Siloxanes hydrogen bonding

By increasing the temperature of treatment, the species interacting via hydrogen bonding react via elimination of a water molecule and form a new (possibly strained) siloxane bond, according with the reaction path reported... 

An understanding of the surface chemistry of silica is required to interpret its chromatographic properties. The silica surface consists of a network of silanol groups, some of which may. be hydrogen bonded to water, and siloxane groups, as shown in Figure 4.2. A fully hydroxylat silica surface contains about 8... 

The cyclotetrasiloxane l,l,5,5-tetraphenyl-3,3,7,7-tetrahydroxycy-clotetrasiloxane forms a stable complex with two pyridine molecules trans to each other across the siloxane ring (316). The adduct may be prepared by the addition of an excess of pyridine to the free silanol the isomeric silanol [Ph(OH)SiO]4 does not form an adduct with pyridine (317). As well as hydrogen-bonding to the pyridine molecules, each of the two crystallographically independent molecules in the unit cell hydrogen-bonds to others of the same type to form two independent infinite chains (Fig. 24). Branching to form sheets by joining the chains, as in [But(0H)2Si]20, is partially blocked by the interactions with the... 

Consider the effects of the N-R group on the structure and reactivity of polysilazanes as susceptible to hydrogen bonding effects. These effects alone should favor ring closure over the respective siloxane analogs. Moreover, for R = H, a new type of depolymerization reaction, analogous to reaction (4), is available as illustrated in reaction (35). Thus, reaction (35) could also contribute to the... 

Fig. 10.2 (A) Cross-section SEM micrograph of the hybrid membrane containing the receptor 1, (B) membrane transport concentration profiles and (C) molecular recognition principles of acidic I and zwitterionic II L-phenylalanine in the heteropoly-siloxane material membrane (1-hydrogen bonding, 2-charge interaction, 3-Van der Waals forces) [29].

J. H. K. K. Hirschbeig, F. H. Beijer, H. A. van Aert, P. C. M. M. Magusin, R. P. Sijbesma, E. W. Meijer, Supramolecular polymers from linear telechelic siloxanes with quadruple hydrogen bonded units , Macromolecules 1999, 32, 2696-2705. 

The self-organization of polysilanols in the presence of other hydrogen bond acceptors has been studied by several groups.512-516 Several other publications have dealt with the stepwise synthesis of siloxane and siloxanol chains.450,517-522 Recent work on fully condensed siloxane rings and silsesquioxane cages involves the non-aqueous hydrolysis of chlorosilanes - as well as mechanistic and structural studies. 

Since adsorption at a mineral surface is a replacement process, we would expect mineral surfaces with weak affinity for water to have the strongest affinity for hydrophobic solutes. Infrared spectroscopy shows that siloxane surfaces on clays with little isomorphic substitution form weaker hydrogen bonds than water forms with itself (64), which corresponds to one of the definitions of a hydrophobic surface offered by Texter et al. (65) Therefore,... 

Hirschberg JHKK, Beijer FH, van Aert HA, Magusin PCMM, Sijbesma RP, Meijer EW. Suptamolecular polymers from linear telechelic siloxanes with quadniple-hydrogen-bonded units. Macromolecules 1999 32 2696-2705. 

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