Polyvinylidene fluoride chemical structure

In addition to the general steric requirements reported in the introductory section for macromolecular isomorphism, if chains differ in chemical structure, they must also show some degree of compatibility to intimate mixing and not too much different crystallization kinetics. The first condition is strictly similar to the one that applies to liquid mixtures. As a well known example, liquids without reciprocal affinity in general cannot form a unique phase. Attempts to obtain mixed crystals from polyethylene and polyvinyl or polyvinylidene fluoride has been unsuccessful hitherto, in spite of the similarity in shape and size of their chains. In view of the above somewhat strict requirements, it is not surprising that relatively few examples of this type of isomorphism have been reported. 

Polyvinylidene fluoride is a crystalline, high molecular weight polymer containing 50% fluorine. It is similar in chemical structure to PTFE except... 

The study of the morphological characteristics of polymeric membranes is of great interest in the area of membrane science (Resting, 1971). It has been known that one of the keys to better membrane performance lies in the structure of the membrane itself. In turn the morphology of a particular membrane depends upon its processing conditions and the physical and chemical properties of the polymer system under consideration. Membranes from polypropylene (Porter, 1982), high-density polyethylene (Porter, 1982), polyvinylidene fluoride (Hiatt etal., 1984 Hiatt, 1985)... 

Polyvinylidene fluoride (PVDF) has a chemical structure similar to that of PTFE except that it is not fully fluorinated. The chemical structure is shown below ... 

The polymers made from 1,1-difluoroethene (or vinylidene fluoride) are known as polyvinylidene fluoride (PVDF). They are resistant to oils and fats, water and steam, and gas and odors, making them of particular value for the food industry. PVDF is known for its exceptional chemical stability and excellent resistance to ultraviolet radiation. It is used chiefly in the production and coating of equipment used in aggressive environments, and where high levels of mechanical and thermal resistance are required. It has also been used in architectural applications as a coating on metal siding where it provides exceptional resistance to environmental exposure. The chemical structure of PVDF is shown in Fig. 11.40. Some products are copolymers. 

Figure 11.40 Chemical structure of polyvinylidene fluoride (PVDF).

Figure 1 Typical superhydrophobic surface structure fabricated by templating method (A) replica of Co/ocas/a-like leaf surface on PDMS template (Singh et al., 2007), (B) a microporous pattern of polyvinylidene fluoride film (Li et al., 2006), (C) superhydrophobic hair shaped polymer surface grown through an AAO template (Zhang et al., 2006) and (D) water droplet resting on a polymer hot-press transferred pattern (Bormashenko et al., 2006). PDMS, polydimethylsiloxane AAO, aluminum oxide. Images reprinted with permission from (A, B) Elsevier, Copyright2007and2006 respectively, (C, D) American Chemical Society, Copyright2006.

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