A polyurethane surface modifier: Contrasting amphiphilic and contraphilic surfaces driven by block and random soft blocks having trifluoroethoxymethyl and PEG side chains

摘要

A conventional MDI-BD-PTMO polyurethane is modified using 2 wt% polyurethanes (U) having copolyoxetane soft blocks with hydrophobic _3F, CF _3CH _2OCH _2- and hydrophilic MEn, CH _3O(CH _2CH _2O) _nCH 2-, 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 leads to a new morphological model whereby fluorous/PEG-hard block nanoaggregates combine to form near surface features culminating in micron-scale texturing. Modification of a conventional MDI-BD-PTMO polyurethane is effected by 2 wt% polyurethanes (U) having copolyoxetane soft blocks with hydrophobic _3F, CF _3CH _2OCH _2- and hydrophilic MEn, CH _3O(CH _2CH _2O) _nCH _2-, n = 3, 7) side chains. Amphiphilic or contraphilic wetting resulted. AFM imaging led to a new morphological model for modified surfaces whereby fluorous/PEG-hard block nano-aggregates (illustrated) combine to form near surface features.