Networks natural polymer

In one of these groups the polymer network consisting of synthetic and natural polymers is formed directly in the process of grafting. The degree of swelling is determined by the reaction condititions including the component ratio, initiation method, and ionogenic monomer content. 

Table 3. Network graft polymers based on synthetic and natural macromolecules...

Models of regular structures, such as zeolites, have been extensively considered in the catalysis literature. Recently, Garces [124] has developed a simple model where the complex pore structure is represented by a single void with a shell formed by n-connected sites forming a net. This model was found to work well for zeolites. Since polymer gels consist of networks of polymers, other approaches, discussed later, have been developed to consider the nature of the structure of the gel. 

Form a graft, block, or interpenetrating network polymer from the natural polymer. 

Fig. 8. — Partial Model of Primary Cell-Wall in Lupin Hypocotyl, Proposed by Monro and Coworkers.49 [The half of the Figure labeled (A) represents the extensin-hemicellulose network, and the half labeled (B) represents the separate, pectic network, which is believed not to involve the wall glycoprotein (extensin). Thus, the cellulose microfibrils (M) are separately cross-linked by two networks of polymers, the first (A) being composed of the wall glycoprotein and polysaccharide (probably hemicelluloses), and the second (B) being composed of the pectic polymers. These two networks have been separated in the Figure for clarity. This model is tentative and incomplete, as the nature of the linkages between the polymers in these two networks has not yet been identified. The...

Gel structures are ubiquitous in foods and responsible for many of their physical properties. The space-filling network of polymers or aggregates provides solidlike properties in the presence of an enormous amormt of water. They are a form of solid water at ambient temperature and in fact they are used to immobilize free water in dietetic products. Gels have been extensively used as model systems to study strue-ture-property relationships due to their simple biphasic nature and the faet that the kinetics of structural changes can be continuously followed by oseiUatory rheometry. 

Natural polymer-based networks have also been investigated. The proteins etc comprising antibodies represent the largest group [164, 166, 169, 189] but this is of course a specialised area. Poly(saccharides), in particular starch [60], dextran [161], dextrin [161] and maltohexose [161], and also natural polypeptides, mainly enzymes [162-165], embody the more accessible biopolymers. In some instances imprinting is achieved through formation of covalent bonds, with crosslinkers like cyanuric chloride or glutaraldehyde. Likewise chitin derivatives similarly crosslinked have been exploited [136]. 

Halls JJM, Walsh CA, Greenham NC, MarsegUa EA, Friend RH, Moratti SC, Holmes AB (1995) Efficient photodiodes from interpenetrating polymer networks. Nature 376 498... 

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