Self-assembly of an environmentally responsive polymer/silica nanocomposite.
Thermoresponsive nanocomposite thin films composed of alternating layers of silica and polymerized N-isopropylacrylamide (NIPAM) or NIPAM plus dodecyl methacrylate (DM) hydrogels were prepared by surfactant-directed evaporation-induced self-assembly (EISA). During EISA, the organic monomers partition within the hydrophobic domains of a lamellar mesophase. In-situ polymerization via a free radical process results in a 1-2 nm thick hydrogel phase sandwiched between layers of silica oriented parallel to the substrate surface. The thermoresponsiveness of PNIPAM is preserved in this confined environment, and the polymeric layers reversibly swell and deswell by a factor of 2 in water upon temperature changes around the transition temperature of PNIPAM (32 degrees C). The composition, mesostructure, and environmental response were studied by detailed NMR, TGA, and SAXS analyses.
Garnweitner
Georg
G
Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131, USA.
Smarsly
Bernd
B
Assink
Roger
R
Ruland
Wilhelm
W
Bond
Evelyn
E
Brinker
C Jeffrey
CJ
D000180:Acrylic Resins / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008689:Methacrylates / Q000737:chemistry*; D036103:Nanotechnology; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D012824:Silicic Acid / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry
D000180:Acrylic Resins; D008689:Methacrylates; D011108:Polymers; D013501:Surface-Active Agents; C115846:dodecyl methacrylate; D012824:Silicic Acid; C052970:poly-N-isopropylacrylamide