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Thermoreversible Hydroferrogels with Tunable Mechanical Properties Utilizing Block Copolymer Mesophases As Template

Title data

Krekhova, Marina ; Lang, Tobias ; Richter, Reinhard ; Schmalz, Holger:
Thermoreversible Hydroferrogels with Tunable Mechanical Properties Utilizing Block Copolymer Mesophases As Template.
In: Langmuir. Vol. 26 (21 December 2010) Issue 24 . - pp. 19181-19190.
ISSN 1520-5827
DOI: https://doi.org/10.1021/la1040823

Project information

Project financing: Deutsche Forschungsgemeinschaft

Abstract in another language

Thermoreversible hydroferrogels (FGs) have been prepared via gelation of aqueous maghemite ferrofluids (FFs) using the triblock copolymer Pluronic P123 as gelator. In the investigated concentration range of 28-42 wt % P123, long-term stable homogeneous FGs can be prepared from FFs with a maximum magheinite content of 14 wt %. For higher FF concentrations up to 29 wt %, however, homogeneous FGs were formed only for gelator contents up to ca. 33 wt %. A combination of rheology and mu-DSC was applied as an alternative method to construct the P123 phase diagram, without the need for visual methods or scattering techniques. Using this procedure, we could show that maghemite nanoparticles can be effectively ternplated by the cubic and hexagonal P123 mesophases in a concentration range of 33-38 wt % P123 and FF concentrations up to 14 wt %, respectively. Most importantly, the phase behavior and the corresponding phase-transition temperatures of P123 were not significantly altered. As a result, the FGs show a reversible temperature-triggered transition from a cubic hard gel to a hexagonal gel, which is linked with a softening of the gel. Furthermore, this concept can be applied to template cobalt ferrite nanoparticle effectively, too. Magnetization experiments revealed that the superparamagnetic behavior of the maghemite nanoparticles, which show a Neel type relaxation, is not altered in the corresponding FGs. In contrast, FGs based on blocked cobalt ferrite nanoparticles show a hysteretic behavior, which indicates a strong mechanical coupling between the P123 mesophase and the magnetic nanoparticles.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: ISI:000285217700083
Keywords: ANGLE NEUTRON-SCATTERING; MAGNETIC-FIELD; AQUEOUS-SOLUTIONS; TRIBLOCK COPOLYMERS; NANOPARTICLE ARRAYS; HEXAGONAL PHASE; DRUG-RELEASE; POLYMER GELS; SHAPE TRANSITION; DYNAMIC MODULUS
Institutions of the University: Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics V > Chair Experimental Physics V - Univ.-Prof. Dr. Ingo Rehberg
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 > Chair Macromolecular Chemistry II
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Macromolecular Chemistry II > Chair Macromolecular Chemistry II - Univ.-Prof. Dr. Andreas Greiner
Profile Fields
Profile Fields > Advanced Fields
Profile Fields > Advanced Fields > Polymer and Colloid Science
Profile Fields > Advanced Fields > Nonlinear Dynamics
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics V
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
500 Science > 540 Chemistry
Date Deposited: 14 Apr 2015 07:10
Last Modified: 13 Aug 2018 06:03
URI: https://eref.uni-bayreuth.de/id/eprint/10072