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Water-ice transformation of few nm nanodroplets plays a critical role in nature including climate change, microphysics of clouds, survival mechanism of animals in cold environments, and a broad spectrum of technologies. In most of these scenarios, water-ice transformation occurs in a heterogenous mode where nanodroplets are in contact with another medium. Despite computational efforts, experimental probing of this transformation at few nm scales remains unresolved. Here, we report direct probing of water-ice transformation down to 2 nm scale and the length-scale dependence of transformation temperature through two independent metrologies. The transformation temperature shows a sharp length dependence in nanodroplets smaller than 10 nm and for 2 nm droplet, this temperature falls below the homogenous bulk nucleation limit. Contrary to nucleation on curved rigid solid surfaces, ice formation on soft interfaces (omnipresent in nature) can deform the interface leading to suppression of ice nucleation. For soft interfaces, ice nucleation temperature depends on surface modulus. Considering the interfacial deformation, the findings are in good agreement with predictions of classical nucleation theory. This understanding contributes to a greater knowledge of natural phenomena and rational design of anti-icing systems for aviation, wind energy and infrastructures and even cryopreservation systems.

Recently, intensive research has been conducted on the development of bacterial repelling surfaces because of the disadvantages of the conventional bactericidal leaching and contact-killing surfaces for practical application. Among these bacteriarepelling methodologies, zwitterionic polymers were widely investigated because of its excellent nonfouling properties, but its durability has limited its widespread use since most of the surfaces were developed by constructing polymer brushes via atom transfer radical polymerization (ATRP). In this study, we developed zwitterionic polymer surfaces with desirable mechanical and chemical durability for long-term use through simple blending of poly(sulfobetaine methacrylate) (PSBMA)/poly(ether sulfone) (PES) semi-interpenetrated networked microgels with hydrophobic PES polymer matrix. Results show that the as-prepared surfaces can efficiently induce hydration layers and, thus, reduce the bacterial attachment through resisting nonspecific protein adsorption. The bacterial adhesion for Escherichia coli and Staphylococcus aureus was investigated under both flow and static conditions. This work has set a paradigm for developing durable antibacterial surfaces with nonfouling properties.

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