Universität zu Köln

Friedrich, Tatjana, Tieke, Bernd, Stadler, Florian J. ORCID: 0000-0002-5849-1485, Bailly, Christian, Eckert, Thomas ORCID: 0000-0003-4054-2915 and Richtering, Walter ORCID: 0000-0003-4592-8171 (2010). Thermoresponsive Copolymer Hydrogels on the Basis of N-Isopropylacrylamide and a Non-Ionic Surfactant Monomer: Swelling Behavior, Transparency and Rheological Properties. Macromolecules, 43 (23). S. 9964 - 9972. WASHINGTON: AMER CHEMICAL SOC. ISSN 0024-9297

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Abstract

Copolymer hydrogels were prepared upon gamma-ray-induced polymerization of aqueous micellar solutions containing N-isopropylaerylamide (NiPAAm) and the surfactant monomer (surfmer) omega-methoxy poly(ethylene oxide)(40)undecyl-alpha-methacrylate (PEO-R-MA-40). Stable, transparent, and thermosensitive hydrogels were obtained in a one-step process. Dose versus conversion measurements showed a complete conversion of comonomer solutions to hydrogels. The size of the surfmer micelles prior and subsequent to polymerization was studied using SAXS measurements. Presence of NiPAAm in the aqueous phase did not influence the size of the PEO-R-MA-40 micelles. During the polymerization process the particle diameter decreased from 7.0 to 5.6 nm probably due to cross-linking in the shell of the micelles. The thermosensitive behavior of the copolymer gels was investigated. The lower critical solution temperature (LCST) of the surfmer-containing gels was higher than for pure poly-NiPAAm (P-NiPAAm) gels, the increase being a direct function of the surfmer concentration. For hydrogels containing small amounts of surfmer, the shrinking at temperatures above the LCST was increased, and the swelling behavior at temperatures below the LCST was slightly increased. The mechanical stability of the copolymer hydrogels was studied using elongational deformation measurements. Presence of surfmer increased the mechanical stability of the hydrogels, the true stress at break being clearly higher for the copolymer gels compared with pure P-NiPAAm gels. A hydrogel containing only 1% (w/w) of surfmer can be elongated up to a true stress being nearly twice as large as for the pure P-NiPAAm gel. This can be explained by the presence of copolymerized micellar aggregates acting as new, stable cross-linking units. A structure model correlating the mechanical properties with a possible network structure is presented.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Friedrich, Tatjana UNSPECIFIED UNSPECIFIED UNSPECIFIED Tieke, Bernd UNSPECIFIED UNSPECIFIED UNSPECIFIED Stadler, Florian J. UNSPECIFIED orcid.org/0000-0002-5849-1485 UNSPECIFIED Bailly, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Eckert, Thomas UNSPECIFIED orcid.org/0000-0003-4054-2915 UNSPECIFIED Richtering, Walter UNSPECIFIED orcid.org/0000-0003-4592-8171 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-490645
DOI:	10.1021/ma1022764
Journal or Publication Title:	Macromolecules
Volume:	43
Number:	23
Page Range:	S. 9964 - 9972
Date:	2010
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	0024-9297
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ANGLE X-RAY; POLY(ETHYLENE OXIDE); AQUEOUS-SOLUTION; GRAFTED HYDROGELS; POLYMERIZATION; MICELLES; POLY(N-ISOPROPYLACRYLAMIDE); MICROEMULSIONS; TEMPERATURE; TRANSITION Multiple languages Polymer Science Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/49064