TY  - JOUR
A1  - Kyriakos, Konstantinos
A1  - Aravopoulou, Dionysia
A1  - Augsbach, Lukas
A1  - Sapper, Josef
A1  - Ottinger, Sarah
A1  - Psylla, Christina
A1  - Rafat, Ali Aghebat
A1  - Benitez-Montoya, Carlos Adrian
A1  - Miasnikova, Anna
A1  - Di, Zhenyu
A1  - Laschewsky, André
A1  - Müller-Buschbaum, Peter
A1  - Kyritsis, Apostolos
A1  - Papadakis, Christine M.
T1  - Novel thermoresponsive block copolymers having different architectures-structural, rheological, thermal, and dielectric investigations
JF  - Colloid and polymer science : official journal of the Kolloid-Gesellschaft
N2  - 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.
KW  - Block copolymers
KW  - Thermoresponsive
KW  - Structural investigations
KW  - Mechanical properties
KW  - Thermal behavior
KW  - Dielectric properties
Y1  - 2014
U6  - https://doi.org/10.1007/s00396-014-3282-0
SN  - 0303-402X
SN  - 1435-1536
VL  - 292
IS  - 8
SP  - 1757
EP  - 1774
PB  - Springer
CY  - New York
ER  -