Polyurethane–acrylate hybrid latexes from miniemulsion polymerization: effect of endgroups on structure and properties

Polyurethanes (PUs) were prepared by condensation of isophorone diisocyanate and polypropylene glycol (PPG) using butane diol as a chain extender. Methoxy or methacrylic endgroups of PUs were obtained upon reacting the residual isocyanate group (NCO) moiety with either methanol or hydroxyethylmethacrylate (HEMA). The resulted PUs were dissolved in mixtures of acrylic monomers, and then the miniemulsion polymerization was conducted. These PUs were quite efficient hydrophobes for polyurethane (PU)‐acrylate hybrid miniemulsion polymerization. It was also demonstrated from the results of differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) that the microphase separation of soft and hard phase of PUs in hybrid latexes was more significant than that of original PUs. The PU containing the methacrylic endgroup was almost fully cross‐linked during miniemulsion polymerization, resulting in less hard–hard segment of PU hydrogen bond in the hybrid polymer. Some specific morphologies were also discussed from transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS). The mechanical properties of these films were studied from the strain–stress curves.