Main chain polymers, hydrogen bonding

In a second hypothesis, one can consider that the adsorption is mainly due to hydrogen bonds and that electrostatic attraction between polymer and particles only brings them together. In such case, the influence of c and r on the stability should be related to the number of amide groups available for hydrogen bounds and the increase of salinity should lead to the collapse of the chain and reduce the probability of interparticles bridging. 

This concept has been extended using a poly(aniline) as the main conductive polymer (Fig. 61) [215]. Again, a main chain polymer poly(acrylnitrile) able to form ionic hydrogen-bonded complexes (2-acrylamido-2-methyl-... 

Other examples of different polymer systems referring to hydrogels [226] and dendrimers have been described [227], relying mainly on unspecific, but multiple side-chain oriented hydrogen bonds. 

Sophisticated experimental methods allow the development of models for polymers in dilute and semi-dilute solutions. Chain stiffness may be represented by the Kuhn segment lengths and determined in dilute solution. Models for cellulose and cellulose derivatives have recently been published whose main features are the irreversible aggregation of chains, if hydrogen bonding is possible even in dilute solutions. Trisubstituted cellulose derivatives or cellulose in hydrogen bond breaking solvents exist as molecular dispersed chains. How-... 

IV. Hydrogen-Bonded, Supramolecular Polymers in Isotropic Solution A. Main-Chain Polymers... 

The same design principles used to describe hydrogen-bonded, liquid-crystalline polymers, may also be used to classify hydrogen-bonded polymers in isotropic solution. The first examples described herein are main-chain polymers constructed from ditopic monomers (Figure 7). 

Soluble supramolecular polymers have been prepared based on hydrogen bonding [19,20], and they are largely classified into main-chain polymers [8,75] and side-chain (liquid-crystalline) polymers [76]. In this section, we focus on the soluble mesoscopic assemblies in organic media, which display directed molecular organization through solvophobic interactions. 

It is interesting to note that the conversion of electronic to vibrational energy results in scission of the more stable pendant C—H bond rather than the main chain C—C bond. The observed results are consistent with this process because of the glassy nature of the polymer at room temperature. Almost certainly the main-chain bonds break and make . This proposal is supported by the observation that p-halogenated polystyrenes yield the halogen hydride, hydrogen and a cross-linked polymer on photolysis. 

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