TY  - JOUR
AU  - Kyriakos, Konstantinos
AU  - Aravopoulou, Dionysia
AU  - Augsbach, Lukas
AU  - Sapper, Josef
AU  - Ottinger, Sarah
AU  - Psylla, Christina
AU  - Aghebat Rafat, Ali
AU  - Benitez-Montoya, Carlos Adrian
AU  - Miasnikova, Anna
AU  - Di, Zhenyu
AU  - Laschewsky, André
AU  - Müller-Buschbaum, Peter
AU  - Kyritsis, Apostolos
AU  - Papadakis, Christine M.
TI  - Novel thermoresponsive block copolymers having different architectures—structural, rheological, thermal, and dielectric investigations
JO  - Colloid & polymer science
VL  - 292
IS  - 8
SN  - 1435-1536
CY  - Berlin
PB  - Springer
M1  - FZJ-2015-01167
SP  - 1757 - 1774
PY  - 2014
AB  - Thermoresponsive block copolymers comprising long, hydrophilic, nonionic poly(methoxy diethylene glycol acrylate) (PMDEGA) blocks and short hydrophobic polystyrene (PS) blocks are investigated in aqueous solution. Various architectures, namely diblock, triblock, and starblock copolymers are studied as well as a PMDEGA homopolymer as reference, over a wide concentration range. For specific characterization methods, polymers were labeled, either by partial deuteration (for neutron scattering studies) or by fluorophores. Using fluorescence correlation spectroscopy, critical micellization concentrations are identified and the hydrodynamic radii of the micelles, r h mic , are determined. Using dynamic light scattering, the behavior of r h mic in dependence on temperature and the cloud points are measured. Small-angle neutron scattering enabled the detailed structural investigation of the micelles and their aggregates below and above the cloud point. Viscosity measurements are carried out to determine the activation energies in dependence on the molecular architecture. Differential scanning calorimetry at high polymer concentration reveals the glass transition of the polymers, the fraction of uncrystallized water and effects of the phase transition at the cloud point. Dielectric relaxation spectroscopy shows that the polarization changes reversibly at the cloud point, which reflects the formation of large aggregates upon heating through the cloud point and their redissolution upon cooling.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000339888900004
DO  - DOI:10.1007/s00396-014-3282-0
UR  - https://juser.fz-juelich.de/record/187538
ER  -