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Novel thermoresponsive block copolymers having different architectures-structural, rheological, thermal, and dielectric investigations

  • 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 inThermoresponsive 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.show moreshow less

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Metadaten
Author:Konstantinos Kyriakos, Dionysia Aravopoulou, Lukas Augsbach, Josef Sapper, Sarah Ottinger, Christina Psylla, Ali Aghebat Rafat, Carlos Adrian Benitez-Montoya, Anna Miasnikova, Zhenyu Di, André LaschewskyORCiDGND, Peter Müller-Buschbaum, Apostolos Kyritsis, Christine M. Papadakis
DOI:https://doi.org/10.1007/s00396-014-3282-0
ISSN:0303-402X (print)
ISSN:1435-1536 (online)
Parent Title (English):Colloid and polymer science : official journal of the Kolloid-Gesellschaft
Publisher:Springer
Place of publication:New York
Document Type:Article
Language:English
Year of first Publication:2014
Year of Completion:2014
Release Date:2017/03/27
Tag:Block copolymers; Dielectric properties; Mechanical properties; Structural investigations; Thermal behavior; Thermoresponsive
Volume:292
Issue:8
Pagenumber:18
First Page:1757
Last Page:1774
Funder:Deutsche Forschungsgemeinschaft (DFG) within the priority program SPP1259 "Intelligente Hydrogele" [Pa771/4, Mu1487/8, La611/7]; Bavarian Research Alliance within the "Bavarian Funding Programme for the Initiation of International Projects"; Deutscher Akademischer Austauschdienst within the program "Hochschulpartnerschaften mit Griechenland"
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie
Peer Review:Referiert