Poly structural modelling

The implementation of the scattering approach and of some simphfied electronic structure models for describing the transport behavior of short poly(dG)-poly(dC) DNA wires [14] have been recently independently proposed within two main classes of models. One involves dephasing [123-125] and the other involves the hybridization of the r-stack [122]. 

Homopolypeptides provide useful secondary structural models for spectroscopic studies on proteins and the ROA spectra of poly(L-lysine) in the three most important conformers are shown in Fig. 7.4. Poly(L-lysine) at alkaline pH... 

Figure 6. Application of packing energy minimization method to poly(ethylene oxide) (16). (a) Starting model of uniform helix (b) stable crystal structure model obtained by energy minimization calculations and (c) the structure determined by x-ray analysis.

Poly(oxyethylene) (POE) (-OCH2CH2—) is an unusual polyether with practically uiilimited solubility in water, unlike other structurally related polymers. At elevated temperatures, however, the isotropic aqueous solution of POE separates into two phases. The mechanism of the water solubility of POE and the phase behavior has attracted much attention of many investigators. Various mechanistic models have in fact been proposed to account for these phenomena a water structure model, a hydrogen bond model, and a conformational model. ... 

Table 5. UV curing in film matrix of the HDDA/BA equimolar mixture, under nitrogen, by poly(ABP-co-AEE)s and by the corresponding combination of poly(ABP) with the ethereal low-molecular-weight structural model IEE [18]...

The photoinitiation activity of poly(ABP)/DMA and IBP/DMA, as compared with that found for poly(ABP) and IBP alone, clearly confirms that the presence of amine activates both the systems. 4-[4-(7V,V-dimethylamino)phenyl] butanoate of 4-hydroxy benzophenone (DMABP), the low-molecular-weight structural model of poly(ABP-co-DMAS), having benzophenone and tertiary amine functions in the same molecule, is foimd [18,22,53] to display an intermediate activity with respect to those observed for poly(ABP)/DMA and poly(ABP-co-DMAS) systems (Table 11). 

Polymeric systems based on side-chain acyloxime moieties and prepared by copolymerization of 1,2-diphenyl-l,2-ethanedione-2-0-acryloyloxime with men-thyl acrylate [poly(BMOA-co-MtA)], have been used as photoinitiators in the UV curing, under nitrogen, of the HDDA/BA equimolar mixture and their activity compared with that of the corresponding low-molecular-weight structural model compound 1,2-diphenyl-l,2-ethanedione-2-0-acetyloxime (BMOAc) [61,84]. 

The relationship between structure and photoinitiation activity has been examined for polymeric systems bearing side-chain 1-substituted cyclohexyl-phenyl ketone moieties in the UV curing of the HDDA/BA equimolar mixture [19,20]. Indeed, the activity of poly[(l-acryloxycyclohexyl)phenyl ketone] [poly (APK)] and styrene/4-chloromethyl-styrene/l-(4-styrylmethyloxy)cyclohexyl phenyl ketone copolymers (PABOK) has been compared with that of the corresponding low-molecular-weight structural models such as 1-hydroxy-cyclohexyl phenyl ketone (HPK), 1-acetoxy-cyclohexyl phenyl ketone (ACPK) and l-(4-isopropyl-benzyloxy) cyclohexyl phenyl ketone (PIBOK). 

Moreover, poly(a-methylolbenzoin methyl ether acrylate) [poly(MBA)] has been checked in the UV induced polymerization of styrene and compared with poly(AB) and other low-molecular-weight structural models such as benzoin, a-methylol benzoin methyl ether (MBE) and a-methylol ben2 in methyl ether acetate (MBAc) [107]. 

As reported in Table 26, poly(MAPO) and poly(MAPO-co-MMA) systems are found [124] to display a higher photoinitiation activity in clear coating formulations, expressed in terms of half-time of the curing process, essentially due to their shorter induction period, as compared with the structural model PIVPO. The polymeric systems, therefore, appear to be preferable for their higher productivity in clear coatings formulations. 

In order to obtain complete solubility of poly(VBPO) and poly(VBPO-co-MMA)s in the HDDA/BA equimolar mixture, UV curing experiments have also been repeated on the same acrylic formulation diluted with chloroform and the results compared with those found for the corresponding low-molecular-weight structural model compound 4-isopropyl-benzoyldiphenylphosphinoxide (IBPO). 

Structure development in blends of poly aniline doped with camphor sulfonic acid (PANI-HCSA) and PA was studied by Hopkins and co-workers (206) using SAXS and SANS. At 3 vol% PANI loading concentration, salt domains with characteristic length of 22 nm are expected to be present in the blend with PA12. This differs from the blend of PAG where a fractal geometry was foimd. For higher salt concentrations, no simple structural model was found. 

THE STRUCTURAL MODEL OF NANOCOMPOSITES POLY(VINYL CHLORIDEVORGANOCLAY FLAME-RESISTANCE... 

The Structural Model of Nanocomposites Poly(Mnyl Chloride)/... 

The composition calculated for a maximum packing density in terms of Fig. 6 and 7 coincides very well the analytical data of the polymer oxidized to its optimum conductivity. Some workers in the field favour an alteirnative structural model which consists again of sheets of polymer chains but with the zig-zag-plane in the plane of the sheet. This model is based on the assumption that there will be an appreciable interaction between the TT-electrons of the chain and the counterions, notably with I -ions in the case of iodine-oxidized poly(aceSylene).,48,49 the same time this model negates appreciable electronic interactions between adjacent chains. 

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