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pH-Triggered softening of crosslinked hydrogen-bonded capsules

Title data

Elsner, Nils ; Kozlovskaya, Veronika ; Sukhishvili, Svetlana A. ; Fery, Andreas:
pH-Triggered softening of crosslinked hydrogen-bonded capsules.
In: Soft Matter. Vol. 2 (2006) Issue 11 . - pp. 966-972.
ISSN 1744-6848
DOI: https://doi.org/10.1039/b608317j

Official URL: Volltext

Abstract in another language

We report here the first AFM single capsule mechanical measurements on hydrogen-bonded polymeric multilayer microcapsules made of poly(vinylpyrrolidone)/poly(methacrylic acid) (PVPON/PMAA) and of poly(N-vinylpyrrolidone-co-NH2-20)/poly(methacrylic acid) (PVPON-co-NH2-20/PMAA), as well as of capsules derived from these systems via chemical crosslinking. The stiffness of the non-crosslinked hydrogen-bonded capsules was found to be proportional to the square of the wall thickness which is in agreement with previous observations on other multilayer capsules and continuum mechanical theory. The found elastic modulus of 610 MPa for low pH (= 2) is typical for a highly stable, glass-like structure similar to electrostatically bound multilayers. At pH > 6, (PMAA) capsules obtained through chemical crosslinking of hydrogen-bonded (PVPON/PMAA) multilayers, or crosslinked (PVPON-co-NH2-20/PMAA) capsules showed a sharp hundreds-fold stiffness decrease to similar to 1 mN/m which was orders of magnitude lower than those reported earlier for polymeric multilayer systems. pH-Triggered softening was reversible and highly reproducible. Softening of both (PMAA) and (PVPON-co-NH2-20/PMAA) crosslinked capsules resulted from increased PMAA ionization, and additional dissociation of intermolecular hydrogen bonds occurred in the case of (PVPON-co-NH2-20/PMAA) crosslinked system.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors > Chair Physical Chemistry II - Univ.-Prof. Dr. Andreas Fery
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Physical Chemistry II
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Former Professors
Result of work at the UBT: No
DDC Subjects: 500 Science > 500 Natural sciences
500 Science > 530 Physics
500 Science > 540 Chemistry
Date Deposited: 09 Dec 2014 06:33
Last Modified: 09 Dec 2014 06:33
URI: https://eref.uni-bayreuth.de/id/eprint/4030