The dynamic control of thermal transport properties in solids must contend with the fact that phonons are inherently broadband. Thus, efforts to create reversible thermal conductivity switches have resulted in only modest on/off ratios, since only a relatively narrow portion of the phononic spectrum is impacted. Here, we report on the ability to modulate the thermal conductivity of topologically networked materials by nearly a factor of four following hydration, through manipulation of the displacement amplitude of atomic vibrations. By varying the network topology, or crosslinked structure, of squid ring teeth-based bio-polymers through tandem-repetition of DNA sequences, we show that this thermal switching ratio can be directly programmed. This on/off ratio in thermal conductivity switching is over a factor of three larger than the current state-of-the-art thermal switch, offering the possibility of engineering thermally conductive biological materials with dynamic responsivity to heat.

In this work, the effect of laser fluence on Au nanoparticles synthesized via laser ablation in liquids is studied for 1064 nm irradiation with 25 ps pulses. Particle size and polydispersity is found to display a negative trend with fluences up to ∼14 J cm(-2). Erratic size tendencies are observed at low fluences, i.e. slightly above the ablation threshold. This overall behavior is reconciled with recent computational studies and to fluctuations in ablation due to surface morphology. The effectiveness of the commonly used surfactant sodium dodecyl sulfate (SDS) is shown to diminish at higher fluence due to pyrolysis. In addition, shadowgraph imaging of the cavitation bubble is shown as a useful technique for determining the ablation threshold. Our findings are in good agreement with threshold values determined by traditional methods and are comparable to computational values, when differences in pulse duration are taken into account.

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