Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles

Addison, Timothy, Cayre, Olivier J., Biggs, Simon, Armes, Steven P. and York, David (2010) Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles. Langmuir, 26 9: 6281-6286. doi:10.1021/la904064d

Author Addison, Timothy
Cayre, Olivier J.
Biggs, Simon
Armes, Steven P.
York, David
Title Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles
Journal name Langmuir   Check publisher's open access policy
ISSN 0743-7463
Publication date 2010-05-04
Sub-type Article (original research)
DOI 10.1021/la904064d
Volume 26
Issue 9
Start page 6281
End page 6286
Total pages 6
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Abstract Using a layer-by-layer (LbL) approach, this work presents the preparation of hollow microcapsules with a membrane constructed entirely from a cationic/zwitterionic pair of pH-responsive block copolymer micelles. Our previous work with such systems highlighted that, in order to retain the responsive nature of the individual micelles contained within the multilayer membranes, it is important to optimize the conditions required for the selective dissolution of the sacrificial particulate templates. Consequently, here, calcium carbonate particles have been employed as colloidal templates as they can be easily dissolved in aqueous environments with the addition of chelating agents such as ethylenediaminetetraacetic acid (EDTA). Furthermore, the dissolution can be carried out in solutions buffered to a desirable pH so not to adversely affect the pH sensitive micelles forming the capsule membranes. First, we have deposited alternating layers of anionic poly[2-(dimethylamino) ethyl methacrylate-block-poly(2-(diethylamino)ethyl methacrylate)] (PDMA-PDEA) and cationic poly(2-(diethylamino)ethyl)methacrylate-block-poly(methacrylic acid) (PDEA-PMAA) copolymer micelles onto calcium carbonate colloidal templates. After deposition of five micelle bilayers, addition of dilute EDTA solution resulted in dissolution of the calcium carbonate and formation of hollow polymer capsules. The capsules were imaged using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which shows that the micelle/micelle membrane is sufficiently robust to withstand dissolution of the supporting template. Quartz crystal microbalance studies were conducted and provide good evidence that the micelle multilayer structure is retained after EDTA treatment. In addition, a hydrophobic dye was incorporated into the micelle cores prior to adsorption. After dissolution of the particle template, the resulting hollow capsules retained a high concentration of dye, suggesting that the core/shell structure of the micelles remains intact. Finally, thermogravimetric analysis (TGA) of dried capsules confirmed complete removal of the sacrificial inorganic template. As far as we are aware, this is the first demonstration of LbL assembled capsules composed entirely from responsive block copolymer micelles. The results presented here when combined with our previous findings demonstrate that such systems have potential application in the encapsulation and triggered release of actives.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Faculty of Engineering, Architecture and Information Technology Publications
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