Layer-by-layer assembly of zeolite crystals on glass with polyelectrolytesas ionic linkers

ZSM-5 crystals and glass plates tethered with trimethylpropylammonium iodid e and sodium butyrate, respectively, (denoted as Z(+), Z(-), G(+), and G(-) , respectively) were prepared. Treatment of G(-) with Z(+) suspended in eth anol results in monolayer assembly of Z(+) on G(-) (G(-)/Z(+)) with high su rface coverage. The zeolite crystals have a strong tendency to closely pack and align with the b-axis normal to the glass plate, despite large positiv e zeta potentials. Subsequent treatment of G-/Z+ with Z- leads to second-la yer assembly of Z(-) on G(-)/Z(+) (G(-)/Z(+)/Z(-)), but with rather poor co verage. Sequential treatment of G(+) with poly(sodium 4-styrenesulfonate) ( Na+PSS-), poly(diallyidimethylammonium chloride) (PDDA(+)Cl(-)), and Na+PSS - followed by Z(+) yields glass plates assembled with monolayers of Z(+) wi th very high surface coverage through the composite polyelectrolyte linkers (G(+)/PSS-/PDDA(+)/PSS-/Z(+)). The zeolite crystals also have a strong ten dency to closely pack and align with the b-axis perpendicular to the substr ate plane. The binding strength between the zeolite crystals and glass plat es is much higher in G(+)/PSS-/PDDA(+)/PSS-/Z(+) than in G(-)/Z(+). Repetit ion of the sequential PSS-/PDDA+/PSS-/Z+ layering for five cycles yields gl ass plates assembled with pentalayers of ZSM-5 crystals [G(+)/(PSS-/PDDA(+) /PSS-/Z(+))(5)]. The observed degrees of coverage and alignment of zeolite crystals in each layer were very high up to the third layers despite the no nuniformity of the sizes and shapes of the zeolite crystals used in this st udy. This report thus demonstrates the feasibility of layer-by-layer assemb ly of micrometer-sized zeolite crystals on glass through electrostatic inte raction between surface-bound, full-fledged ionic centers, especially by us e of polyelectrolyes as the linkers.