Buildup of Polyelectrolyte Multilayers of Polyethyleneimine and Microfibrillated Cellulose Studied by in Situ Dual-Polarization Interferometry and Quartz Crystal Microbalance with Dissipation
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- 作者：Christian Aulin ; Imre Varga ; Per M. Claesson ; Lars Wå ; gberg ; Tom Lindströ ; m
- 刊名：Langmuir
- 出版年：2008
- 出版时间：March 18, 2008
- 年：2008
- 卷：24
- 期：6
- 页码：2509 - 2518
- 全文大小：549K
- 年卷期：v.24,no.6(March 18, 2008)
- ISSN：1520-5827
文摘
Polyethyleneimine (PEI) and Microfibrillated cellulose (MFC) have been used to buildup polyelectrolyte multilayers(PEM) on silicone oxide and silicone oxynitride surfaces at different pH values and with different electrolyte andpolyelectrolyte/colloid concentrations of the components. Consecutive adsorption on these surfaces was studied byin situ dual-polarization interferometry (DPI) and quartz crystal microbalance measurements. The adsorption dataobtained from both the techniques showed a steady buildup of multilayers. High pH and electrolyte concentrationof the PEI solution was found to be beneficial for achieving a high adsorbed amount of PEI, and hence of MFC, duringthe buildup of the multilayer. On the other hand, an increase in the electrolyte concentration of the MFC dispersionwas found to inhibit the adsorption of MFC onto PEI. The adsorbed amount of MFC was independent of the bulkMFC concentration in the investigated concentration range (15-250 mg/L). Atomic force microscopy measurementswere used to image a MFC-treated silicone oxynitride chip from DPI measurements. The surface was found to bealmost fully covered by randomly oriented microfibrils after the adsorption of only one bilayer of PEI/MFC. Thesurface roughness expressed as the rms-roughness over 1 
m2 was calculated to be 4.6 nm (1 bilayer). The adsorbedamount of PEI and MFC and the amount of water entrapped by the individual layers in the multilayer structures wereestimated by combining results from the two analytical techniques using the de Feijter formula. These results indicatea total water content of ca. 41% in the PEM.
m2 was calculated to be 4.6 nm (1 bilayer). The adsorbedamount of PEI and MFC and the amount of water entrapped by the individual layers in the multilayer structures wereestimated by combining results from the two analytical techniques using the de Feijter formula. These results indicatea total water content of ca. 41% in the PEM.