The solution behaviors of sulfonated alkali lignin-based polymers (SBAL) at different pH values were investigated by means of dynamic light scattering and transmission electron microscopy (TEM).The results indicated that with the increase of pH

the hydrophilic functional groups of SBAL:sulfonic

carboxyl and phenolic hydroxyl groups were ionized gradually.With the increase of pH

the molecular configuration of SBAL changed from coil chain to extended chain.Moreover

the adsorption characteristics of SBAL on solid/liquid interface at different pH values were determined using a quartz crystal microbalance with dissipation monitoring (QCM-D) and electrostatic layer-by-layer self-assembly

as well as UV-Vis spectroscopy and atomic force microscopy (AFM).The results showed that with the pH increased from 3 to 12

the adsorption amount of SBAL on gold plate and quartz slide decreased at first and then increased

the lowest amount was at pH=9.The adsorption configuration changed from rigid to soft

tight to loose and then tight again.The adsorption conformations of SBAL on gold plate and quartz slide with poly(diallyldimethylammonium chloride) (PDAC) showed mushroom-like structure

pancake-like structure and polymer brushes in the acidic

neutral and alkaline conditions

respectively.Cation- interaction was the main driving force between SBAL and PDAC in the acidic and neutral conditions and the adsorption strength was weak.However

electrostatic interaction played an important role between SBAL and PDAC in the alkaline condition and the adsorption strength was strong.