Slippery and hydrophilic surfaces find critical applications in areas as diverse as biomedical devices, microfluidics, antifouling, and underwater robots. Existing methods to achieve such surfaces rely mostly on grafting hydrophilic polymer brushes or coating hydrogel layers, but these methods suffer from several limitations. Grafted polymer brushes are prone to damage and do not provide sufficient mechanical compliance due to their nanometer‐scale thickness. Hydrogel coatings are applicable only for relatively simple geometries, precluding their use for the surfaces with complex geometries and features. Here, a new method is proposed to interpenetrate hydrophilic polymers into the surface of diverse polymers with arbitrary shapes to form naturally integrated “hydrogel skins.” The hydrogel skins exhibit tissue‐like softness (Young's modulus ≈ 30 kPa), have uniform and tunable thickness in the range of 5–25 µm, and can withstand prolonged shearing forces with no measurable damage. The hydrogel skins also provide superior low‐friction, antifouling, and ionically conductive surfaces to the polymer substrates without compromising their original mechanical properties and geometry. Applications of the hydrogel skins on inner and outer surfaces of various practical polymer devices including medical tubing, Foley catheters, cardiac pacemaker leads, and soft robots on massive scales are further demonstrated.
This article reports a chromic polymer, which is responsive to its shape memory properties and has both the behavior of shape memory polymers and chromic materials. We employed a strategy to fabricate such a smart material, which represents a new principle for making chromic materials. This material is made of shape memory polyurethane with tetraphenylethylene units (0.1 wt %) covalently connected to the soft-segments (PCL, M w 5 4000). The material displays biocompatibility, shape fixity of 88-93%, and almost 100% shape recovery and has reversible mechanochromic, solvatochromic, and thermochromic shape memory effect. The memory chromism represented by the reversible change of emission intensity shows negative correlation with shape fixity, temperature, and existence of solvent. It may be explained that when the soft segments are molten or dissolved in solvent, the shape recovery switch is open, the AIE units are free from crystal binding and can migrate easily to larger areas, thus the AIE units/particles are far apart from each other and the barrier for rotation of phenyl groups is reduced, which lead to the reduction of emission intensity, appeared by no colors or pale colors, and vice versa. Since the switch is a fundamental structural character of SMPs, the shape memory properties have led to the chromism and we call this memory chromic. Shape memory polymers (SMPs) are one group of the most promising smart materials and have drawn increasing interests because of their great potential in different applications such as sensors, actuators, biomedical devices, and textiles.  Typical SMPs have networks realized by the formation of well separated hard and soft phases. The hard phase acts as netpoints, which determine the permanent shape while the soft phase as the switch and can immobilize the temporary shape with different transition stimuli. Take the thermal sensitive SMPs as an example: when they are deformed above the transition temperature (T trans ) of soft segments and then cool down, the network will be fixed and the internal stress will be stored (such process is called programming). Upon heating to T trans or above, the internal stress will be released which enables the recovery of the polymer to the origin shape. With the rapid development of SMPs, recent research interest moves to the integration of SMPs with additional functions such as biodegradability, drug release, and thermochromism.
Uranium present in low concentration in ocean water has the potential to greatly augment current fuel reserve for nuclear power generation, but the challenge of extracting it economically remains. Two new designs of seawater uranium extraction systems are proposed in this paper, a stationary system and a continuous system both of which utilize a braided polymer adsorbent. The stationary system simplifies the recovery procedure and it is predicted to produce uranium at $326/kg. The continuous system is attached to an offshore wind turbine system to eliminate the need for additional mooring and increase the overall energy gathering ability of the wind farm system. This system could maximize the adsorbent yield and achieve a production cost of $403/kg of uranium.
In the present work, a facile approach was employed to fabricate a UV/heat dual-responsive triple shape memory polymer (SMP) by simply mixing Zn(Mebip)2(NTf2)2, a metallosupramolecular unit formed by coordinating 2,6-bis(N-methyl-benzimidazolyl)-pyridine (Mebip) ligands to zinc di[bis(trifluoromethylsulfonyl)-imide] (Zn(NTf2)2), into one part of epoxy resin.
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