Polymers intact

To assess the practical application of a-Gal polymers, intact human serum (male, blood type AB) instead of purified human anti-Gal antibody using the inhibition ELISA (Table 2). The results indicated the activity enhancement of the a-Gal polymers as compared to the monomer. The same trends were observed in the interaction of a-Gal polymers with different isotypes of the antibody and with the varied densities of the a-Gal epitope conjugated to the polymer. Interestingly, the IC50 observed with the purified antibodies were... 

Ionic aggregate f f Hydrophilic end group Hydrophobic polymer Intact protein Denaturated protein... 

The term polymer is derived from the Greek words poly and meros, meaning many parts. We noted in the last section that the existence of these parts was acknowledged before the nature of the interaction which held them together was known. Today we realize that ordinary covalent bonds are the intramolecular forces which keep the polymer molecule intact. In addition, the usual type of intermolecular forces—hydrogen bonds, dipole-dipole interactions, and London forces—hold assemblies of these molecules together in the bulk state. The only thing that is remarkable about these molecules is their size, but that feature is remarkable indeed. 

The cellulose molecule contains three hydroxyl groups which can react and leave the chain backbone intact. These alcohol groups can be esterified with acetic anhydride to form cellulose acetate. This polymer is spun into the fiber acetate rayon. Similarly, the alcohol groups in cellulose react with CS2 in the presence of strong base to produce cellulose xanthates. When extruded into fibers, this material is called viscose rayon, and when extruded into sheets, cellophane. In both the acetate and xanthate formation, some chain degradation also occurs, so the resulting polymer chains are shorter than those in the starting cellulose. 

The functionalization of poly(phen5isilane) [99936-07-9] by reaction with CCl and with CBr has also been reported (117). This yields polymers containing Si—Cl or Si—Br bonds, but leaves the Si—C H bonds intact. 

Polypyrroles. Highly stable, flexible films of polypyrrole ate obtained by electrolytic oxidation of the appropriate pyrrole monomers (46). The films are not affected by air and can be heated to 250°C with Htde effect. It is beheved that the pyrrole units remain intact and that linking is by the a-carbons. Copolymerization of pyrrole with /V-methy1pyrro1e yields compositions of varying electrical conductivity, depending on the monomer ratio. Conductivities as high as 10 /(n-m) have been reported (47) (see Electrically conductive polymers). 

There are a variety of reaction systems that allow the formation of cellulose trinitrate [9046-47-3]. HNO in methylene chloride, CH2CI2, yields a trinitrate with essentially no degradation of the cellulose chain (53). The HNO /acetic acid/acetic anhydride system is also used to obtain the trinitrate product with the fiber stmcture largely intact (51,52). Another polymer analogous reaction utilises a 1 1 mixture of HNO and H PO with 2.5% P2O5 to achieve an almost completely nitrated product (54). 

The dienes used are such that the double bonds in the polymer are either on a side chain or as part of a ring in the main chain. Hence should the double bond become broken the main chain will remain substantially intact. Dienes commonly used include dicyclopentadiene, ethylidene-norbomene and hexa-1,4-diene Table 11.17). 

Acrylate polymers also have fully saturated polymer backbones free of any heteroatoms in the main chain. This makes the polymers highly resistant to oxidation, photo-degradation and chemical attack. The acrylate groups are esters, which could be hydrolyzed under severe conditions. However, the hydrophobic nature of most acrylic polymers minimizes the risk for hydrolysis and, even if this reaction happened to some extent, the polymer backbone would still be intact. Other desirable acrylate properties include the following ... 

For additional evaluation of the effect of hydrophobization and the molecular weight of the polymers on the biological immuno-stimulating activity, we investigated the ex vivo cytokine (interIeukin-6 [IL-6], and tumor necrosis factor [TNFj-inducing activity from human peripheral whole blood cells of hydrophobized polymers by use of fractionated poly(M A-CDA) with narrow poly-dispersity. Since this assay uses the intact human cells, it shows more accurate results than in vitro assay using cultured cell line [25]. 

The calculations are applied to a polymer sample following a Schulz-Zimm distribution with Mw = 1.03 x 10s and Mw/N4n = 1.017. These values are representative for the polymer fractions used in most of the experiments in transient elongational flow [147, 155], To visualize the evolution of the degradation, it is convenient to make a distinction between the polymer fraction N from the starting material which remains intact and the fraction Nf newly formed following the degradation process... 

As is the case for cationic polymerisation, anionic polymerisation can terminate by only one mechanism, that is by proton transfer to give a terminally unsaturated polymer. However, proton transfer to initiator is rare - in the example just quoted, it would involve the formation of the unstable species NaH containing hydride ions. Instead proton transfer has to occur to some kind of impurity which is capable for forming a more stable product. This leads to the interesting situation that where that monomer has been rigorously purified, termination cannot occur. Instead reaction continues until all of the monomer has been consumed but leaves the anionic centre intact. Addition of extra monomer causes further polymerisation to take place. The potentially reactive materials that result from anionic initiation are known as living polymers. 

As indicated, this process is defined as mechanical recycling, since the PVC polymer is not broken down into its monomers. Yet, a main difference with classical mechanical recycling is that in the latter the full PVC formulation is kept intact. Here the components that make up the full formulation are separated. This results in the important advantage that the Vinyloop process can deal with rather complicated formulations. According to Solvay the regenerated PVC is comparable in quality to the primary product. 

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