Hyperbranched Polyesters Terminated with Alkyl Chains of Different Length at the Air/Water Interface and on Solid Substrates

Hyperbranched polymers (HBPs) are considered less expensive substituents of dendrimers in many applications. It is still a matter of discussion to what extent properties of structurally defected HBPs are similar to those of dendrimers with almost perfect structures. To answer this question, thorough investigations of both classes of dendritic polymers are needed. In this work we present the studies of self-assembly of anaphiphilic hyperbranched polyesters with end groups modified with long hydrophobic chains of different length. Despite the structural nonideality, hyperbranched polyesters form remarkably stable monolayers at the air/water interface even when the terminal groups are functionalized with comparatively short heptanoic chains. Depending on the chain length of the terminal functionalities and temperature, the polymers form monolayers of morphologies ranging from stiff solidlike to soft liquidlike. Langmuir films of the modified polyesters were studied using surface pressure (static and dynamic modes), Kelvin potential measurements, Brewster angle microscopy, relaxation measurements, and compression/decompression experiments. The monolayers were transferred onto silicon and gold substrates using the Langmuir-Blodgett technique. The transferred films were studied using AFM, X-ray reflectivity, and PM-IRRAS measurements. The investigated polymers uniformly covered the surface of the substrates forming compact monolayers.