Langmuir behavior and ultrathin films of new linear-dendritic diblock copolymers

The dendrimer end group modification of a series of PEO-PAMAM linear-dendritic diblock copolymers to various chemical functionalities is described. The molecular weight of the PEO block was 2000, and the dendrimer generations used were one to four. The amphiphilic behavior of the modified diblocks was studied by spreading monolayers of the material at the air-water interface of a Langmuir trough and recording the pressure-area isotherm. Stearate-terminated diblocks were found to give stable monolayers which formed condensed phases on compression. The limiting area per molecule in the condensed phase measured from the pressure-area isotherm suggests interesting effects of dendrimer morphology, curvature, and size on the organization of the diblock monolayer at the air-water interface. Physisorbed films of the diblocks with third and fourth generation dendrimer blocks were made by transferring the diblock monolayer onto hydrophobically functionalized surfaces and are reported here for the first time. Films made by transferring at high surface pressures were continuous, free of holes, and relatively smooth. Z-type multilayer films were formed for both of the diblocks studied.