Free-energy driven dispersion formation is of intense interest because microscopic to nanoscopic phase separation from macroscopic phases of chemical components involves an intriguing balance of chemical forces that result in apparent thermodynamic stability. We earlier demonstrated how stimuli-responsive block copolymers comprising polymerize ionic liquid (PIL) blocks could be prepared by modified emulsion polymerization approaches and demonstrated reversible particle precipitation in the nano-scale range. Here we report a single-pot condensation polymerization approach to synthesizing polyurethanes (PUs) in solvent, wherein aqueous compatibility is induced by using imidazolium hydroxide salts (ionic liquids) as chain terminating groups. Effects of various diisocyanates, diols, crosslinking agents, and chain terminators on the creation of PUDs (polyurethane dispersions) are described concerning impact on spontaneous self-dispersing when such PUs are dried (of solvent) and placed in water. The size evolution of such (self) dispersion is examined by videography and by dynamic light scattering, and size reduction from more strenuous activation by sonication is studied. Effects of indifferent salt on aqueous stability are measured, and anion-dependent stimuli-responsiveness is demonstrated and characterized. This stimuli-responsiveness appears based on tuning imidazolium-anion pair solubility by anion exchange. Film formation is also examined. Water-sensitive films with weak mechanical properties are obtained and appear promising for hydrogel delivery applications.

Self-dispersing and stimuli-responsive polyurethane dispersions

255th National Meeting (2018)

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