Document Detail


Photoisomerizable and Thermoresponsive N-isopropylacrylamide-Surfmer Copolymer Hydrogels Prepared upon Electrostatic Self-Assembly of an Azobenzene Bolaamphiphile.
MedLine Citation:
PMID:  23355321     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Photoreactive and thermoresponsive N-isopropylacrylamide (NIPAM)-surfmer copolymer hydrogels containing 4,4'-di(6-sulfato-hexyloxy)azobenzene (DSHA) dianions are described. The functional hydrogels are obtained in a two steps. First a micellar aqueous solution of (11-(acryloyloxy)undecyl)trimethylammonium bromide (AUTMAB) and NIPAM is exposed to (60) Co-gamma irradiation, and a thermoresponsive copolymer gel is obtained. Second, DSHA is included by shrinking the gel at 50 °C and subsequent reswelling in an aqueous solution of DSHA disodium salt at 20 °C. Reswelling is accompanied by electrostatic adsorption of DSHA dianions at the positively charged AUTMAB headgroups replacing the bromide ions. Gels containing trans-DSHA are transparent yellow at room temperature (λ(max) = 370 nm), while gels containing cis-rich DSHA are orange (λ(max) = 460 and 330 nm). Energy dispersive X-ray measurements indicate that 41% of the bromide ions are exchanged if trans-DSHA is used for adsorption, and only 7.5% if cis-DSHA is used. The incorporation of DSHA lowers the lower critical solution temperature (LCST) from 34 to 32 °C. Below the LCST, DSHA can be switched from the trans- to the cis-rich state and vice versa upon irradiation with UV (λ = 366 nm) or visible light (λ ≥ 450 nm). Above the LCST no photoreaction takes place.
Authors:
Tatjana Friedrich; Tamara Mielke; Monika Domogalla; Maria Hentschel; Katharina Kraus; Bernd Tieke
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-28
Journal Detail:
Title:  Macromolecular rapid communications     Volume:  -     ISSN:  1521-3927     ISO Abbreviation:  Macromol Rapid Commun     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9888239     Medline TA:  Macromol Rapid Commun     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Affiliation:
Department of Chemistry, University of Cologne, D-50939 Cologne, Germany.
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