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Photoisomerizable and Thermoresponsive N-isopropylacrylamide-Surfmer Copolymer Hydrogels Prepared upon Electrostatic Self-Assembly of an Azobenzene Bolaamphiphile.
- Source :
- Macromolecular Rapid Communications; Mar2013, Vol. 34 Issue 5, p393-398, 6p
- Publication Year :
- 2013
-
Abstract
- 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 <superscript>60</superscript>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<subscript>max</subscript> = 370 nm), while gels containing cis-rich DSHA are orange ( λ<subscript>max</subscript> = 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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10221336
- Volume :
- 34
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- Macromolecular Rapid Communications
- Publication Type :
- Academic Journal
- Accession number :
- 85807382
- Full Text :
- https://doi.org/10.1002/marc.201200630