GHz femtosecond bursts make a silicone-graphene coating superhydrophobic in one step, 161°
Authors report that radicals from earlier subpulses accumulate within sub-nanosecond bursts, giving a composite coating a low-adhesion surface without posttreatment.
A study in Science Advances describes a femtosecond laser method that converts a composite coating into a superhydrophobic surface in one step. The coating consists of methylphenyl silicone resin, graphene, CuFe2O4 and SiO2. After treatment with GHz femtosecond bursts, it showed a contact angle of 161° ± 0.7° and low adhesion, without posttreatment science.org
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Short-lived radicals usually decay before they can drive long-range reactions, which makes laser-induced radical chain reactions hard to sustain. The authors used bursts to couple excitation events in time. Reactive intermediates from preceding subpulses then remain available for subsequent reactions and accumulate transiently, compared with isolated-pulse excitation.
Wettability changed in a threshold-like, nonlinear way near 430 subpulses. Compared with a single-pulse femtosecond regime with microsecond spacing, the sub-nanosecond burst produced more extensive chemical conversion, including bond reorganization and phase transformation. The authors describe pulse-timing control of radical chemistry as a time-domain strategy for ultrafast materials synthesis.
