Interchain spacing

Finally, a number of observed amyloid diffraction patterns, which are often quite disoriented, giving arced diffraction peaks, show simply the interchain spacing (H) at around 4.8 A on the meridian and the intersheet spacing at around 10-11 A on the equator. In Figs. 1C, D, and 2C, the... 

McQuade DT, Kim J, Swager TM (2000) Two-dimensional conjugated polymer assemblies interchain spacing for control of photophysics. J Am Chem Soc 122 5885-5886... 

Even within the limitations of fixed conformation, early force fields were deficient. The predicted unit cell dimensions were too small by more than 20 percent This situation was remedied by adjusting nonbonded potentials describing the fluorine-fluorine and carbon-fluorine interactions until predicted unit cell dimensions adequately reproduced experimentally measured values. This fitting was actually carried out using structural information from several polymers and was not an ad hoc parameterization for PTFE. It should also be pointed out that reproducing PTFE cell dimensions was a process of achieving an approximately correct interchain spacing for an approximate helix since the actual crystalline structure was not known at that time. Subsequently, it has become... 

Extensive studies of the temperature dependence of the PD have been made by DXS and neutron scattering experiments.34-36 The PD at room temperature is incommensurate with the basic lattice with a repeat distance of 6.67 dpt—pt. At room temperature there is little correlation between the chains whereas at 37 K the PD/CDWs are partially ordered in three dimensions. At 80 K the correlation length along the chains is over 100 Pt atoms whereas the interchain correlation length is only about five interchain spacings.35... 

The crystallinity of m-polyacetylene has been estimated to be 76-84% by x-ray diffraction while trans-polyacetylene is 71-79 %6). Observations on Durham polyacetylene 445) showed that the diffraction peak narrowed, and the interchain -spacing decreased, during isomerization and annealing. The x-ray coherence length, a measure of the crystallite size perpendicular to the chains, increased from 2.6 nm to 7.1 nm, compared with 30 nm for polyethylene. 

Metallic polymers have a lower density of electrons both the length of the repeat unit along the chain and the interchain spacing are relatively large compared to the interatomic distances in conventional metals. Typically, for metallic polymers N is of the order 5 x 10 cm . Thus, for metallic polymers, the plasma frequency is at approximately 1 eV [66,67]. The reflectance of high quality, metallic polypyrrole (doped with PF ) is shown in Fig. III-2. Metallic polymers exhibit high reflectance (and thus look shiny ) in the infrared, but they are semitransparent in the visible part of the spectrum. The residual absorption... 

S content (%) Conversion (%) Intersheet spacing, A (diffmction angle 26) Interchain spacing, A (diffraction ai e 26) ... 

The first indicates an increase and the second a decrease in permselectivity. The Increase, on the basis of the previously cited structural interpretation, may be attributed to the attainment of the critical interchain spacing or pore diameter. The decrease may be related to a disruption in the uniformity of these spacings. This nonuniformity is due to closer alignment of polymer chains in some regions at the expense of strain-induced separation of polymer chains in other regions. 

The structures with D = 3 (frameworks) are usually most stable mechanically, thermally, and chemically. The layered (D = 2) and chain (D = 1) structures, and especially structures with finite anions (D = 0) with similar bond strength and polarity, are more labile many of these may absorb water into the interlayer or interchain space, or hydrolyze to produce amorphous products or even be water-soluble. In addition, structures with D = 1 or 2 usually display strong anisotropy of the conductivity and/or thermal expansion (although some exceptions are possible). Multiple examples with D = 0, 2, and 3 are listed in Sections 7.4—7.6. 

Pace and Datyner assume that thermal expansion occurs, on average, by a uniform increase in interchain spacing for temperatures both above and below Tg. The temperature dependence of E on T through p is linear over temperature intervals of -50K, and E... 

All these observations are consistent with the hypothesis of deep disorder in both the chain and the 3D structures, the first one being sufficient to explain the loss of the ferrimagnetic properties. The existence of intermediate hydrated materials tends to support the idea of a fragile material, losing progressively water molecules initially located within the interchains space and coordinated to the Mn(II) ion. Thermal differential and gravimetric analyses confirm these views... 

Figure 2. Highly stable sensor polymer designed to bind and detect TNT and DNT. The rigid three dimensional structure provides for interchain spacing that prevents fluorescence quenching and allows for the formation of galleries capable of binding nitroaromatics.

S content Conversion Intersheet spacing, A Interchain spacing, A... 

Figure 3. Linear stacks of mixed valence Ft complex cations and TCNQ anions (the interchain spacing determines the stoichiometry)...

---