Studies of interactions between silane coupling agents and cellulose fibers with liquid and solid‐state NMR

Abstract

The hydrolysis of three alkoxy-silane coupling agents, γ-methacryloxypropyl trimethoxy silane (MPS), γ-aminopropyl triethoxy silane (APS), and γ-diethylenetriaminopropyl trimethoxy silane (TAS), was carried out in ethanol/water solutions (80/20 w/w) at different pH values and followed by ¹H, ¹³C and ²⁹Si NMR spectroscopy. Acidic media were found to stabilize the hydrolyzed forms. As expected, the formation of silanol groups was followed by their self-condensation to generate oligomeric structures, yielding, ultimately, solid homopolycondensated structures, as analyzed by ²⁹Si and ¹³C high-resolution solid-state NMR. Hydrolyzed MPS in acidic media was then successfully adsorbed onto a cellulose surface and the ensuing substrates submitted to thermal treatment at 110–120 °C under reduced pressure, in order to create covalent bonds between cellulose and the coupling agent. Copyright © 2007 John Wiley & Sons, Ltd.