Single polyelectrolyte multilayers deposited onto silica microparticles and silicon wafers

Single polyelectrolyte component multilayers, exemplified by poly(vinyl amine) (PVAm), have been prepared using a method of 3,3′,4,4′-benzophenonetetracarboxylic-dianhydride (BTCDA)-mediated electrostatics and hydrogen bonds LbL assembly. The PVAm with low (15,000 g/mol) and high (340,000 g/mol) molar mass was adsorbed at pH 9.5 onto silica microparticles with particle diameter of 0.015–0.040 mm. The BTCDA cross-linking of the PVAm adsorbed onto silica microparticles results in a surface covered with carboxylic groups. The silica/PVAm–BTCDA, negatively charged over a wide range of pH, can adsorb a new positively charged PVAm layer. A regular increase in the single (PVAm/BTCDA)n polyelectrolyte multilayer onto silica microparticles was observed by streaming potential measurements using a particle charge detector. X-ray photoelectron spectroscopy, the elemental and thermogravimetric analysis, were employed to monitor the (PVAm–BTCDA)n multilayer construction. The topography and thickness of the films deposited on silicon wafers, as a function of the number of PVAm layers, was investigated by atomic force microscopy. Both molar masses (15,000 and 340,000 g/mol) of PVAm were suitable for building (BTCDA)-mediated LbL assembly onto silica microparticles, even the behavior of PVAm on the multilayer formation strongly depends on the molar mass.

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► A new facile route to build single polyelectrolyte multilayers onto solid surfaces was developed.
► BTCDA cross-linking of PVAm adsorbed onto silica results in a surface covered with COOH groups.
► Charge overcompensation of surface took place after each cross-linking stage.