Layer‐by‐layer self‐assembly of a lignin–poly(vinyl alcohol) based polyelectrolyte with a conductivity method

Abstract

ABSTRACTIn this study, we made a new attempt to examine the relationship between the conductivity and the concentration of a polyelectrolyte solution and to prepare multilayer films with cationic lignin and polyanions through layer‐by‐layer self‐assembly. The nitrogen content of trimethyl lignin quaternary amine salt (TLQA) was 3.56%, and the carboxyl content of carboxymethylated poly (vinyl alcohol) (CMPVA) was 0.62 mmol/g. Attenuated total reflectance spectra confirmed that TLQA and CMPVA were fabricated and assembled successfully. The concentration of TLQA had a polynomial correlation with the conductivity [correlation coefficient (R2) = 0.9953], and the concentration of CMPVA was linear with the conductivity (R2 = 0.9819). The electrostatic sequential adsorption process was monitored with a UV–visible spectrophotometer, and the morphology of the (TLQA/CMPVA)n (where n is the number of double membranes) multilayer film was observed by atomic force microscopy and scanning electron microscopy. When the absorbance of the (TLQA/CMPVA)n multilayer film increased linearly, the linear equation was y = 0.0267x + 0.07453 and R2 was 0.9735. When five layers of TLQA and CMPVA were assembled, the surface root mean square roughness of TLQA and CMPVA were 21.07 and 65.28 nm, respectively. When the number of layers increased, the film surface roughness increased. The stability of the multilayer films in aqueous solution was determined by a conductivity meter. The (TLQA/CMPVA)n multilayer film was stable in water. The results of the research demonstrate for the first time that TLQA and CMPVA could be assembled and successfully driven by electrostatic forces. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44416.