Ultrathin layers of phosphorylated cellulose derivatives on aluminium surfaces

Abstract

In recent works the self‐assembly process has been investigated to replace the present chromating procedure on reactive metals like aluminium and to improve the lacquer adhesion and corrosion inhibition. These self‐assembling layers were formed of small bifunctional organic molecules with phosphate or phosphonic acid groups attached to the metal substrate. The idea of this work was to apply these results and techniques to cellulose derivatives on implant metals. The formation of ultrathin layers of phosphorylated cellulose derivatives has been reported previously. These ultrathin layers were built on metal substrates like aluminium, titanium or steel for adhesion promotion and corrosion inhibition. Hydroxypropyl‐2‐phosphatepropyl cellulose was synthesised for adhesion on hydrophilic metallic surfaces. Hydroxypropyl‐2‐cinnamoylpropylester cellulose was prepared in order to crosslink the adsorbed layers. The layers were formed on metal surfaces via dip coating from dilute solutions and characterised by means of contact angle measurements, SEM investigations and FT‐IR spectroscopy. Initial corrosion tests were performed.

Single and Double Polymer Layer Arrangements of Acid Groups Containing Cellulose and Basic Groups Containing Polyethyleneimine on Steel

“…In particular, it is well known that the presence of phosphate groups in organic molecules leads to strong adhesion on reactive metal surfaces, which is fundamental for effective corrosion protection 31, 32. Monolayers of cellulose phosphate underline this understanding33 when deposited on aluminum substrates. On the other hand, the findings for layers thicker than a monolayer architecture bearing acidic phosphate groups are somewhat contradictory: obviously such layers of thicknesses ranging from the nanometer to submicron level also act as ion exchange membranes and induce acid corrosion,34 which amongst other things can lead to undesired coloration of polymer layers.…”

“…For this purpose, promising approaches for steel based on single layers of cellulose‐phosphate have been reported in the literature 34. Additionally, the promising performance potential of cellulose phosphate polymers includes very good film forming properties on metal surfaces,33 general non‐toxic behavior35 and application as a thin film 36…”

Recent Development in Phosphonic Acid-Based Organic Coatings on Aluminum

“…[6] Water contact angle measurements (WCA) [5,7,10,16,25,26] Orientation of molecules and binding mode to aluminum…”

“…From the investigation of the temporal behavior of WCA, information about surface coverage and chain ordering was obtained [5]. Finally, the stability of the adsorbed layers was determined by recording advancing and receding contact angles by repeated cycling [10,26].…”

Synthesis and SAM formation of water soluble functional carboxymethylcelluloses: thiosulfates and thioethers

“…Some examples are summarized in the following. oxides of aluminium, titanium and steel (Kowalik et al 2000;Jaehne et al 2002). i-pentyl cellulose (Schaub et al 1992), as well as trimethylsilyl derivatives (Schaub et al 1993) are suitable for the formation of Langmuir-Blodgett multilayers on hydrophobic substrates.…”