A Polyurethane Surface Modifier: Contrasting Amphiphilic and Contraphilic Surfaces Driven by block and random Soft...

A conventional MDI-BD-PTMO polyurethane was modified using 2 wt.% polyurethanes (U) having copolyoxetane soft blocks with hydrophobic 3F, CF₃CH₂OCH₂- and hydrophilic MEn, CH₃O(CH₂CH₂O)_nCH₂-, n = 3, 7) side chains. In contrast to neat 3F-co-MEn-U, 2 wt.% 3F-co-MEn-U compositions have physically stable morphologies and wetting behavior. Surface composition (XPS) and amphiphilic or contraphilic wetting are controlled by the 3F-co-MEn polyoxetane soft block architecture and MEn side chain length. Importantly, θ_rec can be tuned for 2 wt.% 3F-co-MEn-U compositions independent of swelling, which is controlled by the bulk polyurethane. AFM imaging led to a new morphological model whereby fluorous/PEG-hard block nano-aggregates combine to form near surface features culminating in micron scale texturing.