TY  - JOUR
A1  - Raju, Rajarshi Roy
A1  - Liebig, Ferenc
A1  - Hess, Andreas
A1  - Schlaad, Helmut
A1  - Koetz, Joachim
T1  - Temperature-triggered reversible breakdown of polymer-stabilized olive
BT  - silicone oil Janus emulsions
JF  - RSC Advances
N2  - A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis.
KW  - microgels
KW  - step
Y1  - 2019
U6  - https://doi.org/10.1039/c9ra03463c
SN  - 2046-2069
VL  - 9
IS  - 35
SP  - 19271
EP  - 19277
PB  - RSC Publishing
CY  - London
ER  - 
TY  - JOUR
A1  - Schürings, Marco-Philipp
A1  - Nevskyi, Oleksii
A1  - Eliasch, Kamill
A1  - Michel, Ann-Katrin
A1  - Liu, Bing
A1  - Pich, Andrij
A1  - Böker, Alexander
A1  - von Plessen, Gero
A1  - Wöll, Dominik
T1  - Diffusive Motion of Linear Microgel Assemblies in Solution
JF  - Polymers
N2  - Due to the ability of microgels to rapidly contract and expand in response to external stimuli, assemblies of interconnected microgels are promising for actuation applications, e.g., as contracting fibers for artificial muscles. Among the properties determining the suitability of microgel assemblies for actuation are mechanical parameters such as bending stiffness and mobility. Here, we study the properties of linear, one-dimensional chains of poly(N-vinylcaprolactam) microgels dispersed in water. They were fabricated by utilizing wrinkled surfaces as templates and UV-cross-linking the microgels. We image the shapes of the chains on surfaces and in solution using atomic force microscopy (AFM) and fluorescence microscopy, respectively. In solution, the chains are observed to execute translational and rotational diffusive motions. Evaluation of the motions yields translational and rotational diffusion coefficients and, from the translational diffusion coefficient, the chain mobility. The microgel chains show no perceptible bending, which yields a lower limit on their bending stiffness.
KW  - microgels
KW  - linear assemblies
KW  - in situ fluorescence microscopy
KW  - shape analysis
KW  - rotational diffusion
KW  - translational diffusion
KW  - bending stiffness
KW  - actuation
Y1  - 2016
U6  - https://doi.org/10.3390/polym8120413
SN  - 2073-4360
VL  - 8
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Vukicevic, Radovan
A1  - Neffe, Axel T.
A1  - Luetzow, Karola
A1  - Pierce, Benjamin F.
A1  - Lendlein, Andreas
T1  - Conditional Ultrasound Sensitivity of Poly[(N-isopropylacrylamide)-co-(vinyl imidazole)] Microgels for Controlled Lipase Release
JF  - Macromolecular rapid communications
N2  - Triggering the release of cargo from a polymer network by ultrasonication as an external, non-invasive stimulus can be an interesting concept for on-demand release. Here, it is shown that, in pH-and thermosensitive microgels, the ultrasound sensitivity of the polymer network depends on the external conditions. Crosslinked poly[(N-isopropylacrylamide)-co-(vinyl imidazole)] microgels showed a volume phase transition temperature (VPTT) of 25-50 degrees C, which increases with decreasing pH. Above the VPTT the polymer chains are collapsed, while below VPTT they are extended. Only in the case of maximum observed swelling, where the polymer chains are expanded, the microgels are mechanically fragmented through ultrasonication. In contrast, when the polymer chains are partially collapsed it is not possible to manipulate the microgels by ultrasound. Additionally, the ultrasound-induced on-demand release of wheat germ lipase from the microgels could be demonstrated successfully. The principle of conditional ultrasound sensitivity is likely to be general and can be used for selection of matrix-cargo combinations.
KW  - ultrasound
KW  - polymers
KW  - microgels
KW  - lipase release
KW  - controlled release
KW  - thermoresponsive polymers
KW  - biomaterials
Y1  - 2015
U6  - https://doi.org/10.1002/marc.201500311
SN  - 1022-1336
SN  - 1521-3927
VL  - 36
IS  - 21
SP  - 1891
EP  - 1896
PB  - Wiley-VCH
CY  - Weinheim
ER  -