Low-surface-energy materials

The specialty class of polyols includes poly(butadiene) and polycarbonate polyols. The poly(butadiene) polyols most commonly used in urethane adhesives have functionalities from 1.8 to 2.3 and contain the three isomers (x, y and z) shown in Table 2. Newer variants of poly(butadiene) polyols include a 90% 1,2 product, as well as hydrogenated versions, which produce a saturated hydrocarbon chain [28]. Poly(butadiene) polyols have an all-hydrocarbon backbone, producing a relatively low surface energy material, outstanding moisture resistance, and low vapor transmission values. Aromatic polycarbonate polyols are solids at room temperature. Aliphatic polycarbonate polyols are viscous liquids and are used to obtain adhesion to polar substrates, yet these polyols have better hydrolysis properties than do most polyesters. 

Altering the surface energy of wood to improve compatibility with low surface energy materials such as polyolefins. 

Low Surface Energy Materials Based on Liquid Crystal-Block Copolymers... 

Conventional polymers do not always possess the combination of desired bulk and surface properties for a specific application. The polymer materials used for microfluidic devices are innately hydrophobic, low-surface-energy materials and thus do not adhere weU to other materials brought into contact with them. This necessitates their surface modification/treatment to render them adhesive. This has prompted the development of a variety of polymer modification techniques, with the aim of developing new materials from known and commercially available polymers that have desirable bulk properties (elasticity, thermal stability, permeability, etc.) in conjunction with newly tailored surface properties (adhesion, biocompatibUity, optical reflectivity, etc.). 

Modifying an Electrospun Fiber Mat with Low Surface Energy Materials... 

Superhydrophobic surfaces (water contact angles higher than 150°) can only be achieved by a combination of hydrophobicity (low surface energy materials) with appropriate surface texture. In nature one can find an array of impressive and elegant examples of superhydrophobic surfaces. For example, on a lotus leaf rain drops bounce off after impact, then entirely roil off the lotus leaf and drag along any dirt particles, without leaving residues. 

This is excellent, except with thermoplastics and rubber where performance is substantially reduced. Low surface-energy materials (polyolefines, fluo-ropolymers and silicone rubbers, for example) may not be bonded without special surface preparation. 

For comprehensive listings of experimental surface tension values for a wide variety of polymers, the reader is referred to several excellent references 3,4-5. The surface tension of even the most polar polymers generally fall well below that of water (as shown in Figure 4) so that in terms of surface tension, polymers should be considered at best only mildly hydrophilic. Poljnners are low surface energy materials in comparison with other classes of materials by virtue of their low mass density and consequently a low interaction density, as is demonstrated in Table 1, which shows typical values for a range of different types of materials. 

In recent years, due to a plethora of potential applications of superhydro-phobicity in daily life, many elforts have been taken to fabricate artificial superhydrophobic surfaces. Depending on the application and material, different methods have been employed to create superhydrophobic smfaces [8], Most of these methods involve either creating a micro/ nano-structme on an inherently hydrophobic material [9,10] or treating a specific micro/nano-structure with a hydrophobic coating [11-14]. For instance, for metallic materials, roughened surfaces have to be coated with low surface energy materials. 

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