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Effect of polymer backbone

Effect of polymer backbone. We can make use of local concentration effects. [Pg.2]

Shah VM, Hardy BJ, and Stem SA. Solubility of carbon dioxide, methane and propane in silicone polymers. Effect of polymer backbone chains. J Polym Sci 1993 B31 313-317. [Pg.265]

The effect of different backbones on ero.sion rates was demonstrated in a study of the homologous poly[ (p-carboxyphenoxy)alkane] series. As the number of methylene groups in the backbone increased from 1 to 6, thus decreasing the reactivity of the anhydride linkage and rendering the polymer more hydrophobic, the erosion rates underwent a decrease of three orders of magnitude (4). [Pg.47]

There are, however, things about the polymer structure which are not known for certain. We assume that the reaction occurs in a random manner along the polymer backbone but there is little evidence at all concerning this problem and a detailed analysis must await future research. In addition, we know very little about the effects of polymer tacticity on the reaction shown in Equation 21. This also remains to be studied. On the other hand, we are confident that this reaction does not lead to a novel crosslinking reaction sequence since these polymers are soluble in a number of different solvents (Table II). [Pg.97]

In all cases, previously reported polymer-bound PTCs are ones which contain one PTC site/functionalized arm of polymer. Because of the ability to vary the nature of the substrate introduced onto the polymer arm, the preparation of a polymer-bound PTC with more than one PTC site/ functionalized arm of polymer becomes possible. In theory, then, the number of grams of polymer backbone material needed to carry a particular level of required PTC active-site equivalency would be less for a "multi-site substance compared to previously reported polymer-bound "single-site" PTCs. Similar considerations apply as well to nonpolymeric "multi-site" PTCs derived from simple, polyhalo substrates. Therefore, in general, "multi-site" PTCs offer the potential (1) of providing greater PTC activity on a PTC site/g of PTC needed for catalytic activity basis and (ii) of effecting a particular synthetic transformation under milder and/or more efficient conditions. Thus, economy of scale and efficiency are important considerations for both polymeric and nonpolymeric "multi-site" PTCs. [Pg.170]

Figure 3.31 Effect of the number of polymer backbone bonds on the Newtonian viscosity... Figure 3.31 Effect of the number of polymer backbone bonds on the Newtonian viscosity...
While for m-l.c. s the state of order is only determined by the anisotropic interactions of neighbouring molecules, for the polymers additionally a disturbing effect of the backbone via the flexible spacer on the anisotropic order of the mesogenic side chains is to be expected and vice versa. Therefore it is of interest to investigate whether... [Pg.121]

Although the interface models by the MD methods provide a picture of the atomic distribution of the interface, because of the limitation of the MD method, the details of the interface structure in the vicinity of the electrode is not accurate. The effect of polymer side groups and backbone on the interface structure, specifically the... [Pg.338]

Leech, D., Forster, R.)., and Smyth and Vos, ).G. (1991) Effect of composition of polymer backbone on spectroscopic and electrochemical properties of ruthenium(l l)bis(2,2 -bipyridyl)-containing 4-vinylpyridine styrene copolymers. Journal of Materials Chemistry, 1 (4), 529-635. [Pg.75]

The stabilizing effects of polymer molecules are critically dependent upon their spatial extension and, thus, upon their conformation. It is therefore necessary to preface our detailed consideration of the stabilizing effects of polymer molecules by a discussion of their conformational properties. The number of conformations that are accessible to the normal carbon backbone polymer is of order 2", where n is the number of bonds in the polymer. Clearly, even for quite low molecular weights (e.g. 10 000), the number of individual conformations available to each polymer molecule is of order 2 ( 10 °), which is astronomically large. Consideration of individual conformations of polymers is clearly precluded. Statistical procedures have therefore been devised for describing polymer conformations. [Pg.62]

PALS results allow a comparison of the effect of polymer substituent and backbone chemistry on the relative size and concentration of free volume elements. The methane solubility is not strongly correlated with the PALS free volume parameters (similar to the result shown for fractional free volume in Figure 6a). The methane diffusivity and permeability of these polyisophthalamides are strongly... [Pg.318]

Effect of the Backbone (PEL) Structure on Subsequent Protein Adsorptlcn. The graft copolymer architecture was found to influence the subsequent serum-adsorption suppression. All of the polymers investigated demonstrate adsorption on silicon/ titanium dioxide surfaces in the areal density range of about 150 ng/cm, as shown in Figure 9. Of the two comb copolymers with PEG side chains of mol wt 5000, PLL(375)-g[5.6]-PEG-(5) demonstrates only a slightly more pronounced suppression... [Pg.242]

The previous discussions on the effect of spacer unit and the effect of mesogenic unit on mesomorphic behaviour were illustrated using a small range of polymer backbones. [Pg.108]

However, there is an enormous number of possible polymer backbones that can be used for generating SCLCPs, but only a small selection have been widely used in the synthesis and evaluation of SCLCPs. In general, poly(siloxanes) and poly(aciylates) constitute the vast majority of SCLCPs. The reported role of the spacer group is to decouple the effects of the backbone from those of the mesogenic side chains. Accordingly, the backbone should not influence the mesomorphic properties of SCLCPs. However, decoupling is... [Pg.108]


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Polymer backbone

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