Polymer/salt hybrids

VIII. Polymer/Salt Hybrid Including Boron-Stabilized Imidoanion 190... 

VIII. POLYMER/SALT HYBRID INCLUDING BORON-STABILIZED IMIDOANION 190... 

To improve the lithium transference number, a typical approach has been the preparation of a polymer/salt hybrid,8 17 in which an ionic group is immobilized in... 

As described in previous sections (Sections VI and VII), macromolecular design of polymer/salt hybrids with a highly dissociable lithium borate unit proved to be a valuable approach for single-ion conductive polymers. To further improve the degree of lithium salt dissociation, we have designed a polymer/salt hybrid bearing the boron-stabilized imidoanion (BSI)38 (Fig. 10). 

The ionic conductivity of these polymer/salt hybrids was evaluated after the polymers were thoroughly dried under vacuum (Fig. 12a). These polymers showed... 

Figure 12 (a) Temperature dependence of ionic conductivity, (b) VFT plots for polymer/salt hybrids 10. 

Table 6 Glass Transition Temperature, Ionic Conductivity and VFT Parameters For Polymer/Salt Hybrids 10...

Ambient temperature molten salt can be obtained by several methods. One effective way to obtain a room-temperature molten salt is by the introduction of polyether chains to ions. The term polyether/salt hybrid is used in this chapter as a common name for polyether oligomers having anionic or cationic charge(s) on the chain (Figure 22.1). Polyethers, such as poly-(ethylene oxide) (PEO), are known as representative ion conductive polymers [1]. Polyether/salt hybrids have been studied as a kind of room-temperature molten salt apart from the development of onium-type ionic liquids [2]. The preparation of ionic liquids consisting of metal ions has been one of the important goals in this research field. Polyether/salt hybrid derivatives give one such solution for this task. 

On the other hand, we have reported the preparation of gel-type polymer electrolytes using polyether/salt hybrid oligomers [12]. A network-type PPO film was swollen with the PPO/triiluoromethylsulfonamide Uthium salt hybrid. The obtained gel containing 50 wt% of PPO/salt hybrid showed a low Tg of —62°C. The PPO/salt hybrid behaved as not only an added salt but also a plasticizer. The ionic conductivity was over 10 S cm at room temperature. Furthermore this gel electrolyte showed a favorable lithium-ion transference number of 0.7-0.8. 

Similarly, using the same particles as those used for the synthesis of CdS QDs (see Sect. 6.2, Fig. 36), silver nanoparticles could be deposited onto carboxylated poly(MMA-co-MAA) particles using silver salts as precursors [315, 316]. As for the case of CdS, periodic structures of polymer/silver hybrid colloids were elaborated. The method obviously opens a new avenue for production of optically responsive materials with a controlled periodicity. In another work using commercial llOnm carboxylate-functionalized PS particles as templates, Hao et al. reported the synthesis of silver nanodisks formed through chemical reduction of silver salts in DMF [332]. The composite particles obtained (Fig. 39) exhibited an intense electronic spectrum differing markedly from those of spheres. Still using... 

Most eukaryotic mRNA molecules have up to 250 adenine bases at their 3 end. These poly (A) tails can be used in the affinity chromatographic purification of mRNA from a total cellular RNA extract. Under high salt conditions, poly (A) will hybridize to oligo-dT-cellulose or poly(U)-sepharose. These materials are polymers of 10 to 20 deoxythymidine or uridine nucleotides covalently bound to a carbohydrate support. They bind mRNA containing poly (A) tails as short as 20 residues. rRNA and tRNA do not possess poly (A) sequences and will not bind. After washing the mRNA can be eluted with a low salt buffer. 

The reaction of epoxides with C02 affords either CCs or polymers [119], and many reports have been made [120-125] and different active catalysts described [126-130] such as alkyl ammonium-, phosphonium-salts and alkali metal halides, in this respect. The main drawbacks here are the need for a high catalyst concentration, a high pressure (5 MPa of C02), and a temperature ranging from 370 to 400 K. The recovery of the catalysts for reuse is also a key issue, and in order to simplify the recovery process various hybrid systems have been developed, an example being that prepared by coupling 3-(triethoxysilyl)propyltriphenylphosphonium bromide with mesoporous silica [131]. In this case, the reaction was carried out in the absence of solvent, under very mild conditions (1 MPa, 263 K, 1 mol% loading of catalyst, 6h), such that the hybrid catalyst could be recovered and recycled several times. 

This section describes systems which are at the border of what has been defined as being the scope of this review and therefore does not pretend to be comprehensive. Indeed, if there is a wealth of strictly inorganic materials and glasses into which NIR-crnitting lanthanide ions have been incorporated and which are clearly excluded from the review, there also exist a continuum between these materials and molecular entities, for instance coordination polymers and clusters which have been described in the two preceding sections. In continuity with these concepts are micro- and mesoporous materials into which lanthanide salts or complexes can be incorporated or attached. These are essentially zeolites and sol-gel materials, either conventional or the so-called inorganic-organic hybrids, as well as polymers. 

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