Fabrication And Caracterization Of Self-assembled Chitosan/Lignosulfonate Multilayer Films

Recent years,the so-called layer-by-layer(LBL) deposition technique of oppositely charged polyelectrolytes can be successfully applied to prepare organic ultrathin films.For their simple fabrication(operation),precisely controlled film thickness and structure,broad range of materials that is available for incorporation into polyelectrolyte multilayers(PEMs),they are applied abroad in many different fields such as drug release,biosensors,photoelectric materials and membrane separation.This paper is concerned with the characters of dilute aqueous solutions of polyelectrolytes(CS＆LGS) and is a system investigation of the basic properties of the multilayers. The influences of many factor on the multilayers are also been studied.Firstly,the surface tension and rheology behavior of dilute aqueous solutions of polyelectrolytes(CS＆LGS) are researched using surface tensiometer and rheometer.As a result, both of CS and LGS also are surfactant and the mixture of CS and LGS can reduce the surface tension until up to the least surface tension while the proportion is 6:4 of LGS/CS.Different mixtures with different property have different critical micelle concentration,with the scale decrease the critical micelle concentration decrease.The mixture solution belongs to non-Newtonian fluid when the shear rate is low,when shear rate than a value it become Newtonian fluid.The ratio of the mixture affects the viscosity.Secondly,the adsorption mechanism and factor that influenced the buildup of PEMs and its structure were studied using UV-VIS spectrum,Contact angle measurement(CA),FTIR spectrum, AFM,FSEM.The results of UV-VIS and CA prove that CS and LGS assembled into multilayers successfully.Through the FTIR test,we can conclude that hydrogenolysis happened in the self assembly process.UV-Vis spectroscopy indicated that the layer growth of CS/LGS films follows the exponential growth model that could be described as:Y=a*e^(n/b)+c,where a,b and c are three parameters.Since this model was found to fit a lot of literature reported cases,the influence on this model related three parameters were discussed.Thirdly,results of UV-VIS showed that the adsorption amount can be basic constant,as the concentration of polyelectrolyte,composition of the organic solvent/water mixtures.While salinity effect the adsorption amount.The stability of the multilayers was measured using TG and EC.TG showed there are two main peaks during the process of thermal degradation,which are weight lost peak of CS and LGS respectively.The results show that the prepared film is more steady than the chitosan film.The stability of the nano films in distilled water under different temperatures is studied by conductivity test.The results of the test indicate that sample films stay stable under the temperature of 24.5 and 60℃,however,when it comes to 100℃,the sample films begin to lose their stability.