In this study, biphasic polymer latexes were synthesized by surfactant-free-emulsion polymerization of butyl methacrylate, poly(ethylene glycol) methyl ether methacrylate, and 2-(methacryloyloxy) ethyl trimethyl ammonium chloride. The latexes synthesized were composed of hydrophobic core phase and hydrophilic shell phase. Nano-structured film morphology could be obtained by annealing the biphasic polymer latexes between the two transition temperatures. It was found that the unique film morphology gave a viscoelastic property to the film. Scanning electron microscope and atomic force microscope images revealed that the biphasic polymer latexes deposited effectively onto the entire hair surface upon conditioning with 1 wt% polymer concentration in water. Consequently, they formed a smooth polymer membrane thereon, showing a high potential for a new hair cosmetic ingredient.