Principle of Porous Polymers

The book was initially eonstrueted with a historical development sequenee of porous polymers eombined with illustrations of structure-property correlations. Eaeh ehapter provides an example of a particular element of porous polymers. Chapter 1 provides a summary of porous polymers and discusses the relationship between structure and function. In Chapter 2, the design principles of porous polymers are diseussed and modification methods are introdueed, while Chapter 3 introduees the synthetic routes and reactions used in polymerization. An understanding of these reactions is essential if we are to understand the origin of the ordered or amorphous structure of porous polymers. Chapter 4 describes the first porous polymers, developed in the 1990s and named hypercrosslinked polymers or Davankov-type resins. Chapter 5 focuses on the first soluble polymer with intrinsic microporosity that was reported in 2002. Meanwhile, Chapter 6... 

CO2 as a byproduct during the combustion of fuels in industrial plants and automobiles is a major contributor to global warming. Hence, the selective capture of carbon dioxide requires special attention from the scientific community. The principle sources of CO2 that cause harm to the environment are contaminated natural gas, containing a mixture of methane and CO2 (known as pre-combustion), and exhaust gas generated in industiy or from automobiles (post-combustion). Separate physical conditions are needed for CO2 capture from pre- and post-combustion mixtures, and a variety of porous polymer networks, both soluble and insoluble, have been involved in CO2 capture with consideration of their pore dimensions. " ... 

Figure 22.1 Principle of swelling polymer-based responsive barriers, (a) fibrous membrane, (b) porous membrane.

Presently, the most successful adsorbents arc microporous carbons, but there is considerable interest in other possible adsorbents, mainly porous polymers, silica based xerogels or zeolite type materials. Regardless of the type of material, the above principles still apply to achieving a satisfactory storage capacity. The limiting storage uptake will be directly proportional to the accessible micropore volume per volume of storage capacity. 

When a dilute solution of a polymer (c << c ) is equilibrated with a porous medium, some polymer chains are partitioned to the pore channels. The partition coefficient K, defined as the ratio of the polymer concentration in the pore to the one in the exterior solution, decreases with increasing MW of the polymer (7). This size exclusion principle has been used successfully in SEC to characterize the MW distribution of polymer samples (8). 

Gas-filled plastics are polymer materials — disperse systems of the solid-gas type. They are usually divided into foam plastics (which contain mostly closed pores and cells) and porous plastics (which contain mostly open communicating pores). Depending on elasticity, gas-filled plastics are conventionally classified into rigid, semi-rigid, and elastic, categories. In principle, they can be synthesized on the basis of any polymer the most widely used materials are polystyrene, polyvinyl chloride, polyurethanes, polyethylene, polyepoxides, phenol- and carbamideformaldehyde resins, and, of course, certain organosilicon polymers. 

Physical and chemical properties of polymers are dependent on their molecular weight and molecular weight distribution. The separation principle in SEC is based on the forced transport of the polymer molecules through the porous stationary-phase media under the conditions of suppressed interactions of the... 

Adsorbents are used in medicine mainly for the treatment of acute poisoning, whereas other extracorporeal techniques based on physico-chemical principles, such as dialysis and ultrafiltration, currently have much wider clinical applications [1]. Nevertheless, there are medical conditions, such as acute inflammation, hepatic and multi-organ failure and sepsis, for which mortality rates have not improved in the last forty years. These conditions are usually associated with the presence of endotoxin - lipopolysaccharide (LPS) or inflammatory cytokines - molecules of peptide/protein nature [2]. Advantages of adsorption over other extracorporeal techniques include ability to adsorb high molecular mass (HMM) metabolites and toxins. Conventional adsorbents, however, have poor biocompatibility. They are used coated with a semipermeable membrane of a more biocompatible material to allow for a direct contact with blood. Respectively, ability of coated adsorbents to remove HMM solutes is dramatically reduced. In this paper, preliminary results on adsorption of LPS and one of the most common inflammatory cytokines, TNF-a, on uncoated porous polymers and activated carbons, are presented. The aim of this work is to estimate the potential of extracorporeal adsorption technique to remove these substances and to relate it to the porous structure of adsorbents. 

Industrial cells are mainly bipolar consisting of a large number of individual plate cells connected back to back and coupled in blocks according to the filter press principle. If the electrolysis is carried out under pressure, the energy consumption can be reduced by 20%. Further recent developments are the use of porous electrodes, high temperature steam electrolysis and the SPE-process (solid polymer electrolyte). Heavy water, D2O, can be produced as a byproduct in water electrolysis through enrichment in the electrolyte. 

The selective reduction of steroid ketones by means of LiAlH4-activated template polymers can be carried out following the principle of an ion exchanger. Although the application of polymers in template syntheses is currently limited, and the reactions do not always run satisfactorily, this method appears to be a landmark for future rational syntheses. Microporous phases with three-dimensional lattice networks and defined pore structures and sizes can be obtained by the use of molecules or hydrated ions of alkali metals or alkaline earth metals as templates [73]. A concept developed by the Mobil Oil Company for the synthesis of porous materials employs a regular arrangement of molecules formed... 

The principles and apphcations of SLM separation processes have been reviewed several times [4-7]. Briefly, in an SLM system an organic solvent is immobihzed in the pores of a porous polymer or inorganic support material by capillary forces, separating two aqueous solutions the feed (donor) and the strip (receiving, acceptor) phase (Fig. 3.1). The compounds are separated from the aqueous sample feed phase into an organic solvent immobilized in a support diffusing through the membrane phase, and then they are continuously back extracted to the other side of the membrane into the... 

The principle of the method is as follows the polymer sample, dissolved in a proper solvent, is injected at time zero at the entrance of a column which, in general, is metallic and which is filled with a porous gel then it is swept along the column by an eluent, i.e. pure solvent, which an adequate applied pressure forces to circulate through the column (see Fig. 1.13). The experiment shows that polymers with higher masses come out first. 

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