Accumulated radicals by GHz femtosecond burst drive one-step superhydrophobic conversion

Short-lived radicals usually decay before they can drive long-range reactions, making laser-induced radical chain reactions difficult to sustain. Here, we used GHz femtosecond bursts to temporally couple excitation events, allowing reactive intermediates from preceding subpulses to remain available for subsequent reactions and favoring their transient accumulation relative to isolated-pulse excitation. Consistent with this temporally coupled process, the methylphenyl silicone resin/graphene/CuFe 2 O 4 /SiO 2 composite coating exhibits a threshold-like nonlinear wettability transition near 430 subpulses. Compared with the microsecond-spaced single-pulse femtosecond regime, the sub-nanosecond GHz burst produces more extensive chemical conversion, enabling one-step bond reorganization and phase transformation and yielding a low-adhesion superhydrophobic surface with a contact angle of 161° ± 0.7° without posttreatment. Pulse-timing–controlled radical-mediated chemistry thus provides a time-domain strategy for ultrafast materials synthesis.