Molla Islam - Penetration of Polyelectrolytes into Charged Poly(N-isopropylacrylamide) Microgel Layers Confined between Two Surfaces.

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      Publication Details (including relevant citation   information): Islam, Molla R., Serpe, Michael J.,   Macromolecules (Washington, DC, U. S.),   2013, 46 (4), pp 1599-1606

      Abstract: PH and temp. sensitive   poly(N-isopropylacrylamide) (pNIPAm) microgel-based etalons were   fabricated by sandwiching a "monolithic" microgel layer between   two semitransparent, 15 nm Au layers. The devices exhibit visual   color and multipeak reflectance spectra, both of which primarily   depend on the distance between the Au surfaces (mediated by the   microgel diam.). In this submission, we fabricate etalons from   either pNIPAm-co-acrylic acid (pNIPAm-co-AAc) or   pNIPAm-co-N-(3-aminopropyl)methacrylamide hydrochloride   (pNIPAm-co-APMAH) microgels and investigate their response to the   presence of polycations or polyanions. We show that when the   etalon is at a pH that renders the microgels multiply charged,   the microgel layer of the etalon deswells in the presence of the   oppositely charged polyelectrolyte; it is unresponsive to the   presence of the like charged polyelectrolyte. Furthermore, the   etalon's response depended on the thickness of the Au overlayer.   For example, low mol. wt. (MW) polyelectrolyte could penetrate   all Au overlayer thicknesses, while high MW polyelectrolytes   could only penetrate the etalons fabricated from thin Au   overlayers. We hypothesize that this is due to a decrease in the   Au pore size with increasing thickness, which excludes the high   MW polyelectrolytes from penetrating the microgel-based layer.   These devices show promise as MW selective sensors and   biosensors. [on SciFinder(R)]

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