Attraction between chains

Considering the structure to be ionic, explain why there are no strong forces of attraction between chains. 

In Chapter 6 we talked about the ability of solvent molecules to interact with and surround amorphous polymer chains, leading to the formation of polymer solutions. A closely related phenomenon utilizes a low-molar mass compound to penetrate a polymer and reduce the forces of attraction between chains. Such a compound is called a plasticizer. It must be compatible with the polymer and is almost always nonvolatile. Solvent molecules actually plasticize a polymer sample before forming a solution. However most solvents are not good permanent plasticizers because they diffuse to the surface and evaporate. 

Having forsworn polar substituents, the prescient polymer chemist would quickly see that by elimination, the logical composition would be a polymeric hydrocarbon. The chains would then have to be very smooth and well-fitting to achieve crystallization, because the forces of attraction between chains would be quite weak. The smoothest chain would be one of methylene groups. On consulting the literature, the chemist would be encouraged by the fact that the... 

For x > 0, we have a repulsive solute-solvent interaction which amounts to an attraction between chains, and this repulsion counterbalances the excluded volume effects. 

But dieir most interesting result is related to free surface. What is nice is that they obtained this without being biased by any theoretical prediction ... 

The ability of IR spectroscopy to probe the environment in which bonds vibrate allows it to be used to examine structural ordering of surface modifier molecules. If alkyl chains for example are in a liquid-like state of disorder the dispersion forces of attraction between chains are not maximised and vibration of the C-H bonds is influenced almost solely by the bond stiffness. If on the other hand the chains are in an ordered crystalline array, dispersion forces are maximised. This causes the C-H bonds to become very slightly longer (and therefore weaker) than when in the liquid state. This reduction in stiffness causes the asymmetric C-H stretching vibration frequency of a Cjg alkyl chain to reduce by 3-5 cm. Such frequency shifts have been used by Kellar and co-workers [48] to investigate ordering of oleic acid monolayers and by Liauw and co-workers [13, 49]. Vaia and co-workers [50] have also used this approach to examine the order of alkyl chains of quaternary alkyl ammonium intercalants in organo-clays for nanocomposite applications. 

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