Design of high-performance curling mascara through utilization of smart thermoresponsive polymer

In this study, methoxy poly(ethylene glycol)-b-poly(D,L-lactide), or mPEG-PLA, was used as the smart thermoresponsive polymer in our mascara formulation. The utility of mPEG-PLA in a mascara formulation was investigated by a stepwise build-up in an oil in water (O/W) emulsion. The experimental results may pave the way to a strategy of developing more cosmetic formulation with thermoresponsive shape memory polymers (SMPs).

mPEG-PLA was first incorporated in a simple emulsion for rheological evaluation such as shear flow viscosity and small deformation oscillation measurements over the relevant temperature settings to mascara application. Then, wax and pigment were incorporated to complete the basic formulation as an O/W mascara and evaluated rheologically as before. Finally, the formulation was applied by a heated mascara applicator to false lashes to evaluate its curing and lifting effect.

With 0.8% concentration of mPEG-PLA, the viscosity was able to increase from 0.20 Pas·s to 1.00 Pas·s. At 1.0% concentration of mPEG-PLA, the emulsion samples with mineral oil were evaluated from 55°C to 25°C for its storage modulus (G') and were found to have a consistent shear-thinning characteristic across all temperature range. The sample containing the polymer (M-1) arrived at a markedly higher elasticity when compared against the sample without (M-0). The same result holds true for the set of samples formulated with beeswax instead of mineral oil. When the formulations were applied with a heated mascara applicator on false eyelashes, the formulation containing mPEG-PLA was found to produce a more pronounced and longer-lasting curl.

This preliminary rheological study of an O/W mascara containing mPEG-PLA demonstrated that thermoresponsive SMP can be added to enhance the curl and lifting effect of a mascara formulation.