Low cost, controlled crystallinity, chemical, and mechanical stability enable application of polymers in energy, water, electronics, and biomedical industries. Recent studies have shown that tailoring surface properties of polymers impacts their durability and functionality in these applications. However, the functionality and performance of polymer‐based devices and systems are greatly affected by the modification method and the process parameters, highlighting the need for understanding these methods and their mechanisms of operation in detail. The selection of the modification method invariably decides the properties enhanced in the polymer. In this review, various polymer surface modification treatments are discussed. These methods are categorized into physical, chemical, thermal, and optical ways, while illustrating their advantages and disadvantages. This review also explores the surface modification of polymers by patterning which encompasses one or more surface treatment methods. An application‐oriented study is presented discussing the relative importance of a method pertaining to a specific field of end‐application.

Understanding the mechanisms of snow adhesion to surfaces and its subsequent shedding provides means to search for active and passive methods to mitigate the issues caused by snow accumulation on surfaces. Here, a novel setup is presented to measure the adhesion strength of snow to various surfaces without altering its properties (i.e., liquid water content (LWC) and/or density) during the measurements and to study snow shedding mechanisms. In this setup, a sensor is utilized to ensure constant temperature and liquid water content of snow on test substrates, unlike inclined or centrifugal snow adhesion testing. A snow gun consisting of an internal mixing chamber and ball valves for adjusting air and water flow is designed to form snow with controlled LWC inside a walk-in freezing room with controlled temperatures. We report that snow adheres to surfaces strongly when the LWC is around 20%. We also show that on smooth (i.e., RMS roughness of less than 7.17 μm) and very rough (i.e., RMS roughness of greater than 308.33 μm) surfaces, snow experiences minimal contact with the surface, resulting in low adhesion strength of snow. At the intermediate surface roughness (i.e., RMS of 50 μm with a surface temperature of 0 °C, the contact area between the snow and the surface increases, leading to increased adhesion strength of snow to the substrate. It is also found that an increase in the polar surface energy significantly increases the adhesion strength of wet snow while adhesion strength decreases with an increase in dispersive surface energy. Finally, we show that during shedding, snow experiences complete sliding, compression, or a combination of the two behaviors depending on surface temperature and LWC of the snow. The results of this study suggest pathways for designing surfaces that might reduce snow adhesion strength and facilitate its shedding.

Conformal coating of cylindrically‐patterned carbon nano tube micropillars with a dielectric poly‐tetravinyltetrameth ylcyclotetrasiloxane) (PV4D4) film using initiated chemical vapor deposition (iCVD), followed by lithiation for 3 days in a 1 M solution of LiClO4 in propylene carbonate (PC) and annealing at 110 °C for 1 hour, results in partial capillarity‐driven collapse of cylinders and the formation of porous CNT “microcupcakes” that offer potential application as electrodes in 3D Li+ batteries. More details can be found in article number https://doi.org/10.1002/admi.201801247 by Srinivasa Kartik Nemani, Hossein Sojoudi, and co‐workers. Courtesy of Hossein Sojoudi, Sanha Kim, and Gareth H. McKinley, Karen K. Gleason, and A. John Hart groups at MIT.

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Accumulation of atmospheric icing, particularly wet snow, on the visual sensors/navigators of autonomous vehicles (AVs) increases the possibility of accidents by obstructing the lenses of the sensors. Here, two navigator designs were suggested that use airflow across the lens surfaces of the AVs to prevent snow accumulation on them. The impact of airflow intensity across the lens, wind velocity (relative velocity of wind with respect to vehicle), and liquid water content of snow on prevention of snow accumulation on the lenses of the AVs was explored experimentally. Here, artificial snow grains were formed using a novel snow gun and their average sizes at low liquid water content (LWC of ≈ 8%) and high liquid water content (LWC of ≈ 28%) were measured to study the impact of grain sizes on snow accumulation on camera lenses. The effects of wind velocity, snow density, and diameter of the snow grains on their trajectory in the testing section were also studied numerically. The results indicated that the snow grains with higher velocity, density, or diameter possessed higher inertia forces and were more prone to collide with the navigator, increasing collision efficiency of snow grains. We realized that the airflow across the lens effectively prevented snow accumulation on the lens at vehicle/wind velocities of up to 20 mph. The proposed designs actively reduced the snow accumulation on the camera lens, promising to be applied in future AVs. Graphic abstract

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