The Adsorption Behavior Of Self-assembly Amphiphilic Particles At The Air-water Interface

It had studied the interaction and interface adsorption of the two self-assembly amphiphilic particles at the air-water interface in this paper. One self-assembly amphiphilic nanoparticles were formed by surfactant and polymer, another self-assembly hydrophobic bacterial particles were formed by bacteria and chitosan. After the characterizing the physicochemical properties of amphiphilic particles, the research methods of the interfacial adsorption behavior were including LB films analysis and interface dilational rheology method.The amphiphilic nanoparticles were formed by mixing cationic surfactants alkyltrimethylammonium bromide DTAB or TTAB and poly (sodium4-styrene-sulfonate) based on electrostatic attraction. The results showed that the amphiphilic nanoparticles can absorb at the air-water interface and form a Langmuir monolayer, with the surface tension of the solutions declining sharply. The surface pressure variation with time showed that the instability and dissociation or rearrangement of the amphiphilic nanoparticles at the air-water interface. Interfacial effect induced amphiphilic particles dissociated to surfactant/polymer complex molecules.The main conclusions of this system were as follows:(1) The amphiphilic nanoparticles formed by DTAB/PSS were negatively charged and it formed by TTAB/PSS was positively charged. The surface pressure variation with time showed that the interface self-assemble particles occurring self-dissociation dynamic process. PSS promoted the dissociation of amphiphilic nanoparticles at the interface.(2) In a low frequency oscillation process, the reason why the dilational viscosity reached at a peak was a polyelectrolyte/surfactant composited membrane formed by the amphiphilic nanoparticles dissociation and rearrangement. It caused the more viscous behavior. With the longer hydrophobic carbon chain of the surfactant, the interaction between the components and the modulus of expansion were smaller.Another system of this study was the adsorption behavior of self-assembly complexs formed by hydrophobic bacteria particles LSH-5 or bacterial S-1 and chitosan at the air-water interface. The self-assembled bacterial S-1/chitosan complexes were formed mainly based on the electrostatic interaction between them. The main summaries of this system were as follows:(3) TEM figure showed that it formed a network structure through the interaction between the S-1 bacteria and chitosan. Under a certain surface pressure, the Langmuir trough monolayer of self-assembly composited bacteria particles formed by chitosan and bacterial S-1 could be adsorbed stable at the air-water interface, it did not occur self-dissociated. On the contrary, hydrophobic bacterial particles LSH-5 was unstable at the air-water interface and would spontaneously shift from an unstable non-equilibrium state to a stable equilibrium, until bacteria particles were saturated at interface.(4) With the increasing concentration of chitosan, acetic acid concentration, the concentration of bacteria, the total number of the sub-phase ion (charge) and the sub-phase salinity, the elastic modulus and the viscous modulus of hydrophobic bacterial particle were increased.