Synthesis and liquid-liquid extraction of non-agglomerated Al(OH)3 particles for deposition of cellulose matrix composite films

A cathodic electrophoretic deposition (EPD) method has been developed for the deposition of quaternized hydroxyethyl cellulose ethoxylate (QHECE) films. A quartz crystal microbalance was used for in-situ investigation of the deposition yield in dilute QHECE solutions. The deposition rate increased with increasing QHECE concentration in the range of 1-10gL^-1. Aluminium hydroxide (AH) was prepared by a chemical precipitation method and used as a flame retardant additive for QHECE. AH particle agglomeration was avoided by a new strategy, based on combined synthesis and liquid-liquid extraction method. In the biomimetic surface modification approach, 3,4-dihydroxybenzaldehyde (R'-CHO) and 2,3,4-trihydroxybenzaldehyde (R''-CHO) were used for particle modification during synthesis. The Schiff base reaction at the water-n-butanol interface between R'-CHO or R''-CHO adsorbed on the particle surface in water, and hexadecylamine in the n-butanol phase, allowed for efficient particle modification and phase transfer from water to the n-butanol phase. The extraction mechanism was confirmed by FTIR investigation. The modified particles showed good suspension stability and were utilized for the EPD of smooth and uniform QHECE-AH films. The formation a composite material, which contained flame retardant AH in the QHECE matrix was confirmed by the thermogravimetric and differential thermal analyses. Further development of the particle synthesis and liquid-liquid extraction method can be used for the fabrication of advanced QHECE composites, containing various functional materials.