Janus Hybramers: Self-Adapting Amphiphilic Hyperbranched Polymers

Abstract

Janus structures have attracted a great deal of interest because of their fascinating properties and potential for applications. In this study, we demonstrate that hyperbranched polymers, bearing randomly placed docosyl (C22 alkyl segment) and PEG segments on their periphery, can readily reconfigure so as to segregate the alkyl and PEG segments, thereby generating Janus-type structures that we have termed Janus hybramers. DSC studies clearly reveal an endothermic transition that corresponds to the melting of the docosyl domains, while Langmuir isotherms demonstrate that these polymers form stable monolayers that appear to undergo a slight densification beyond a critical surface pressure; this suggested possible crystallization of the docosyl segments at the air–water interface. AFM studies of the transferred monolayers reveal various interesting aggregate morphologies at different surface pressures suggestive of island formation at the air–water interface; at the same time they also provided an estimate o...