Poly order parameter

It is considered that, if ideal, optically active poly(alkyl(aryl)silane) homopolymer and copolymer systems could be obtained which had stiffer main-chain structures with longer persistence lengths, it should be possible to clarify the relationship between the gabs value and the chiral molar composition. The magnitude of the chirality of the polyisocyanates allowed precise correlations with the cooperativity models.18q In the theory of the cooperative helical order in polyisocyanates, the polymers are characterized by the chiral order parameter M, which is the fraction of the main chain twisting in one helical sense minus the fraction of the main chain twisting in the opposing sense. This order parameter is equal to the optical activity normalized by the value for an entirely one-handed helical polymer. The theory predicts... 

Fig. 12.1.1 Dependence of order parameter, S. of the secondary polymer, spin-labeled poly (methyl methacrylate) (PMMA) and polystyrene (PST), bound to poly(maleic anhydride—styrene )-grafted silica on hexane content in ethyl acetate-hexane cosolvent. Numbers in parentheses are number average molecular weight of the secondary polymer. (From Ref. 48.)...

The strongest residual dipolar couplings were also edited in a non-rotating crosslinked poly(isoprene) series by exciting DQ and triple-quantum coherences in the short time regime [62,63]. From this, the dynamic order parameters of the methylene and methyl groups were estimated and correlated with the crosslink density. Essentially the same behaviour was found as for SBR. 

Low polarisation ratios (<2 1) for absorption had also been found for amorphous PPV (1) deposited from solution by spin-coating on rubbed poly(tetrafluoroethylene) [PTFE]. It is evident that this could be improved on by making use of the high order parameter and self-organising properties of the nematic phase of liquid crystalline electroluminescent polymers such as those (16, 28 and 78-82) shown in Table 6.16. - 2 ° This was then found subsequently to be the case using thermotropic liquid crystalline polyfluorenes, such as 28 and 80 shown in Table 6.6 and segmented PPV derivatives, such as 81. The nematic phase exhibits the lowest viscosity of... 

NMR-studies indicate a reduced segmental mobility and higher order parameter for the central hydrocarbon fragments of bola-surfactants [437] compared to the tail ends of the corresponding monomers. The differences however are less pronounced as for oligomeric poly soaps [68, 69],... 

Takahashi Y, Miyaji K (1983) Long-range order parameter of form II of poly(vinylidene fluoride) and molecular motion in the relaxation. Macromolecules, 76 1789... 

Marx A, Thiele C (2009) Orientational properties of poly-y-benzyl-L-glutamate influence of molecular weight and solvoit on order parameters of the solute. Chem Eur J 15 254-260... 

Anwer and Windle [109,110] reported the kinetics of the alignment of poly (p-hydroxybenzoic add-co-2,6-hydroxynaphthoic acid) s of different molar masses ranging from 4600 to 36000 g mol in a magnetic field applied at elevated temperatures in the nematic state. The order parameter of a specimen held in a magnetic field increased rapidly with time and finally reached a plateau value. The data obtained fitted the following equation ... 

Unoriented poly (p-hydroxybenzoic acid-co-2,6-hydroxynaphthoic acid) exhibited smoothly wandering director fields in three dimensions. Alignment with a 1.1 T magnetic field for 30 min at 300 C transformed this structure to domains with an anisotropic shape within which the polymer was highly oriented, and the global order parameter amounted to 0.85 [110]. Boundaries were of the splay-bend type and involved a 180 director rotation. At lower field strengths, the domains were less... 

Samples of oriented Vectra A950 (poly(hydroxy-benzoic acid (73%) -co-hydroxy-naphthotic acid (27%))), obtained from the surface skin of injection molded specimens, were annealed at different temperatures and the order parameter was assessed by IR spectroscopy and X-ray scattering in a recent study of Wiberg and Gedde [127]. They found... 

To understand the transition to supersonic velocities we also make use of a description of the lattice in terms of both optical and acoustic order parameters. Here, we study a strictly ID model that is a direct map of the fPA structure. However, as far as the properties of the drifting polaron are concerned, the model is more general and quantitatively describes these properties in other polymeric systems, e.g., poly(paraphenylene vinylene) or polythiophene. In the ID model, the displacement of the lattice sites entering Equation 2.14 and Equation 2.16 is described by a single variable u . In the description of the geometry of conjugated polymers, fPA in particular, it is common to study a smoothed atomic displacement order parameter. This optical order parameter is given by... 

It cannot be stressed enough that electric, magnetic, and mechanical (shear fields) produce in fact similar ejfects of enhancing orientation, thus increasing the order parameter s, and also affecting mechanical and other properties in ways already discussed above. There exist even favorite methods of achieving orientation for certain classes of materials. Thus, magnetic fields are typically used to orient poly acrylates, while polysiloxanes are routinely oriented by imposition of ac electric fields. 

Lorthioir, C. Deloche, B. Courtieu, J., Experimental Evidence for a Negative Orientational Order Parameter in a Uniaxially Compressed Poly(dimethylsiloxane) Network. Macromolecules 2001, 34,8835-8837. 

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