic force microscope (AFM). The copolymer was adsorbed at pH 9 from various copolymer concentrations; QCM-D measurements indicate that the level of desorption when rinsed at pH 9 depends on the initial copolymer concentration. The adsorbed films produced at pH 9 generally have low charge densities; adjusting the solution pH to 4 results in a significant protonation of the constituent copolymers and a related interfacial structural change for the copolymer film. OR studies show no significant change during pH cycling, while QCM-D measurements indicate that the adsorbed mass and dissipation alter dramatically in response to the solution pH. The difference between the QCM-D adsorbed masses and dissipation values at pH 4 and 9 were found to be dependent on the initial copolymer concentration. This is due to differences in the initial conformations within the adsorbed copolymer layers at pH 9. The effect of the PDMA chain length on the pH-responsive behavior has also been studied; both the QCM-D adsorbed mass and dissipation of PDMA54-PDEA24 (shorter PDMA block) at pH 4 and 9 were observed to be greater than those of PDMA9X-PDEA2Y (longer PDMA block). This suggests that the normal extension of the adsorbed PDMA54-PDEA24 copolymer films is more significant than that of the PDMA9X-PDEA2Y films on silica.

Original languageEnglish
Pages (from-to)372-379
Number of pages8
JournalJournal of Colloid and Interface Science
Volume303
Issue number2
DOIs
Publication statusPublished - 15 Nov 2006
Externally publishedYes

Fingerprint Dive into the research topics of 'Effects of copolymer concentration and chain length on the pH-responsive behavior of diblock copolymer micellar films'. Together they form a unique fingerprint.

  • Cite this