| Amphiphilic block copolymer frequently form phase-separated structure.It is similar to small molecular surfactant which can spread on the liquid surface.Therefore,the study of amphiphilic block copolymer LB film has received more attention recent years.By controlling the separation structure,the ultrathin films can be produced with determined morphology,known size and well defined order.It is difficult to study the rich structure and aggregation behavior of LB f ilm during surface area compression.The aggregation and assembly behavior of polystyrene-b-poly(4-vinyl pyridine)(PS-b-P4VP)and polystyrene-b-poly(4-vinyl pyridine)/1-pyrenebutyric acid(PS-b-P4VP/PBA)were studied by using Langmuir-Blodgett(LB)technique and atomic force microscopy(AFM)respectively.Chloroform as a solvent,the dilute solution of PS-b-P4 VP and PS-b-P4VP/PBA were dropped on the water surface.After chloroform evaporation,Langmuir monolayer isotherm and LB film morphology of PS-b-P4 VP and PS-b-P4VP/PBA were studied.The paper is mainly studied the influence on the block ratios and surface pressure of PS-b-P4 VP at the air/water interface,as well as the effect of small molecule addition and spreading solution concentration on aggregation morphology of PS-b-P4VP/PBA at the air/water interface.Through the analysis of Langmuir isotherm and AFM height image,it was shown that as size of hydrophilic block(P4VP)increased,Langmuir isotherms moved to the right which meant that area per molecule increased and resulted in much more aggregation and assembly behavior of Langmuir monolayer,and the morphologies of LB films changed from nanoplate to nanostrands,and last to nanodots.The film thickness decreased as the increasing of P4 VP content.With increasing of the surface pressure,the aggregation structure would become denser.When the surface pressure to a certain value,the aggregation structure would show stacking and form bilayer or multilayer.PS-b-P4 VP mixed with 1-pyrenebutyric acid(PBA),then molecules can form hydrogen-bonding with P4 VP between the carboxylic acid group of 1-pyrenebutyric acid and pyridine ring of P4 VP.A great impact on Langmuir monolayer with much hydrophilic P4 VP which Langmuir isotherms moved to the right,area per molecule increased,the morpholog y showed obvious change.Adding PBA,morphology transition showed the trends like increasing the volume fraction of P4 VP segment,morpholog ies changed from planar to strands or rod-like structure.With the increasing of concentration of PS-b-P4VP/PBA,the film morphologies gradually changed from rod-like structure to dots and the morphologies tended to in order. |
